In situ time-resolved characterization of novel Cu–MoO2 catalysts during the water–gas shift reaction

Abstract

A novel and active Cu–MoO2 catalyst was synthesized by partial reduction of a precursor CuMoO4 mixed-metal oxide with CO or H2 at 200–250 °C. The phase transformations of Cu–MoO2 during H2 reduction and the water–gas shift reaction could be followed by in situ time resolved XRD techniques. During the reduction process the diffraction pattern of the CuMoO4 collapsed and the copper metal lines were observed on an amorphous material background that was assigned to molybdenum oxides. During the first pass of water–gas shift (WGS) reaction, diffraction lines for Cu6Mo5O18 and MoO2 appeared around 350 °C and Cu6Mo5O18 was further transformed to Cu/MoO2 at higher temperature. During subsequent passes, significant WGS catalytic activity was observed with relatively stable plateaus in product formation around 350, 400 and 500 °C. The interfacial interactions between Cu clusters and MoO2 increased the water–gas shift catalytic activities at 350 and 400 °C.