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

Abstract

Abstract Well-designed Ni/Al2O3–SiO2 catalysts synthesized with nickel as the active metal and alumina–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 diffuse 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·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 · 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°C. The stability of C-Ni4-Si1 was further investigated, and it was shown to react continuously and stably for more than 800 min at 550°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.