Towards full one-pass conversion of carbon dioxide to methanol and methanol-derived products

Journal of Catalysis, Volume 309,  Pages 66-70. (2014).

Atul Bansode, Atsushi Urakawa 

Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain.

 

Abstract

The rising concerns about global warming and imbalance in the carbon cycle urge rapid development of efficient CO2 conversion processes. We report an exceptionally productive process for the synthesis of methanol via continuous catalytic hydrogenation of CO2 under high-pressure conditions (up to 360 bar) over co-precipitated Cu/ZnO/Al2O3 catalysts. Outstanding one-pass CO2 conversion (>95%) and methanol selectivity (>98%) were achieved under an optimized range of reaction conditions. At a very high GHSV of 182,000 h−1 over a commercial methanol synthesis catalyst, the process delivers , which is by far the highest yield value reported to date, at the expense of lowered CO2 conversion (65.8%) and methanol selectivity (77.3%). Using a mixed bed consisting of the Cu/ZnO/Al2O3 and H-ZSM-5 catalysts, one-step conversion of CO2 into dimethyl ether with remarkable selectivity (89%) was attained at the equivalent or higher CO2 conversion level. Furthermore, we demonstrate that the effluent stream of methanol, rich in H2 and water, from the methanol synthesis reactor can be directly fed to a reactor containing the H-ZSM-5 catalyst for selective production of alkane (85%) or alkene (42%), depending on the operating pressure of the secondary reactor.

 

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Additional Information

Methanol is one of the most widely suggested alternatives to fossil fuels for chemical energy carrier and C1 building-block. This concept was emphasized by the Nobel Laureatein 1994, George A. Olah using the term “Methanol Economy” as our future direction. Methanol is an excellent fuel and a key starting material in industrial reactions such as syntheses of formaldehyde and acetic acid. Importantly, methanol can be synthesized from CO2 by catalytic hydrogenation. The approach is particularly promising as a strategy for Carbon dioxide Capture and Utilization (CCU) because of its high reaction rate, requiring a small plant area.Consequently, it is a promising solution in various (e.g. power, cement, steel, and chemical) industries emitting a large amount of CO2to close the carbon cycle with abundant CO2 captured from the CO2 sources. The unique approach of this work to the reaction is the utilization of high-pressure (up to 360 bar) to benefit from the thermodynamics and enhanced reaction kinetics under supercritical state, achieving the close-to-full conversion of CO2with the very high selectivity to methanol. At a high space-velocity, we achieve several times higher yields of methanol than commonly reported as excellent values. Onegreat advantage of high-pressure processes for this reaction is the required smaller reactor size compared to low-pressure processes because of compressibility of the reactants feed (mixture of CO2 and H2), rendering this approachconvenient for the sites where CO2 is captured/stored and a small-scale (or even transportable)CO2 conversion processisneeded. The technology is available for out-licensing and/or joint development.

 

Towards full one-pass conversion of carbon dioxide to methanol and methanol-derived products

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