Influence of hydronium ions in zeolites on sorption.

Influence of hydronium ions in zeolites on sorption.
Angew Chem Int Ed Engl. 2019 Jan 02;:
Authors: Eckstein S, Hintermeier PH, Zhao R, Baráth E, Shi H, Liu Y, Lercher J
Abstract
In presence of sufficient concentrations of water, stable, hydrated, hydronium ions are formed in the pores and at the surface of solid acids such as zeolites. For a medium pore zeolite, such as zeolite MFI, the hydrated hydronium ions consist of eight water molecules and have an effective volume of 0.24 nm³. In their presence, larger organic molecules can only adsorb in the portions of the pore that are not occupied by hydronium ions. In consequence, the available pore volume decreases proportionally to the concentration of the hydronium ions. The higher charge density (the increasing ionic strength) that accompanies an increasing concentration of hydronium ions leads to an increase in the activity coefficients of adsorbed substrates, thus, weakening the interactions between the organic part of the molecules and the zeolite and favouring the interactions with polar groups. The quantitative understanding of these interactions allows linking a collective property such as hydrophilicity and hydrophobicity of zeolites to specific interactions on molecular level.
PMID: 30600885 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - January 2, 2019 Category: Chemistry Authors: Eckstein S, Hintermeier PH, Zhao R, Baráth E, Shi H, Liu Y, Lercher J Tags: Angew Chem Int Ed Engl Source Type: research