Preparation and characterization of a novel gradient porous ZSM-5 zeolite membrane/PSSF composite and its application for toluene adsorption

A novel gradient porous ZSM-5 membrane/PSSF composite was prepared by the wet lay-up papermaking process and secondary growth process. Firstly, the paper-like sintered stainless steel fibers (PSSFs) support was prepared by the wet lay-up papermaking process and sintering process, then a ZSM-5 membrane was fabricated on this PSSF support by secondary growth process. The morphology and structure of ZSM-5 membrane/PSSF composite were characterized by SEM, XRD and ASAP 2020, respectively. The experimental results indicated that the junctures of stainless steel fibers were completely sintered together to form a three-dimensional network structure and ZSM-5 membrane was fabricated on the PSSF support. The specific surface area of composite was 145.1 m2/g, which was calculated with the BET (Brunauer–Emmett–Teller) method, and the total pore volume was 0.1547 cm3/g. The adsorption breakthrough curve of toluene in the structured fixed bed filled with both granular activated carbons (GACs) of 2.4 cm in the inlet of bed and NaZSM-5/PSSF composites of 0.6 cm in the outlet of bed was also investigated, comparing with that in individual GAC fixed bed with bed height of 3 cm. The length of unused bed was calculated according to the breakthrough curve data. The experimental results showed that the length of unused bed in structured fixed bed was obviously decreased.