High-temperature low-pressure adsorption of branched C5-C8 alkanes on zeolite beta, ZSM-5, ZSM-22, zeolite Y, and mordenite

Henry constants, low-coverage adsorption enthalpies, van't Hoff preexponential factors, and separation factors of C-5-C-8 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.