Promoting Methanol Synthesis and Inhibiting CO2 Methanation with Bimetallic In-Ru Catalysts

In this work, we investigated the promotional effects of In on Ru for the synthesis of methanol via CO2 hydrogenation in the liquid phase. Incorporation of In to Ru results in a methanol selectivity of similar to 85% at 240 degrees C and 3.4 MPa (CO2/H-2 = 1/3). Additionally, no methane was observed under the conditions studied (200-240 degrees C). The combination of In and Ru modulates Ru sites geometrically and electronically. X-ray diffraction and X-ray photoelectron spectroscopy provided evidence of the structural evolution from mixed metal oxides to alloy and intermetallic phases and charge transfer from In to Ru, respectively. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy studies using probe molecules (CO2+H-2, CO, formic acid, methanol), as well as CO-temperatureprogrammed reaction and H-2-D-2 exchange experiments, were conducted to provide insight into the promotional effect of In. With the incorporation of In, surface formate and methoxy species were stabilized to promote the formation of methanol. Methanation, which is a dominant pathway on monometallic Ru, was inhibited with promoter addition.

Automated summary

The addition of indium to ruthenium catalyst can effectively promote the CO2 hydrogenation to methanol reaction, enhancing methanol selectivity and inhibiting methane formation. The combination of indium and ruthenium influences the site structure and electronic state of ruthenium, stabilizing surface formate and methoxy species to facilitate methanol formation.