Symposium 3.3

 CARBON DIOXIDE CAPTURE,

STORAGE, AND RECYCLING 

(3 sessions)

Keywords

CO2 capture storage and recycling, post-combustion, oxycombustion, chemical looping, amine processes, sorbents, MOF materials, solar fuels from CO2, synthesis of chemicals, water splitting, catalysis, electrocatalysis, photocatalysis, reduction

Organisers

Thibault CANTAT (CEA / DSM / IRAMIS, Gif-sur-Yvette, FR), Berend SMIT (EPFL-Lausanne, Switzerland and UCAL-Berkeley, USA), Samuel SAYSSET (Lead Technology Advisor, ENGIE Research, FR)

Symposium Honorary Contribution (short video):  THL: Avelino CORMA (ITQ, U-Valencia, ES)

 

Abstract

Among the 17 sustainable development goals (SDG), adopted by the UN 70th General Assembly in December 2015, SDG 13 “Urgent action to combat climate change” is of direct concern for geochemists and chemists. Global CO2 emissions generated by fossil fuels combustion is a major cause of climate change through increasing greenhouse effect. Given our dependence on fossil fuels, all scenarios for the “energetic transition” call for carbon capture and storage technologies as one of the few realistic means to reduce CO2 emissions before renewable energy sources may replace these fossil fuels. In addition, as 7 % of hydrocarbons are used for chemicals, CO2 can become an attractive source of carbon for the chemical industry. Moreover, we will have a continuous need for transportation fuels and intermittent renewable energies can in principle be stored as chemicals, optimally as liquid oxygenated hydrocarbons. To that end, at least a fraction of captured CO2 could be used to react with dihydrogen produced by water splitting. This “power to liquid fuels and chemicals” route appears as the most sensible way to avoid emitting more CO2, since recycling is an endergonic process. Present or future technologies for carbon capture and recycling rely mostly on chemistry which is also crucial to properly address underground storage safety issues. The general objective of this symposium will be to highlight the most significant advances in chemical research and development on this critical aspect of SDG 13, but also to identify bottlenecks and pitfalls. Post-combustion carbon capture technologies may be based on reactive absorption from gas into liquid phases (e.g. amine to carbamate processes), or physisorption from gas phase into microporous solids. In both cases, a regeneration step is mandatory to release pure CO2 from the liquid solvent or solid sorbent, and compression must be applied at some point in order to ensure efficient storage (e.g. injection into underground tight reservoirs) Oxycombustion processes burn hydrocarbons in pure O2 and produce an easily separable mixture of CO2 and H2O. The penalty of using pure O2 is to some extent balanced by the avoided dilution in N2. So-called “chemical looping” processes achieve hydrocarbons combustion by contact with transition metal oxides as oxygen carriers and carbon scavengers. Re-oxidising the carbides by O2 in a regeneration step allows recovering pure CO2 as well as the remaining part of the hydrocarbons heating value. For all cases, the overall energy balance will crucially determine the overall viability: this symposium is expected to help foresee the most competitive processes under this respect. Along “power to liquid fuels and chemicals” routes, reductive recycling of CO2 has to be coupled with water splitting as a source of H2, which involve catalytic (photo-)electrolysis, or direct photocatalysis, in separate or combined steps. If separated, the hydrogenation step itself may use either homogeneous or heterogeneous catalysis. This symposium should allow one to compare all options on the basis of process intensity and atoms economy.