Inverse Gas Chromatography Study of n-Alkane and 1-Alkene Adsorption on Pure-silica LTA (ITQ-29) and CHA

Exploring Cage Effects of Alkane Adsorption on SSZ-39 (AEI) and SSZ-13 (CHA) Zeolites: A Comparative Study

“…As seen in Figure , the Henry constants increase from C 2 up to C 5 , although propane’s Henry constants could not be accurately measured, its apparent Henry constants value at the lowest flow rate (20 N mL/min) are depicted indicatively. In the absence of mass transfer limitations, it is anticipated that the Henry constants for propane would fall between the values for ethane and n -butane, based on previous computational predictions and experimental observations. ,− ,, No flow rate mass transfer limitations were observed for the other carbon numbers (Figure S4). Starting from C 5 , the Henry constants start to decline, reaching a local minimum at C 8 (Figure ).…”

“…Very long alkanes are unable to fit inside one cage, even when highly coiled; thus, configurations where the molecules are located in two (or more) cages will eventually arise. In this transition area, from one cage adsorption to multicage adsorption, two possible adsorption mechanisms are proposed: the coiled chain and the stretched chain mechanisms. ,− ,, In the coiled chain mechanism, the chain of carbon atoms initially coils up within a single cage, optimizing its interactions with the cage’s wall. As the chain exceeds the size that can be coiled within a single cage, a portion of the chain extends through the pore window, switching to a multicage adsorption mechanism.…”

“…Toward this purpose, n -alkanes offer an ideal choice as probe molecules, as a systematic analysis of their adsorption properties as a function of carbon chain length provides deeper insight into the effect of pore structure on the adsorption mechanisms. In our recent study, we have used n -alkanes and 1-alkenes (ranging from C 2 to C 12 ) to investigate the adsorption properties on pure-silica CHA and Linde Type A (LTA) zeolites. Notably, for CHA-type zeolites, a remarkable nonmonotonous increase in Henry constant with increasing carbon number was observed, a phenomenon referred to as “cage effects”, − for n -alkanes and 1-alkenes.…”

“…In our recent study, we have used n -alkanes and 1-alkenes (ranging from C 2 to C 12 ) to investigate the adsorption properties on pure-silica CHA and Linde Type A (LTA) zeolites. Notably, for CHA-type zeolites, a remarkable nonmonotonous increase in Henry constant with increasing carbon number was observed, a phenomenon referred to as “cage effects”, − for n -alkanes and 1-alkenes. In contrast, for most zeolite frameworks such as faujasite (FAU), mordenite (MOR), and Mobil-type five (MFI), − the Henry constant exhibits a typical monotonic increase with carbon numbers.…”

“…Cage effects have been found in molecular simulations for erionite (ERI), CHA, and LTA-type zeolites , and therefore believed to be more generic in nature. In contrast, cage effects only have been experimentally observed on CHA-type zeolites. , For the AEI framework, the potential presence of such cage effects has not been previously investigated by using experimental or computational methods.…”