Henry constants, low-coverage adsorption enthalpies, van't Hoff preexponential factors, and separation factors of C5−C8 alkanes are determined on beta, ZSM-5, ZSM-22, mordenite, and Y zeolites at 473−648 K using tracer and perturbation chromatographic techniques. Three different adsorption behaviors were encountered depending on the zeolite type:  (1) nonselective competitive adsorption of isoalkanes and n-alkanes inside the micropores (zeolite Y), (2) preferential adsorption of the n-alkanes over the isoalkanes inside the micropores (beta, ZSM-5 and mordenite), and (3) selective adsorption of the n-alkanes in the micropores and of the isoalkanes on the external crystal surfaces (ZSM-22). Linear and mono- and multibranched alkanes can be separated on columns of ZSM-22 and beta zeolites.

A mechanism has been found that explains the distribution of products obtained in the isomerizations of long‐chain alkanes on ZSM‐22 and SAPO‐11 catalysts so well that it should now be possible to tailor reactions for the synthesis of branched hydrocarbons. The reactions occur at the external surface of the catalyst according to a lock‐and‐key model (shown on the right); thus, the classical concept of shape‐selective catalysis within micropores is substantially extended.

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The conversion of a mixture of n-hexane, n-heptane, n-octane and n-nonane, in the presence of hydrogen over zeolite Pt/H−Y is modeled using a multicomponent adsorption−reaction scheme. Adsorption parameters for the relevant hydrocarbon molecules are determined using the chromatographic technique. Intrinsic reaction parameters are obtained by the fitting of the model to reaction rate data from catalytic experiments, using the independently determined adsorption parameters. Preferential conversion of the longer n-alkanes in mixtures is caused by competitive adsorption favoring the heavy compounds. Apparent reaction rates in mixtures are controlled by adsorption, increasing with chain length of the n-alkanes, rather than by the individual intrinsic reaction rates of the different n-alkanes, which are similar.