Green methanol synthesis by catalytic CO2 hydrogenation, deciphering the role of metal-metal interaction

The current work deals with the synthesis, characterization and activity studies of zeolite based Ag-Cu bimetallic catalysts for CO2 hydrogenation to methanol. To probe the effect of Ag-Cu weight ratio, Ag-Cu with 1:9, 2:8, 4:6 and 1:1 wt ratios were synthesized by impregnation method. Thermo-gravimetric analysis revealed that catalysts stability was improved by Ag enrichment to the zeolite based Ag-Cu bimetallic catalysts. X-ray diffraction studies showed that zeolite structure has been modified by the incorporation of Ag-Cu metals to the bare zeolite. Nitrogen adsorption desorption studies manifested that BET surface area, pore size and pore volume were less affected by variation in Ag-Cu weight ratio. Formation of nano-sized Ag-Cu bimetallic catalysts with high dispersion was illuminated by Field Emission Electron Microscopy (FESEM). X-ray Photoelectron Spectroscopy (XPS) findings revealed greater metal-metal chemical interaction as a consequent of Ag addition to the zeolite based Ag-Cu bimetallic catalysts. Activity studies of zeolite based Ag-Cu bimetallic catalysts exhibited the promoting role of Ag in CO2 hydrogenation to methanol. The structure activity studies observed Ag-Cu metal-metal chemical interaction as the key factor controlling the rate of methanol synthesis.