Abstract
Formulation of a Network and the Study of Reaction Paths for the
Sustainable Reduction of CO2 Emissions
Rebecca Frauzema, Pichayapan Kongpannab, Kosan Rohc, Jay H. Leec, Varong
Pavarajarnd, Suttichai Assabumrungratb, Rafiqul Gania
aCAPEC,
Department of Chemical and Biochemical Engineering, Technical University of
Denmark, Søltofts Plads, Building 229, Kongens Lyngby, Denmark
b Center
of Excellence in Catalysis and Catalytic Reaction Engineering, Department of
Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330,
Thailand
c Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of
Science and Technology 291 Daehak-ro (373-1 Guseong-dong), Yuseong-gu, Daejeon
305-701, Republic of Korea
dCenter
of Excellence in Particle Technology, Department of Chemical Engineering,
Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
Various organizations, especially the Intergovernmental Panel on Climate
Change, have stated that global warming is an ever-increasing threat to the
environment and poses a problem if not addressed. Therefore, efforts are being
made to find methods of reducing contributors to global warming, primarily
greenhouse gas emissions. Of these, carbon dioxide (CO2) is the largest source
and, hence, the reduction of the amount emitted is primary focus of
developments [1]. A new and promising process that reduces the emissions is the
conversion of CO2 into useful products, such as methanol and dimethyl
carbonate (DMC) [2].
In this work, through a computer-aided framework for process network
synthesis-design, a network of conversion processes that all use emitted CO2 is
investigated. CO2 is emitted into the environment from various sources: power
generation, industrial processes, transportation and commercial processes.
Within these there are high-purity emissions and low-purity emissions. Rather
than sending these to the atmosphere, it is possible to collect them and use them
for other purposes. Targeting some of the largest contributors: power generation,
manufacturing, chemical industry, it is possible to determine the amounts
available. Once the CO2-sources are known, it is possible to determine how to
utilize these through process network optimization.
Abstract
In addition to the source information, reaction details are vital. Understanding
the conversions that are thermodynamically feasible, process co-reactants,
catalysts necessary, operating conditions and reactions, is the next step. The
products that are formed fall into categories: fuels, bulk chemicals and specialty
chemicals. While fuels, such as methanol (MeOH), have the largest market, this
network will include a variety of thermodynamically feasible conversion paths
[3]. From reviews of work previously done, there are ranges of possible products
that are formed directly from CO2 and another co-reactant. Methanol, dimethyl
ether, dimethyl carbonate and ethylene carbonate are just some of the products
that can be formed.
With the information of sources and reactions, a tree of reaction paths is formed
and investigated. This forms a superstructure of CO2 utilization to a variety of
products. Each of the paths in the network involves CO2 and a co-reactant, such
as hydrogen, which may also be captured from process purge streams. The
process network evolves as some of the reactions involve products from other
reactions as a reactant. Combining the possible products that can be formed and
the reactants that are required yields a network of products that can be created
using only the CO2 emissions and not adding any CO2 emissions through the
reactions.
Studies and detailed simulations have been performed on CO2 conversion to
methanol, synthesis gas processes, dimethyl carbonate production, and other
processes. The detailed simulations are performed on the paths that are selected
based on basic calculations on each path. Then, those paths that are targeted
from base calculations are further simulated for detailed information. From these
detailed simulations, results are provided, enhancing the superstructure for an
improved analysis. In addition, the aim is to create sustainable alternatives for
the production of these products with an overall reduction of CO2, both in the
material and energy streams.
With the use of computer-aided tools, this network, and the information
contained within it, is generated. The detailed simulations, of CO2 conversion to
methanol, synthesis gas production and DMC manufacture, provide in-depth
knowledge of the various paths that are most promising. The economic
feasibility and sustainability are assessed to identify the final, more sustainable
network. Overall, the target is the formation of a network that reduces emissions
Abstract
by forming desirable chemical products without emitting noticeable amounts of
CO2 and other greenhouse gases, and creating more energy efficient processes.
References:
[1] IPCC, 2013. Climate Change 2013: The Physical Science Basis. Contribution of Working
Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.
[Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y.
Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, New York, 1535 pp.
[2] Olah, George Andrew., G. K. Surya. Prakash, and Alain Goeppert. Beyond Oil and
Gas: The Methanol Economy. Weinheim: WILEY-VCH, 2009. Print.
[3] Xiadoding, Xu and J.A. Moulijn. “Mitigation of CO2 by Chemical Conversion:
Plausible Chemical Reactions and Promising Products.” Energy and Fuels. 10, 305-325.
1996.
Keywords:
Process Design, Sustainability, Global Warming, Carbon Dioxide, Conversion