Preparation of fly ash nickel catalyst and its application in catalytic pyrolysis of rice straw for syngas production

The catalytic pyrolysis of rice straw for syngas (H2 + CO) production with nickel oxide (NiO)/fly ash catalysts was investigated in a horizontal fixed-bed quartz tube reactor. Besides, X-ray diffraction, X-ray fluorescence, field emission scanning electron microscopy, and Brunauer-Emmett-Teller analysis were employed to study the physiochemical properties of the catalysts before and after catalytic pyrolysis of biomass. The results illustrated that NiO was uniformly loaded on the surface of fly ash via a filament-like coating. Furthermore, the effects of calcination temperature (400 to 700 °C), reaction temperature (550 to 800 °C), holding time (5 to 35 min), and NiO loading (5 to 30 wt%) on the catalyst performance were investigated. Analysis of the gas composition showed that the NiO/fly ash catalyst had the best ability to increase H2 and CO concentration at a 400 °C calcination temperature, 600 °C reaction temperature, 20 wt% NiO loading, and 20 min holding time. Compared with rice straw pyrolysis alone at these conditions, the concentration of H2 and CO experienced a steep increase from 7 vol% to 41 vol% and 18 vol% to 34 vol%, respectively. The catalyst developed in this research opens a new pathway for the utilization of fly ash in the field of biomass pyrolysis.