(363c) Methanol Synthesis from CO2 Hydrogenation with Ru/Mo Bimetallic Phosphides

Potassium promoted molybdenum phosphide (K-MoP) has been recently reported as a promising catalyst in methanol synthesis via CO₂ hydrogenation due to its stability and resistance to CO₂ poisoning.¹ Improvements in the catalytic performance of Mo-based phosphides are possible by taking advantage of the unique properties of transition metal phosphides. As an example, the catalytic properties of monometallic phosphides can be tuned by geometric, electronic, stabilizing, synergistic, and/or bi-functional effects through the formation of bimetallic phosphides.^2-3

In this presentation, we will highlight the remarkable improvement in methanol yields through the incorporation of Ru into MoP. Specifically, in liquid phase reactions at 200 ^oC with the initial charge of 10 bar CO₂ and 30 bar H₂, we determined Ru-Mo phosphide produces methanol with 2.5x higher CO-normalized methanol formation rates than MoP. The Ru/Mo ratio strongly influenced the methanol formation rate at various temperatures. Additionally, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments provide features associated with formate species on the surface of the metal phosphides. Additional experiments were performed using formic acid and CO as reactants to assess the ability of various bimetallic and monometallic phosphides to reduce these possible intermediates. Again, we observe higher methanol production rates when using the bimetallic catalysts. Overall, these experiments showcase the ability to modify the reactivity of phosphide catalysts for methanol formation through the creation of bimetallic compositions.

References:

• Nørskov, J. K.; Jaramillo, T. F., Angew. Chem. 2018, 130, 15265.
• Oyama, S. T., Catal. Today. 2009, 143, 94.
• Alonso, D. M.; Wettstein, S.G.; Dumesic, J.A., Chem. Soc. Rev. 2012, 41, 8075.