Glycerol steam reforming over La–Ce–Co mixed oxide-derived cobalt catalysts

Abstract

La–Ce–Co mixed oxide derived Co catalysts were prepared by a co-precipitation method varying the molar ratio of Ce/La in the range of 0.1–0.9, but keeping the Co content constant (1 mol). The physico-chemical properties of the samples were investigated by Atomic Absorption Spectrometer (AAS), X-ray diffraction (XRD), laser Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-diffused reflectance spectroscopy, BET surface area, hydrogen chemisorption and temperature programmed reduction techniques. These catalysts, after reduction, were evaluated for glycerol steam reforming in the temperature range of 500–700 °C and at atmospheric pressure. The characterization results of the catalysts after reduction revealed the collapse of the perovskite structure and dispersion of Co-metal on the mixed oxide (La₂O₃–CeO₂) support. The possibility for tuning the dispersion of the Co metal to derive maximum activity and minimum coke formation was examined. The catalyst derived from the mixed oxide, La_0.7Ce_0.3CoO₃, exhibited the best catalytic activity at 700 °C with complete conversion of glycerol and a 68% hydrogen yield. The active cobalt area contributes a major part of the BET surface area of the reduced catalysts, and this is correlated well with the turnover frequency (TOF). The high dispersion with the formation of Co particles of 4–5 nm size, helped in achieving low coke formation.