A novel, modified CaO for use as a CO2 sorbent was prepared by dipping 2.0 wt.% V2O5 in CaO. A vanadate, Ca2V2O7, was generated in the modified CaO and analyzed via X-ray diffraction. The experiments show that Ca2V2O7 neither adsorbed CO2 nor improved the microstructure of the sorbent; however, it accelerated the CO2 capture rate of CaO, as well as the decomposition rate of CaCO3, during the carbonation/calcinations cycles, thereby improving the CO2 capture capacity of the CaO-based sorbent and reducing the energy consumption of calcination. A process that separates hydrogen from syngas has been investigated by combing the chemical looping of a Fe-based catalyst (as the oxygen-transfer material) and that of the modified CaO (as the CO2 sorbent) in a fixed-bed reactor. Two operational stages, one for hydrogen enrichment and the other for solid regeneration, were alternately implemented under atmospheric pressure. The effects of the gas flow velocity, temperature, solid composition, and steam concentration on the hydrogen yield during the enrichment stage were investigated. The obtained information was used to optimize the operational conditions of the enrichment stage, and a hydrogen purity above 99.5% and a hydrogen yield reaching 27.91 mmol/g Fe catalyst were achieved. A total of 13 cycles were completed using the same solids. The regeneration of iron oxide during each regeneration stage reached 98% and that of the modified CaO was above 94%; however, a gradual decline in the performance of the solids after the third cycle occurred because of sorbent sintering. (C) 2012 Elsevier Ltd. All rights reserved.