Ni/SiO2 catalysts derived from carbothermal reduction of nickel phyllosilicate in the hydrogenation of levulinic acid to ?-valerolactone: The efficacy of nitrogen decoration

Ni catalysts derived from the carbothermal reduction of nickel phyllosilicate were investigated and their application in the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) was revealed. The most effective catalyst (S3M1.5@NiPS-600) was prepared by using a sucrose-melamine mixture (molar ratio = 2:1) as the reducing agent with a proper thermal treatment (maintained at 600 degrees C for 2 h). By using S3M1.5@NiPS-600, a high GVL productivity (1387 mmol GVL/g surface Ni/h), good recyclability (4.9% loss of initial activity in five cycles), and a negligible deactivation rate were observed. The promising outcome was attributed to grafted carbon and nitrogen species on the carbothermally reduced Ni/SiO2 catalyst. Grafted carbon species improve catalyst stability whereas immobilized nitrogen species induce Ni delta+ (delta>2) with a strong Lewis acidity. Paired Ni delta+ and Ni0 sites are active in the reduction of the ketone group of LA, thereby enhancing the production of GVL.

Automated summary

Ni catalysts obtained by carbothermal reduction exhibit excellent performance in the hydrogenation of levulinic acid, with high stability and GVL productivity.