Study of the reactivity of Double-perovskite type oxide La 1−x M x NiO 4 (M = Ca or Sr) for chemical looping hydrogen production

Abstract La 2-x M x NiO 4 perovskite oxygen carriers (OC) doped with Ca and Sr (x = 0.05 and 0.20) in the site La were prepared by microwave assisted combustion method and calcined at 800 °C for 2 h. A reactivity study was carried out applying pulses of H 2 , O 2 and CH 4 . The reactions involved in each step, as well as H 2 production, were studied to evaluate the redox properties of each OC. The crystalline structure, morphology, reduction and oxidation profiles were determined by XRD, SEM and TPR/TPO cycles, respectively. The results indicate that the dopant (Ca or Sr) strongly affect the structure and reactivity of the OC. The increase in dopant concentration increased the degree of crystallinity and the amount of the A 2 BO 4 phase formed. The increase in dopant concentration decreased the reducibility of the perovskite. OCs doped with Ca showed higher conversion percentages, and also higher H 2 production. In carriers doped with Sr no coke formation was observed.