Preparation Of Halloysite-Supported Mn Catalyst And Its Microwave Pyrolysis Of Formaldehyde

Since the reform and opening up,China's industry and manufacturing industry have developed rapidly,and economic construction has made significant achievements.At the same time,however,emissions of volatile organic waste gases?VOCs?have increased year by year in industrial and manufacturing processes;VOCs are the English abbreviation for volatile organic compounds.Most VOCs have a strong pungent odor and are toxic and carcinogenic,causing great harm to the environment and the human body.Therefore,the efficient purification of organic waste gas from industrial and manufacturing processes has far-reaching significance for China's environmental protection.At present,the common methods for treating VOCs waste gas include organic combustion gas purification technologies such as direct combustion method,catalytic combustion method,biological oxidation method,photocatalytic oxidation method and plasma technology.Among them,the catalytic combustion method has the characteristics of simple process and complete removal of exhaust gas,and has received extensive attention.In the catalytic combustion method,the most important is the catalyst.The?-MnO₂ catalyst is a commonly used catalyst in the catalytic combustion method,but the?-MnO₂ catalyst will self-agglomerate during the catalytic process,thereby reducing the catalysis of the?-MnO₂ catalyst.active,The halloysite?HNTs?material is a porous material,which can well disperse the?-MnO₂ catalyst,increase the specific surface area of the?-MnO₂ catalyst,and increase the catalytic activity.In this paper,the ?-MnO₂ catalyst with high formaldehyde activity was prepared by hydrothermal redox method.The structure of?-MnO₂ catalyst supported by the loading of halloysite?HNTs?was studied by adding different masses of halloysite?HNTs?materials.And the effects of catalytic activity by means of X-ray diffraction?XRD?,scanning electron microscopy?SEM?,specific surface area Brunauer Emmett Teller?BET?and Fourier transform infrared spectroscopy?FT-IR?Characterize,Furthermore,the effects of?-MnO₂ catalyst and?-MnO₂/HNTs composites on the catalytic oxidation of formaldehyde were investigated by means of tube furnace heating and microwave heating.And the change of the initial concentration of formaldehyde and the inlet gas velocity,the effect of the prepared composite catalyst on the performance of formaldehyde.?1?The effect of the prepared composite catalyst on the catalytic oxidation of formaldehyde after loading the?-MnO₂ catalyst on the HNTs.The halloysite?HNTs?material is a porous structural material,and it has been found that an appropriate amount of halloysite?HNTs?loading can significantly increase the specific surface area and catalytic activity of the?-MnO₂ catalyst.a,HNTs/?-MnO₂?0:1?,b,HNTs/?-MnO₂?1:0?,c,?-MnO₂/HNTs?1:1?,d,?-MnO₂/HNTs?1:2?,e,?-MnO₂/HNTs?2:1?five composite catalysts;With the addition of halloysite?HNTs?materials,the specific surface area of the prepared composite catalysts increased,and the sample c,?-MnO₂/HNTs?1:1?had the highest specific surface area,reaching 82.63 m²/g,which is 1.74 times the?-MnO₂ catalyst.In the catalytic oxidation of formaldehyde,using the tube furnace heating method,the prepared composite catalyst showed more excellent catalytic activity,among which the?-MnO₂/HNTs?1:1?with the highest catalytic activity were compared with the?-MnO₂ catalyst.The temperature at which the complete conversion of formaldehyde(T₁₀₀)is lowered by 50°C,while the thermal stability of?-MnO₂/HNTs?1:1?is better.?2?The effects of composite catalysts on the catalytic oxidation of formaldehyde were studied under microwave heating and tube furnace heating.Most of the related research is to use the tube furnace heating method.Compared with other experiments,this experiment will also use the microwave device heating method.Microwave heating has the characteristics of high heating rate and low energy consumption;At the same time,the characteristics of the microwave can effectively reduce the activation energy in the catalytic oxidation of the prepared composite catalyst,and thus reduce the complete conversion temperature of the prepared composite catalyst to formaldehyde.Compared with the tube furnace heating method,the temperature of complete conversion of formaldehyde(T₁₀₀)of?-MnO₂ catalyst and?-MnO₂/HNTs?1:1?composite catalyst is reduced by 35°C and 40°C,respectively,under microwave heating mode.Under the heating mode of the microwave device,the thermal stability of the prepared composite catalyst is significantly better than that of the conventional resistance furnace.?3?Under the two different heating modes of microwave device heating and tube furnace heating,the effects of initial concentration of formaldehyde and inlet gas velocity on the activity of?-MnO₂ catalyst and?-MnO₂/HNTs composite catalyst for catalytic oxidation of formaldehyde were investigated.At the same heating temperature,the conversion of formaldehyde decreases as the initial concentration of formaldehyde increases.With the increase of formaldehyde inlet velocity,the conversion rate of formaldehyde decreases with the increase of the inlet velocity of formaldehyde at the same heating temperature.The prepared composite catalyst can adapt to the increase of initial concentration and the increase of intake velocity.Higher conversion...