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

摘要

Tuning the valence state and reducibility of Co active site in Co-based catalysts to improve catalytic perfor-mances 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 reduc-ibility 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 C-C 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 C-C cleavage and excellent catalytic durability.

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