The promoting role of Ga in ZnZrOx solid solution catalyst for CO2 hydrogenation to methanol

Catalytic conversion of CO 2 into methanol utilizing green hydrogen produced from renewable energy is a promising route to realize carbon neutrality. Although ZnZrO x solid solution catalyst displays excellent catalytic performance, it is still highly desired to make any further improvement. Herein, we found the promoting effect of incorporating Ga into ZnZrO x solid solution catalyst in CO 2 hydrogenation to methanol. Ga promoted ZnZrO x (GaZnZrO x ) solid solution catalyst exhibits CO 2 conversion of 8.8% and methanol space time yield of 630 mg g cat −1  h −1 that are higher than those of ZnZrO x solid solution catalyst (7.7%, 556 mg g cat −1  h −1 ) at 320 °C, while the highly selectivity toward methanol remains unchanged. Chemisorption and H 2 -D 2 exchange results show that GaZnZrO x solid solution catalyst displays higher capacity for the adsorption and activation of H 2 than ZnZrO x solid solution catalyst. Electron paramagnetic resonance result suggests that more oxygen vacancies are derived after incorporating Ga into ZnZrO x solid solution catalyst. In situ diffuse reflectance infrared Fourier transform spectra indicate that the HCOO* and CH 3 O* species are the main intermediate species. The higher IR intensity of intermediate species and lower CH 3 O*/HCOO* ratio on GaZnZrO x solid solution catalyst suggest that the hydrogenation of HCOO* to CH 3 O* is boosted. These results reveal the promoting effect of incorporated Ga into ZnZrO x solid solution catalyst that improves the adsorption and activation of H 2 and CO 2 , thus enhancing catalytic performance of methanol synthesis from CO 2 hydrogenation.