Disentangling the activity-selectivity trade-off in catalytic conversion of syngas to light olefins.

Breaking the trade-off between activity and selectivity has been a long-standing challenge in the field of catalysis. We demonstrate the importance of disentangling the target reaction from the secondary reactions for the case of direct syngas conversion to light olefins by incorporating germanium-substituted AlPO-18 within the framework of the metal oxide-zeolite (OXZEO) catalyst concept. The attenuated strength of the catalytically active Brønsted acid sites allows enhancing the targeted carbon-carbon coupling of ketene intermediates to form olefins by increasing the active site density while inhibiting secondary reactions that consume the olefins.

Tuning the Crystal Phase to Form MnGaO -Spinel for Highly Efficient Syngas to Light Olefins.

The oxide-zeolite (OXZEO) catalyst design concept has been demonstrated in an increasing number of studies as an alternative avenue for direct syngas conversion to light olefins. We report that face-centered cubic (FCC) MnGaO -Spinel gives 40 % CO conversion, 81 % light olefins selectivity, and a 0.17 g g  h space-time yield of light olefins in combination with SAPO-18.

Steering the reaction pathway of syngas-to-light olefins with coordination unsaturated sites of ZnGaO spinel.

Significant progress has been demonstrated in the development of bifunctional oxide-zeolite catalyst concept to tackle the selectivity challenge in syngas chemistry. Despite general recognition on the importance of defect sites of metal oxides for CO/H activation, the actual structure and catalytic roles are far from being well understood. We demonstrate here that syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene-acetate (acetyl) intermediates by the surface with coordination unsaturated metal species, oxygen vacancies and zinc vacancies over ZnGaO spinel-SAPO-34 composites.