(A) study on the adsorption and catalytic oxidation of volatile organic compounds over zeolites and mesoporous molecular sieves

Abstract

Adsorption and catalytic oxidation have been recognized as the most economical and efficient technologies for the control of volatile organic compounds (VOCs). Especially when these two processes are combined together into an advanced adsorption-oxidation system, the energy efficiency of the system can be maximized with the reduced volume of VOC stream of low concentration. The hydrophobic zeolites has been considered as a key material in the adsorption-oxidation combined system, because they usually exhibit large adsorption capacity for VOCs even in highly humid atmosphere, and they can be utilized as good catalyst supports. In addition to hydrophobic zeolites, conventional mesoporous molecular sieves, M41S family, has been drawn much attention in adsorption and catalysis due to their large surface area and unique pore structures. However their low hydrothermal stability limits practical application to adsorption and catalysis. In this study, hydrophobic zeolites and mesoporous molecular sieves were proposed and investigated the applicability as potential adsorbents as well as catalyst supports to develop the adsorption-catalytic oxidation combined processes. The first research object was focused to synthesize hydrothermally stable mesoporous molecular sieves to be applied to practical adsorption and catalysis. By using nanoclustered zeolite seeds - zeolite seeds crystallization method - the steam stable mesoporous molecular sieves (SM-41) were successfully synthesized. The hydrothermal stability of synthesized SM-41 was dramatically increased, which was confirmed from the hydrothermal treatment test followed by structural analysis such as $N_2$ adsorption isotherm study, XRD and FTIR. The enhanced hydrothermal stability might result from the crystallization of amorphous walls of conventional MCM-41 by using zeolite seeds. Applicability of zeolites and mesoporous materials including newly synthesized SM-41 to adsorption of VOCs was investigated by adsorpti...