Study On Non-Noble Metal Oxides Catalyze The Low Temperature Combustion Of Chlorobenzene

The environmental issues of the emission of volatile organic compounds（VOCs）are getting worse with the rapid growth of industry.The volatile organic compounds（VOCs）that include chlorine have drawn a lot of attention due to their toxicity,carcinogenicity,and ease of buildup in the environment.Because of its low operating temperature and great efficiency,catalytic oxidation is one of the treatment technologies that has received the most attentions.Therefore,it is essential to design and prepare an effective catalyst to catalyze the oxidation of volatile organic compounds that include chlorine.In this paper,a series of cobalt-based double perovskite catalysts and Cu/Ce-MOF-were prepared for the catalytic oxidation of chlorobenzene,and the structure-activity relationship between the physicochemical properties and catalytic activity of the catalysts was studied.The missing surface A site of the cobalt-based double perovskites La₂BCo O₆（B=Cu,Fe,Ni,Al）was prepared in this study by nitric acid etching,which was then used for the catalytic combustion of chlorobenzene.In order to expose additional B’and B’’（Cu,Co）active sites without compromising the structure,the specific surface area is modified by adjusting the nitric acid concentration and etching time.La₂Cu Co O₆ demonstrated the highest level of catalytic activity out of this group of double perovskite catalysts.La₂Cu Co O₆ had a T₉₀ that was 250°C lower after being etched with 5%nitric acid.The structure and properties of prepared catalysts have been well characterized by XRD,SEM,TEM,XPS,H₂-TPR,NH₃-TPD.Nitric acid etching modification dramatically boosted the quantity and strength of acid sites on the catalyst’s surface,which facilitated chlorobenzene adsorption and dissociation.Additionally,nitric acid etching altered the surface charges of the Cu and Co sites and provided the Cu⁺+Co³⁺?Cu²⁺+Co²⁺oxidation cycle,all of which promoted the generation of surface reactive oxygen species,improved oxygen mobility,and increased catalytic activity.La₂Cu Co O₆ with a 5%nitric acid etching yielded good catalytic stability at T₉₀.After being evaluated for 100 h,conversion of chlorobenzene only decreased 9%.This research offers a fresh technique for creating stable,highly effective catalytic combustion catalysts that contain chlorine VOCs.Secondly,to improve the dispersion of Cu O on support and reduce the size of Cu O nanocrystal,the Ce-MOF catalyst precursor was prepared the solvothermal approach.Cu²⁺in the solution was then caught by the EDTA grafting method,resulting in a highly distributed nanoscale Cu layer on the rod-like Ce-MOF.The same catalyst was prepared by the impregnation method.The catalytic oxidation activity of chlorobenzene on these two catalysts,as well as the relationship between Cu particle size and dispersion in Cu-Ce-MOF catalysts,were compared.All the prepared catalysts have been well characterized by XRD,SEM,TEM,XPS,H₂-TPR,NH₃-TPD to find out the differences of structure and properties.The results demonstrated that the grafted catalyst exhibited a greater catalytic activity for the oxidation of chlorobenzene.The characterization results revealed finer Cu particles,more uniform dispersion,and a more powerful contact force between Cu and Ce.This is due to the incorporation of a portion of Cu into the Ce lattice,which alters the lattice structure and increases the amount of oxygen vacancies,both of which are essential for the catalytic oxidation of chlorobenzene.The Cu-Ce-MOF catalyst prepared by grafting method was superior to the impregnation method for the combustion of chlorobenzene.It offers both theoretical and experimental support for the development of highly active catalysts.