The Synergetic Effect of Dual Active Sites in ZnO-ZrO2 Catalyst for CO2 Hydrogenation to Methanol

The reaction of CO2 2 hydrogenation to methanol is a typical reaction requiring simultaneous activation of CO2 2 and H2. 2 . The ZnO-ZrO2 2 solid solution catalyst has been demonstrated to be an excellent catalyst, and the dual active site of Zn-O-Zr has been a key active site. However, the actual surface configuration of Zn and Zr and how CO2 2 and H2 2 are activated on the active sites remain unclear. Here, our research shows that there is a synergetic effect of dual active sites in the ZnO-ZrO2 2 catalyst for CO2 2 hydrogenation to methanol. In the 5%ZnO-ZrO2 2 catalyst, which has a low density of Zn-O-Zr sites, the dominant form of zinc coordination is as an isolated Zn site. The main coordination form of 20%ZnO-ZrO2 2 catalyst with moderate density of the Zn-O-Zr site is the (Zn)-OZr-O-(Zn) site. The main coordination form of 40% ZnO-ZrO2 2 catalyst with high density of the Zn-O-Zr site is (Zn)-O-(Zn) site. The catalyst with a Zn-O-Zr site of moderate density exhibits more efficient activation of H2 2 and CO2 2 and a lower energy barrier for the rate-determining step, which leads to superior catalytic activity. This work discovers the synergetic effect of the Zn-O-Zr sites in the ZnO-ZrO2 2 catalyst for CO2 2 hydrogenation to methanol and sheds light on the importance of the active site synergetic effect on multisite catalysts.