Introduction Great research efforts worldwide are invested into CO2 emission reduction. A possible way is CO2 valorization into chemicals. By reaction with hydrogen, CO2 is converted to methanol, which can be used for chemical energy storage or feedstock.1 In order to dispose of a recent data base for reactor design purposes in the context of an industrial project, methanol synthesis kinetics were determined using state-of-the-art catalysts Cu/ZnO/Al2O3 (CuZA) and Cu/ZnO/ZrO2 (CuZZ), both optimized for CO2/H2 feeds. Reactions considered were: (1) CO2 + 3 H2 = CH3OH + H2O (2) CO + 2 H2 = CH3OH (3) CO2 + H2 = CO + H2O Experimental Catalytic tests were carried out in a fixed bed reactor with 135 mg of catalyst, primarily at 50 bar total pressure and GHSV 8000 h-1. Some tests at higher pressure and GHSV were made to evaluate model applicability to these conditions. Temperature was varied between 200 and 240 °C, H2 partial pressure from 12 to 38 bar, CO2 partial pressure from 4 to 12 bar. Results and discussion CuZZ catalyst performance was superior with respect to CuZA insofar as similar methanol productivities at lower conversions were observed thanks to better selectivity. Experimental results were analyzed using a simple power law-model and the more complex model of Graaf et al.2 Activation energies found for the two catalysts are similar. H2 pressure variation has a higher impact than CO2 pressure variation: As reaction order in H2 is higher, overstoichiometric H2 allows to improve methanol productivity and selectivity at the same time. Finally, the experimental results indicate that reaction (2) is not significantly involved in methanol synthesis from CO2. Conclusion The availability of kinetic data for methanol synthesis from CO2/H2 feeds in industrial conditions prepares the ground for real-world applications. Acknowledgement. The authors thank ANR VItESSE2 for financial support. References (1) Olah, G. A.; Goeppert, A.; Prakash, G. K. S. J. Org. Chem. 2009, 74, 487–498. (2) Graaf, G. H.; Stamhuis, E. J.; Beenackers, A. A. C. M. Chem. Eng. Sci. 1988, 43, 3185–3195.

Kinetics of methanol synthesis from carbon dioxide and hydrogen

249th National Meeting (2015)

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