Kinetics of the water–gas shift reaction over nanostructured copper–ceria catalysts

Abstract

Water–gas shift reaction was studied over two nanostructured CuxCe1−xO2−y catalysts: a Cu0.1Ce0.9O2−y catalyst prepared by a sol–gel method and a Cu0.2Ce0.8O2−y catalyst prepared by co-precipitation method. A commercial low temperature water–gas shift CuO–ZnO–Al2O3 catalyst was used as reference. The kinetics was studied in a plug flow micro reactor at an atmospheric pressure in the temperature interval between 298 and 673K at two different space velocities: 5.000 and 30.000h−1, respectively. Experimentally estimated activation energy, Eaf, of the forward water–gas shift reaction at CO/H2O=1/3 was 51kJ/mol over the Cu0.1Ce0.9O2−y, 34kJ/mol over the Cu0.2Ce0.8O2−y and 47kJ/mol over the CuO–ZnO–Al2O3 catalyst. A simple rate expression approximating the water–gas shift process as a single reversible surface reaction was used to fit the experimental data in order to evaluate the rate constants of the forward and backward reactions and of the activation energy for the backward reaction.