Research On Preparation Of Nano-structured Metal Oxide And Catalytic Removal Of VOCs

As one of the main reasons of air pollution,VOCs has produced serious environmental issue and influenced people’s health.There are many methods to solve VOCs,catalytic oxidation method could decompose VOCs into carbon dioxide and water without secondary pollution.It’s important to synthesize an efficient,stability,economy and wide application range catalyst for VOCs degradation and mitigation of environmental problems.In this paper,we prepared different nano morphology and structure of Co₃O₄ catalytic materials and these materials were used in formaldehyde（HCHO）,ethanol（EtOH）,ethyl acetate（EA）,toluene（PhMe）of catalytic performance research,and then did a series of characterization of the catalysts.The main research contents of this topic are as follows:（1）The nanorod（NR-）and nano flower（NF-）Co₃O₄ catalysts were synthesized via hydrothermal method using Co²⁺ ions,the spherical（NS-）Co₃O₄ catalyst was prepared by using single-dispersion hard carbon sphere via a template impregnation method.Finally,we synthesized nanoparticle（NP-）Co₃O₄ catalyst by chemical precipitation method.These catalytic materials were used for evaluate ethyl acetate catalytic properties and the complete oxidation temperature are 210℃.The TOFs of NP-Co₃O₄ catalysts are 0.217 s-1.The NP-Co₃O₄ catalyst has the smallest particle size（14 nm）and larger specific surface area（50.825 m²/g）.The reduction temperature is 10-60℃lower than that of NR-,NF-and NS-Co₃O₄,and more CO3+cations and surface-active oxygen adsorption.（2）The performance of roasting temperature,concentration,space velocity（GHSV）and H2O（g）on the catalyst was tested.With the increase of roasting temperature,concentration and GHSV,the catalyst activity decreased.After adding water vapor,the conversion rate of EA decreased from 97%to 93%,and recovered to 97%after removing water vapor,showing a certain water resistance.（3）Three-dimensional ordered mesoporous KIT-6 molecular sieve was synthesized by hydrothermal method.3D-Co₃O₄ and CuO/Co₃O₄ catalyst with 5-20%loading capacity were prepared by impregnation method using KIT-6 as hard template,XRD shows that 3D-Co₃O₄ and CuO/Co₃O₄ catalyst perfectly copied KIT-6 structure.The catalysts were used to evaluate the oxidation performance of formaldehyde,ethanol,ethyl acetate and toluene.The complete conversion temperature of formaldehyde,ethanol,ethyl acetate and toluene over 3D-Co₃O₄ catalyst were 170℃、210℃、230℃ and 270℃,respectively.CuO supported Co₃O₄ catalyst can significantly improve the VOCs catalytic performance,and the activity of the catalyst is affected by the CuO load and the types of VOCs.