Novel Mesoporous Catalysts For Oxidative Removal Of Volatile Organic Compounds

This paper focuses on the purification of VOCs emission caused by solvent use and spraying,the second largest emission source in the VOCs component list in cities.Compared with the pollution discharge industries such as refining,petrochemical and so on,this kind of organic pollutants need and pay more attention to low-temperature catalytic oxidation catalysts with high efficiency purification.In this study,a composite metal oxide of Mn Co Ox and Mn Ce Ox was designed and synthesized by a simple template method.This catalyst with a three-dimensional cubic regular pore structure exhibited excellent catalytic oxidation activity of VOCs.In this paper,the performance of the catalyst was evaluated by oxidation experiments of ethyl acetate（E.A）,ethanol（Et OH）and formaldehyde（HCHO）,and its structural properties were analyzed by a series of characterization methods,and innovative research results were obtained as follows:（1）Single metal oxide catalysts 3D-Mn O2 and 3D-Co3O4 with regular mesoporous structure were synthesized using KIT-6 mesoporous silicon as the hard template by template casting method.A series of three-dimensional mesoporous catalysts with different molar ratios of manganese and cobalt were synthesized by the method of.Finally,micro-spherical manganese-cobalt composite metal oxidation catalysts were synthesized by coprecipitation method using the same precursor solution.It was used in the catalytic oxidation of ethyl acetate,and the effects of calcination temperature,reaction space velocity（GHSV）and H₂O（g）on the reaction activity were tested.The results showed that T_100%of 3D-Mn7Co1O_xwas 150℃(1 000 ppm,30 000 h^-1),and the complete conversion temperature(T_100%)would be reduced by increasing the reaction space velocity(60 000 h^-1).The results show that higher specific surface area,lower hydrogen reduction temperature,more active oxygen species,and more high-valent metal ion content will all play a positive role in the catalytic reaction activity,especially the two variable valences with close atomic numbers.The interaction between the state metals accelerates the oxidation-reduction rate,and the appropriate molar ratio of metals can make the catalyst always maintain a high surface active adsorbed oxygen content,thereby obtaining a high catalytic activity.（2）Using KIT-6 mesoporous silicon as a hard template,a series of manganese and cerium composite metal oxide catalysts with regular three-dimensional mesoporous structure but different metal contents and proportions were synthesized by template casting method.The pore structure provides it with a larger specific surface area（135.53 m²/g）,the6nm pores of the KIT-6 template endow the catalyst with a smaller particle size,The addition of metal cerium increases the content of adsorbed active oxygen and lattice oxygen,and the bimetallic interaction of manganese and cerium enhances the oxygen mobility and promotes the flow of bulk lattice oxygen to surface lattice oxygen.Finally,the catalytic material can completely oxidize 300 ppm of formaldehyde at 100°C.（3）Synthesize ternary manganese-cobalt-cerium composite metal oxide catalyst based on the high activity of the a forementioned binary composite metal,and coat it on the cordierite honeycomb ceramic material to make a monolithic catalyst,and oxidize the monolithic catalyst by oxidizing the monolithic catalyst.The experiment examines the actual purification capacity under working conditions.It is confirmed that the mesoporous composite metal oxide catalyst has the prospect of industrial application.