Effect of benzene alkylation on the state of aluminium in zeolite ZSM-5

• Published in: Zeolites 1986-05, Vol.6 (3), p.169-174
• Main Authors: Aukett, P.N., Cartlidge, S., Poplett, I.J.F.
• Format: Article
• Language: English
• Subjects: Acid sites; benzene alkylation; Catalysis; Catalysts: preparations and properties; Catalytic reactions; Chemistry; Exact sciences and technology; General and physical chemistry; General. Nomenclature, chemical documentation, computer chemistry; non-framework aluminium; realumination; Theory of reactions, general kinetics; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; ZSM-5
• ISSN: 0144-2449; 1873-3115
• DOI: 10.1016/0144-2449(86)90043-6

Three catalysts, H-ZSM-5(400), H-ZSM-5(700) and Na,H-ZSM-5(400) activated in air at 400° or 700°C, were found to have acid sites which changed in number and strength during the alkylation of benzene with propene. The shape selective properties were different for each zeolite and changed markedly with the degree of carbon lay-down. Na,H-ZSM-5(400) has predominantly weak acid sites and tetrahedrally coordinated aluminium only. The hydrogen-zeolites each contain ∼ 20% non-framework aluminium about half of which is reinserted into their frameworks during the alkylation reactions. With H-ZSM-5(400) the non-framework aluminium is present as discrete species giving rise to strong acid sites. Further activation at 700°C converts some discrete aluminium species to hydroxyalumina within the zeolite channels.