酸碱、高温改性13X分子筛及其对苯乙烯的吸附

针对原样13X分子筛吸附速率和吸附容量低的问题，通过碱溶液(NaOH，NH₃)和酸溶液(CH₃COOH，HCl)对13X分子筛进行浸渍改性，并对酸改性后的分子筛进行高温二次处理，考察了试剂种类、试剂浓度、浸渍时间、焙烧温度、焙烧时间5个因素对分子筛吸附性能的影响，并采用SEM和BET进行了表征。结果表明：最佳改性条件是盐酸浓度6.0 mol·L⁻¹、浸渍时间24 h、焙烧温度450 ℃、焙烧时间6 h；在最佳条件下制备的改性分子筛极大提高了对苯乙烯的吸附速率和吸附容量；改性后的分子筛对苯乙烯的动态吸附更符合准2级动力学模型，R²均大于0.98；SEM表征结果说明改性后分子筛表面孔隙率明显增加；BET比表面积分析结果说明酸改性可使分子筛各类孔面积增加，而高温改性会使BET比表面积和中孔面积增加，微孔面积降低；相关分析结果显示，改性分子筛对苯乙烯动态饱和吸附量与BET比表面积和中孔面积均呈显著正相关。

Acid,alkali and high temperature modified 13X molecular sieve and its adsorption of styrene

In order to improve the adsorption rate and adsorption capacity of 13-X molecular sieves, it was modified by basic solutions (NaOH, NH3) and acidic solutions (CH3COOH, HCl), and the acid modified molecular sieves were further treated by high temperature. The effects of reagents, concentration, immersion time, calcination temperature and calcination time on the adsorption performances of the modified molecular sieves towards styrene were investigated. SEM and BET were used to characterize the molecular sieves as well. Results indicated that the adsorption rate and adsorption capacity of styrene by the modified 13-X molecular sieves were significantly improved under the optimum modification conditions as follows: hydrochloric acid concentration of 6 mol·L-1, immersion time of 24 h, calcination temperature of 450 ℃, and calcination time of 6 h. And the kinetic process of styrene onto the modified molecular sieves could be fitted by pseudo-second-order kinetic model with R2 larger than 0.98. SEM images indicated that the surface porosity of molecular sieves was significantly elevated after the modification. BET analysis showed that acid modification could improve the specific surface area, micropore and mesopore areas of molecular sieves, while high temperature modification could improve the specific surface area and mesopore area but reduce the micropore area. Correlation analysis indicated that the dynamic saturated adsorption capacity of styrene onto the modified molecular sieves had a good positive correlation with the BET specific surface area and mesopore area.