On the Adsorption of Gaseous Mixtures of Hydrocarbons on High Silica Zeolites

Abstract

An experimental study of the interactions of an equimolar binary gaseous mixture of toluene and n-hexane, model molecules of aromatic and aliphatic fuel-based pollutants, with two dealuminated high silica zeolites is here presented for the first time. Zeolites Y and ZSM-5 with diverse textural and surface properties were chosen as adsorbents, and the effects of their physicochemical features (predominantly the pore size architecture and silanol content) on sorption capacity were studied. The host−guest (i.e., sorbent-molecules) interactions were studied by FTIR and SS-NMR spectroscopies. IR optical adsorption isotherms of both toluene and n-hexane coadsorbed on the zeolites allowed the determination of the concentration of the adsorbed molecules. Variable temperature SS-NMR spectroscopy allowed the description of the mobility of the pollutant molecules when coadsorbed at the interface of the zeolites micropores. Finally, we describe how the proposed innovative approach can be of general use to determine the selectivity of adsorbent materials for a mixture of hydrocarbons.

Combined solid-state NMR, FT-IR and computational studies on layered and porous materials

“…419 The coadsorption of the antibiotic and vanillin by the zeolite Y occurred in the range of pH typical of natural waters (5)(6)(7)(8) available. [420][421][422] In the study of Sacchetto et al FT-IR and ssNMR spectroscopy were used to elucidate the type and strength of the host-guest and guest-guest interactions between the model molecules singly adsorbed on the zeolites surfaces at different loadings/pressures. 420 At low loading, toluene displayed π-H-bondings with zeolite silanols (more numerous in Y than in ZSM-5)…”

“…porosities has been addressed by a combination of FT-IR and microgravimetric analysis of each single molecule adsorbed on the two supports. 421,422 Different molar absorption coefficients of n-hexane at 1380 cm -1 (methyl bending mode)…”

Study of Confinement and Catalysis Effects of the Reaction of Methylation of Benzene by Methanol in H-Beta and H-ZSM-5 Zeolites by Topological Analysis of Electron Density

“…8 According to Sacchetto and co-workers, the knowledge of host−guest interactions occurring in zeolites could be helpful to improve adsorption properties of these materials, thus extending their application fields. 9 Using FTIR and SS-NMR spectroscopy and computational calculations they showed that interactions between pollutant molecules and zeolite cavities play a key role in the adsorption process.…”

Experimental Determination of the Molar Absorption Coefficient of n‐Hexane Adsorbed on High‐Silica Zeolites

“…n ‐Hexane was chosen as a representative model of an aliphatic compound because of great interest from environmental and industrial points of view, especially considering its presence in petrochemical plants . Two dealuminated zeolites, HSZ‐Y and ZSM‐5 (SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively), were selected because of our earlier experimental and computational combined studies focused on environmental issues …”

“…[15,16] Twod ealuminated zeolites, HSZ-Y and ZSM-5 (SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively), weres elected because of our earlier experimental andc omputational combined studies focused on environmental issues. [17][18][19][20] Specifically,amultidisciplinary FTIR, solid-state NMR (SS-NMR) spectroscopy,a nd thermogravimetric analysis( TGA) approach has been adopted to study the host-guest interactions of n-hexanee ntrapped inside the abovementioned porous solids and on their external surfaces;t hus determining the amount and affinity of the aliphatic molecule for the two zeolites. Weak interactions between SiOH species present at the surfaceo fb oth zeolites and n-hexane molecules, along with framework/molecule interactions, due to dispersive forces, have been enlightened.…”