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.