Preparation Of Highly Active Cobalt Based Catalysts And Their Performance In Ethanol Steam Reforming For Hydrogen Production

The development of Chinese energy industry is transforming in the direction of renewable and clean.Hydrogen energy is considered to be one of the most ideal,efficient and cleanest renewable energy sources to replace fossil fuels.In recent years,governments have introduced hydrogen energy policies to support the development of the hydrogen energy industry,which has led to an exceptionally rapid development of the hydrogen energy sector.Among the many technological approaches to hydrogen production,ethanol steam reforming has been of great interest to many researchers because of its non-toxic feedstock,wide source and convenient transportation and storage.In the ethanol steam reforming reaction,the catalyst activity determines the overall performance of the reaction.Therefore,the optimization of catalyst modification is the main research direction at present.In this paper,BaCoO3 were perovskite "all-in-one" catalysts and prepared by citric acid(CA)and ethylenediaminetetraacetic acid(EDTA)assisted sol-gel method,and modified with different ratios of nickel doping.The performance of the xNi/BaCoO3 catalysts was tested by medium and high temperature heterogeneous catalytic reforming in ethanol water steam reforming hydrogen production system and characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),fully automated physical adsorption(BET)and so on.The results indicated that B-N-C-20 with 20%Ni doping showed the best catalytic performance,with ethanol conversion of 100%and H2 selectivity of nearly 70%at the reaction temperatures of both 600℃ and 650℃.This was attributed to the fine branching structure of B-N-C-20 in the form of blocks and thin rods with significantly increased specific surface area.The small amount of Ni doping enhanced the Ba and Co phase’s reduction performance and improved the catalytic activity of the material.In order to investigate the effect of different metal phase precursors on the performance of cobalt-based catalysts,NA-MA and AA-MA catalysts were prepared by impregnation method using cobalt nitrate and cobalt acetate,respectively.The surface morphology structure of AA-MA was tested to be more dense,and the material was found to be powdered rather than hard lumpy during the preparation process,which was more convenient for subsequent processing.The Co3O4 particles were smaller in size and evenly distributed,and showed significant improvement in ethanol conversion and stability in the performance test,which inhibited the methanation reaction of CO and CO2 to a certain extent and promoted the methane reforming reaction.Based on the most commonly used impregnation method,a new catalyst preparation method is proposed in this paper:vacuum rotary evaporation technique.The water bath heating method,overall rotation and internal low-pressure conditions promote the formation and movement of bubbles,greatly reduce the material preparation time.These factors enhance mixing effect between particles and improve the microstructure of the catalyst,as evidenced by the 34.3%increase in specific surface area,smaller crystal size and higher dispersion of Co3O4 and CeO2.The comparative results of ethanol conversion,product selectivity and stability tests also prove that vacuum rotary evaporation technology has a better impregnation effect.