Highly efficient mesoporous ZSM-5 for trace olefin removal from aromatic stream

Abstract

Steam cracking and reforming processes always produce aromatic streams containing trace amounts of olefins, which are harmful to certain processes and applications in the petrochemical industry. In the aromatics complex, clay is used to remove trace olefins. Unfortunately, it has a limited lifespan and must be replaced frequently. In this study, mesoporous ZSM-5 is investigated for its application in the removal of trace olefins. It is prepared using two templates: Tetrapropylammonium bromide and Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, resulting in a mesoporous structure with a high pore volume and external surface area. There is an optimum amount of DMOD necessary to achieve the desired degree of mesoporosity within a zeolite. Even though mesoporous ZSM-5 has a similar surface area to microporous ZSM-5, its external surface area is 1.3 to 2.0 times greater than conventional ZSM-5. Consequently, mesoporous ZSM-5 has a higher activity when it comes to removing trace olefins from an aromatic stream than microporous ZSM-5.