R&D Progress of and Feasibility
Study Report on Mercury-free
Catalyst in China
Foreign Economic Cooperation Office, Ministry of
Environmental Protection of the People’s Republic of
China
December, 2011
Contents
1. DEVELOPMENT OF PVC INDUSTRY AND MERCURY USAGE IN CHINA....................... 1
1.1 DEVELOPMENT OF PVC INDUSTRY IN CHINA ........................................................................ 1
1.2 STATUS QUO OF MERCURY USE IN CALCIUM CARBIDE PROCESS-BASED PVC INDUSTRY .......... 8
2. PROGRESS OF MERCURY POLLUTION PREVENTION AND CONTROL IN THE
CALCIUM CARBIDE PROCESS-BASED POLYVINYL CHLORIDE INDUSTRY .................... 9
2.1 UNDER GUIDANCE OF INDUSTRIAL POLICIES, BOOSTING THE MERCURY POLLUTION PREVENTION
AND CONTROL ..........................................................................................................................
9
2.2 SPEED UP THE TECHNOLOGICAL INNOVATION, PROMOTING THE MERCURY CONSUMPTION
REDUCTION OF THE INDUSTRY BY NEW TECHNOLOGY ................................................................
12
3. IMPORTANCE AND URGENCY OF THE R&D OF THE MERCURY-FREE CATALYST .. 15
4. R & D DEVELOPMENT OF MERCURY-FREE CATALYST AT HOME AND ABROAD .... 18
4.1 FOREIGN MERCURY-FREE CATALYST RESEARCH SITUATION ................................................. 18
4.2 MERCURY-FREE CATALYST RESEARCH SITUATION OF CHINA ................................................ 20
4.3 PROBLEMS IN R & D PROCESS .......................................................................................... 25
5. FEASIBILITY ANALYSIS AND TECHNICAL & ECONOMIC PROSPECTS OF
MERCURY-FREE CATALYST ................................................................................................. 28
5.1 TECHNICAL FEASIBILITY ASSESSMENT ................................................................................ 28
5.2 ANALYSIS ON TECHNICAL AND ECONOMIC PROSPECTS......................................................... 30
6. KEY AREA OF FUTURE WORK ........................................................................................ 33
6.1 CONTINUOUSLY STRENGTHENING THE APPLICATION AND PROMOTION OF THE MERCURY
POLLUTION PREVENTION AND CONTROL TECHNOLOGY ..............................................................
33
6.2 PROMOTING THE DEVELOPMENT AND INTRODUCTION OF RELEVANT POLICIES, REGULATIONS AND
STANDARDS
........................................................................................................................... 34
6.3 STRENGTHENING THE RESEARCH AND DEVELOPMENT OF THE MERCURY-FREE CATALYST ...... 35
6.4 STRIVING FOR FINANCIAL SUPPORTS FROM MULTIPLE CHANNELS ......................................... 36
1. Development of PVC Industry and Mercury Usage in
China
1.1 Development of PVC Industry in China
1.1.1 Overview of China’s PVC Industry
Polyvinyl chloride (PVC) is not only one of the five general synthetic
resins, but also a pillar product for the sustainable development of
the chlor-alkali industry. With a chlorine consumption proportion of
more than 30%, PVC is an important staple organochlorine product.
PVC is a kind of thermoplastic synthetic resin developed early in
China. Currently, according to different sources of raw materials and
routes of production processes, domestic PVCs can be roughly
divided into two sorts – calcium carbide process-based PVC and
ethylene process-based PVC. The ethylene process route covers
the production of 1,2-dichloroethane (EDC) through ethylene
oxychlorination with petroleum ethylene as its raw material, the
polymerization of PVC through ethylene dichloride (EDC) pyrolysis
to vinyl chloride monomer (VCM), and PVC production through
import of a small amount of 1,2-dichloroethane and VCM.
Since its inception, the PVC industry has played a vital role in
construction of China’s national economy, thus the development of
the PVC industry is closely associated with that of the national
economy. In the 21st century, the continuous growth of national
economy has stimulated the demand of chemical and building
material industries, offering a broad space for the development of
domestic PVC industry. Promoted by multiple favorable factors, the
overall scale and strength of the industry have been growing in
recent years. Since 2003, China’s PVC industry has entered the
ascending channel, and its scale has maintained an average annual
growth rate of over 10%. At present, China has steadily occupied the
first place among the PVC producers across the world.
Statistics by China Chlor-Alkali Industry Association show that by the
end of December 2010, China had 94 PVC manufacturing
enterprises, with a total capacity of 20.427 million tons per year. The
PVC production capacity was mainly distributed in Shandong, Inner
Mongolia, Henan, Tianjin and Xinjiang, and there were seven
provinces and autonomous regions where the PVC capacity
exceeded 1 megaton. In 2010, the number of enterprises with a PVC
1
capacity of at least 400,000 tons per year increased to 17, and their
gross capacity accounted for 45.8% of the total. China’s PVC
industry is moving in the large-scale direction.
>200 万吨
100-200 万吨
50-100 万吨
<50 万吨
> 2 million tons
1-2 million tons
0.5-1 million tons
< 0.5 million tons
Figure 1: Distribution of PVC Capacity in China
With regard to output, China’s PVC output has witnessed an evident
increase in the 21st century, and particularly in 2005, stimulated by
many positive factors, such as the fast expansion of domestic
capacity and rapid increase in downstream demand, the PVC output
increased by 33.15%. From 2006, the annual output increase slowed
down due to the large scale base of plants of domestic PVC industry
and the declining growth rate of downstream industry demand. From
the second half of 2008, the global financial crisis resulted in the
contraction in demand of domestic PVC industry, production
restriction and negative output growth for the first time. After that,
along with the recovery and development of the national economy,
China’s PVC output was somewhat restored and has reached 11.3
million tons by the end of 2010. (See Figure 2)
2
1200
40
1000
35
33.15
32.04
30
23.4
25.58
22.84
800
20.08
17.77 18.34
25
20
18.1
15
600
10
3.85
400
5
0
-5
200
-9.26
0
-10
-15
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
PVC产量
年增长率%
PVC 产量
年增长率
PVC output
Annual growth rate
Figure 2: Variation Trend of PVC Output in China (2000-2010) (Unit: 10,000
tons, %)
With years of rapid development, the evolvement of domestic PVC
industry and the entire chlor-alkali industry has taken on some new
characteristics and trends:
(1) The focus of large-scale and resource-oriented production is
shifted westward
As of the end of 2010, the average production capacity of domestic
PVC enterprises had already topped 200,000 tons per year,
indicating a significant increase compared with less than 50,000 tons
per year at the turn of the century. Especially over the last few years,
relying on their resource superiority, such as abundant coal and
electricity, the vast central and western regions have newly
constructed a batch of large-sized supporting chlor-alkali projects of
“PVC + Caustic Soda” with a capacity of above 300,000 tons per
year, enormously enhancing the scale and strength of the chlor-alkali
industry in those regions.
3
(2) The proportion of calcium carbide process-based PVC is
growing
In the past few years, in response to the rising energy cost all over
the world and taking advantage of abundant coal and electricity, the
central and western regions have launched a group of large-scale
calcium carbide process-based PVC supporting projects with a
capacity of above 300,000 tons per year. This has, to a certain
extent, further promoted the overall scale of domestic production
plants for calcium carbide process. Statistics reveal that by the end
of 2010, the scale of calcium carbide process-based PVC plants had
made up 80.9% of gross domestic capacity.
90, 5%
53, 3%
47.5, 3%
628.2, 38%
182, 11%
223, 14%
428, 26%
西北*
华北
华中
西南
华东
东北
华南
Northwest China
西北
North China
华北
Central China
华中
Southwest China
西南
East China
华东
Northeast China
东北
South China
华南
Figure 3: Distribution of Calcium Carbide Process-based PVC Capacity (2010),
(Unit: 10,000 tons/year, %)
*Note: As most of the PVC production plants in Inner Mongolia are located in the northwest
regions neighboring Ningxia, Shaanxi, etc., the PVC plant capacity in Inner Mongolia is hereby
incorporated into that of Northwest China.
(3)
The
product
quality
is
4
constantly
improved
and
differentiation development is formed
In the past few years, thanks to the technical progress made in
calcium carbide process-based PVC process, especially the
successful development and application of such technologies as
automatic control, large polymerizer and its supporting steam
stripping, drying and VCM refining, the quality of calcium carbide
process-based PVC has basically met the requirements on ethylene
process-based PVC. Seen from the greater development
environment, the market demand for high-quality PVC is on the rise.
