Selective hydrogenolysis of C-O bonds in lignin model compounds and Kraft lignin over highly efficient NixCoyAl catalysts

Abstract

The selective hydrogenolysis of CO bonds is critical for the effective valorization of lignin. Herein, we synthesized a series of highly efficient NixCoyAl-T catalysts by a coprecipitation-calcination-reduction method and evaluated their catalytic hydrogenolysis performance towards the CO bonds of lignin-derived aryl ether, using isopropanol as the hydrogen donor source. The results revealed that the Ni0.5Co1.5Al-600 catalyst displayed superior activity and its catalytic performances were strongly influenced by the Ni/Co molar ratios and calcination temperatures. The enhanced dispersion of metal particles and the electron transfer from Ni to Co in Ni0.5Co1.5Al-600 catalyst facilitated the cleavage of CO bonds in lignin model compounds. Furthermore, the β-benzyl-H atom in 2-phenoxy-1-phenylethanol (PPE) also contributes to the cleavage of Caliphatic-O bonds. Under optimized reaction conditions (180 ℃, reaction time 2 h), PPE was completely converted over the Ni0.5Co1.5Al-600 catalyst, and the yield of ethylbenzene and cyclohexanol reached 95.91wt% and 85.73wt%, respectively. These findings demonstrate that the NixCoyAl-T catalytic system holds great promise for the production of valuable chemicals from lignin under mild conditions.