Study On The Mechanism Of Complexing Agents On CuZnAl Catalysts For Ethanol Synthesis From Syngas

Energy is an indispensable material basis for the progress and development of modern society.While enjoying the convenience of energy,human beings are also faced with huge challenges brought by environmental pollution caused by excessive exploitation.Therefore,How to find a way to use energy cleanly and efficiently and speed up the development of clean green energy has become a top priority for countries.The synthesis of ethanol by coal-based gasification to syngas and then catalytic conversion can not only ease the dependence on petroleum energy and improve our coal energy utilization rate,but also reduce the environmental pollution caused by coal combustion,which is considered as one of the research topics with great industrial value and industrial application prospects.In this paper,a one-step synthesis of ethanol from non-noble metal Cu-based catalysts was studied.The Cu ZnAl catalyst was prepared using the original complete liquid phase methods developed by our group,and was modified by adding of a series of organic complexing agents.Their effects on the structure and property of CO hydrogenation to ethanol were also investigated.In addition,the optimal complexing agents and formulations were explored in order to prepare a catalyst with excellent performance for synthesizing ethanol.The catalyst was characterized by XRD,FT-IR,H₂-TPR,NH₃-TPD-MS,XPS and N₂ adsorption and other related methods to obtain the relationship between the macroscopic properties and the microstructure of the catalyst.Main conclusions are as follows:1.Compared with the addition of complexing agents,the reaction process itself had a greater influence on the texture properties of the catalyst.The introduction of a neutral complexing agent would enlarge the Cu particle size and produce anti-reducible Cu⁺as well as reduce the surface Cu content and exacerbate the surface carbon deposition,resulting in a decrease in the CO conversion rate.2.The basic complexing agent could effectively increase the specific surface area of the catalyst during the reaction and promote the dispersion of Cu.It was especially obvious that the suitable amount of ethanolamine was beneficial to strengthen the interaction among Cu,Zn and Al,and more ethanolamine content would reduce the specific surface area and improve the crystallinity of ZnO.3.The compound complexing agents prepared by mixing neutral and alkaline organic complexing agents in different proportions were used to modify the CuZnAl catalysts,and the reduction ability of the corresponding high-valent copper was between the two single-component complexing agent-modified catalysts.In addition,the presence of anti-reducible Cu⁺and a lower amount of weak acid on the surface may be more conducive to the synthesis of ethanol.4.The addition of organic complexing agents improved the catalytic performance.Particularly,the neutral complexing agents achieved the highest selectivity for ethanol and higher alcohols(C₂₊OH)and the basic complexing agents obtained the greatest increase in the CO conversion.However,the compound complexing agent mixed by neutral and basic complexing agents inherited both advantages.When the molar ratio of glucose to ethanolamine was 1:1,the conversion of CO was nearly doubled?4.64%?9.14%?,while the selectivity of ethanol in liquid products remained almost unchanged,reaching 36.24%.