Enhanced Activity of Cu/ZnO/C Catalysts Prepared by Cold Plasma for CO<sub>2</sub> Hydrogenation to Methanol
Zhao Luo, Shoushuai Tian, Zhao Wang
Abstract
An activated carbon-supported Cu/ZnO catalyst for CO2 hydrogenation to methanol has been prepared by the facile plasma decomposition of a Cu–Zn precursor at moderate temperature. The Cu/ZnO/C catalyst prepared by cold plasma featured smaller size and higher dispersion than that prepared by traditional calcination. The low operation temperature plays an important role in this. The catalysts are characterized using a multitechnique approach. X-ray photoelectron spectroscopy results indicate that cold plasma can introduce specific O-containing groups on the carbon surface. It also facilitates the dispersion of active components and H spillover. H2 temperature-programmed reduction profiles and transmission electron microscopy images show that the interaction between Cu, ZnO, and carbon in the Cu/ZnO/C catalyst prepared by cold plasma was stronger than that in the catalyst prepared by calcination. The properties are beneficial to the CO2 hydrogenation reaction. The catalytic performance of the catalysts was tested in a fixed-bed reactor. The Cu/ZnO/C catalyst prepared by cold plasma showed an obvious increase in CO2 conversion, methanol selectivity, and productivity in the catalytic evaluation of catalysts. Moreover, it obtained a remarkable space-time yield of 92.5 gmethanol·kgcat–1·h–1 at 260 °C that is approximately 1.5 times that of Cu/ZnO/C prepared by calcination.