Reactive behaviors of iron-based shift catalyst promoted by ceria

Abstract

The reductive behavior of iron-based shift catalyst promoted by cerium oxide was investigated by temperature-programmed reduction (TPR). Two reduction peaks appeared, centered at 473 and 673 K in reduction gas mixtures. The peaks illustrated that the reduced surface states were different, corresponding the reductive temperatures. The optimum reductive temperature range is from 423 to 723 K for the catalyst. The results of temperature-programmed desorption (TPD) and pulse reaction indicated that the mechanism of the water–gas shift reaction on the catalyst can be considered as a redox process. The reduced Fe–Ce–Cr–O can be oxidized by water and carbon dioxide at reaction temperatures(from 573 to 673 K). Water is decomposed to form hydrogen and adsorbed hydroxyl groups, and carbon monoxide reacts with hydroxyl groups to produce hydrogen and carbon dioxide simultaneously. FT-IR spectroscopy results showed that iron-based catalyst promoted by CeO 2 is a structurally sensitive catalyst. It has excellent activity, selectivity, and stability under reaction conditions. Moreover, on the catalyst surface carbonate-like species were not found under reaction conditions, as established by IR spectra.