China’s PVC growth model will turn from simple throughput increase
to market segmentation and domination through multiple varieties
and brands. With the aggravating competition in PVC market, the
customer demand-centered development pattern which subdivides
product categories and adheres to resin specialization and high-end
tendency of products will be much clearer.
(4) The circular economy and cleaner production are vigorously
promoted
Technically, in order to improve the production capacity of single
kettle plants, enterprises have begun to adopt large-scale
polymerizers of more than 100 cubic meters and the complete
technique thereof, in addition to polymerizers of 70 cubic meters and
the complete technique thereof in general use. Moreover, as to
technical solutions, the employment of advanced formula technology,
hermetic feed technology, anti-sticking technology, new steam
stripping technology, new drying technology, DCS control technology
and the like, has advanced the self-control level and efficiency of
production plants, improved product quality and reduced the
consumption of energy and raw and auxiliary materials by a big
margin. For environmental protection, the technologies developed
include the “hydrochloric acid desorption” to recycle and synthetize
excessive HCl for cyclic utilization; “ultrafiltration membrane +
reverse osmosis membrane” and biomembrance process to treat
centrifugal mother liquid, and “pressure swing adsorption (PSA)
(automated program control)” to recover vinyl chloride, acetylene
and hydrogen in rectified tail gas.
1.1.2 Development background and importance analysis of calcium
carbide process-based PVC industry
Currently, except for a very small number of calcium carbide
process-based PVC plants in India and other places, the majority of
5
global calcium carbide process-based PVC production plants are
located in China.
Adoption of such a characteristic development model different from
the PVC industry in other countries and regions rests primarily on the
following three reasons:
(1) China’s energy structure is featured by "oil and gas shortage,
yet abundant coal"
The conflict between scarce oil and gas resources and huge market
demand has hindered the healthy development of China’s national
economy in recent years too significantly to be ignored. According to
preliminary estimates, if all the existing PVC plants at home use
ethylene process instead, the annual crude oil consumption of China
will increase by about 80 million tons, equivalent to more than 30%
of the total crude oil imports in 2010. It is undoubtedly a heavy
burden for its weak energy supply capacity.
As domestic and international oil and gas resource prices have
mounted up in recent years, the cost of ethylene process-based
PVC production process remains high. Against such backdrop,
domestic ethylene process-based PVC manufacturers are hardly
able to compete with the international giants advantageous in scale
and technologies. Meanwhile, relatively abundant domestic coal
reserves provide an alternative path for the survival and
development of Chinese PVC industry.
Calcium carbide process-based PVC production process with coal
as the primary raw material enormously reduces the production
costs of China’s PVC industry and gives full play to the comparative
advantages of domestic industry. As a result, the domestic PVC
industry has made a qualitative leap on the scale and strength.
Meanwhile, in the context of increasingly complex friction of interests
in the international energy market in the 21st century, reducing
consumption of oil and gas resources and dependence on imported
energy sources is also in accord with the national interests of
safeguarding Chinese energy security.
(2) It is difficult for ethylene process route to fully meet the
demand of comprehensive and healthy development of
domestic PVC industry
Ethylene process-based PVC production route requires the
6
manufacturers having access to large-scale ethylene plants capable
of ethylene supply for PVC production, or settling down in areas
adjacent to the ports to facilitate the import of vinyl raw materials
(such as ethylene, EDC or VCM) from overseas. Such limitation has
led to the present concentration of ethylene process-based PVC
production plants in the eastern coastal areas, making it difficult to
extend to inland and to the less developed western regions, and raw
materials heavily dependent on the import market. For this reason,
the balanced and coordinated development of the whole industry is
hardly achieved by relying solely on the development of ethylene
process-based PVC production route.
In a sense, calcium carbide process-based PVC manufacturers that
take off and grow quickly by virtue of profuse coal resources in
central and western regions represent the new development
direction of PVC industry in China. Furthermore, to a large extent,
they turn around the unfavorable situation of the raw material costs
of domestic PVC industry, but also drive the nationwide coordinated
layout of the PVC industry and boost the economic development in
central and western regions.
(3) Calcium carbide process-based PVC industry has stepped in
a virtuous path
With the recent advances in industrial technologies at home and
abroad, the technical problems in calcium carbide process-based
PVC production have been resolved successively, while enterprises
have made considerable progress in product quality, pollution control,
etc. Centering on the industrial chain characteristics of calcium
carbide process route, some of the major domestic calcium carbide
process-based PVC manufacturers vigorously carry out circular
economic development strategy, and make the industrial chain
taking calcium carbide process-based PVC as core bigger and
stronger, in a bid to build up a large-scale industrial cluster with
"coal-power-salt" integration. Calcium carbide process-based PVC
production route has arisen as an optimal solution to the
development of a considerable number of domestic chlor-alkali
chemical enterprises, notably in central and western regions.
From an overall perspective, the development of calcium carbide
process-based PVC industry is in line with the status of domestic
energy structure and even the objective requirements of domestic
PVC industry and even the whole chlor-alkali industry. Healthy and
7
rapid growth of Chinese characteristic calcium carbide
process-based PVC industry not only lays a foundation for the
great-leap-forward development of China’s chlor-alkali industry in
the past five or six years, but also will serve as the backbone in the
future to enhance the international competitiveness of China’s PVC
industry and the whole chlor-alkali industry .
1.2 Status quo of mercury use in calcium carbide
process-based PVC industry
Catalyst used in the synthesis of vinyl chloride in calcium carbide
process-based PVC production takes activated carbon as the carrier
and is prepared by impregnated adsorption of 10-12% mercuric
chloride. It does not participate in reactions, but its activity may
weaken due to mercury sublimation and catalyst poisoning. If down
to a certain extent, catalyst shall be replaced and deactivated
mercury catalyst will turn into waste mercury catalyst. Mercuric
chloride is used as catalyst in almost all current domestic calcium
carbide process-based PVC production. Given a mercuric chloride
catalyst consumption of 1.2 kg per ton of PVC produced (mercuric
chloride takes up about 11% of the high-mercury catalyst), China’s
PVC output through calcium carbide process is estimated to reach 8
million tons in 2010, and therefore mercury catalyst and mercury
used in the industry amount to about 9,600 tons and 781 tons
respectively. As far as the current situation is concerned, in the rapid
development process of chlor-alkali industry in China, calcium
carbide process-based PVC industry has become one of the major
domestic consumers of mercury.
Mercury is a kind of scarce resource and heavy metal highly
sensitive to environment, and its supply shows a decreasing trend.
Use of and dependence on mercury resources in calcium carbide
process-based PVC production have emerged as an important issue
for development and survival of China’s calcium carbide
process-based PVC industry. How to reduce excessive reliance on
mercury resources is an urgent task related to the development, but
also the key to sustain the development of China’s calcium carbide
process-based PVC industry.
8
2. Progress of Mercury Pollution Prevention and
Control in the Calcium Carbide Process-Based
Polyvinyl Chloride Industry
On December 28, 2009, the State Council approved the Guidelines
for Strengthening the Prevention and Control of Heavy Metal
Pollution (GBF [2009] No. 61) (hereinafter referred to as "Guidelines")
from the Ministry of Environmental Protection, the National
Development and Reform Commission, the Ministry of Industry and
Information Technology and other five ministries, regulating a series
of deployments for strengthening the prevention and control of heavy
metal pollution. The relevant departments developed the heavy
metal pollution prevention plan, and listed the heavy metal-related
chemical industry as one of the key industries on which pollution
prevention and control is conducted.
Since then, with a view to implementing the requirements of the
"Guidelines" of the State Council, enhancing the understanding of
the enterprises and relevant departments over the importance and
urgency of strengthening the mercury pollution prevention and
control, and speeding up the promotion of low-mercury catalyst and
the research and development of mercury-free catalyst, the relevant
state ministries and commissions have released the industrial
policies one by one, guiding the promotion and implementation of
industrial mercury pollution prevention and control work at the policy
level. Meanwhile, co-organized and driven by China Petroleum and
Chemical Industry Association and China Chlor-Alkali Industry
Association, numerous domestic calcium carbide process-based
polyvinyl chloride manufacturers, catalyst manufacturers, research
institutes and others have conducted a lot of meaningful trials and
exploration on the mercury pollution prevention and control, and the
domestic industries have made some achievements on the mercury
pollution prevention and control.
