甲苯与水在不同粒径的13X分子筛表面竞争吸附研究

Competitive adsorption of toluene and water on thesurface of 13X zeolite with different particle sizes

以甲苯作为VOCs代表物,采用固定床吸附含湿甲苯,研究粒径、湿度、温度对13X分子筛吸附容量、吸附时间的影响。从吸附动力学角度出发,采用Yoon-Nelson模型拟合甲苯与水的吸附穿透曲线。结果表明,0.5~1,1.6~2.5,3~5 mm三种粒径在吸附温度40℃,相对湿度RH30条件下平衡吸附容量分别达到19.86,20.41,21.36 mg/g;湿度升高至RH70时,其平衡吸附容量分别降低为0.86,1.78,2.03 mg/g;三种粒径的13X分子筛在湿度相同时,吸附时间与吸附容量随着粒径的增大而增加。RH50条件下,吸附温度由40℃升至80℃的过程中,0.5~1,1.6~2.5,3~5 mm三种粒径的吸附容量分别由12.075,13.577,18.291 mg/g下降至3.083,11.483,12.885 mg/g,相同湿度下,分子筛吸附容量随吸附温度的升高而降低。Yoon-Nelson模型很好地拟合13X分子筛吸附不同湿度VOCs的过程;粒径的改变引起含湿甲苯扩散路径长度的变化,水团簇的形成和路径长度共同影响了水与甲苯的竞争吸附过程,这解释了粒径对多组分吸附结果的影响,并为处理含湿甲苯提供新的思路。

The toluene was taken as the representative of VOCs,and fixed bed was used for adsorbing polluted gas with certain concentration and humidity.In order to the adsorbing performance of 13X molecular sieve containing water vapor toluene,the effects of particle size,humidity and temperature on adsorption capacity and adsorption time were investigated.From the perspective of adsorption kinetics,the Yoon-Nelson model was used to fit the adsorption penetration curve of toluene and water.The results show that,the adsorption capacities at 40℃and RH30 are 19.86,20.41,21.36 mg/g,respectively,when the particle size is 0.5~1,1.6~2.5,3~5 mm.In addition,the humidity increased to RH70,the capacities of adsorption decreased to 0.86,1.78,2.03 mg/g,respectively.The adsorption time and adsorption capacity of the three kinds of 13X molecular sieves increased with the increase of particle size when the humidity was same.Under the conditions of RH50,when the adsorption temperature increased from 40℃to 80℃,the adsorption capacity of 0.5~1 mm,1.6~2.5 mm and 3~5 mm particle sizes decreased from 12.075,13.577,18.291 mg/g to 3.083,11.483,12.885 mg/g,respectively.Under the same humidity,the adsorption capacity of molecular sieve decreased with the increase of adsorption temperature.The Yoon-Nelson model can well fit the process of 13X molecular sieve adsorbing toluene with different humidity before competitive adsorption.The diffusion path length which caused by particle size and formation of water cluster affect the competitive adsorption process of water and toluene.It explains the effect of particle size on multi-component adsorption results,and provide a new idea for the treatment of wet VOCs.