(513am) Metal Phosphides As Highly Active Catalysts for CO2 Hydrogenation Reactions

Carbon dioxide hydrogenation reactions can enable us to synthesise sustainable fuels and chemicals compared to fossil fuel based routes. Reductions in carbon footprint of certain products such as methanol and methane are already being reported at commercial production sites utilising as feedstock captured CO₂ and hydrogen derived from low carbon energy driven electrolysis. This scheme of chemical production provides an opportunity to capture and recycle CO₂ while storing variable sources of renewable energy in the form of chemical bonds. With the increasing grid penetration of renewable energy sources and expected increase in green hydrogen production, there is a need to develop scalable high performance catalysts for CO₂ hydrogenation reactions. CO₂ can directly be hydrogenated to fuels and chemicals such as methane and methanol. Alternatively, CO₂ can be converted to CO via the reverse water gas shift (RWGS) reaction, using hydrogen as co-reactant. By tuning the feed H₂/CO₂ ratio, it is possible to arrive at a product mixture (synthesis gas or “syngas”) suitable for feeding into a commercial methanol synthesis or Fischer-Tropsch reactor for further conversion to desired final products. In this work we identify some metal phosphides as new catalysts for this reaction and report their performance for RWGS. We explore the appropriate performance metrics for RWGS catalysts, in particular focusing on how these vary with the end use of syngas, using CHEMCAD thermodynamic simulations and evaluate our catalysts accordingly. By characterising these catalysts and using insights from their performance in other related chemical transformations we begin to understand the factors governing their activity and selectivity in CO₂ hydrogenation.