Study On Process Analysis And Materials Behavior In Ca-Cu Chemical Looping For High-Purity H₂ Production

As a clean,efficient,safe and sustainable energy,hydrogen is widely used in the fields of energy,chemical,refining,metallurgy and space.At present,hydrogen is mainly produced through natural gas reforming.With the increasing tension of the global energy situation and the environmental pollution problem,the traditional hydrogen production technology by natural gas is more and more difficult to meet the needs of industrial production.In this context,Ca-Cu chemical looping for hydrogen production has emerged.Through coupling the CO₂ absorption/desorption process of the calcium based material and the oxidation/reduction process of the copper based oxygen carrier,the hydrogen production efficiency of the reaction system is greatly improved,and the energy self supply problem in the regeneration process of the calcium based adsorbent is solved.It provides a broad prospect for the clean and efficient utilization of natural gas,and has a positive significance in the supply of industrial raw materials,the effective conversion of energy and the global environmental protection.Therefore,it is necessary to study the reaction process in the system and develop efficient functional materials for its future industrial application.In this work,we firstly calculate and analyze the products under different reaction temperature,pressure and S/C molar ratio in SMR and SESMR based on the minimization of Gibbs free energy method.And the influence of CaO addition on the traditional hydrogen production system is deeply studied.The conditions of SESMR reaction are finally optimized,it can provide a theoretical basis for experimental research and the future industrial application.In addition,the compatibility of commonly used Ni based catalysts and Cu based oxygen carriers in reaction process is studied and reported for the first time.High copper content NiO/CuO composites were prepared by coprecipitation,sol-gel and wet mixing.Their catalytic activity and compatibility for H₂ production was measured using a fixed-bed reactor system equipped with an online gas analyzer.The results show that the presence of CuO could hinder the activity of Ni-based catalysts in H₂ production,even if the CuO content is reduced to 1 wt.%,its existence will also have a negative effect on Ni/Cu composites,and the negative effect of CuO is strengthened with increasing CuO content and calcination temperature during sample preparation.With the help of a series of specific test and characterization techniques（SEM-EDS,TEM,BET,XRD,TPR and XPS）,interaction rules between NiO and CuO was further investigated and understood,and based on that an action mechanism model was proposed.Furthermore,an arrangement of mixed particles that avoiding the intimate contact of CuO/NiO was suggested and tested,and a superior performance was demonstrated while observing no restrictions of CuO on Ni-based catalysts in sorption-enhanced steam-methane reforming under the conditions of Ca-Cu chemical looping.