Experimental investigation of sorption enhanced chemical looping reforming for high purity hydrogen production using CeO2–CaO CO2 sorbent and 15Fe–5Ca/Al2O3 oxygen carrier

Abstract

In this research, high purity hydrogen production is investigated using sorption enhanced chemical looping reforming (SE-CLR). Prior to SE-CLR tests, the cerium promoted calcium based sorbents are synthesized, characterized and applied in calcium loop for CO2 removal. The response surface methodology (RSM) is applied to study the effect of independent variables including sorption temperature (550–650°C), Ce loading (10–30wt.%) and cycle number (1–9) on CO2 removal efficiency. Based on experimental results, the sorbent containing 30% Ce is selected as the best CO2 sorbent in calcium loop process. After that, in SE-CLR process the effect of reduction temperature (550–650°C), oxygen carrier (OC) type (15Fe/Al2O3 and 15Fe-5Ca/Al2O3) and sorbent to oxygen carrier ratio (1–4) are investigated on the purity of produced hydrogen. The results showed that the H2/CO molar ratio approaches in one-step to 17.5 in SE-CLR considering 15Fe–5Ca/Al2O3 oxygen carrier at 600°C and sorbent/OC=3, while it is about 5 in conventional CLR process. It represents the production of hydrogen with high purity (about 89vol. %) in SE-CLR process. The prepared samples including sorbent materials and oxygen carriers are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and energy dispersive X-ray spectroscopy (EDX) techniques.