Toward intimate oxide-zeolite hybrid catalysis for CO2-to-olefins conversion

Climate change is a major environmental concern and the main cause is the excessive emission of anthropogenic greenhouse gases such as CO2. Aside from low-emission processes and reduction strategies, carbon capture and utilization (CCU) of current large point-sources will be of utmost importance to transition from a CO2-exhaust-heavy economy to a more carbon-neutral one. The direct hydrogenation of CO2 into olefins is a promising CCU technique leading to valuable olefins, which are now mostly obtained via highly CO2-emitting steam cracking. The process needs a combination of a redox catalyst (e.g. reducible oxide) and an acidic catalyst (e.g. zeolite). The redox catalyst is employed to reduce CO2 with hydrogen to form methanol, followed by the known methanol-to-hydrocarbon (MTH) process catalyzed by zeolites. Combining both reactions in one reactor leads to economical and energy efficiency savings. The objective is to design truly hybrid catalysts for the CO2-to-olefins via methanol reaction that surpass the art in terms of space time yield, selectivity and/or stability. The exploration of this catalyst synthesis is based on new and generic strategies. The generic physical combination of a reducible oxide with a zeolite is proven to be inefficient, thus other ways of combining are explored. Strategies such as co-genesis of zeolite with reducible oxide phases, whether or not combined with fed-batch synthesis, are expected to lead to a real chemical integration of both functions in one catalyst.