Intermetallic RNiSi (R = Ca, La, and Y) Catalysts with Electron-Rich Ni Sites for Continuous Flow Selective Hydrogenation of Maleic Anhydride.

The industrial advancement of downstream products resulting from the directed hydrogenation of maleic anhydride is hindered by the limitations related to the activity and stability of catalysts. The development of nonprecious metal intermetallic compounds, in which active sites are adjustable in the local structures and electronic properties embedded within a distinct framework, holds immense potential in enhancing catalytic efficacy and stability. Herein, we report that nickel-based silicides catalysts, RNiSi (R = Ca, La, and Y), afford high efficiency in the selective hydrogenation of maleic anhydride. Among the RNiSi with the same tetragonal structure, CaNiSi with complete isolation and highest electron density of Ni sites presents the low apparent activation energy (98.4 kJ/mol). Preferential adsorption of intermediate succinic anhydride via C═O bonds is achieved by the high oxygen affinity of CaNiSi, resulting in chemoselectivity to γ-butyrolactone (>80%). Additionally, the silicide with good resistance to sintering and acid corrosion presents remarkable stability for at least 130 h. The design of the silicide structure will offer fresh perspectives on the development of effective and enduring selective hydrogenation catalysts.