Copper Phyllosilicate-Derived Cu Catalyst for the Water–Gas Shift Reaction: Insight into the Role of Cu+–Cu0 and Reaction Mechanism

Abstract

Cu-based catalysts have been extensively researched for hydrogen production via water–gas shift (WGS, CO+H₂O↔CO₂+H₂) reaction. Yet, the catalyst easily suffers from performance degradation due to Cu⁺/Cu⁰ transformation and particle aggregation. Herein, copper phyllosilicate with different morphologies, i.e., tubular and lamellar, was fabricated by a modified hydrothermal method for the WGS reaction. Compared with the catalyst derived from lamellar copper phyllosilicate (30Cu/SiO₂-L), the one derived from the tubular phyllosilicate (30Cu/SiO₂-T) demonstrates better performance due to the high Cu⁺/(Cu⁰+Cu⁺) ratio. In situ characterizations were conducted to unveil the transformation between Cu⁺ and Cu⁰, which is highly correlated to the CO and H₂O activation. Cu⁺ is primarily responsible for the activation of CO, while Cu⁰ mainly facilitates the dissociation of H₂O. The results show that 30Cu/SiO₂-T follows the redox mechanism, where CO reduces Cu⁺ to Cu⁰ and H₂O oxidizes Cu⁰ to Cu⁺, maintaining the reaction cycle.