Fabrication of highly mesoporous ZSM-48 zeolite by anionic surfactant-organosilane system for catalytic conversion of methanol to gasoline

A highly mesoporous ZSM-48 zeolite has been prepared using low-cost anionic surfactant sodium dodecylsulphate (SDS) as mesopore-generating agent and short-chain 3-aminopropyltrimethoxysilane (APTMS) as co-structure directing agent. The mesoporosity formation took place through the interaction between the silica species/APTMS and SDS molecules existing in the gel composition. In the synthesis solution with a pH slightly less than ten, the methoxysilyl moiety in APTMS was hydrolysed to the –SiO 3 units and became incorporated inside the zeolite crystals while the positively charged ammonium site of APTMS interacted with the negatively charged head group of the SDS. Aggregation of aluminosilicate/APTMS species around the SDS micelles during the crystallization process, led to the formation of a mesoporous zeolite. In this study, a conventional ZSM-48 and seven ZSM-48 zeolites from different mixtures containing SDS, APTMS and SDS-APTMS with different APTMS/SiO 2 molar ratios were synthesized. Changes in the properties of the synthesized samples were investigated by XRD, FTIR, SEM, TEM, nitrogen adsorption/desorption isotherms, NH 3 -TPD and TGA. The optimum ZSM-48/Sur/0.008OS zeolite prepared with APTMS/SiO 2 molar ratio of 0.008 exhibited both bundled needle-like and spherical morphologies. The catalytic conversion of methanol to gasoline (MTG) was evaluated in a fixed-bed reactor, and the results revealed that mesoporosity development using Sur-OS system enhanced catalytic activity of ZSM-48/Sur/0.008OS catalyst compared to the other sample. The optimum zeolite showed long stable phase of 40 h and liquid hydrocarbon yield of 42% was achieved for 100% methanol conversion in 22 h of reaction. The proposed method opens a new and simple route for the synthesis of hierarchically porous ZSM-48 with tunable porosity using low-cost anionic surfactants. • Mesoporous ZSM-48 zeolite was obtained using anionic surfactant as mesogenous template and organsilane as co-structure-directing agent. • Organosilane addition to SDS-gel composition led to formation of highly mesoporous ZSM-48 zeolite. • The results of performance tests were compared with conventional microporous ZSM-48 catalyst. • Mesoporous ZSM-48/Sur/0.008OS zeolite showed good catalytic activity with low deactivation rate.