Modification Of CuCl₂ Or CuCl₂/FeCl₃ By Dielectric Barrier Discharge To Prepare Heterogeneous Catalysts And Their Catalytic Performance For Benzene Hydroxylation

Dielectric barrier discharge（DBD）plasma consists of high-energy electrons and active particles,and it also can be operated at room temperature and atmospheric pressure,which makes it remarkably prominent in preparing the catalyst.The CuCl₂-H₂O₂system shows good hydroxylation activity in benzene hydroxylation.However,CuCl₂is very soluble in organic solvents and water,and is difficult to separate from the reaction system.In order to make it exhibit high activity and can be recycled and reused in benzene hydroxylation reaction,part of Cl^-removed by dielectric barrier discharge to convert CuCl₂into insoluble matter was studied,which can be recycled and reused in benzene hydroxylation.In addition,FeCl₃was introduced into CuCl₂,and the catalyst obtained by DBD plasma exhibited higher catalytic activity in benzene hydroxylation reaction.The main research content is the following two parts:1.CuCl₂·2H₂O powder was exposed to DBD plasma to prepare heterogeneous CuCl₂-DBD catalyst at room temperature and atmospheric pressure.Furthermore,the effects of discharge time,discharge atmosphere and discharge power on the activity of the catalyst were investigated.The results indicated that after DBD plasma treatment,CuCl₂-DBD catalyst exhibited irregular globules with an average size of about 38 nm.The specific surface area was slightly decreased and the pore volume was significantly increased.However,the H3 type mesoporous structure and crystal structure of CuCl₂·2H₂O had not been changed.Cl and crystal water decreased greatly in CuCl₂-DBD,while the contents of Cu and O increased,and new Cu-O bonds had also been observed.CuCl₂·2H₂O can be dissolved in polar solvent（acetonitrile）.CuCl₂-DBD is insoluble in polar solvent（water or acetonitrile）and can be recycled for reuse.CuCl₂-DBD has good adsorption properties for benzene as heterogeneous catalyst.The activity and stability of CuCl₂-DBD in benzene hydroxylation reaction and the optimum conditions of benzene hydroxylation reaction were also investigated.Under optimized conditions,the phenol yield was 18.6%and the selectivity was 95.6%.The catalyst was reused for 4 times,and the activity and stability were basically unchanged.2.Mixed powders of CuCl₂/FeCl₃were exposed to DBD plasma to prepare heterogeneous X%Fe/CuCl₂-DBD catalysts at room temperature and atmospheric pressure.The effect of the molar ratio of FeCl₃to CuCl₂on the catalytic performance of the catalyst was studied,with X%was 4%,8%,12%respectively.And the catalytic performance was the best when the molar ratio of FeCl₃to CuCl₂was 8%.The results indicated that after DBD plasma treatment,new Cu-O and Fe-O bonds had been observed,with a small part of Cu²⁺was reduced to Cu⁺,and Fe₂O₃,CuCl,Cu₂Cl（OH）₃appeared.The morphology of the catalyst was no longer small sphere of uniform size,and the phenomenon of particle agglomeration was obvious.The H3 type mesoporous structure was remained.As the iron content increased,the specific surface area increased.As heterogeneous catalyst,the X%Fe/CuCl₂-DBD catalyst have good adsorption properties for benzene.The activity and stability of X%Fe/CuCl₂-DBD catalyst in benzene hydroxylation reaction and the optimum conditions of benzene hydroxylation reaction with 8%Fe/CuCl₂-DBD were investigated.Under optimized conditions,the phenol yield was 22.3%and the selectivity was 92.6%.The activity of the 8%Fe/CuCl₂-DBD catalyst was higher than CuCl₂-DBD catalyst.The reuseability and stability of8%Fe/CuCl₂-DBD catalyst were basically unchanged.