2.1 Under guidance of industrial policies, boosting the
mercury pollution prevention and control
Under the increasingly serious mercury pollution prevention and
control situation in the calcium carbide process-based polyvinyl
chloride industry, the relevant state ministries and commissions
attached great importance to guiding and promoting the reduction of
mercury emission of the industry at the policy level. Following the
issuance of the Circular on Guidelines for Strengthening the
9
Prevention and Control of Heavy Metal Pollution (Guo Ban Fa [2009]
No. 61) by the General Office of the State Council on December 28,
2009, such policies and measures as Guidelines for Strengthening
the Prevention and Control of Mercury Pollution of the Polyvinyl
Chloride Industry, Implementation Program for Cleaner Production
Technology of the Polyvinyl Chloride Industry and Circular on
Strengthening the Mercury Pollution Prevention and Control in the
Calcium Carbide Process-based Polyvinyl Chloride and Related
Industries (Huan Fa [2011] No.4) were issued successively,
reflecting the principal idea of “mercury minimization and elimination”
for the prevention and control of mercury pollution of the calcium
carbide process-based polyvinyl chloride industry.
Judging from the national industrial policy and facing the important
international responsibilities and obligations undertaken by China,
China shows its determination and positive efforts on the heavy
metal pollution prevention and control. Under such circumstances,
the application of advanced technology for reducing mercury
consumption of the calcium carbide process-based polyvinyl chloride
industry, and the promotion of the scientific & technical
breakthroughs on mercury-free catalyst technology have become
the key contents of the mercury pollution prevention and control of
the industry actively guided by the state.
The industry association sets foot in the actual production situation
of the calcium carbide process-based polyvinyl chloride industry,
actively plays a role of bridge and tie, studies and develops the
admittance conditions for the low-mercury catalyst manufacturers
and waste mercury catalyst recycling enterprises. According to the
mercury pollution prevention thought of "accelerating the elimination
of high-mercury catalyst, realizing the moderate development of
low-mercury catalyst, and speeding up the promotion of
mercury-free catalyst", the relevant industrial policies on mercury
catalyst in the calcium carbide process-based polyvinyl chloride
industry have been studied, and the corresponding elimination and
support policies have been perfected. Meanwhile, relevant
government departments should be coordinated to issue the industry
measures, economic policies and others that encourage enterprises
to adopt low-mercury catalyst, and such economic policies and
measures as reduction of product tax and reduction of sewage
charges of enterprises are proposed for encouragement. At the
same time, the distribution principles and conditions for mercury
catalyst production and waste mercury catalyst recycling should be
10
developed, so as to link with the layout of calcium carbide
process-based polyvinyl chloride manufacturers, thus narrowing the
transport radius of mercury-containing wastes.
In addition, to further improve the organization and management
capabilities in respect of the mercury pollution prevention and control
of the industry, China Petroleum and Chemical Industry Association
and China Chlor-Alkali Industry Association jointly organized and
founded a leading group and a expert group for mercury pollution
prevention and control, wherein the former is composed of leaders of
China Petrochemical and Chemical Industry Association, China
Chlor-Alkali Industry Association, the Ministry of Environmental
Protection, the Ministry of Industry and Information Technology,
China National Petroleum & Chemical Planning Institute and other
relevant departments, and the experts of key enterprises and
research institutes, and the latter is responsible for directing the
mercury pollution prevention and control and making the relevant
decisions. Under the circumstances that the objectives, direction and
implementation methods of mercury pollution prevention and control
of China and the mercury minimization and elimination working
direction, it needs to vigorously promote the promotion and
application of low-mercury catalyst as well as speed up the
development and application of mercury-free catalyst, and other new
environmentally friendly catalysts, so as to make major
breakthroughs as early as possible, thus fundamentally solving the
mercury pollution problems, and ensuring the long-term
sustainability of calcium carbide process-based polyvinyl chloride.
According to current development of the industry and the application
status of mercury catalyst, the calcium carbide process-based
polyvinyl chloride industry of China has developed a preliminary
route for the mercury reduction. (see Table 1)
Table 1: Route for Mercury Reduction of China
Time
First stage
Second stage
Promotion of
low-mercury
catalyst
Stage of promoting
low-mercury catalyst
and reducing
mercury consumption
Complete
replacement of
high-mercury
catalyst by
low-mercury
catalyst
11
Third stage
Research
and
Industrial test of
development,
fixed-mercury
promotion of
catalyst
fixed-mercury
catalyst
Research,
development
Basic research and
and
development stage of
promotion of
mercury-free catalyst
mercury-free
catalyst
Stage of promoting
fixed-mercury
catalyst and
reducing mercury
consumption
Pilot plant test and
industrial test of
mercury-free
catalyst
Stage of
promoting
mercury-free
catalyst and
eliminating
mercury
In accordance with the route for reduction of mercury emission of
China, the first stage focuses on mercury consumption reduction,
emphasizes the promotion of low-mercury catalyst and promotes the
industrial test of fixed-mercury catalyst and the basic research and
development of mercury-free catalyst, with the aim of popularizing
low-mercury catalyst in the entire industry by the end of 2015, so as
to significantly reduce the mercury consumption; the second phase
focuses on the promotion and application of fixed-mercury catalyst
for further reducing the low-mercury catalyst consumption and
promotes the pilot plant test and industrial test of mercury-free
catalyst; and the third stage focuses on full promotion and
application of mercury-free catalyst, until then, the industry will enter
the mercury-free stage.
2.2 Speed up the technological innovation, promoting the
mercury consumption reduction of the industry by new
technology
The mercury in the calcium carbide process-based polyvinyl chloride
production process mainly goes into the waste mercury catalyst,
waste activated carbon with mercury, waste hydrochloric acid with
mercury, and waste alkali and so on. For the rather severe mercury
pollution prevention and control situation of China’s calcium carbide
process-based polyvinyl chloride production, and with the great
importance of the government, the active publication of associations
and the gradual promotion of enterprises, the mercury pollution
prevention and control work of China is moving forward steadily. As
the most direct way to reduce the mercury usage amount of China’s
calcium carbide process-based polyvinyl chloride industry, the
reduction of the usage amount of mercuric chloride catalyst and the
replacement of existing high-mercury catalyst by low-mercury
catalyst or even the mercury-free catalyst can radically reduce the
12
usage amount of mercury in manufacturing enterprises, thus having
become the main direction of China’s industry.
As the most direct way to reduce the mercury usage amount of the
calcium carbide process-based polyvinyl chloride industry, the wide
promotion of the low-mercury catalyst in the industry is of great
significance. The low-mercury catalyst has the use performance
equal to even better than that of the high-mercury catalyst, the
activated carbon is adopted for absorbing the lost mercury in the
calcium carbide process-based polyvinyl chloride production
process and the activated carbon with mercury and the waste
mercury catalyst used are recycled and reused by the qualified
manufacturers. Therefore, the low-mercury catalyst significantly
reduces the consumption and emissions of mercury. According to
preliminary estimates, if all calcium carbide process-based polyvinyl
chloride production plants of China apply the low-mercury catalyst
rather than the high-mercury catalyst, and the cleaner production
technology aiming at mercury pollution prevention and control is
applied, 70 percent of the mercury usage amount will be reduced.
However, at present, enterprises of the calcium carbide
process-based polyvinyl chloride industry have encountered many
difficulties and problems in the promotion and application of the
low-mercury catalyst. From the equipment and technology, the use
of low-mercury catalyst has raised higher requirements on the
process control level of enterprises, and at present, a large number
of calcium carbide process-based polyvinyl chloride manufacturers
of China have great differences in equipment strength and technical
level, restricting the use effect of the low-mercury catalyst to some
extent.
On the other hand, seen from the supply of low-mercury catalyst,
since the use of low-mercury catalyst has been promoted in the
calcium carbide process-based polyvinyl chloride industry of China,
the mercury catalyst manufacturers have launched their own
low-mercury catalysts, and the product quality, the market
competition and other factors have restricted the promotion and
application of the low-mercury catalyst in the industry to some extent.
Industrial Standard on Low-mercury Catalyst for Vinyl Chloride
Synthesis has been released on June 15, 2011, which can effectively
guide the low-mercury catalyst industry and regulate the product
quality, while helping to supervise and urge the catalyst
manufacturers to improve the production technology and product
13
quality of the low-mercury catalyst, thus laying a solid foundation for
further application and promotion of the low-mercury catalyst in the
industry.
With the high attention and substantial support of the state and the
active efforts of the industry, the mercury pollution prevention and
control in the calcium carbide process-based polyvinyl chloride
industry of China is moving forward steadily and has achieved
gratifying results. By the promotion of low-mercury catalyst and the
R&D and application of a series of technologies such as hydrochloric
depth desorption, mercuric chloride processing with sodium
hydrosulfide and waste catalyst recovery by distillation method, the
mercury pollution prevention and control has achieved initial results
on the reduction of the mercury usage amount and the improvement
of the mercury recovery efficiency. Correspondingly, while actively
conducting the mercury pollution prevention and control, the
enterprises of the industry have put a lot of human, material and
financial resources into the research and development and
promotion of advanced technologies, and the improvement and
upgrade of equipment, which objectively increased the economic
pressure of the enterprises of the industry.
