Hydrogen production from ethanol over Ir/CeO2 catalyst: Effect of the calcination temperature

Abstract

The influence of calcination temperature on the structural property and catalytic behavior of Ir/CeO2 for oxidative steam reforming of ethanol (OSR) was extensively investigated. In order to elucidate the structure–performance relationship, the as-prepared catalysts were characterized before and after catalytic test by various techniques such as X-ray diffraction spectroscopy (XRD), Temperature programmed reduction (TPR), High resolution transmission electron microscopy (HRTEM), H2-chemisorption, Raman spectroscopy and Oxygen storage capacity (OSC), etc. The experimental results indicated that various calcination temperatures greatly affected catalyst activity and stability. The catalysts calcined below 550°C (400Ir–Ce, 550Ir–Ce) exhibited the higher values of ethanol conversion and hydrogen yield and the better performance was maintained for up to 60h, resulting from the highly dispersed Ir species and the less coke formation due to the strong metal–support interaction (MSI). On the contrary, the 850Ir–Ce sample, processing weaker MSI, presented a less catalytic behavior, the complete ethanol conversion being reached only at 650°C rather than 450°C compared to the other systems. Stability test of 850Ir–Ce catalyst also revealed that H2 concentration in the outlet gas continuously decreased from 41mol% to 33mol%, which was caused by the combination of deactivating coke formation and the serious sintering of active Ir particles. Such an original and quantified structure sensitivity analysis might shed light on the development of high efficient catalyst for hydrogen production from biomass-derived feedstocks.