Exploring the role of promoters (Au, Cu and Re) in the performance of Ni-Al layered double hydroxides for water-gas shift reaction

Water-gas shift (WGS) reaction is well-known industrial process targeting hydrogen pro-duction. Designing well-performing and economically profitable WGS catalysts is the key toward production of pure hydrogen for application in fuel cell processing systems. Pro-motional role of Au, Cu, or Re in the WGS performance of Ni-Al formulations derived from hydrotalcite precursor was analysed on the basis of deep characterization by BET, XRD, UV -Vis, XPS, and TPR measurements of as-prepared and WGS-tested samples. Additionally, modification by ceria was examined. WGS results revealed that catalyst behaviour was strongly dependent on promoter type. The best performance exhibited gold-promoted Ni -Al layer double hydroxide modified with ceria. This system showed a superior catalytic activity as 99.7% CO conversion at 220 degrees C that correlated well with significantly enhanced reducibility of support. Although Au-containing CeO2-modified Ni-Al catalyst outperformed WGS activity of Cu-and Re-promoted analogues, stability of Re-containing sample and enhanced activity of Cu-based sample after tests at different reaction condi-tions manifested promising results. They leave open space for future investigations addressing improved catalyst performance by tuning Re4+/Re7+ redox structures or opti-mizing catalyst composition.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The water-gas shift (WGS) reaction is an important industrial process for hydrogen production. This study investigated the promotive effects of Au, Cu, or Re in Ni-Al WGS catalysts, as well as the modification by ceria. The results showed that the Au-promoted Ni-Al catalyst modified with ceria exhibited the best performance with 99.7% CO conversion at 220 degrees C. Although the Au-containing CeO2-modified catalyst outperformed Cu and Re-promoted analogues, the stability of the Re-containing sample and the enhanced activity of the Cu-based sample under different reaction conditions showed promising results. Further investigations on improving catalyst performance are warranted.