Surface modification of solution combustion synthesized Ni/Al2O3 catalyst for aqueous-phase reforming of ethanol

The effect of surface modification of an alumina powder supported nano-scale nickel catalyst used in aqueous-phase reforming of ethanol has been explored in this paper. The Al₂O₃ powder was prepared by a solution combustion synthesis (SCS) route and the surface of the powder was modified by a non-thermal RF plasma treatment using nitrogen gas. Catalysts were coated by an impregnation method. The performances of the unmodified and modified Ni/Al₂O₃ catalysts have been compared from a catalytic activity, selectivity, and microstructural point of view. The catalytic activity results showed that while nature, relative ratio and selectivity of the products both in gas and liquid effluents did not change, catalytic activity (in terms of EtOH conversion and H₂ yield per g) of the sample increased after plasma modification. Microstructural (XRD, surface area) analysis showed that phase content and surface area of unmodified and modified catalysts are similar, while TEM and H₂-chemisorption showed higher metal surface area, higher metal dispersion and lower active metal particle size for the modified sample compared to the unmodified sample. The temperature programmed reduction (TPR) analysis demonstrated stronger support-metal interaction and smaller NiO particles for the modified catalyst at lower heat treatment temperature. The temperature programmed desorption (TPD) of ammonia analysis showed stronger acidity for the modified support, which can explain better dispersion of the metal particles on the modified catalyst compared to the unmodified sample.