CO2 has become a plentiful source of carbon, and catalytic conversion of CO2 can be used for sustainable production of chemicals (lower olefins such as ethylene and propylene, methanol, and carbonates), and clean fuels (such as liquid transportation fuels or synthetic natural gas)as well as organic and inorganic materials. Effective use of catalysis and adsorption over nano-porous materials can decouple the traditional link between energy utilization and negative environmental impacts of CO2. As a new direction of sustainable energy development, the hydrogenation of CO2 over novel bimetallic catalysts using H2 produced from H2O using renewable energy, can selectively produce C2-C4= olefins and C5+ liquid hydrocarbons using Fe-based catalysts such as Fe-Co, Fe-Ni, Fe-Pd and Fe-Cu catalysts. Strong synergetic promoting effects were observed when a relatively small amount of a second metal (Co, Ni, Pd, Cu) was added to Fe for C2 and higher hydrocarbons. The use of an alkali promoter can significantly enhance the yields of the C2-C4 olefins and further decrease the yield of CH4. The catalysts can be tailored to yield more C2-C4= olefins and C5+ liquid hydrocarbons. Based on recent studies in our laboratories, experimental research on the new bimetallic catalysts and the spectroscopic characterization coupled with computational studies with DFT provide new insights into the mechanism and potential new reaction pathways for direct catalytic conversion of CO2 to hydrocarbons without going through CO as an intermediate product. In other words, direct conversion of CO2 to olefins and higher hydrocarbons in one single step is possible over the new bimetallic catalysts by going through different yet low energy-barrier reaction pathways that does not involve chemisorbed CO* as intermediate. Thus a new reaction process for CO2 conversion to hydrocarbons becomes possible without using the state-of-the-art based on combination of the catalytic hydrogenation of CO2 with H2 to CO by reverse water gas shift, and then the Fischer-Tropsch synthesis using CO and H2 to hydrocarbons. The new bimetallic catalysts are promising for both fundamental advance in catalytic chemistry and the practical application of CO2 conversion to chemicals and fuels.

New bimetallic Fe-based catalysts for CO2 hydrogenation to C2-C4= olefins and C5+ higher hydrocarbons

256th National Meeting (2018)

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