Highly efficient catalytic hydrogenolysis of lignin model compounds over hydrotalcite-derived Ni/Al2O3 catalysts

Catalytic hydrogenolysis of C-O bonds in lignin provides a promising route to produce high value-added bio-fuels and chemicals. However, designing highly active and stable catalysts for this process is still a challenge. Herein, a series of Ni/Al2O3 catalysts were synthesized by calcination and reduction of layered double hydroxide precursors, and their activities were evaluated in the catalytic conversion of lignin-derived compounds. Diphenyl ether was completely converted with a 100% monomeric selectivity (cyclohexane and cyclohexanol) over the optimized Ni/Al2O3-500 under the optimal conditions of 200 celcius, 0.5 MPa H2 and 1.5 h, indicating the excellent catalytic activity in the cleavage of C-O bonds of the catalyst. The excellent catalytic performances of Ni/Al2O3- 500 were originated from its relatively large specific surface area, well-developed porosity, small crystallite size, high Ni0 concentration and strong interaction between the active metal and support. The reusability experiments show that Ni/Al2O3-500 possesses a relatively high stability for six reuses. Moreover, various lignin model compounds can be completely converted to corresponding monomeric products over Ni/Al2O3-500, indicating the applicability of this ingenious catalyst. The application of the hydrotalcite-derived Ni-based catalysts with high activity and stability provides a promising approach for the efficient hydrogenolysis of lignin derivatives.

Automated summary

C-O bonds in lignin can be efficiently cleaved by a hydrotalcite-derived Ni-based catalyst, leading to the production of high value-added bio-fuels and chemicals. The optimized Ni/Al2O3-500 catalyst exhibits excellent catalytic activity and stability, with complete conversion of diphenyl ether to monomeric products under optimized conditions. This catalyst shows promising potential in the hydrogenolysis of lignin derivatives.