Interplay between Copper Nanoparticle Size and Oxygen Vacancy on Mg-Doped Ceria Controls Partial Hydrogenation Performance and Stability

A series of Cu n CeMgO x catalysts with various copper nanoparticle sizes and surface defect densities were synthesized and tested for partial hydrogenation of 1,3-butadiene (1,3-BD). The data demonstrated a reaction pathway involving the dissociation of molecular hydrogen on the peripheral oxygen vacancies (O v -Cu + ) before reacting with 1,3-BD adsorbed on the corresponding Cu + atoms. Analysis of the performance data indicated that the turnover frequency of these Cu + sites is approximately five times higher than those of the surface Cu 0 sites. Among the catalysts considered, Cu 0.5 CeMgO x with the smallest copper nanoparticle size provided a stable performance for at least 15 h time-on-stream, while the others were easily deactivating because of carbon deposition. Furthermore, unlike the conventional copper-based catalysts, the Cu 0.5 CeMgO x catalyst achieved a complete suppression of total hydrogenation even at space velocities offering a complete 1,3-BD conversion. The findings offer a broad potential for the rational design of noble metal-free, highly selective, and stable copper-based partial hydrogenation catalysts for reactions that are prone to coke formation.