Regulation of product distribution in CO2 hydrogenation by modifying Ni/CeO2 catalysts

Abstract

Conversion of CO2 into value-added chemicals is a potential way for achieving carbon neutrality. A challenge is to controllably tune its product distribution. Thus, Ni/CeO2 catalyst is modified here by doping Mn or In by the sol–gel method. NiMn(4)/CeO2 shows CO2 conversion of 35.3% and CH4 selectivity of 86.6%, whereas NiIn(4)/CeO2 produces dominant CO with selectivity of 99.1% and CO2 conversion of 23.9%. Such catalytic results are highly comparable to those of previously reported Ni-based catalysts, but loading smaller amounts of Ni (1.7 wt%). Addition of Mn or In in Ni/CeO2 significantly promotes formation of surface oxygen vacancies, influences Ni reducibility and enhances catalytic stability. Various characterizations, in situ spectroscopy and DFT calculation results reveal that high CH4 selectivity of NiMn(4)/CeO2 is due to formation of more HCOO* intermediates, whereas introduction of In significantly promotes formation of COOH* species, but inhibits generation of HCOO*, and thus resulting in dominant CO product.