The effect of hydrophilic properties of carbon-supported catalysts for the water–gas shift reaction: a kinetic study

Abstract

Carbon-supported catalysts have been widely investigated and applied in the catalytic reforming reaction and water–gas shift reaction (WGS) for hydrogen production due to their remarkable stability and superior catalytic activity. However, the effect of hydrophilic–hydrophobic properties of carbon-supported catalysts on catalytic performance remains unclear. Among the Pt-based Mn and K co-modified carbon-supported catalysts developed in this study, the catalyst modified with KMnO₄ exhibited the best performance in methanol steam reforming. The KMnO₄ treatment introduced abundant oxygen-containing functional groups and oxygen vacancies on the carbon support, significantly enhancing its hydrophilicity and water adsorption capacity. This facilitated the activation and dissociation of water molecules, which is the rate-determining step in the WGS reaction. The synergistic effect of improved hydrophilicity and increased oxygen vacancies promoted the overall reaction process, thereby enhancing the catalytic performance. Kinetic analysis of the WGS reaction was conducted between 150 °C and 250 °C, using a power-law model to fit experimental data and calculate apparent activation energies. The PtMnK/AC-Ox catalyst exhibited a significantly lower apparent activation energy of 33.1 kJ mol⁻¹, compared to 54.6 kJ mol⁻¹ for the PtMnK/AC catalyst. This lower activation energy highlights the superior performance of the catalyst for the WGS reaction, particularly in promoting efficient CO conversion.