In accordance with the route for the reduction of mercury emission,
the use and popularity of low-mercury catalyst is a transitional stage
for the development of the polyvinyl chloride industry of China, which
will eventually accelerate the thorough and irreversible
transformation from the low-mercury catalyst to mercury-free
catalyst. At present, China is still in the basic research and
development stage of mercury-free catalyst, and with the technical
breakthroughs of research institutions and manufacturers of China,
the initial progress has been made in the fields relevant to the
research and development of mercury-free catalyst; however, the
industrial application even the universal application in the industry
are some way off.
14
3. Importance and Urgency of the R&D of the
Mercury-free Catalyst
As mentioned earlier, almost all manufacturers of China apply the
mercuric chloride catalyst for the production of calcium carbide
process-based polyvinyl chloride. Mercury, as a scarce resource and
a heavy metal highly sensitive to the environment, has been
increasingly exhausted and its supply has been decreasing year by
year. The mercury pollution is getting worse. Therefore, the limit on
the mercury emissions and use has become a global trend. China is
a major mercury consumer and producer, and is involved into all the
seven priorities relevant to mercury, and China is also the major
exporter of mercury-containing products. Currently, with the
increasing appeal for the legally binding international instrument
internationally, China will be subjected to the reduction of mercury
supply and demand in the future, and the waste mercury disposal in
the export trade, it’s safe to say, fundamentally eliminating use of
mercuric chloride catalyst in the calcium carbide process-based
polyvinyl chloride industry and the R&D of the mercury-free catalyst
have become the important aspects for the development of calcium
carbide process-based polyvinyl chloride industry of China.
The necessity and importance for the R & D of the mercury-free
catalyst is mainly reflected in the following areas:
(1) Shortage of mercury resource at home and abroad
In recent 20 years, the development of the polyvinyl chloride industry
and the battery industry of China has accelerated the consumption
of mercury, and the mercury resource in China has basically dried up.
According to the data of Ministry of Land and Resources, China now
only has about 11,000 tons of mercury reserves, excluding the
reserves of strategic resources and the reserves that cannot be
developed or used, and the volume of remaining reserves available
is still unclear. As the amount of available mercury is relatively small,
the current price of mercury has reached RMB 320,000 Yuan/ton,
which was more than double of the price at the beginning of 2010 of
RMB 140,000 Yuan/ton. Meanwhile, the price of mercury catalyst
has risen from RMB 2,600 Yuan/ton at the beginning of the year to
RMB 70,000 Yuan/ton at present. As the European Union has
completely forbidden the mercury exports since July 2011 and
closed major mercury mines, the severe shortage of mercury
resource will seriously affect the survival of the mercury-consuming
15
industries.
(2) Pressure on the reduction of mercury emission from the
international community
The core of discussion on the mercury-related problems by the
international community is to restrict and then eventually eliminate
the use and exploitation of mercury, and to strictly manage the
mercury pollution from a variety of sources and causes; for the
export of mercury-containing products, some countries have raised
the recall mechanism for the mercury-containing products exported.
China is a major mercury consumer, China's total demand for
mercury has occupied more than half of global mercury demand,
ranking the first in the world. And the mercury consumption in the
production of calcium carbide process-based polyvinyl chloride has
accounted for 60% of total mercury consumption of China, which
determines that the acetylene process-based polyvinyl chloride will
be the most important area for the international mercury convention
performance in the future. Under the constraints of the international
mercury convention, the calcium carbide process-based polyvinyl
chloride industry will face the great pressure from no available
mercury resources.
(3) Impact of domestic policies
To strengthen the heavy metal pollution prevention and control of
China and maintain the environmental safety, on December 28, 2009,
the State Council released the Circular of the General Office of the
State Council on the Approval and Transmission of the Guidelines
for Strengthening Prevention and Control of Heavy Metal Pollution
Submitted by the Ministry of Environmental Protection and other
Departments (GBF [2009] No. 61), providing for the objectives of and
requirements on the pollution prevention and control of key
industries. Subsequently, for the key industries of mercury pollution
prevention and control of China, calcium carbide process-based
polyvinyl chloride industry, the Ministry of Industry and Information
Technology, China Petroleum and Chemical Industry Association
and China Chlor-Alkali Industry Association, and China Chemical
Industry Environmental Protection Association jointly drafted
Guidelines for Strengthening the Prevention and Control of Mercury
Pollution in the Polyvinyl Chloride Industry, which points out that all
industries will have used low-mercury catalyst by 2015 and the
recovery rate of the waste mercury catalyst will reach 100%.
16
In February 2010, the Department of Energy Conservation and
Resources Utilization of the Ministry of Industry and Information
Technology released the Implementation Program for Cleaner
Production Technology of the Polyvinyl Chloride Industry, making
clear the working concept of “Mercury Minimization and Elimination".
After that, the Ministry of Industry and Information Technology
released the Notice on Printing and Distributing the Implementation
Program for Cleaner Production Technology of 17 Key Industries
including Polyvinyl Chloride, and the overall goal of cleaner
production for the industry has been regulated in the cleaner
production implementation program for the polyvinyl chloride
industry.
On January 19, 2011, the Ministry of Environmental Protection
released the Notice on Strengthening the Mercury Pollution
Prevention and Control in the Calcium Carbide Process-based
Polyvinyl Chloride and Related Industries (HF [2011] No.4), which
regulates that by the end of 2015, the high-mercury catalyst will have
been completely eliminated; according to the industrial needs, the
low-mercury catalyst production capacity should be expanded in a
reasonable and moderate mode, the low-mercury catalyst
production level should be perfected and raised to meet the needs of
alternative applications; and the research and development of
mercury-free catalyst should be encouraged. In addition, Guidance
Catalogue for Industry Structure Adjustment (2011) includes the
mercury-free and other new, highly efficient and environmentally
friendly catalysts and assistants, mercury recycling & treatment
technology for mercury-containing wastes, and development and
application of alternatives for mercury-containing products into the
encouragement list. Judging from the national industrial policy, the
application of advanced technology for reducing mercury
consumption of the calcium carbide process-based polyvinyl chloride
industry, and the active promotion of the scientific & technical
breakthroughs on mercury-free catalyst technology have become
the key contents of the mercury pollution prevention and control of
the industry actively guided by the state.
On the whole, under the huge impact of the severe mercury
emission reduction situation and the shortage of mercury resource at
home and abroad, the dependence on the mercury-containing
catalyst has been the bottleneck for the development of the calcium
carbide process-based polyvinyl chloride industry. The R & D of
mercury-free catalyst is the only way to solve this problem
17
fundamentally, which affects the sustainable development of the
industry and is relevant to the survival of the entire industry.
4. R & D Development of Mercury-free Catalyst at home
and abroad
The replacement of mercury-containing catalyst by new
mercury-free catalyst is the fundamental way to resolve the problem
that there is huge mercury consumption in the calcium carbide
process-based polyvinyl chloride industry of China, and has always
been the research focus of the polyvinyl chloride industry. According
to the data collected from trade journals both at home and abroad,
by the research over the catalytic activities of a variety of metal
chlorides both at home and abroad, it is found that the catalyst
efficiencies and selectivity of some metals are superior to those of
the mercuric chloride system, indicating that mercury-free catalyst
has certain potential for development, but the stability is still
unsatisfactory, and the large-scale industrialization has not been
applied at present. The researches of mercury-free catalyst at home
and abroad are divided into the solid phase catalytic system and the
liquid phase catalytic system.
4.1 Foreign mercury-free catalyst research situation
4.1.1 Solid phase mercury-free catalyst
The mercury-free catalyst research began with the solid phase
mercury-free catalyst. The solid phase catalyst dominated by
activated carbon or aluminum oxide load mercury-free metal chloride
is the direction of the early mercury-free catalyst study. Although
many scholars have researched the elements with 4d and 5d
electrons and with external electronic structures similar with mercury
in the VIII, IB, IIB groups, the different experimental conditions
resulted in that no consistent catalytic activity relationship is reached
and the capacity of catalytic activity cannot be explained.
The foreign researches in recent years have mainly focused on
some precious metal salts, such as K2PtCl6 and HAuCl4, which have
better reactivity in laboratory, but the industrial application is hard to
be realized due to high costs.
18
Aker Solutions was a European company with the patent of
acetylene-based vinyl chloride technology, who started the research
and development of mercury-free catalyst from 1995-1996.
