Preparation And Characterization Of Co-Zr Cataly- Sts And Their Catalytic Performance For The Toluene Oxidation

Toluene is one of the common volatile organic compounds,causing serious harm to the ecological environment and human health.Among the many elimination methods,the catalytic combustion method has been widely concerned because of its high removal efficiency of toluene,but the key to using catalytic combustion is to choose the right catalyst.Co_xZr_1-xO₂catalysts are prepared by precipitation method,hydrothermal method,thermal decomposition method and impregnation method.Among them,the particles of the Co_bZr_1-bO₂ catalyst prepared by hydrothermal method are uniformly spherical,the pore structure is developed,and the specific surface area can reach 82.3 m²?g^-1,so it has the best catalyst activity.Under the conditions of space velocity of 20000 mL??g·h?^-1 and concentration of 1000ppm,the conversion temperature of completely oxidized toluene is as low as260 ^oC.Life test shows that the catalyst can maintain activity for a long time,no significant deactivation is found within 30 h.In the case of O₂ excess,the apparent activation energy of the oxidation of toluene on the Co_bZr_1-bO₂catalyst is 64.43 kJ·mol^-1.Co-Zr composite oxide catalysts with different molar ratios are prepared by the hydrothermal method.The results show that catalyst prepared with a cobalt-zirconium molar ratio of 3:1 has a regular morphology,a uniform sphere distribution,a well-developed pore structure,abundant surface oxygen species and Co²⁺species on the surface.Thus it has the best catalytic activity,the conversion temperature of 90%toluene oxidation is 237 ^oC under the conditions of space velocity of 20000mL??g·h?^-1 and concentration of 1000 ppm.