Micro-mesoporous catalysts based on ZSM-5 zeolite synthesized from natural clay nanotubes: Preparation and application in the isomerization of C-8 aromatic fraction

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 453; p. 139581
• Main Authors: Demikhova, N.R., Rubtsova, M.I., Kireev, G.A., Cherednichenko, K.A., Vinokurov, V.A., Glotov, A.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2023
• Subjects: C-8 aromatics; Halloysite nanotubes; Hard template; Isomerization; Micro-mesoporous ZSM-5; Template-free synthesis; C-8 aromatics; Template-free synthesis; Halloysite nanotubes; Hard template; Isomerization; Micro-mesoporous ZSM-5
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.139581

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•A novel approach for ZSM-5 zeolite synthesis from halloysite nanotubes was proposed.•Halloysite actsas a hard templateprovidingmesopores formation.•Influence of template presence onzeolitepropertieswasstudied.•Pt-catalysts based in hierarchical ZSM-5 were investigated in C-8 cut isomerization.
Micro-mesoporous zeolite with ZSM-5 morphology was successfully synthesized by soft template and template-free methods using natural halloysite aluminosilicate nanotubes as a hard template and a source of aluminum and silicon. Formation of ZSM-5 crystal structure was confirmed by XRD. Textural properties and structural characteristics of functional materials, supports, and Pt-containing catalysts were examined by N2 physisorption, NH3-TPD, Py-FTIR, TEM, SEM, XRF techniques. Specific BET surface area of ZSM-5 zeolite prepared using TPABr as an organic template (ZSM-5(t):HNT) is 583 m2/g, whereas for the template-free counterpart (ZSM-5(tf):HNT) it reaches 225 m2/g. According to the Py-FTIR data, concentrations of Brønsted acid sites for ZSM-5(t):HNT and ZSM-5(tf):HNT are 295 and 93 μmol/g, whereas concentrations of Lewis acid sites are 79 and 41 μmol/g, respectively. Activity and selectivity of Pt catalysts based on the micro-mesoporous ZSM-5 zeolite-derived supports were evaluated in isomerization of C-8 aromatic fraction depending on the process conditions (temperature, feed space velocity). Because of the hierarchical micro-mesoporous structure, both catalysts provide xylenes transformation through the two isomerization routes (intra- and intermolecular). However, for the catalyst based on support synthesized through the template-free methods, the monomolecular reaction route is more preferable, and therefore the number of side reactions (disproportionation, transalkylation, and dealkylation) decreases.