Catalytic Degradation And Mechanism Of VOCs By MOFs Supported Metal Nanoparticles

With the high industrialization of modern society,PM_2.5and ozone have become the most prominent substance of air pollution in our country at the present stage.Volatile organic compounds（VOCs）as the important precursor pollutants of PM_2.5and ozone,which is the key to the deterioration of the atmospheric environment.The supported noble metal catalysts have been demonstrated outstanding catalytic performance for the catalytic degradation of volatile organic compounds（VOCs）,but their high price,easy poisoning and sintering deactivation will limit their further applications.Therefore,it is very important to synthesize efficient and stable supported metal catalysts.（1）One promising approach is to develop supported noble metal catalysts with highly dispersed active sites and strong interface interactions for reducing the catalyst cost,promoting VOCs adsorption and enhancing ability in the catalytic oxidation of VOCs.Herein,we prepared a series of highly dispersed metal nanoparticles（Pt,Pd,Ru）on metal-organic frameworks（metal/MOFs）through the impregnation-reduction of method.Metal/MOFs catalysts exhibited excellent catalytic performance with nearly 100%conversion efficiency and CO₂yield for the catalytic oxidation of different VOCs including ethyl acetate,n-hexane and toluene.Besides,metal/MOFs exhibited high reusability,good water resistance as well as excellent stability over 150 hours on the on-stream reactions at260°C.Furthermore,the catalytic oxidation mechanism was revealed by the study of reaction intermediates via in-situ diffuse reflectance infrared Fourier transform spectroscopy（In-situ DRIFTS）and mass spectroscopy.We anticipate that this work may shed light on material design for catalytic oxidation of VOCs using noble metal catalysts supported on porous materials.（2）In order to further improve the catalytic performance of single metal/Ui O-66catalysts and introduce another metal to replace part of noble metal Pt,so as to further improve the economic benefits,this work selects the Pt-Co/Ui O-66 system through the screening of various bimetallic（Pt-Co,Pt-Cu,Pt-Ag）/Ui O-66 catalysts,and makes an in-depth study on the catalytic system.At the same time,in the aspect of material synthesis,the loading method of the material was further optimized,and Pt-Co/Ui O-66 catalyst with higher dispersion and smaller nano-size was synthesized.In addition,while continuing the performance exploration of last work（water resistance,stability et al.）,the influence of the loading ratio between Pt and Co on the catalytic performance is also studied.The results show that when the theoretical loading ratio is 1:1,the catalyst has the highest Pt²⁺/Pt~0and O_ads/O_latratio,which means that the catalyst platinum in this proportion exists in a higher oxidation state and has a better ability to activate oxygen molecules.Moreover,the material shows excellent catalytic activity for toluene,ethyl acetate and n-hexane,which can completely degrade 500 ppm toluene at 165°C,ethyl acetate at 230°C and n-hexane at220°C,which is lower than that of Pt loaded in the same proportion（180°C,260°C,240°C）.It can be seen that the introduction of Co greatly improves the catalytic performance of the catalyst.We hope that this work can provide help for the development of new applications of porous materials supported bimetallic catalysts in environmental catalysis.