According to the Company, in the mid-1990s, an acetylene
process-based vinyl chloride factory in the Middle East conducted
the industrial test for more than 12 months, but because the
acetylene process-based vinyl chloride production had no market
efficiency, the factory changed the process to the ethylene process.
Since 2006, Aker Solutions and Johnson Matthey have jointly
developed the mercury-free catalyst for the production of the vinyl
chloride monomer by acetylene process. The catalyst, a special
formula, is a strip cylinder with a diameter of 3 mm. It can be used in
the existing tubular reactor, without changing the production
conditions. The metal in the waste catalyst can be extracted for
preparing new catalyst. The experiments conducted by the Sonning
Common R & D Center of Johnson Matthey in the UK show that, the
mercury-free catalyst can produce the activity higher than that of the
mercury catalyst. At present, the company has started cooperation
with Chinese enterprises. In addition to the technical issues which
call for further verification, the operating cost and economy of the
company are also difficult to be determined.
4.1.2 Liquid phase mercury-free catalyst
The liquid phase catalyst is commonly known as homogeneous
complex (coordination) catalyst, and the transition metal complex
soluble in the solvent is used as the catalyst; all the reactions are
completed in the homogeneous liquid phase system at the
temperature of below 200 ℃.
In the 1980s, GJ Hutchings, inspired by the organic amine-based
alkali manufacturing mechanism in his study of solid phase
mercury-free catalyst, developed the acetylene hydrogen chloride
liquid
phase
mercury-free
catalytic
system
containing
Tri-n-butylamine-hydrochloride, isopropyl alcohol, dodecane and
chloroauric acid; however, the highest conversion rate of acetylene
was only 1.8%. In 1989, Hills AG in Germany proposed the following
information in a patent that: if the palladium compound is used as
catalyst for acetylene hydrochlorinate reaction in the aliphatic or
cycloaliphatic carboxylic acid amide, the mass fraction of active
material will be 0.1% - 1% and the conversion rate of acetylene will
be higher than 80%, but the patent hasn’t mentioned the service life
of the catalytic system. After that, all the patents of United States,
19
Japan, Italy and other countries released followed the basic principle
of GJ Hutchings, and none of them mentioned the activity life of the
catalyst and focused on the research of interaction of various
components of the catalytic system, catalytic mechanism and reason
for the inactivation of the catalyst.
The oversea mercury-free catalyst researches in recent years have
mainly focused on some precious metal salts, which are
characterized in better reactivity but poor industrial application due to
high cost.
4.2 Mercury-free catalyst research situation of China
The mercury-free catalyst research of China has begun in the 1980s.
As early as in 1973, Mr. Chen Rongti, a famous coordination chemist
of China, has accepted the research subject of vinyl chloride
mercury-free catalyst submitted by Tianjin Science and Technology
Commission and started the initial exploration over the mercury-free
catalytic system. After decades of efforts and with the close
cooperation of production enterprises and research institutes, the
active tries and exploration over different catalyst formulas, carrier
types, catalyst preparation methods, applicable reaction technology
and reactors have been made.
To actively promote the research and development of the
mercury-free catalyst and the industrial application of new
technologies, the Technology Innovation Strategic Alliance of
Calcium Carbide Process-Based Polyvinyl Chloride Mercury-Free
Catalyst Industry was set up in Xinjiang in August 2010. The
“Alliance” has China Petroleum and Chemical Industry Association
as its chairman and China Chlor-Alkali Industry Association as the
secretary-general, and was spontaneously founded by more than ten
calcium carbide process-based polyvinyl chloride manufacturers,
scientific research institutes and research institutions engaged in
R&D and promotion of mercury-free catalyst in China. The Alliance is
voluntarily organized by the China Petroleum and Chemical Industry
Association as a means to share information on R&D of
mercury-free catalyst. Sizeable enterprises on PVC production and
related institutes join the Alliance as the members. The Alliance has
been put into operation for more than one year and under the
circumstances of lacking fund support, it promotes the
breakthroughs in key technologies for R&D of mercury-free catalyst
through the regular communication among its members. The
20
establishment of the Alliance sets up the mercury-free catalyst
research and development system with the core of industrial
association and the close cooperation of industry, academic and
research institutes. The "Gas-solid-based mercury-free catalyst" and
the "gas-liquid-based mercury-free catalyst" technologies have been
defined as the key research projects of the industrial alliance.
We have conducted a survey on 4 major mercury-free catalyst
research and development enterprises and 5 research institutions of
China in this year, of which 3 PVC enterprises and 4 research
institutions have a feedback. According to relevant documents and
the results of questionnaire survey, with the continuous attempts and
exploration over the researches of the mercury-free catalyst and
supporting technologies, reactors and others by some research
institutions and calcium carbide process-based polyvinyl chloride
manufacturers of China, the research and development of the
mercury-free catalyst technology has made certain progress, some
research institutions have cooperated with the manufacturers for
planning or conducting the pilot plant test on the mercury-free
catalyst formulas and for conducting the production line test.
4.2.1 Solid phase mercury-free catalyst and progress
China has studied the solid phase mercury-free catalyst earlier with
the research direction of gas-solid reaction and focusing on
exploration of the mercury-free catalytic system with fixed-bed
reactor and fluidized-bed reactor.
On reaction technology, some research institutions conducted the
research and development of the mercury-free catalyst based on
gas-solid phase fixed-bed reaction technology. The metallic
elements of VIII, IB, IIB groups, that is, the precious metal elements
and some transition metal elements are used as the active
components of the catalyst, and the activated carbon and new
molecular sieve with specific pore structures and frameworks and
surface groups as the catalyst carrier. Meanwhile, the institutions
have tried to apply the technology to the gas-liquid bubble column
reaction technology. At the same time, some research institutes
have cooperated with the enterprises to carry out research over the
industrial pilot plant test and application of the mercury-free catalyst
circulating fluidized bed for synthesizing the calcium carbide
process-based vinyl chloride. Now, the solution for the loss of active
components of the mercury-free catalyst and the optimized formula
21
process were obtained, and the plants for bench-scale test of
industrial fluidized bed of feather weight were built for the industrial
bench-scale test of the optimized catalyst formula. The test results
show that, the catalytic system has better indicators. The next step
will be the mercury-free catalyst synthesis for kiloton polyvinyl
chloride production capacity and the evaluation of the bench-scale
test on fluidized bed.
Seen from the catalyst formula, one of the research directions is to
use the precious metal with high activity as the main active
component of the catalyst. Some research institutions selected
organic or inorganic substance as the assistant of complex agents,
which is highly dispersed on the carrier by electronic transfer and
bonding. Different metal assistants are selected depending on the
supporting synergy among metals for improving the deactivation
resistance property of the metal catalyst, reducing the usage amount
of precious metals, and facilitating the recovery of precious metal
catalysts. Now, substantial progress has been made in the research,
the equipment for pilot plant test is being built and the patents are
applied for. Another research direction is to use suitable transition
metals rather than precious metals, and to select other metal
assistants according to the mechanism of action, so as to promote
the reaction among metals, thus significantly enhancing the
performance of the active components of the catalyst.
At present, some enterprises have cooperated with research
institutions for completing the preparation and evaluation of the
precious metal and non-precious metal catalysts with the carriers of
activated carbon and porous oxide. It is understood that, the
non-precious metal catalyst with the carrier of activated carbon can
significantly improve the stability of the activated carbon carrier, but
its activity is lower than that of the activated carbon. For the precious
metal catalyst, the reactivity of activated carbon catalyst with two
active components is investigated, and the results show that the
precious metal has very good catalytic property and has relatively
high acetylene conversion rate; in the research of non-precious
metal catalyst with the carrier of porous oxide, it is found that the
self-made oxide carrier with active component has higher activity,
and the activity of precious metal catalysts is much lower than that of
the precious metal catalysts with the carrier of activated carbon and
also lower than that of the non-precious metal catalysts. In the
research of the mercury-free catalytic system, the preparation and
evaluation of the precious metal and non-precious metal catalysts
22
with the carrier of molecular sieve are made, the formula with high
activity & stability and low active component has been preliminarily
screened out, and the comparative evaluation over the carrier
modification has been completed. It hopes to eventually form an
optimized program for the mercury-free catalyst carrier processing,
preparation process and catalyst evaluation.
Based on the different active components used, some institutions
have adopted complex method, chemical plating method and other
innovative methods to form the self-assembly of the active
components of catalyst to some extent, thus ensuring the active
components properly load on the carriers of different natures,
maximizing the performance of the active components, increasing
the stability of the catalyst, and prolonging the service life of the
catalyst. At present, the supported precious metal catalyst
successfully developed by using the complex method is undergoing
the pilot plant test, and the supported transition metal catalyst
successfully developed by using the chemical plating method has its
bench-scale test completed in the laboratory.
