Unravelling the active sites and structure-activity relationship on Cu–ZnO–Al₂O₃ based catalysts for water-gas shift reaction

Herein, we investigated the main active sites and structure-sensitivity of the water-gas shift (WGS) reaction over ternary Cu–ZnO–Al₂O₃ (CZA) catalysts. CZA catalysts with various Cu contents were synthesized by the homogeneous one-step coprecipitation method. The Cu content mainly affected the number of active Cu sites and was closely related to the WGS activity. Turnover frequency (TOF) values were independent of Cu dispersion, indicating that the CZA catalyst is structure-insensitive in WGS. The ratio of surface Cu⁺ species also strongly influenced the activity of the CZA catalyst. TOF based on the total active Cu species showed a constant value, but the CO conversion was linearly increased with the number of surface Cu⁺ species.