Synergistic Catalysis of Al and Zn Sites of Spinel ZnAl2O4 Catalyst for CO Hydrogenation to Methanol and Dimethyl Ether

Activation and surface reactions of CO and H2 on spinel ZnAl2O4 catalyst under CO hydrogenation reaction conditions were studied using temperature-programmed surface reaction spectra and in situ diffuse reflectance Fourier transform infrared spectroscopy. CO and H2 activation was found to occur at the Al and Zn sites of ZnAl2O4 catalyst to form active bidentate formate species and reversibly adsorbed hydrogen species for methanol/diemthyl etherproduction, respectively. The hydrogenation of resulting bidentate formate species at the Al site is the rate-controlling step and exhibits a barrier of 83.8 kJ/mol. These results reveal the synergistic catalysis of Al and Zn sites of spinel ZnAl2O4 and rate-controlling step in catalyzing CO hydrogenation to methanol/dimethyl ether, which greatly deepens fundamental understanding of oxides-catalyzed CO hydrogenation reaction.