Tailoring the structure and acid site accessibility of mordenite zeolite for hydroisomerisation of n-hexane

0490608 - ÚFCH JH 2019 RIV NL eng J - Journal Article
Pastvová, Jana - Pilař, Radim - Morávková, Jaroslava - Kaucký, Dalibor - Rathouský, Jiří - Sklenák, Štěpán - Sazama, Petr
Tailoring the structure and acid site accessibility of mordenite zeolite for hydroisomerisation of n-hexane.
Applied Catalysis A - General. Roč. 562, JUL 2018 (2018), s. 159-172. ISSN 0926-860X. E-ISSN 1873-3875
R&D Projects: GA ČR GA15-12113S; GA MŠMT(CZ) LM2015073; GA MŠMT(CZ) EF16_013/0001821
Institutional support: RVO:61388955
Keywords : Isomerisation * Micromesoporous structure * Mordenite (MOR) zeolites * n-hexane * Supermicroporosity
OECD category: Physical chemistry
Impact factor: 4.630, year: 2018

Mordenite zeolites with diffusion-restricted access to the acid sites located in mono-dimensional 12-ring channels and 8-ring side pockets have found broad applications as catalysts for hydroisomerisation of linear C5and C6alkanes and other highly relevant acid-catalysed processes. The accessibility of the porous structure of mordenite (MOR) zeolite is traditionally enhanced by dealumination, but this is invariably connected with a dramatic reduction in the aluminium content and corresponding concentration of the acid sites in the zeolites. Here we describe the preparation of MOR zeolite with high micropore volume, three-dimensional supermicropores (d ∼ 7.5 Å) and good acid site accessibility by concurrent extraction of Si and Al using postsynthesis fluorination-alkaline-acid treatment. The concurrent extraction of Si and Al enables formation of more developed supermicroporous structure and preservation of the molecular Si/Al. The procedure yields MOR with a crystalline structure in which the Si/Al ratio and the micropore volume can be tailored (Si/Al from ∼ 6, VMIup to 0.25 cm3.g−1) by the chemical conditions of the treatment. The Al-rich 3D supermicroporous structure with accessible Brønsted and Lewis active sites provides strongly enhanced activity, selectivity and long-term catalytic stability in the transformation of n-hexane into the corresponding branched isomers.
Permanent Link: http://hdl.handle.net/11104/0284780