Hydrothermal stability of fluorine‐induced microporous silica membranes: Effect of steam treatment conditions

Abstract

A fluorine‐SiO2 membrane was prepared using triethoxyfluorosilane (TEFS) as a Si precursor, and its hydrothermal stability was evaluated. The TEFS membrane calcined at 750°C had fewer Si‐OH and Si‐F groups in its network structure and showed H2 permeance that was greater than 10−6 mol m−2 s−1 Pa−1 with H2/N2 and N2/SF6 permeance ratios of 10 and 210, respectively. This membrane performance was relatively stable under the temperature (< 500°C) used for steam treatment, regardless of the steam partial pressure (30, 90 kPa). On the other hand, when the steam treatment temperature was increased beyond 500°C, gas permeance decreased significantly and the membrane became highly selective for He and H2 over smaller molecules (He/N2: > 600, H2/N2: > 100). The relationship between the activation energy of H2 and the permeance ratios (He/H2, He/H2O, H2/H2O) of a TEFS‐derived membrane under steam treatment higher than 600°C resulted in a network pore size that approximated in conventional microporous SiO2 membranes.

Synthesis of size-controlled boehmite sols: application in high-performance hydrogen-selective ceramic membranes

“…6e, S18 and Table S9 †. Remarkably, the high temperature of steam treatment may have an inverse influence on the hydrothermal stability, 69 which highlights the stable performance of the Si–Ta membrane under 650 °C in this research.…”

A Brief Overview of the Microstructural Engineering of Inorganic–Organic Composite Membranes Derived from Organic Chelating Ligands

“…Doping a material with an anion or cation is used to direct a membrane's microstru ture or functionality towards developing an enhanced performance. For example, fluori as an anion has been used to add a functionality to an organosilica membrane for im proved propylene/iso-butane separation [41], for the improved hydrothermal stability a silica membrane [42,43] or for microstructural control of the membrane pore size [4 Palladium doping of a silica membrane has been used to improve hydrogen permsele tivity [44]. Nickel doping of aminosilica has also been recently studied [45,46].…”