Selective Transformation of CO and H into Lower Olefins over In O -ZnZrO /SAPO-34 Bifunctional Catalysts.

Because lower olefins (C -C ) are important bulk petrochemicals, their direct production from CO hydrogenation is highly attractive. However, the selectivity towards C -C by the modified Fischer-Tropsch synthesis is restricted to 56.7 % with high undesired methane selectivity. Here, a series of bifunctional catalysts containing In O -ZnZrO oxides and various SAPO-34 zeolites with different crystal sizes (0.4-1.5 μm) and pore structures was developed for the production of lower olefins by CO hydrogenation. The C -C selectivity reached as high as 85 % among all hydrocarbons with very low CH selectivity of only 1 % at a CO conversion of 17 %. This demonstrated that the small crystal size, hierarchical pore structure, and appropriate amount of Brønsted acid sites of SAPO-34 endowed the bifunctional catalysts with high C -C selectivity. This work shows an efficient way for developing bifunctional catalysts for direct CO hydrogenation to lower olefins.