Tuning Lattice Strain of Copper Particles in Cu/ZnO/Al₂O₃ Catalysts for Methanol Steam Reforming

As a hydrogen carrier, methanol can be utilized to provide on-site hydrogen for fuel cells via a methanol steam reforming (MSR) reaction. The ternary Cu/ZnO/Al2O3 catalyst presents outstanding catalytic activity and excellent CO2 selectivity (>97%). The defects in the copper lattice (e.g., stacking fault or twinning), which are usually accompanied by microstrain, constitute the highly active sites in the Cu/ZnO/Al2O3 catalyst. However, the strategies to rationally tune the lattice strain are still limited. Herein, we reported a facile approach to regulate the Cu lattice strain with various organic acids via the mechanochemical method. In the meanwhile, we developed a method to quantify the microstrain in the Cu lattice combining X-ray diffraction (XRD) and N2O titration techniques. The catalyst with abundant microstrain presents a superior turnover frequency value of 691 h–1, and the correlation between turnover frequency and lattice strain proves the dominant role of defects of Cu particles in improving the catalytic performance. This insight into the lattice strain in Cu/ZnO/Al2O3 offers an alternative approach to synthesize highly efficient catalysts with abundant defects in the Cu lattice.