Pyrolysis/reforming of rice husks with a Ni–dolomite catalyst: Influence of process conditions on syngas and hydrogen yield

The influence of process conditions on the production of syngas and H₂ from biomass in the form of rice husks was investigated using a two-stage pyrolysis/catalytic reforming reactor. The parameters investigated were, reforming temperature, steam flow rate and biomass particle size and the catalyst used was a 10 wt.% Ni–dolomite catalyst. Biomass was pyrolysed in the first stage, and the product volatiles were reformed in the second stage in the presence of steam and the Ni–dolomite catalyst. Increase in catalyst temperature from 850 °C to 1050 °C marginally improved total syngas yield. However, H₂ yield was increased from 20.03 mmol g⁻¹ at 850 °C to 30.62 mmol g⁻¹ at 1050 °C and H₂ concentration in the product gas increased from 53.95 vol.% to 65.18 vol.%. Raising the steam flow rate increased the H₂ yield and H₂ gas concentration. A significant increase in H₂:CO ratio along with a decrease in CO:CO₂ ratio suggested a change in the equilibrium of the water gas shift reaction towards H₂ formation with increased steam flow rate. The influence of particle size on H₂ yield was small showing an increase in H₂ production when the particle size was reduced from 2.8–3.3 to 0.2–0.5 mm.