Selective hydrogenation of diphenyl ethers over NiCo bimetallic catalyst

The selective cleavage of ether bonds by non-noble metal catalysts is crucial for the valorization of lignin. Bimetallic catalysts were prepared by wet impregnation using SiO2-Al2O3 as the supports and Ni and Co as the active metal sites. The prepared bimetal catalysts possess higher catalytic activity than single Ni or Co catalysts and could efficiently cleave the CO bonds of diphenyl ether (DPE), under relatively mild conditions (160 °C, 1 MPa H2, 2 h). The XPS characterization suggested the interactions between Ni and Co in the bimetal catalysts, which could bring synergy effects between metals and increase the catalytic activity. The H2-TPR analysis confirmed that the presence of Ni lowered the reduction temperature of Co oxides in the bimetallic xNiyCo/SA catalyst compared to the monometallic Co/SA catalyst, which would increase the amount of metallic Co. Based on the product distribution, it could be proposed that the hydrogenation of DPE over catalyst 15Ni15Co/SA was mainly via the reaction path of “partial hydrogenation-hydrogenolysis-hydrogenation" process. The catalytic activity of catalyst15Ni15Co/SA could be recovered after regeneration. It also exhibited versatility for the cleavage of other CO bonds.