Proximity Effect of Fe–Zn Bimetallic Catalysts on CO2 Hydrogenation Performance

Abstract

The interaction between a promoter and an active metal crucially impacts catalytic performance. Nowadays, the influence of promoter contents and species has been intensively considered. In this study, we investigate the effect of the iron (Fe)–zinc (Zn) proximity of Fe–Zn bimetallic catalysts on CO2 hydrogenation performance. To eliminate the size effect, Fe2O3 and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method. By changing the loading sequence or mixing method, a series of Fe–Zn bimetallic catalysts with different Fe–Zn distances are obtained. Combined with a series of characterization techniques and catalytic performances, Fe–Zn bimetallic proximity for compositions of Fe species is discussed. Furthermore, we observe that a smaller Fe–Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides. Appropriate proximity of Fe and Zn (i.e., Fe1Zn1-imp and Fe1Zn1-mix samples) results in a suitable ratio of the Fe5C2 and Fe3O4 phases, simultaneously promoting the reverse water–gas shift and Fischer–Tropsch synthesis reactions. This study provides insight into the proximity effect of bimetallic catalysts on CO2 hydrogenation performance.Graphical