Synthesis of methanol via CO <sub>2</sub> hydrogenation catalyzed by La <sub>2</sub>O <sub>2</sub>CO <sub>3</sub>/Cu catalysts
Jun He, Chenglong Yu, Zhijuan Zhao, Bo Guan, Bin Zhang, Yanru Zhang, Longbo Zhang, Yanyan Wang, Ying Wang, Yahui Wu, Jia Guo, Li Yang, Tianbin Wu, Qingli Qian, Hongxing Wang, Buxing Han
Abstract
The development of efficient Cu-based heterogeneous catalysts for CO<sub>2</sub> hydrogenation to methanol has been an appealing subject. Inspired by the concept of inverse catalysts, a series of La<sub>2</sub>O<sub>2</sub>CO<sub>3</sub>/Cu nanorod composites with varying Cu contents (denoted as LOC/Cu-<i>x</i>, where <i>x</i> stands for the mass ratio of La and Cu in the catalysts) were prepared by combining coprecipitation and calcination processes. Remarkable composition-dependence of catalytic activity and selectivity were observed when different LOC/Cu-<i>x</i> (<i>x</i> = 0.1, 0.2, 0.5, 1, 3 and 5) were used to catalyze the CO<sub>2</sub> hydrogenation. The predominant product shifted from methane to methanol with the increasing Cu content. The highest reaction rate (13.3 mmol·g<sub>Cu</sub><sup>−1</sup>·h<sup>−1</sup>) and methanol selectivity (85.5%) were achieved when LOC/Cu-1 was tested at 200 °C. The LOC was not active for the reaction, while the Cu itself displayed poor catalytic performance. The Cu–LOC interactions significantly affected the nature of the catalysts, including mutual electron transfer, crystal structure, morphology, porosity, surface Cu valence and capability of adsorbing the reactant gases, etc., which account for the outstanding behavior of the LOC/Cu-1 catalyst. This work provides a new strategy for the design and optimization of Cu-based catalysts.