Structural investigations on zeolitic faujasite/benzene host/guest systems (Si/Al = 2.43 and ≈ 200) by using combined powder diffraction, adsorption calorimetry and molecular mechanics simulations

Abstract

The NaY(Si/Al =2.43)/benzene (1) and DAY(Si/Al ≈ 200)/benzene (2) systems are investigated by combined adsorption calorimetry, X-ray or neutron powder diffraction and computer simulation techniques. For (1) and (2) a good estimation of the sorption heats is obtained. A complementary study of a prehydrated NaY/benzene (3) system is also realized. For (1), ( 2) and (3) the BZ(C)/BZ(W) ratios, the distributions (localization and population) of these two independent sorbate species and the variations of the cubic unit-cell parameters are given. In (3) two ordered WI′ and WII water species exist and their distributions are reported. For this system a substantial cation migration is evidenced. In (2) two independent and totally disordered benzene species exist. It is concluded that adsorption calorimetry yields decisive informations on the adsorption mechanisms.

Insight into the Contribution of Isolated Mesopore on Diffusion in Hierarchical Zeolites: The Effect of Temperature

“…The saturate loadings for S-0 and S-15 at 300 K are ∼40 and 55 molecules/UC, respectively. The outcome shows that the calculational results are in good agreement with the experimental result of 39.5 molecules/UC . Interestingly, the relative adsorption amount of H-models and S-0 were reversed with the increase of pressure at all temperatures (as shown in Figure SI1 in the Supporting Information).…”

“…The outcome shows that the calculational results are in good agreement with the experimental result of 39.5 molecules/UC. 61 Interestingly, the relative adsorption amount of H-models and S-0 were reversed with the increase of pressure at all temperatures (as shown in Figure SI1 in the Supporting Information). The lower adsorption capacity of S-15 at lower pressure range is ascribed to the destruction of micropores in hierarchical zeolite.…”

Hydrated Cs+-Exchanged MFI Zeolites: Location of Extraframework Species in CsxHyMFI·zH2O Phases from X-ray Powder Diffraction and Differential Molar Adsorption Calorimetry

“…(1) In MFI-type materials the charge compensating Cs cations are located on a restricted number of sites (five in the dehydrated samples and three in the hydrated phases), and in the presence of sorbed polar or nonpolar molecules these cations do not cooperatively migrate or assemble and agglomerate themselves in order to only yield a single coordination center. − …”

A combined experimental and theoretical study of the simultaneous occupation of SIa and SI′ sites in fully dehydrated K–LSX

“…As can be expected, the site occupancy varies depending on both the nature and the content of the cations, the latter being determined by the framework Al content. Besides, the occupancy can strongly change upon addition of adsorbed molecules that can displace the exchanged ions, as is for instance the case with water which by forming bulky hydration spheres around the cations can extract them from the inside of the hexagonal prisms towards less constrained locations, in sodalite cages or in supercages [8].…”