Adsorption on Ti- and Al-containing mesoporous materials prepared from fluorosilicon

Abstract

Mesoporous molecular sieves were synthesized from fluorosilicon compounds and Ti, Al with the hydrolysis reaction of H2SiF6 in an ammonia–surfactant mixed solution. The solid products were characterized by XRD, EDS, nitrogen adsorption and desorption. In order to improve the hydrothermal stability of the mesoporous structure cationic surfactants used as templates were removed by acidified solvent extraction. It was found that well-crystalline mesoporous molecular sieves were obtained after several hours at atmospheric condition. The optimum operating conditions for the economical synthesis of mesoporous materials were also studied. Adsorption isotherms of benzene, CO2 and H2O were measured on well-crystalline mesoporous molecular sieves. The benzene adsorption capacity of mesoporous molecular sieve containing Ti was found much higher than that of the mesoporous molecular sieve containing Al, zeolite X and dealuminated zeolite Y. The zeolite X and the dealuminated zeolite Y are commercial materials that are currently used for the removal of light hydrocarbons. It was also found that the adsorption capacity of both CO2 and water vapor of mesoporous molecular sieves were higher than those of NaX at high relative pressure. This result well illustrates the application of silica-based mesoporous materials as adsorbents for removing volatile organic compounds, CO2 and water vapor.