Inverse shape selectivity in molecular sieves: Observations, modelling, and predictions

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

“…In the literature one can find many other types of shape selectivity, such as the "concentration" or "solvent" effect, 435,436,[438][439][440][441] the "confinement" or "solvent" effect, 444,445,500,501 molecular traffic control, 467,502 secondary shape selectivity, 466 inverse shape selectivity, 469 and the "cage" or "window" effect. 357,359 …”

“…329,417 Van Nostrand and co-workers (Chevron) coined the term"inverse shape selectivity" to denote the accelerated formation rate of reaction intermediates that have a shape more commensurate with the framework topology than others. [469][470][471] Even though quantum chemical simulations indicate that this form of transition state shape selectivity is conceptually feasible, 32 the original example turned out to be a form of sorption shape selectivity and not of transition state shape selectivity. 248 In this review, we try to further integrate adsorption controlled shape selectivity into mass transport and transition state controlled shape selectivity.…”

Computer Simulations of Shape Selectivity Effects

“…The traditional network postulates that the dialkylcyclopropyl transition states only play a role in hydroisomerization, and that they have to open and form a fully fledged branched alkene before hydrocracking occurs [36,37]. The alternative network postulates that the dialkylcyclopropyl transition states do not have to open before hydrocracking sets in, and that they themselves can initiate molecular scission [32]. Both kinetic networks are equally suitable for explaining …”

“…Derouane postulated that ''molecular traffic control'' might occur when small molecules can diffuse through small and large molecules through large channels of one and the same molecular sieve [28,29]. Van Nostrand and coworkers coined the term ''inverse shape selectivity'' to denote the accelerated formation rate of reaction intermediates that have a shape more commensurate with the framework topology than others [30][31][32].…”

Supercritical catalysts of light hydrocarbon conversion. DOE PETC eighth quartery report, July 1, 1995--September 30, 1995

“…Another kind of shape selectivity [40] has been inferred from the observation that some reactants and transition states can be stabilized relative to smaller species because of a good fit in the catalyst pores, which maximize attractive van der Waals forces. This effect is absent in larger pores.…”