Reaction Mechanism Of Copper-based Catalysts In Methanol Steam Reforming And Sorption Enhanced Process

With the development of human society,the demand for energy continues to increase,and the subsequent environmental problem cannot be ignored.Hydrogen production through the steam reforming reaction of renewable biomass methanol is an important approach for industrial hydrogen production,which reduces the combustion of fossil fuels and thereby the environmental pollution.Copper-based catalysts are the most commonly used catalysts for methanol steam reforming.However,due to low Taman temperature of Copper,the sintering is an urgent problem.At the same time,the fundamental understanding of the structure and mechanism of copper-based catalysts can help to obtain more efficient catalysts to produce hydrogen.In addition,introducing sorption enhanced process to the traditional methanol steam reforming reaction could absorb carbon dioxide in situ and promote the water-gas shift reaction to increase the purity of hydrogen and reduce the content of carbon monoxide.Firstly,this paper systematically studies the effect of Al content on the catalyst structure and performance based on Cu/ZnO/Al₂O₃ catalyst.A series of zinc oxide supports containing Al are first prepared by co-precipitation,and then impregnated with copper of the same mass fraction.Experimental results show that a small amount of Al ions can be doped into zinc oxide to promote the reduction properties of the catalyst,thereby increasing the proportion of surface copper-zinc alloy and enhancing the intrinsic activity of the catalyst.When the Al content is saturated,the aluminum oxide will cover the catalyst surface and decrease the proportion of copper-zinc alloy.Cu/ZnO-x Al catalyst promotes the formation of formic acid intermediate in the reaction,suppresses the excessive production of carbon monoxide,and improves the carbon dioxide selectivity and hydrogen purity.Secondly,the methodology of ion doping is also utilized,and the Cu-Mg O/Al₂O₃bifunctional catalyst is synthesized using the sol-gel method for the sorption enhanced methanol steam reforming reaction.The surface copper maintains a small particle size and high reaction performance during the multi-cycle reaction in the presence of magnesium oxide additives.Copper ions play a significant role in promoting the CO₂sorption and desorption properties of magnesium oxide,thereby reducing the regeneration temperature and inhibiting the sintering of copper-based catalysts.The synergistic effect of copper and magnesium oxide makes Cu-Mg O/Al₂O₃ bifunctional catalyst express higher catalytic/sorption performance and cycle stability.Finally,the purity of hydrogen reaches 99.3%.This paper provides new ideas for the design of high-efficiency copper-based catalysts and bifunctional catalysts through the study of copper-based catalysts in methanol steam reforming and sorption enhanced process.