Studies On Copper-Based Catalysts Of Methanol Steam Reforming For Hydrogen Production

As the global energy situation develops towards high efficiency,cleanliness and low carbon,hydrogen energy as a recognized clean secondary energy,has broad application prospects.As a good hydrogen carrier,methanol is widely used in the field of distributed hydrogen production and methanol-hydrogen fuel cells.At present,the hydrogen production technology by methanol steam reforming is a research hotspot in the field of methanol hydrogen production.In view of the high CO concentration of reforming tail gas and poor hightemperature thermal stability of traditional copper-based catalysts,this paper is optimized from the aspects of catalyst composition and preparation methods to develop high-performance industrial catalysts.The research content includes:optimizes the composition and preparation method of the catalyst based on the correlation with the catalyst performance;explores the influence of factors such as reduction temperature,water-to-alcohol ratio,liquid hourly space velocity,reaction pressure on the catalyst performance,and further test the stability of the catalyst at different temperatures.The results of the study are as follows:(1)Through the correlation between catalyst components and activity,combined with related spectroscopy,it is found that the methanol conversion rate is related to the reduction and dispersion of CuO in the catalyst,and the CO concentration of the reforming tail gas is closely related to the CO adsorption capacity.The CuO content in the copper-zinc-aluminum catalyst has a great influence on the low-temperature methanol conversion rate.The appropriate CuO content will reduce the inhibition of the phase formation of the active phase;the addition of CeO2 or ZrO2 is beneficial to improve the low-temperature methanol conversion rate.When both are added at the same time,it can further improve the performance of the catalyst,which may be related to the formation of a zirconium-cerium solid solution;by comparing the addition of different oxides,the addition of MgO is most conducive to the reduction of the CO content in the reforming tail gas;the final catalyst composition is preferably 40Cu20Zn-10Ce-10Zr-2Mg/20Al,in which the catalyst prepared by the co-precipitation method has better performance.(2)Through the correlation study of CO2 reverse water-gas shift evaluation and CO-TPD spectrum,it is found that when the catalyst has a strong CO adsorption capacity,it can inhibit the occurrence of reverse water gas shift,and also make it easier for CO to react to form CO2,which in turn reduces the CO content in the reformed tail gas.(3)The preferred reaction conditions are:catalyst reduction temperature T=300℃,water-alcohol molar ratio S/M=1.2:1,liquid hourly space velocity LHSV=2h-1,reaction pressure P=0.1MPa,reaction temperature T=250℃.The evaluation result is that the methanol conversion rate is 99.8%,and the CO content in the reformed tail gas is only 0.36%.Furthermore,the life and high temperature stability were investigated at reaction temperature T=250℃(72h)and reaction temperature T=300℃(100h).The methanol conversion rate remained above 95%,with good stability,and basically met the requirements of industrial applications.