SusChemE 2015
International Conference on Sustainable Chemistry & Engineering
October 8-9, 2015, Hotel Lalit, Mumbai
Implementation of Economically and Ecologically Green Processes by
Developing Selective Catalysts and Catalytic Processes
Hitesh V., Babu G.P., Priya B., Shraddha V., Shilpa W. and Vidya S.
Procat Tech LLP, Works A-94, MIDC phase 1, Dombivli (E)- 421203, Thane dist, Maharashtra.
1. Introduction:
The advent of science resulted into understanding and assessing the problems related with the
major chemical industries that are using the traditional catalysts and catalytic processes. Last
few decades the scientific community reported the methods to modify most of the
commercially important catalysts / catalytic processes that are associated with the problems
such as corrosion, waste disposal, intensive energy usage and the lower product yield. All the
green processes that are recommended not fully implemented in practice due to either few of
them are less / no profit making or comparatively the plant design for such green processes
demand initial huge investments.
In this paper a few polluting catalyst and catalytic processes are considered for modification
and thereby suggesting alternate clean processes which are economically and ecologically
important. These catalytic processes are evaluated not only in the laboratory scale but also
established on the pilot plant scale operation.
2. Material and Methods:
Using standard method the zeolite type (ZSM5, Beta and TS-1) catalysts were
hydrothermally prepared by using suitable organic templating agents. Vapor phase reactors
(Glass and metal) were used to test O-alkylation, isomerizaion and dehydration reactions.
Hydroxylation and acylation reactions were carried out in batch reactors.
3. Significant Results and Discussion:
3.1
O-Alkylation: phenol and cresols are commercially alkylated using liquid base
catalyst and dimethyl sulphate as alkylating agent thereby resulting into formation of desired
product along with undesired large volumes of waste alkali and alkali salt solution which
needs to be disposed off. A solid base catalyst “modified alumina + basic zeolite” is
developed to alkylate –OH group of the phenol / cresols i.e. R–OH to R–OCH3 (with >99%
selectivity) using methanol as alkylating agent in vapour phase reaction.
Conventional process
Green process
Green process
3.2
Hydroxylation: commercially O-alkylation of catechol to guaiacol is carried out by
using amorphous solid base catalyst that involves formation of 2 – 5% veratrole (on guaiacol)
as an impurity. Separation of guaiacol and veratrole from the product mixture by distillation
is a difficult step as they have very close boiling points. However, hydroxylation of anisole
using H2O2 and crystalline zeolite type catalyst (titanium silicalite) gave guaiacol and methyl
ether of hydroquinone (MEHQ) which are easily separable to >99% purity and are high value
products with no veratrole impurity in the product.
Conventional process for Guaiacol
Green Process for Guaiacol
3.3
Gas purification: Commercially, the supported noble metal catalysts are imported and
used in industries for manufacturing and supplying of pure N2 gas with low concentration of
O2 as impurity. We attempted to prepare such catalyst by selecting suitable support and
treating with noble metal to achieve desired metal dispersion. The catalyst prepared in the
pilot plant is supplied to few customers who are involved in manufacture of pure gases.
Also as a safety measure it is important that at room temperature to remove the low
concentration of H2 gas from the uncontrolled nuclear / organic reaction effluent gases. Few
catalysts were prepared in the laboratory by combining noble metals and depositing them on
the support and further for performance testing the reactor chamber was fabricated. The
laboratory trials are completed in removal of hydrogen from air at room temperature.
3.4
Isomerization: Using zeolite type catalysts we attempted to isomerize the low value
toluidine isomer to d achieved consistent activity and selectivity towards formation of
equilibrium concentration of high value isomers for longer duration of reaction time. We
extended the application of the zeolite catalyst with minor modification even for
isomerization of cresols.
3.5
Dehydration: Commercially the dehydration of aliphatic alcohols to ethers is carried
out by using different grades of alumina catalysts. We achieved selectivity towards
dehydration of alcohols to ethers (>99.5% ether) by modifying the surface acidity of alumina
and converting few aluminium atoms from octahedral to tetrahedral co-ordination structure.
Aliphatic alcohols such as methanol, ethanol, n-propanol and n-butanol are used for
dehydration to respective ethers by using modified aluminium oxide catalyst.
3.6
Acylation: anisole was acylated in the laboratory and in the pilot plant reactors by
using solid zeolite (beta) type catalyst at 110-120 ˚C and acetic anhydride or propionic
anhydride as acylating agents. The catalyst is filtered from the product mixture and reused for
multiple acylation cycles.
4.
Conclusions:
A few catalysts and processes that are environmentally clean and energy efficient are
identified and tested in both laboratory and pilot plant scale.
References
[1] R. A. Sheldon, I. Arends and U. Hanefeld, Green Chemistry and Catalysis, Wiley-VCH Verlag Gmbh & Co.
KGaA, Weinheim, Germany, 2007.
Keywords: O-alkylation; anisole hydroxylation; alcohol etherification; anisole acylation; gas purification