In addition, in the research of the solid phase mercury-free catalyst,
some research institutions not only use the activated carbon as the
carrier, but also focus on the use of new molecular sieves, utilizing
the special pore structure and surface property of the new molecular
sieves to improve the performance of active components and
strengthen the stability of the catalyst. Meanwhile, the institutions
have made a lot of attempts on the regeneration and reuse of
deactivated catalyst and other post-treatments and process
conditions and have achieved some progress.
4.2.1 Liquid phase mercury-free catalyst and progress
In recent years, China began to actively carry out the liquid phase
mercury-free catalyst research. By making the most of foreign
research results, China has carried out a number of exploratory
experiments and researches.
On the liquid phase mercury-free catalytic system, a research
institution at present has designed with a new solvent which serves
as the carrier of the catalytic system; selected the non-mercury metal
ion as the catalyst, solving the mercury pollution problem; and
applied the form of gas-liquid reaction, realizing the miniaturization of
VCM reactor.
23
It is understood that, the catalyst with gas-liquid reaction is used in a
tower or tubular reactor which is characterized in that the new
solvent has good solubility property against organic and inorganic
substances, ensures the reaction occurs under the homogeneous
conditions, and reduces the equipment size. The reactor is small and
is of low investment; the new solvent has a wide operational
temperature range, good thermal stability and chemical stability. The
reactor is safe and reliable and compared with the traditional
fixed-bed reactor, the liquid phase catalytic reaction system does not
use the solid carrier, so it has great heat transfer effect, avoids the
local overheating and reduces the catalyst sublimation, thus
prolonging the service life of the catalyst, reducing the consumption,
saving the costs and realizing the environmental protection; the
catalyst production process is also environmentally-friendly, because
the system does not use the solid carrier, so no pulverization,
hardening or other problems will appear, and the synthetic VCM
process is simple. Besides, there is no pollution caused by the solid
carrier production and processing. After 720 hours of continuous
operation of the catalytic system, it is found the catalyst is free from
loss, the metal ions are free from inactivation, and the conversion
rate and the selectivity remain unchanged; the catalytic system is
free from maintenance and the production capacity is not affected. In
addition, the new solvent is environmentally friendly. The new
solvent has quite low vapor pressure and is odorless, pollution-free,
non-flammable, and easy to be separated from products, easy to be
recovered, suitable for repeated use and easy to use; the recovery of
metals from new solvent is simple and the metal used can be
recycled and re-activated, without secondary pollution.
Currently, the liquid phase catalyst has relatively high VCM
conversion rate under laboratory conditions, and after long-term
continuous operation, the new solvent is free from loss, the metal
ions are free from inactivation, and the conversion rate and the
selectivity remain unchanged; its bench-scale test has been
completed in the laboratory. In the pilot plant test, it is proposed to
adopt the tower reactor for further improving the conversion rate.
However, due to high cost of the mercury-free catalyst, the
economical efficiency of its industrial application requires to be
further improved.
On the whole, with the joint efforts of production enterprises,
research institutions, and professional institutions of China, the
research and development of the mercury-free catalyst in China is
24
forming a force, and has made certain progress in the different
research directions by the multi-angle shoulder-to-shoulder stance.
4.3 Problems in R & D process
As mentioned earlier, at present, relevant production enterprises and
research institutions of China have focused on the research and
development of the mercury-free catalyst and conducted the
scientific and technological breakthroughs on the mercury-free
catalyst (including solid phase and liquid phase mercury-free
catalysts), the supporting reactor thereof (fixed bed , fluidized bed,
etc.) and other concerned. After several years of efforts, production
enterprises and research institutions have made some progress, but
also found some problems in the research and development.
(1) Stability of the mercury-free catalyst
In the laboratory stage, the enterprises and research institutions
have found some mercury-free catalysts with the initial activity or
selectivity greater than those of the mercuric chloride catalysts, but
they are not put into industrial application, mainly because the
stability of the mercury-free catalyst is not satisfactory and it is
inactivated in a very short period of time, which cannot reach the
industrial requirements. The carbon deposit on the catalyst surface,
loss of active components of the catalyst, change of the valence
state of the metal ion may greatly affect the stability of catalysts.
Therefore, how to maintain the stability of the mercury-free catalyst,
and how to speed up the regeneration of the mercury-free catalyst
after the inactivation have been the key subjects for study over the
mercury-free catalytic system.
(2) Selection of reactors
There are three reactors for preparing polyvinyl chloride by
acetylene process: fixed-bed reactor, bubble column reactor and
high-pressure autoclave reactor, all of which have their own
strengths and weaknesses. The gas-solid phase fixed-bed reactor
has a long history of application; however, how to quickly and
effectively remove heat and maintain the stability of catalyst and the
reaction has always been one of the drawbacks to be solved.
Although the bubble column reactor and the high-pressure autoclave
reactor can effectively avoid this phenomenon, their technological
characteristics obstruct their wide application in industry.
25
(3) Control over catalyst cost
In the research and development of the mercury-free catalyst, one of
the suitable active components for the catalyst is previous metal.
The precious metal catalyst is used in the reaction of acetylene
process-based polyvinyl chloride and has the advantages of high
activity, high selectivity, high yield and others. However, compared
with the traditional mercury catalyst, the precious metal catalyst has
higher cost, greatly increasing the burden on enterprises and
restricting the application of precious metal catalyst. It’s safe to say,
the development of high-performance precious metal catalyst and
the bench-scale test in laboratory are of a very high possibility
technically. The key for the research & development and the
promotion of the mercury-free catalyst is to develop the type passing
the rigorous market test with suitable cost. Therefore, it is necessary
to develop new methods and new technologies, and apply a variety
of ways to minimizing the usage amount of the precious metal in the
catalyst in the preparation process, so as to bring into full play the
effectiveness of precious metal, prolong the service life of the
catalyst, and intensify the efforts of recycling the precious metal
catalyst.
The existing research results show that, most patented mercury-free
catalysts for the calcium carbide process-based vinyl chloride are
the precious metal solid phase catalysts with the carrier of the
activated carbon, with a few of patented liquid phase catalysts.
Precious metal catalyst has rather high activity and from the
perspective of industrial application, the cost of fully relying on
precious metal catalyst can be high. There is some concern when
put into commercialized production operation, the shortage and high
price of raw material would not sustain the production of catalyst to
meet the demand of the whole carbide PVC industry.
Nevertheless, it is clear that the industry is also facing the
implications of the future mercury treaty limiting global mercury
supply. Industry also forecasts that the sole mercury mine in China
could be exhausted within 5 years, further the need to drive
innovation and adaptation in the sector. Overall, the industry needs
to think about the future cost and availability of mercury. Therefore,
more information is needed about the availability of the alternative
catalyst metal and its disadvantages over mercury.
The study over the non-precious metal catalysts is relatively slow,
mainly due to the poor activity and the easy-to-deactivate feature of
26
such catalysts; the research over the liquid phase catalyst is
increasing. Such technical basis provides new ideas for the research
over the mercury-free catalyst for the calcium carbide process-based
vinyl chloride, so as to develop the catalysts with the active
components of precious metals of low contents or of non-precious
metals and the liquid-phase mercury-free catalysts. The new
mercury-free catalyst is of high activity and little carbon deposit and
can be regenerated and reused. Meanwhile, with the development of
reactor technologies, the mercury-free catalyst preparation process
and the supporting reactors are developed, reducing the technical
difficulties in the industrialization of the mercury-free catalyst and
becoming the new trend in the calcium carbide process-based
mercury-free catalyst field.
27
5. Feasibility Analysis and Technical & Economic
Prospects of Mercury-Free Catalyst
With the rapid development of China's calcium carbide acetylene
process-based polyvinyl chloride and the restriction of the
international environment on the mercury resource application of
the industry, the research on the mercury-free catalyst for the
calcium carbide process-based vinyl chloride has become the
technical barrier for the sustainable development of the calcium
carbide process-based polyvinyl chloride industry of China. Subject
to resource constraints, the petroleum ethylene process has
become the dominated polyvinyl chloride process in foreign
countries, and the mercury-free catalyst for the calcium carbide
process-based vinyl chloride has been less studied. And China’s
industry, under the great attention of industry and the active efforts
of enterprises and research institutes, has made a number of
attempts on the study over the mercury-free catalyst system and
has made some progress.
