Process Optimization Of Adsorption Concentration And Catalytic Combustion For The Treatment Of Xylene Waste Gas

VOCs are one of the major atmospheric pollutants following SO₂,NO_X and particulate matter.They will cause great harm to human body and environment when they volatilize into the atmospheric environment.Xylene is one of the VOCs substances and is selected as the object of this study.In this paper,the combined process of adsorption concentration-catalytic combustion is applied to treat xylene waste gas of high air volume and low concentration,and the concentration and treatment of xylene are integrated,which has important research value.In this paper,a set of adsorption concentration-catalytic combustion device was designed,which was divided into three parts.The first part was the process optimization of the adsorption treatment of xylene waste gas.The second part was the process optimization of activated carbon desorption and regeneration.The third part was the process optimization of adsorption concentration-catalytic combustion for the treatment of xylene waste gas.The results were as follows.?1?The main factors affecting the adsorption of activated carbon were adsorption temperature,gas concentration,gas flow velocity,and bed thickness.The optimum process conditions for adsorption of xylene by activated carbon were determined.20?was the ideal adsorption temperature in this experiment.200³00mg/m³ was the appropriate gas concentration.0.83m/s was the ideal gas flow velocity.In industry production,the optimal adsorption effect could be achieved by increasing the bed thickness for the high gas concentration and gas flow velocity.?2?With the change of gas concentration,the isothermal adsorption capacity curve of activated carbon for xylene was suitable for A-type adsorption isotherm.The adsorption isotherm can be fitted by Langmuir or Freundlich isothermal equation.The correlation coefficient was more than 0.940,and the fitting result was ideal.?3?The main factors affecting the desorption regeneration of activated carbon were desorption temperature,gas flow velocity,and bed thickness.The optimum process conditions for desorption regeneration of activated carbon were determined.100?was an ideal desorption temperature in this experiment.0.14m/s was an ideal gas flow velocity.100mm was an ideal bed thickness.?4?After regeneration at different desorption temperatures,the specific surface area,pore volume,and adsorption capacity of activated carbon decreased,and the average pore size increased,and the re-adsorption rate of activated carbon was less than 1.The regeneration performance of activated carbon was better under high temperature,and the regeneration performance of activated carbon gradually deteriorated after repeated regeneration.?5?The noble metal catalyst was selected as the catalyst for this study.The catalyst was based on the?-Al₂O₃ as the carrier and the noble metal Pt and Pd as the main active components.The main influencing factors in catalytic combustion experiments were gas concentration and gas flow velocity,and the optimal reaction temperature for catalytic combustion was determined to be 220²30?.?6?In the adsorption concentration-catalyzed combustion experiment,with the increase of the reaction time,the export concentration of xylene showed a trend of increasing first and then decreasing,and the change trend was almost the same as the import concentration,and the removal rate was maintained at about 90%.In general,the catalytic combustion effect was ideal at a reaction temperature of 230?.In summary,it is feasible to use a combined process of adsorption concentration and catalytic combustion to treat xylene waste gas of high air volume and low concentration.The optimum process parameters of the combined process are obtained in this paper:adsorption?adsorption temperature is 20?,gas concentration is 200³00mg/m³,gas flow velocity is 0.83m/s?,desorption regeneration?desorption temperature is 100?,gas flow velocity is 0.14m/s,bed thickness is 100mm?,catalytic combustion?reaction temperature is 230??.The optimum process conditions explored in this paper can provide technical support for the practical application of the process.