Abstract: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. Key words:13-X molecular sieves/ modification/ adsorption/ styrene.
图1分子筛吸附苯乙烯蒸气实验流程示意图 Figure1.Flow diagram of molecular sieve adsorption styrene vapor experiment
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College of Earth and Environmental Science, Lanzhou University, Lanzhou 730000, China Received Date: 2019-01-11 Accepted Date: 2019-05-22 Available Online: 2019-09-17 Keywords:13-X molecular sieves/ modification/ adsorption/ styrene Abstract: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.