(445a) C2 Oxygenates from Syngas: Understanding and Improving Methanol Carbonylation Using Modified Mordenite Catalysts
The carbonylation of methanol suffers from deactivation and hydrocarbon formation occurring concurrently on acid zeolites. Mordenites contain acid sites in 12 membered rings which catalyze carbonylation, but also catalyze hydrocarbon formation through trimethyl oxonium cation intermediates3. Acid sites in the 8 membered rings of the zeolite structure also catalyze the carbonylation reaction, however do not contribute to hydrocarbon formation. Selectively poisoning the sites in the 12 membered rings over the 8 membered rings improves selectivity and stability. The contribution of this work is a selective cation-free poison that is air-calcination stable and selectively blocks sites that produce hydrocarbons over carbonylation sites. Reactivity studies, variation in synthetic conditions and precursors, and catalyst characterization are used to understand and improve the performance in the conversion of syngas to C2 oxygenates with nearly 90% selectivity.
1 Subramani, V. & Gangwal, S. K. A Review of Recent Literature to Search for an Efficient Catalytic Process for the Conversion of Syngas to Ethanol. Energy & Fuels 22, 814-839, doi:10.1021/ef700411x (2008).
2 Cheung, P., Bhan, A., Sunley, G. J., Law, D. J. & Iglesia, E. Site requirements and elementary steps in dimethyl ether carbonylation catalyzed by acidic zeolites. Journal of Catalysis 245, 110-123, doi:https://doi.org/10.1016/j.jcat.2006.09.020 (2007).
3 Boronat, M., Martinez, C. & Corma, A. Mechanistic differences between methanol and dimethyl ether carbonylation in side pockets and large channels of mordenite. Physical Chemistry Chemical Physics 13, 2603-2612, doi:10.1039/C0CP01996H (2011).