Hydrogen Production from Chemical Looping Steam Reforming of Ethanol over Perovskite-Type Oxygen Carriers with Bimetallic Co and Ni B-Site Substitution

Abstract

This paper describes the synthesis of a series of La1.4Sr0.6Ni1−xCoxO4 perovskite OCs using co-precipitation method by employing Co and Ni as the B-site components of perovskite and the synergetic effect of Co doping on chemical looping reforming of ethanol. A variety of techniques including N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and H2 temperature-programmed reduction (TPR) were employed to investigate the physicochemical properties of the fresh and used OCs. The activity and stability in chemical looping reforming were studied in a fixed bed reactor at 600 °C and a S/C ratio of three. The synergetic effect between Ni and Co was able to enhance the catalytic activity and improve the stability of perovskite OCs. La1.4Sr0.6Ni0.6Co0.4O4 showed an average ethanol conversion of 92.4% and an average CO2/CO ratio of 5.4 in a 30-cycle stability test. Significantly, the H2 yield and purity reached 11 wt.% and 73%, respectively. The Co doping was able to significantly improve the self-regeneration capability due to the increase in the number of oxygen vacancies in the perovskite lattice, thereby enhancing the sintering resistance. Moreover, Co promotion also contributes to the improved WGS activity.