Role of the structure and morphology of zirconia in ZnO/ZrO2 catalyst for CO2 hydrogenation to methanol

The global carbon dioxide (CO2) emission problem is getting increasingly severe nowadays. Hence a suitable CO2 hydrogenation technology to obtain methanol is an efficient way to achieve carbon neutrality. Zinc oxide (ZnO) nanoparticles were loaded on zirconium dioxide (ZrO2) with different morphologies via the impregnation method. This was followed by the investigation of the effect of zirconia structure and morphology on the interfacial synergy manifested in the catalysts and the catalytic performance in CO2 hydrogenation. The results showed that the CO2 conversion of the ZnO/ZrO2 catalyst possessing a hollow nanoframe-like morphology was significantly enhanced. This catalyst also exhibited the highest methanol space-time yield, which was 1.78 times higher than that of the ZnO/ZrO2 catalyst having an aggregate shape of irregular particles. The unique morphology effectively inhibited the transition of the metastable tetragonal ZrO2 (t-ZrO2) to the monoclinic ZrO2 (m-ZrO2) while forming a special interfacial structure with the loaded ZnO to strengthen the interfacial interaction. This enhanced the hydrogen activation capacity and generated more oxygen vacancies favorable to the activation of CO2.