Active nanointerfaces sites for low-temperature water-gas shift reaction over inverse configuration Nb–CeO2/Cu catalysts

Abstract

A comparative investigation of inverse Nb–CeO2/Cu catalysts obtained via sol–gel, coprecipitation, hydrothermal, and incipient wetness impregnation methods was performed against a normal configuration for hydrogen production through a water–gas shift reaction. Exposed oxygen-deficient Nb–CeO2 (111) facet sites deposited on Cu (111) facets with enhanced densities of Ce3+, Cu+, and Ov species for high reducibility were confirmed using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Nb–CeO2/Cu catalyst prepared by coprecipitation exhibited the highest activity of 68 % CO conversion, 100 % H2 selectivity at 360 °C, and gas hourly space velocity of 43,535 h−1. The lowest activation energy (39.67 kJ/mol) and high turnover frequency illustrate facilitated water dissociation and CO oxidation in close vicinity across nanointerfaces. For the Nb–CeO2/Cu catalyst prepared by the coprecipitation method, nanosized Nb–CeO2 stabilized over the porous Cu support was optimum for generating interfaces and facilitating catalytic performance. It is to underscore that the catalyst prepared by coprecipitation exhibited constant H2 production under realistic conditions for 102 h, demonstrating the robust structural features of the configuration Nb–CeO2/Cu.