Chemical Looping-Steam Reforming of Biogas and Methane over Lanthanum-Based Perovskite for Improved Production of Syngas and Hydrogen

Biogas is a renewable energy resource that can be effectively utilized for hydrogen (H-2) generation. Chemical looping-steam reforming (CL-SR) of biogas produces syngas and pure H-2 in a two-stage redox process using an oxygen carrier (OC). The objective of this study was to evaluate the applicability of the lanthanum-based perovskite OC for CL-SR of biogas and methane. La0.95Ce0.05Ni0.2Fe0.8O3 perovskite was used for reforming biogas and methane in a fixed-bed reactor. Several key features of this OC were studied using nitrogen adsorption-desorption (Brunauer-Emmet-Teller method), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The perovskite and porous structure of the OC were evident from the outcome of SEM and XRD techniques. The presence of lattice oxygen was evident in the XPS spectra. The availability of lattice oxygen facilitated partial oxidation of methane and produced optimal syngas and H-2. In a fixed bed, the material (2 g) was reduced in the 750-850 degrees C range using methane (flow of 20-40 mL/min). At 850 degrees C, the syngas ratio (H-2/CO) was 2.3 mol/mol, while the values of H-2 and CO yields were 67.6 and 49.5%, respectively. Upon reduction with biogas, the yield values improved to 79 (H-2) and 62% (CO). The subsequent oxidation step using steam resulted in a H-2-rich product. The chosen La-based perovskite OC was stable for 20 redox cycles, and the average values of the syngas ratio and yields of H-2 and CO were 1.5, 60, and 52%. The purity of H-2 during the oxidation step over 20 cycles was 95%. Thus, the chosen OC was attractive for the CL-SR process.