The Shape Selectivity of Paraffin Hydroconversion on TON-, MTT-, and AEL-Type Sieves

• Published in: Journal of catalysis Vol. 188; no. 2; pp. 403 - 412
• Main Authors: Maesen, Th.L.M., Schenk, M., Vlugt, T.J.H., Jonge, J.P.de, Smit, B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 10.12.1999; Elsevier
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; molecular simulations; paraffin hydroisomerization; pore mouth catalysis; shape selectivity; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; zeolites; paraffin hydroisomerization; shape selectivity; zeolites; molecular simulations; pore mouth catalysis; Hydrocarbon; Catalytic hydrocracking; Pore structure; Enthalpy; Theoretical study; Zeolite; Experimental study; Porous material; Molecular sieve; Heterogeneous catalysis; Simulation; Alkane; Thermodynamic properties; Heat of adsorption
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1006/jcat.1999.2673

Based on a comparison between simulated and measured adsorption properties, we demonstrate that both normal and mono-methylparaffins are able to fully enter the pores of TON-, MTT-, and AEL-type molecular sieves. This disproves the theory that mono-methylparaffins only partially enter these pores and that normal paraffins are predominantly hydroisomerized at the pore mouths of these sieves. Instead, we attribute the high selectivity for paraffins with terminal methyl groups to product shape selectivity, and the low selectivity for paraffins with neighboring methyl groups to transition state selectivity. These traditional shape selectivity concepts explain not only the detailed product distribution of n-heptane hydroconversion, but also that of longer-chain n-paraffins.