Catalytic Property For VOCs Oxidation And Preparation Of Catalytic Materials Coated By Cerium-manganese

Nowadays environment pollution is becoming more and more serious.It is very harmful to human’s health and make people’s life unconvinient.Scientists found many ways to solve these problems,but most of them degrade pollutants that need to consume energy.So these ways are not cost-effective.The solar energy is inexhaustible and very pure.This paper deeply researched the preparation,characterization and mechanism of TiO₂ and MnO₂ coated by cerium manganese compound.The main research results and innovations are as follows:1.The nanocomposite of amorphous cerium manganese oxide supported on nano TiO₂（CeMn_xO_y/TiO₂）was prepared by the facile hydrothermal redox reaction of Ce（NO₃）₃ and KMnO₄ in the presence of nano TiO₂.The CeMn_xO_y/TiO₂nanocomposite was characterized by XRD,TEM,SEM,EDX,XPS,BET,CO-TPR,and diffusive reflectance UV-Vis-IR absorption.It exhibits efficient thermocatalytic activity for the oxidation of the carcinogenic and recalcitrant benzene,which is comparable to that of the expensive noble metal catalyst（0.5%Pt/Al₂O₃）,and is much higher than the CeO₂/TiO₂ and MnO_x/TiO₂ nanocomposites with the same metal/Ti molar ratio.Its specific CO₂ production rate(r_CO2)at 220℃(88.6μmol g^-1min^-1)is 6.3 and 7.5 times higher than the nanocomposites of CeO₂/TiO₂ and MnO_x/TiO₂,respectively.The highly efficient thermocatalytic activity of the CeMn_xO_y/TiO₂ nanocomposite is attributed to its higher oxygen activity,compared to the nanocomposites of CeO₂/TiO₂ and MnO_x/TiO₂.Remarkably,the CeMn_xO_y/TiO₂nanocomposite can be driven by simulated solar light for benzene oxidation.It exhibits highly efficient catalytic activity with the irradiation of the full solar spectrum,visible-infrared,and infrared light.Its initial CO₂ production rate is 117.0,94.8 and 37.9μmol g^-1_catalystmin^-1,under the irradiation of the full solar spectrum,visible-infrared light with wavelength above 420 nm,and infrared light with wavelength above 830 nm,respectively.This is attributed to the fact that the CeMn_xO_y/TiO₂ nanocomposite efficiently transforms the absorbed solar energy into thermal energy,due to its strong absorption in the full solar spectrum region,resulting in a significant increase in its temperature above its light-off temperature.2.Firstly,we prepared the OMS-2 by the facile hydrothermal redox reaction of Mn（NO₃）₂ and KMnO₄.Then made the nanocomposite of amorphous cerium manganese oxide supported on nano OMS-2 by the facile hydrothermal redox reaction of Ce（NO₃）₃ and KMnO₄ in the presence of nano TiO₂.According the atom ratio of（Mn+Ce）/Mn,we made three samples for comparation which atom ratio of（Mn+Ce）/Mn are 2.5%,5%and 10%.The CeMn_xO_y/OMS-2 nanocomposite was characterized by XRD,TEM,BET,CO-TPR and diffusive reflectance UV-Vis-IR absorption.All the sample are crytomelane.The highly efficient thermocatalytic activity of the CeMn_xO_y/OMS-2 nanocomposite is attributed to its higher oxygen activity,compared to the nanocomposites OMS-2.Remarkably,the CeMn_xO_y/OMS-2nanocomposite can be driven by simulated solar light for benzene oxidation.The specific CO₂ production rate(r _CO2)of CeMn_xO_y/OMS-2-5.0%at 200℃(77.3μmol g^-1min^-1)is 4.68 times higher than the nanocomposites of OMS-2(16.5μmol g^-1min^-1).It exhibits highly efficient catalytic activity with the irradiation of the full solar spectrum.The initial CO₂ production rate of CeMn_x O_y/OMS-2-5.0%is 539.7μmol g^-1_catalystmin^-1under the irradiation of the full solar spectrum which is 12.5 times higher than OMS-2.We also found a kind of photoactivation effect which is different with the traditional photocatalytic effect.Which show that the lattice oxygens become more active with irradiation.