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

The selective hydrogenolysis of C O bonds is critical for the effective valorization of lignin. Herein, we synthesized a series of highly efficient Ni x Co y Al-T catalysts by a coprecipitation-calcination-reduction method and evaluated their catalytic hydrogenolysis performance towards the C O bonds of lignin-derived aryl ether, using isopropanol as the hydrogen donor source. The results revealed that the Ni 0.5 Co 1.5 Al-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 Ni 0.5 Co 1.5 Al-600 catalyst facilitated the cleavage of C O bonds in lignin model compounds. Furthermore, the β-benzyl-H atom in 2-phenoxy-1-phenylethanol (PPE) also contributes to the cleavage of C aliphatic -O bonds. Under optimized reaction conditions (180 ℃, reaction time 2 h), PPE was completely converted over the Ni 0.5 Co 1.5 Al-600 catalyst, and the yield of ethylbenzene and cyclohexanol reached 95.91wt% and 85.73wt%, respectively. These findings demonstrate that the Ni x Co y Al-T catalytic system holds great promise for the production of valuable chemicals from lignin under mild conditions.