Anchoring Pd species over defective alumina to achieve high atomic utilization and tunable electronic structure for semi-hydrogenation of acetylene

Semi-hydrogenation of acetylene is one of the most promising methods to eliminate acetylene from ethylene / acetylene mixtures to avoid Ziegler−Natta polymerization catalysts being poisoned. Given that acetylene is always over-hydrogenated on conventional palladium-based catalyst, it is of great importance to facilitate the desorption of ethylene to enhance the ethylene selectivity. Herein, we report a simple method to anchor Pd by unsaturated penta-coordinated aluminum (Al 3+ penta ) on Al 2 O 3 (meso-Al 2 O 3 ). Characterized by 27 Al-NMR, XRD, HR-TEM, CO chemisorption and XPS, Pd/meso-Al 2 O 3 catalyst had a highly dispersion and unique electronic property of Pd, thus exhibiting a high ethylene selectivity (~83%) while the acetylene conversion is > 99%. Besides, the agglomeration of Pd is suppressed by the metal-support interaction (MSI) between Pd and meso-Al 2 O 3 support. Therefore, the preparation method of the catalyst is relatively simple and has certain commercial application prospects. Pd anchored on Al 2 O 3 by unsaturated penta-coordinated aluminum was found efficient for the catalyst performance improvement. • Pd species are anchored to Al 2 O 3 by unsaturated penta-coordinated aluminum, which improves the dispersion of Pd species. • The electronic structure of Pd species is adjusted by unsaturated penta-coordinated aluminum, which has high selectivity in semi-hydrogenation of acetylene reaction. • Mesoporous Al 2 O 3 with unsaturated penta-coordinated aluminum is synthesized by a simple method, which is inspiring for the production of commercial Al 2 O 3 .