Optimized Ni/Al2O3-SiO2 Catalyst for Steam Reforming of Phenol with Enhanced Hydrogen Production and Stability

Well-designed Ni/Al2O3-SiO2 catalysts synthesized with nickel as the active metal and alu-mina-silica as the catalyst mixture support were investigated for steam reforming of phenol with enhanced hydrogen production and stability. The prepared catalysts were characterized using x-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller (BET), Fourier transform infrared, hydrogen temperature-programmed reduction, pyridine dif-fuse reflectance infrared Fourier transform spectroscopy (Py-IR), and thermal gravimetric-differential scanning calorimetry (TG-DSC) techniques in detail. The BET results show that their specific surface areas ranged from 29.832 to 220.330 m2 center dot g-1. The Py-IR results indicate the existence of large Lewis acid regions in the pure C-Ni ("C-Nix-Siy" means the Ni/Al2O3- to-SiO2 catalyst prepared with Ni(CH3COO)2 center dot 4H2O with SiO2 support mass ratios of y/(x + y).) and C-Ni4-Si1. The effects of the Ni/Al2O3-to-SiO2 mass ratio, reaction temperature, and active metal salt anion species on catalytic activity were studied. The results show that the C-Ni4-Si1 catalyst using nickel acetate tetrahydrate as the active metal salt with an SiO2 mass ratio of 20 wt% achieves a maximum phenol conversion of 97.3 % and hydrogen production of 92.7 % at 550 degrees C. The stability of C-Ni4-Si1 was further investigated, and it was shown to react con-tinuously and stably for more than 800 min at 550 degrees C with excellent catalytic reaction stability. A final weight loss of only 9.31 % shown in the TG-DSC result of the spent C-Ni4-Si1 catalyst confirmed the excellent thermal stability and low coking rate of C-Ni4-Si1.