5.1 Technical feasibility assessment
Currently, the research of China’s industry on the mercury-free
catalyst focuses on the solid phase and liquid phase mercury-free
catalytic systems. Judging from the comparison, both the solid
phase mercury-free catalytic system and the liquid phase
mercury-free catalytic system have their own advantages and
disadvantages in respect of service life, activity, stability and others.
When the solid phase mercury-free catalyst is applied, gas-solid
reaction occurs, and the precious metal or similar precious metal is
used as the main active component of such catalyst. However, due
to carbon deposit on catalyst surface and the loss of active
component of the catalyst and other issues, the activity and life of
such catalyst are not satisfactory. Meanwhile, it is found in the
experiment that the catalytic system under study has the
disadvantages that temperature runaway is likely to occur in the
catalytic reaction, the temperature is difficult to be controlled, the
catalyst recovery and regeneration are not easy to be realized, etc.
In addition, because the solid phase catalyst is filled in the tube of
the reactor, cooling water is applied to the external of the tube to
reduce a lot of heat released by the reaction; therefore, the solid
phase catalytic reactor has to occupy a large area, while the
28
increase of actual output is very limited.
Judging from the active component of the solid-phase catalyst, the
non-precious metal catalyst and the similar precious metal catalyst
still have a gap with the existing mercury catalyst in respect of
catalytic activity, transforming effects and others; therefore, after
various studies and attempts on catalyst formulas, currently, the
enterprises and research institutions at home and abroad still select
the precious metal as the active component of the mercury-free
catalyst. The precious metal is the material with higher catalytic
activity other than mercury, and in spite of higher cost and poorer
stability, the precious metal is simply for the laboratory test, and has
a very high possibility technically.
On the selection of mercury-free catalyst reactor, the gas-solid
phase fixed-bed reactor is more widely used in the calcium carbide
process-based polyvinyl chloride manufacturers in China, but
before the application of the mercury-free catalyst, it is necessary
to resolve the problems such as how to quickly and effectively
remove the heat, and maintain the stabilities of catalyst and
reaction. Although the bubble column reactor and the high-pressure
autoclave reactor can effectively avoid this phenomenon, their
process features obstruct the wild application in the industry.
The liquid-phase mercury-free catalyst has the gas-liquid reaction,
with uniform and stable temperature control, and the local
overheating will not be caused; therefore, the hot points of bed
layers of the catalyst will not be damaged, thereby reducing the
heat transfer load of the reactor system; the active component of
the catalyst is soluble in the homogeneous liquid phase system, so
no carbon deposit will be produced on the catalyst surface, and the
pulverization of the catalyst will not be caused by the impact of the
gas pressure or the abrasion among particles. Therefore, the
catalytic activity and stability of the liquid phase catalytic system are
better than those of the solid phase mercury-free catalytic system
in theory. However, on the other hand, the solid phase mercury-free
catalytic system cannot match with the existing vinyl chloride
industrial production plants, so its industrial promotion will require
the development of suitable vinyl chloride converter for matching; In
addition, the cause for deactivation of the liquid mercury-free
catalyst is still uncertain, so its regeneration and recycling are
subject to certain restrictions.
29
The solid phase mercury-free catalytic system and the liquid phase
mercury-free catalytic system under study have their own
shortcomings in the technical development process, requiring
further improvement and perfection. With more efforts on the R & D
by production enterprises, universities and research institutes of
China, the successful breakthrough on the mercury-free catalyst
from the technical level is still quite possible.
5.2 Analysis on technical and economic prospects
At present, the development of the mercury-free catalyst at home
and abroad is still in the research and exploration stage. The
technical possibility of the success of research and development is
only the important foundation for the research and development,
application, and promotion of the mercury-free catalyst. The real
industrial test or even the full promotion in the calcium carbide
process-based polyvinyl chloride industry of China requires the
economic evaluation over the mercury-free catalyst. To a certain
extent, the cost of the mercury-free catalytic system and the
acceptance degree by existing manufacturers decide whether the
industrial application of the mercury-free catalyst can be achieved,
thus fundamentally removing the important source of the mercury
pollution in the calcium carbide process-based polyvinyl chloride
industry of China.
From the economic considerations on the R&D and promotion of
the mercury-free catalyst, as noted earlier, various studies and
attempts on catalyst formulas come out the result that, the
enterprises and research institutions at this stage still select the
precious metal as the active component of the mercury-free
catalyst based on its activity and selectivity advantages. The high
price of precious metal objectively increases the production and
use cost of the mercury-free catalyst. And at present, the calcium
carbide process-based polyvinyl chloride of China has nearly the
same cost as the overseas ethylene process, and under the
circumstances that the manufacturers of China have to operate at
the break even or even a slight loss, the costly precious metal
mercury-free catalyst will be more difficult to promote in the industry.
Currently, some overseas institutions plan to promote the
mercury-free catalyst preliminarily researched among the calcium
carbide process-based manufacturers in China. There is some
concern when put into commercialized production operation, the
shortage and high price of raw material would not sustain the
30
production of catalyst to meet the demand of the whole carbide
PVC industry. More information is needed about the availability of
the alternative catalyst metal and its disadvantages over mercury in
order for this technology to be widely accepted by Chinese
manufacturers.
Currently, the key for the research and development of the precious
metal catalyst is to, on the premise of cost control, effectively
reduce the usage amount of precious metal in the catalyst and
apply the new technology and new process for maximizing the
effectiveness of precious metals, so as to realize the organic
technical and economic combination of the mercury-free catalyst.
Seen from the adaptation of the mercury-free catalytic system to
existing production plants, the solid phase mercury-free catalytic
system can basically adapt to existing production processes and
production plants of China’s calcium carbide process-based
polyvinyl chloride manufacturers, and because the solid phase
mercury-free catalytic system can well adapt to existing production
plants, the technical requirements on the existing installations are
not high in the application and promotion stage, that is to say, the
solid phase mercury-free catalytic system has not high additional
costs in industrial test and promotion stages but has strong
operability. On the contrary, although the liquid phase mercury-free
catalyst has the advantages of strong activity, high conversion rate,
no limitation of catalyst mechanical strength, easy recycling of
metals and others, its gas-liquid reaction results in the mismatching
with the calcium carbide process-based production plants of China,
and the development of corresponding vinyl chloride converter and
support equipment thereof is quite difficult, which increases the
technical and financial needs for matching with the mercury-free
catalyst.
Considering the rather high economic and technical cost possibly
faced by R&D and promotion of mercury-free catalyst and its
subsequent related supporting techniques, selection of optimal
R&D and promotion program for industrial mercury-free catalyst by
taking account of the technicality and economy of mercury-free
formula as well as the economy of subsequent industrial promotion
is the key factor to be considered in R&D of calcium carbide
process-based polyvinyl chloride mercury-free catalyst in China.
On the whole, the research of the mercury-free catalyst has to go
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through technical, engineering and economic assessments, with
the difficulties gradually increasing. Once a problem is found in any
stage, the industrial application and promotion of the mercury-free
catalyst cannot be realized. Thus, in a sort of sense, the research
and development of the mercury-free catalyst is of great uncertainty.
Meanwhile, due to the uncertainty in the research and development
of the mercury-free catalyst, all stages, from the formula screening
at the research and development stage, the plant setup, running
test and data acquisition at the industrial test stage to the design
and reconstruction of supporting equipment at the promotion stage
and others concerned, require a lot of funds.
In a sort of sense, the enormous funding gap at each stage during
the research and development of the mercury-free catalyst has also
been an important factor restricting the research and development
of the mercury-free catalyst to some extent. In addition, under the
severe mercury pollution prevention and control situation both at
home and abroad and the increasing scarcity of mercury, the R & D
and application of mercury-free catalyst are particularly critical.
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6. Key areas of future work
In the face of the increasingly severe heavy metal pollution and
control situation in China, the government, the industrial
associations, and the manufacturers are cooperating with each
other to enhance the promotion of low-mercury catalyst, to conduct
the cleaner production and circular economy by applying the
effective mercury recovery technology, and to take effective
measures to promote the mercury pollution prevention and control
of the calcium carbide process-based polyvinyl chloride industry.
Priority must be assigned to achieving cost-effective mercury-free
PVC production processes. China can reduce the demand for new
mercury for its manufacturing sectors by fostering the development
of closed-loop systems that manage mercury as a valuable
resource, and by reducing the requirement for mercury in
manufacturing processes and products.
At the same time, China needs to increase financial support and
policy support, and further promote the research and development
of mercury-free catalyst, so as to facilitate the mercury-free
application in the calcium carbide process-based polyvinyl chloride
industry of China.
