Novel Bimetallic Cu–Pd Nanoparticles as Highly Active Low-Temperature WGS Catalysts

Abstract

Water gas shift (WGS) reaction is a key industrial process to produce hydrogen from CO and H2O. However, conventional Cu-based WGS catalysts are easily deactivated by sulfur compounds, which are ubiquitous in syngas. Cu–Pd nanoparticles of size 8–10 nm were synthesized as a function of the Cu/Pd ratios and investigated as promising sulfur-tolerant WGS catalysts. Significant improvement in the WGS activity was observed in the Cu–Pd catalysts after calcination at 800 °C in air. Pd addition enhanced the reducibility of CuO and Cu0 dispersion and limited the formation of CuAl2O4 spinel during calcination at 800 °C. The additional reducible and catalytically active CuO species was generated by the Cu migration from the CuO shell covering the Cu–Pd nanoparticles onto the γ-Al2O3 support during the 800 °C calcination. The optimal Cu–Pd catalyst characterized by the CuO/CuAl2O4 ratio of 2.37 showed the highest WGS activity, thermal stability, and sulfur tolerance among all Cu-based catalysts reported in this study.