Heteroatom doped iron-based catalysts prepared by urea self-combustion method for efficient CO_2 hydrogenation

摘要

This work describes a novel route for the fabrication of heteroatom doped iron-based catalysts (spinel-like structure) through urea self-combustion method, and catalytic performances over these self-combustion catalysts are investigated in detail. It is found that catalytic performances are affected by the properties of doped metals. Owing to the high methanation activity of Ni and Co, NiFe2Ox and CoFe2Ox catalysts present high CH4 selectivity compared to Fe2O3 catalysts. MgFe2Ox exhibits high olefin hydrogenation ability. By contrast, the utilization of Cu and Zn promotes catalytic activity and olefins selectivity via regulating surface CO2 adsorption and carbides content. Among these spinel catalysts, the ZnFe2Ox catalyst shows the best CO2 hydrogenation performance. Enhanced CO2 adsorptions as well as active species of carbides result in the benign hydrogenation behavior. Meanwhile, the effects of Zn/Fe molar ratio are also investigated. It is worth noting that the catalytic performance can be improved regardless of the added amount of Zn promoter. Nevertheless, the catalytic performance reaches the best level when the Zn/Fe molar ratio equals 1/2. The proposed method provides a new strategy different from traditional catalyst preparation process for catalytic hydrogenation of CO2 into highly valuable products.