Anchoring nickel sites on ceria-coated silica to enhance the catalytic stability for the vapor phase levulinic acid hydrogenation

Abstract

The preparation of the binary metal NiCe-based catalysts involved a 2-step protocol, the ceria was first coated on SiO2 which was then utilized to disperse Ni nanoparticles. Various techniques including N2 adsorption/desorption, ICP-OES, XRD, HRTEM, XPS, H2-chemisorption, H2-TPR, NH3-TPD, and TG etc. were performed to study the microstructure, redox, acid property and deactivation. The results revealed that CeO2 and metallic Ni were well dispersed on the support surface, the synergistic effect between the two metal species was conserved well. The content of CeO2 had considerable effects on redox and metallic properties rather than the acidic property. The dispersion of metallic Ni played a dominant role in promoting the catalytic activity. The levulinic acid conversion attained 84.0 % with a γ-valerolactone selectivity of 98.8 % on Ni/SiO2@2CeO2 sample with the highest dispersion of 9.8 %. The amorphous CeO2 suppressed the sintering of metallic Ni nanoparticles and improved the coke resistance, leading to better catalytic activity within 20 h time on stream.