Immobilized Ni Clusters in Mesoporous Aluminum Silica Nanospheres for Catalytic Hydrogenolysis of Lignin

It remains a substantial challenge to develop a strategy to manipulate the defects of a support which affect the dispersion and morphology and ultimately the catalytic performance of active metals. Herein, we report the surface defect control on the support by evenly incorporating Al into the framework of mesoporous silica nanospheres (MSNs), which further anchored Ni clusters. Immobilized Ni clusters with an average size of 1.2 nm were highly dispersed inside the channel of mesoporous aluminum silica nanospheres (MSN-Al). X-ray absorption spectra showed that most of Ni atoms were reduced to the metallic state. Immobilized Ni(O) clusters facilitated the hydrogenolysis of lignin C-O linkages. After the reaction, two-dimensional heteronuclear single quantum correlation (HSQC) nuclear magnetic resonance revealed that the total beta-O-4 linkages of organosolv lignin were completely depolymerized. Ultimately, the total mass yield of phenolic monomers on the Ni/MSN-Al catalyst was about 2 times higher than that of the Ni/gamma-Al2O3 catalyst from the hydrogenolysis of organosolv lignin.