Phosphate modified ZSM-5 for the shape-selective synthesis of para-diethylbenzene: Role of crystal size and acidity

• Published in: Applied catalysis. A, General Vol. 484; pp. 8 - 16
• Main Authors: Hodala, Janardhan L., Halgeri, Anand B., Shanbhag, Ganapati V.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 22.08.2014; Elsevier
• Subjects: Alkylation; Catalysis; Catalysts; Chemistry; Crystals; Ethyl alcohol; Ethylbenzene; Exact sciences and technology; General and physical chemistry; Ion-exchange; p-diethylbenzene; Phosphate modification; Phosphates; Selectivity; Shape selectivity; Surface physical chemistry; Synthetic aperture radar; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vapor phase; Vapor phases; Zeolite; Zeolites: preparations and properties; ZSM-5; Phosphate modification; Vapor phase; ZSM-5; p-diethylbenzene; Shape selectivity; Zeolite; Alkylation; Phosphates; Modification; Shape; Crystals; Acidity; Selectivity; Heterogeneous catalysis; Synthesis
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2014.07.006

•Alkylation of ethylbenzene with ethanol over phosphate modified ZSM-5.•Effect of phosphate modification on activity and selectivity.•Relation between acid site density and phosphate content.•Detailed study on crystal size and acidity on activity and para-selectivity.•Detailed study on effect of operating parameters on catalyst performance. Pore engineered ZSM-5 zeolite in extrudate form was prepared and used as shape-selective catalyst for vapor phase ethylation of ethylbenzene to selectively form para-diethylbenzene. The physico-chemical properties of the catalyst were established by XRD, N2 sorption, FTIR, FESEM, NH3-TPD and 31P MAS NMR. Alkylation of ethylbenzene with ethanol was carried out in a continuous, down-flow, tubular reactor, at atmospheric pressure and H2 as a carrier gas in vapor phase. Effect of silica to alumina ratio (SAR), crystal size, acidity of phosphate modified ZSM-5, stepwise phosphate modification and reaction conditions were studied in detail. ZSM-5 with SAR 187 was found to contain optimum acidity for phosphate modification to achieve good conversion and high selectivity for p-diethylbenzene. Under optimized reaction conditions, viz. temperature=380°C, ethylbenzene:ethanol mole ratio=4:1, WHSV=3h−1, H2/reactants=2, 5PZSM-5W catalyst gave 22.8% of ethylbenzene conversion with ∼98% selectivity for para-diethylbenzene.