Ni nanoparticles supported on mesoporous silica (2D, 3D) architectures: highly efficient catalysts for the hydrocyclization of biomass-derived levulinic acid

Ni nanoparticles supported on various mesoporous silicas with 2D (COK-12) and 3D architectures (KIT-6 and SBA-16) exhibited superior catalytic performance in the vapor-phase hydrocyclization of biomass-derived levulinic acid at atmospheric pressure. The catalysts were systematically characterized by XRD, N-2 physisorption, FTIR, SEM-EDAX, NH3-TPD, TPR, H-2 chemisorption, HRTEM, and XPS techniques. The retention of the mesoporous structure of the catalysts was confirmed by the low angle XRD, pore size distribution, SEM, and TEM. TPR results suggested the presence of Ni particles inside the 3D-pore architecture of SBA-16 and KIT-6. Whereas in the case of 2D-architectured silica (COK-12), most of the Ni particles were laid on the surface of the support and/or no particles were found in the inside of the pore. The physico-chemical characteristics like confinement-effect and interconnected network of the catalysts play a crucial role in the catalytic activity and product distribution. Deep hydrogenation of levulinic acid to 2-methyl tetrahydrofuran was observed over Ni supported on 3D architectured silicas (KIT-6 and SBA-16) which can be attributed to confinement of Ni nanoparticles in 3D architectured silicas.