Enhanced hydrogen production by sorption-enhanced steam reforming from glycerol with in-situ CO2 removal in a fixed-bed reactor

Abstract

For the fixed-bed reactor configuration in the sorption-enhanced steam reforming process (SERP), solid mixture of catalyst and sorbent is stationary and alternatively exposed to reaction and regeneration conditions for multi-cycles by periodically switching the feed gases for enhanced hydrogen production with in-situ CO2 removal. A NiO/NiAl2O4 catalyst was synthesized by the co-precipitation method with rising pH technique and the crystalline spinel phase of NiAl2O4 was formed under the calcination temperature of 900°C. The catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), thermo-gravimetric analysis (TGA), and N2 adsorption–desorption. The non-stoichiometric thermodynamic calculation was carried out to determine the effects of temperature and in-situ CO2 removal on the enhancement of hydrogen production by SERP from glycerol at 425–700°C. The multi-cycles on reaction and regeneration for hydrogen production by SERP from glycerol were performed by NiO/NiAl2O4 catalyst and CaO based sorbent in a fixed-bed reactor. The results showed that hydrogen production by SERP can be clearly divided into three periods, and the experimental gaseous products were compared with non-stoichiometric thermodynamic calculations. It is obvious that H2 purity was greatly increased, and CO2, CO and CH4 concentrations were reduced by in-situ CO2 removal during the pre-breakthrough period. It is found that enhanced hydrogen production was mainly depended on in-situ CO2 removal. The operation durations for producing high-purity hydrogen of more than 90% were decreased with the increase of the cycles. It may due to the decrease in the reactivity of CaO based sorbent after multi-cycles reaction and regeneration.