Acid-durable intermetallic CaNi2Si2 catalyst with electron-rich Ni sites for aqueous phase hydrogenation of unsaturated organic anhydrides/acids

Abstract

The study of the aqueous-phase selective hydrogenation of maleic anhydride to succinic acid is important for expanding the coal chemical industry chain and promoting biomass conversion. The key lies in the development of highly efficient and stable non-noble metal catalysts. Herein, we report a novel intermetallic CaNi2Si2 catalyst with high activity and stability for the aqueous-phase selective hydrogenation of maleic anhydride. The results from the experiments and theoretical calculations demonstrated that the high catalytic performance was due to the synergy of the electron-rich Ni active sites, enhanced adsorption of C=C bonds, and favorable activation of H2. The yield of succinic acid can be 100% over the CaNi2Si2 catalyst at the contact time of 5.4 gcat/(mmolreactant·min−1) under 3 MPa and 120 °C in the continuous flow reactor. Furthermore, the special coordination environment and electronic structure of Ni in CaNi2Si2 inhibit the formation of carboxylates, thus enhancing the acid resistance in the reaction environment. The fine design and regulation of the structure of intermetallic silicides will be important references for the controllable optimization of maleic anhydride hydrogenation catalysts and provide new insights into the development of efficient and stable selective hydrogenation catalysts in harsh reaction environments.