Engineering oxygen vacancies and nickel dispersion on CeO2 by Pr doping for highly stable ethanol steam reforming

Abstract

Catalytic steam reforming of ethanol has drawn great attention for sustainable hydrogen production. This paper describes the development of various CeO2 supported Ni catalysts for efficient steam reforming of ethanol. Different amounts of Pr were doped into ceria using a sol-gel strategy compared with the traditional impregnation method. The physicochemical properties of the fresh and spent catalysts, e.g., Ni dispersion, oxygen vacancies, and metal-support interaction, were well characterized by various techniques, including X-ray diffraction, N2 adsorption-desorption, H2 temperature-programmed reduction, H2 chemisorption, Raman, electron paramagnetic resonance, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Highly dispersed Ni nanoparticles, abundant oxygen vacancies and enhanced metal-support interaction have been achieved by properly doping of praseodymium (Pr) and the sol-gel preparation. The origin of abundant oxygen vacancies in Pr-doped CeO2 supported Ni catalyst has been revealed by density functional theory (DFT) calculations. Active and stable steam reforming of ethanol have been achieved on CeO2 supported Ni with suitable Pr doping. Complete conversion of ethanol has been maintained for more than 7200 min without any activity loss at 600 °C and atmospheric pressure with H2O/C2H5OH of 4 and C2H5OH-H2O gas hourly space velocity (GHSV) of 44,240 ml/gcat h−1 when Ni was loaded on 20%-Pr doped ceria (10Ni-CePr0.20). The rate of coke deposition on the optimal catalyst was as low as 0.00056 gc/gcat·h.