Effect of Sr Substitution on the Novel La1-xSrxCo0.5Ni0.5O3-δ Perovskite-Type Catalysts for Hydrogen Production in Ethanol Steam Reforming

Abstract

La1-xSrxCo0.5Ni0.5O3-δ perovskites with different substitution of La by Sr have been firstly synthesized and applied as catalysts for ethanol steam reforming (ESR). The effect of partial Sr substitution on the performance and stability of La1-xSrxCo0.5Ni0.5O3-δ for ESR was investigated. The synthesized samples were characterized by XRD, SEM, BET, and EDS techniques. The results show that with the increase of substitution of La by Sr, the pore size and surface area of La1-xSrxCo0.5Ni0.5O3-δ perovskite increase. The doping of Sr causes changes in the specific surface area, pore volume, and pore size of the catalyst, which in turn causes changes in its catalytic activity. Meanwhile, La0.1Sr0.9Co0.5Ni0.5O3-δ with a highest SBET presents the highest ethanol conversion rate among all the samples. The modifications of catalyst characteristics caused by the Sr substitution in La1-xSrxCo0.5Ni0.5O3-δ directly affect its catalytic performance in the ESR. What is more, the influences of operating parameters on the catalytic activity of La0.1Sr0.9Co0.5Ni0.5O3-δ were studied in detail, and the optimum conditions were determined and applied for stability experiments. When the temperature is lower than 500°C, the selectivity of gas products is most likely affected by the dehydrogenation of ethanol and the decomposition of acetaldehyde. Meanwhile, the improving hydrogen selectivity and reducing the formation of by-products can be achieved by increasing the reaction temperature. The best catalytic performance for hydrogen production was achieved with La0.1Sr0.9Co0.5Ni0.5O3-δ which presented the highest ethanol conversion (98.7%) under the optimal reaction conditions. La0.1Sr0.9Co0.5Ni0.5O3-δ perovskites with higher strontium degree of substitution exhibited an excellent activity and stability of the catalysts derived.