6.1 Continuously strengthening the application and
promotion of the mercury pollution prevention and control
technology
China’s production enterprises should optimize the production
process to reduce catalyst consumption, properly handle the
potential mercury pollution sources, and actively implement the
circular economy and the cleaner production, so as to further
strengthen their mercury pollution prevention and control capacity.
The development of a mercury free catalyst is a critical element
required to achieve the government’s announced goals for this
sector, including by 2020 to promote mercury-free catalyst use and
gradually achieve mercury-free production across the PVC
industry.
A policy of preventing fresh mercury from entering China’s
industrial PVC system is under consideration based on a
recommendation made by the China Council for International
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Cooperation on Environment and Development in its Special Policy
Study on Mercury Management in China and could be an important
step toward mercury pollution prevention and achieving
mercury-free production across the PVC industry.
The enterprises should be supported to enhance the application
and promotion of the low-mercury catalyst, the application of the
low-mercury catalyst and the efficient mercury recovery technology
should be promoted, and the construction of a demonstration
project for the integration of low-mercury catalyst production and
waste mercury catalyst recycling by new technology should be
driven. The industrial associations further organize the optimization
and perfection of the low-mercury catalyst production and use,
develop the low-mercury catalyst promotion plan, hold the universal
design training courses on low-mercury catalyst use and mercury
pollution prevention and control, and accelerate the promotion of
advanced mercury pollution prevention and control technology and
products.
6.2 Promoting the development and introduction of
relevant policies, regulations and standards
The state develops specific regulations, practically implants the
concept of mercury-free catalyst to all industries, and truly
implements the mercury catalyst governance. In addition, the state
further strengthens the supervision, ensures each link from the
basic research and development to final large-scale production of
the mercury-free catalyst and the technology is real, reliable, free
from false information and purposeful, and ensures quick and
effective realization of the goals, proper arrangement of the funds
and appropriate use of the funds. Based on the China Council
Report, binding regulations and improved enforcement measures
are under consideration for phasing policies in to track and control
mercury entering the VCM/PVC sector’s waste streams and
by-products.
Meanwhile, the industrial associations and the enterprises are
actively promoting the low-mercury catalyst production, the
construction of recycling demonstration unit and the release of the
waste and low-mercury catalyst recycling qualifications, and
seeking for the economic, environmental, tax and other policies
beneficial to the development of the calcium carbide process-based
polyvinyl chloride industry. The state, through studying and
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developing the environment admittance system for mercury catalyst
production and waste mercury catalyst recycling, perfects the
mercury catalyst production and waste mercury catalyst recycling
management, directs and supervises the implementation of the
Program for Comprehensive Mercury Pollution Prevention and
Control in the Calcium Carbide Process-Based Polyvinyl Chloride
Industry, and actively promotes the mercury pollution prevention
and control of the industry.
6.3 Strengthening the research and development of the
mercury-free catalyst
Due to the important significance and effect of the research and
development of the mercury-free catalyst to the calcium carbide
process-based polyvinyl chloride industry, it is especially important
to increase the fund investment and policy assistance for the basic
research and development of the mercury-free catalyst, and
promote the research institutes and research institutions to carry
out the project. Section 6.4 addresses funding support.
Chinese industry, in particular, notes the need for a transparent and
accountable review process to assess the performance factors of
promising technologies as they develop. In recognition of this,
UNEP has initiated the development of a peer review process as
one mechanism to verify the performance of mercury free catalyst
in a Chinese VCM production line in a transparent and open
process. UNEP will continue to work with government and industry
representatives in China and internationally to establish and
implement a fair and transparent process. This peer review
process is designed as a review mechanism for emerging
technologies at the commercial testing level. The peer review
process is not designed to promote any one particular technology.
At the same time, it is necessary to enhance the publicity efforts,
ensure the calcium carbide process-based polyvinyl chloride
manufacturers attach more importance to the development and
promotion of mercury-free catalyst, encourage enterprises to
actively participate in the research and development, and promote
the cooperation between manufacturers and research institutes, so
as to make the basic research and development enter the right path
as soon as possible and lay a solid foundation for the pilot and
promotion of the mercury-free catalyst. At the moment, the China
Petroleum and Chemical Industry Association encourages
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enterprises to enhance the investment of R&D on mercury-free
catalyst mainly through Working Conferences of PVC production
companies.
In addition, the state should give full play the role of strategic
alliances on the mercury-free catalyst, integrate the mercury-free
catalyst research forces of China and implement the mercury-free
catalyst pilot study relying on enterprises, so as to make
breakthroughs within the shortest period of time. The Government
will take steps to encourage uptake of mercury free technologies as
they are developed while continuing efforts to develop competing
methods.
6.4 Striving for financial supports from multiple channels
There is an urgent need for significant investments in research on
mercury-free technologies and processes for PVC production in
China. Given the enormous funding gap in promoting the mercury
pollution prevention and control work in the calcium carbide
process-based polyvinyl chloride industry of China, striving for
financial supports from multiple channels to meet the demands
of the promotion of the low-mercury catalyst and the research and
development of the mercury-free catalyst is extremely important for
the development from “mercury minimization” to "mercury
elimination" in the calcium carbide process-based polyvinyl chloride
industry of China. Multiple funding channels include Chinese
Government, industry and international channels.
i. Industry
Seen from the current situation, besides the large funding gap in
the research and development of the mercury-free catalyst, with a
large number of calcium carbide process-based polyvinyl chloride
manufacturers in China and their great differences in the production
status and the equipment and technology levels, the promotion of
both low mercury catalyst and mercury-free catalyst requires a lot
of funds for improvement or updating of equipment or technologies
of enterprises. In addition, funds should be invested into
improvement of the corresponding enterprise management level,
thus strengthening the automation management, personnel training,
etc. At present, the polyvinyl chloride industry of China has a
relatively low overall profit level, and most enterprises have
difficulties in production and operation, so under such
circumstances, the funds from enterprises are unable to support
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the promotion of the low-mercury catalyst and the R&D and
promotion of the mercury-free catalyst. Nevertheless given the
reality of limited mercury supply in the future, facilities that continue
using the coal-based process should invest in the transformation to
lower-mercury and eventually to mercury-free methods.
ii) Government of China
Given the practical problems in mercury pollution prevention and
control in China, enhancing the support for the promotion of the
low-mercury catalyst and the R&D of the mercury-free catalyst
through striving for fund supports from multiple channels is
extremely important and has a great effect on the calcium carbide
process-based polyvinyl chloride industry of China.
Based on the recommendation in the China Council Report, the
government intends to explore how to foster these technologies
further by instituting economic instruments and financial incentives
to assist the sector’s transformation to mercury-free processes.
iii) International Channels
While the funds for R & D of mercury-free catalyst are actively
sought after from the relevant state departments, regional and
global financial aids are particularly important for the smooth
implementation of the mercury pollution prevention and control, and
the research and development of the mercury-free catalyst in the
calcium carbide process-based polyvinyl chloride industry of China.
FECO and Norway are carrying out a project called
“Sino-Norwegian Cooperative Project on Mercury - Capacity
building for reducing mercury pollution (SINOMER II)” (2010-2013).
This project contains a sub-project, called" Technology and policy
options for reducing intentional mercury use in industry and
products”, study of VCM is part of the work, including: Investigate
the process of mercury-containing catalysts in China. Present
technological alternatives to the current Hg use in industries and
products based on international experiences. Present policy
options for promoting reducing Hg use in catalysts and disposal of
used Hg-catalysts.
UNEP will continue to work with government and industry
representatives in China and internationally to promote a peer
review process as a review mechanism for emerging technologies
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at the commercial testing level. UNEP has indicated it will fund
participation in such a review process as appropriate and as funds
are available.
In addition, UNEP has supported two multi-stakeholder meetings in
China related to the PVC industry (June 2009 and September 2011)
and has further indicated it will continue to support China in
promoting such information sharing in the future, as requested and
as resources allow. UNEP is also working with MEP to develop a
proposal to the Global Environment Facility to strengthen China’s
capacity for identification of mercury sources and priority actions to
address mercury issues under a future global convention so that to
protect human health and the environment from the toxic exposure
of mercury. While this project is general to all mercury uses and
releases in China, this project will help build capacity at the national
level in China to address the PVC industry.
In closing, it is suggested to set up a special support fund for R&D
and promotion of mercury-free catalyst in the calcium carbide
process-based polyvinyl chloride industry, coordinated by MEP
jointly with UNEP.
This fund would be developed by a
International Partnership Task Force that would work together to
identify needs, work plan and fundraise to promote mercury
reductions from this sector. This would incorporate considerations
of the future international Mercury convention, including potential
funding and technical support that will be available through the
Convention.
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