Study On Preparation And Catalytic Performance Of Copper-Based Catalytic Materials In Urea-Choline Chloride DES

Widely employed in a variety of fields,deep eutectic solvent（DES）has been a significant supplement to non-aqueous solvent,as it adheres to the principles of green chemistry.Among them,urea-choline chloride（2:1）deep eutectic solvent is one of the earliest and most studied deep eutectic solvents,widely used in the preparation of functional materials,organic synthesis,biomass extraction and other fields.And it has the prospect of industrialization.However,the existing preparation technology only exists in the small preparation stage of the laboratory,which cannot support the subsequent industrial mass production.Therefore,the improvement of synthesis technology is a research focus.At the same time,urea-choline chloride DES has also shown its advantages in the preparation of metal catalytic materials.Therefore,a new preparation process of urea-choline chloride DES was first developed in this paper,and a copper-based catalyst for Fenton oxidation was prepared by using it as solvent and auxiliary reagent,and the catalytic performance of the catalyst was investigated.（1）The wet preparation process of urea-choline chloride DES was studied,and subsequent scale-up experiment was carried out.The synthesis of urea-choline chloride DES and its influencing factors were investigated by monitoring the changes of refractive index,electrical conductivity and density during the preparation.The effects of dry and wet preparation on the properties of urea choline chloride DES products were compared.By employing infrared spectroscopy,the molecular structure of urea-choline chloride DES was determined.The surface charge density distribution of urea and choline chloride molecules in urea-choline chloride DES was simulated by COSMO-RS module in AMS software,and the mechanism of hydrogen bonding was analyzed.The experimental results of wet preparation showed that the main properties of DES prepared by wet method were similar to those of DES by dry method when the molar ratio of choline chloride to urea was 1∶2,the temperature of the first stage was controlled at 80℃for dehydration,and the temperature of the second stage was controlled at 120℃for dehydration.At the same time,the amplification process was designed,and the kilogram class experiment was successfully carried out in the jet circulation reaction unit,and qualified DES products were obtained.In addition,DES prepared by wet method does not appear the phenomenon that the product often solidifies when prepared by dry method,which provides a new idea for the industrial scale-up production of urea-choline chloride deep eutectic green solvent.（2）Two kinds of copper-based catalysts,Cu Mn₂O₄and Cu₂（OH）₃Cl were prepared using urea-choline chloride DES as solvent.Using SEM and XRD,the surface structure of the catalyst was characterized and applied to the Fenton oxidation degradation of two dyes（methylene blue trihydrate and methyl orange）to investigate its catalytic performance.The results show that Cu Mn₂O₄ can be prepared using urea-choline chloride DES as solvent,and the structure and composition of the catalyst obtained are different from that prepared in water,and the crystallinity is better,but the subsequent catalytic performance is poor.Cu₂（OH）₃Cl prepared with urea-choline chloride DES as solvent showed good activity for the degradation of two dyes.At neutral and normal temperature,methylene blue trihydrate can reach 99.8%degradation when the amount of H₂O₂ and catalyst is 0.25 m L and 0.4 g/L.At neutral and normal temperatures,methyl orange can reach 78.8%degradation when the amount of H₂O₂ and catalyst is 1m L and 0.4 g/L.Cu₂（OH）₃Cl showed pseudo-first-order degradation kinetics for both dyes,and the degradation rate and efficiency of methylene blue trihydrate was much higher than that of methyl orange.Meanwhile,the cyclic test results show that Cu₂（OH）₃Cl still has strong catalytic activity after repeated use.（3）Cu supported polyimide catalyst material was prepared by urea-choline chloride DES and applied to photo-Fenton degradation of methyl orange dye.Among them,urea-choline chloride DES can be used as solvent and deprotonation reagent,so that copper can be better loaded on the polyimide.Characterizing the catalytic material through SEM,XRD,infrared spectroscopy,EDS,TEM and XPS,and the formation of polyimide structure and the loading of Cu were verified.The catalytic performance of the catalyst was further examined,with a single factor experiment to investigate the effect of catalyst dosage,H₂O₂dosage,p H,light intensity,initial concentration,and other conditions on the ultimate degradation efficiency.Orthogonal test was then employed to optimize the conditions.Finally,with a methyl orange concentration of 10 mg/L,p H=3,500W of light,H₂O₂ of 0.15m L,and the catalyst dosage was 3 g/L.Through kinetic fitting,the pseudo-first-order kinetic model was obtained,and The rate constant decreases as the initial concentration increases.To assess the recovery and recycling of the catalyst,a cycle test was conducted.After four cycles,the catalytic effect can still reach 96.9%.It is concluded that·OH and h⁺are active in degrading dyes by free radical quenching experiments,and their degradation mechanisms and electron transfer mechanisms are analyzed.