Electron density donation of concomitant peroxide anions in La0.25Ce0.75O1.88 boosting cobalt-catalyzed ethanol steam reforming for hydrogen production

Abstract

Tuning the valence state and reducibility of Co active site in Co-based catalysts to improve catalytic performances is desirable for hydrogen production from ethanol steam reforming (ESR) reaction. In this work, we fabricate Co/LaxCe1−xO2−x/2 (x = 0.5, 0.25, 0.17) catalysts and investigate their catalytic performances for ESR reaction. Our studies manifest that the catalytic performances of Co-based catalysts have been effectively improved by La doping in CeO2. Among the investigated catalysts, Co/La0.25Ce0.75O1.88 exhibits the highest catalytic activity and durability, the hydrogen yield reaches as high as 80 % at ethanol conversion of 100 %, with an excellent durability during long-time (58 h) catalytic experiment. X-ray photoelectron spectroscopy (XPS) and hydrogen temperature programmed reduction (H2-TPR) studies demonstrate that the valence state and reducibility of the Co/La0.25Ce0.75O1.88 are effectively regulated via donation of electron density from the concomitant peroxide anions in La0.25Ce0.75O1.88 to the supported cobalt catalyst, the CC bond cleavage capability has been significantly enhanced to boost the hydrogen-production efficiency from ESR reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies reveal that Co/La0.25Ce0.75O1.88 shows a remarkable preference for producing C1 products, the Co species in low valence state and with high reducibility result in highly efficient CC cleavage and excellent catalytic durability.