Structural two-phase evolution of aminosilica-based silver-coordinated membranes for increased hydrogen separation

Abstract

Hybrid organosilica membranes of silver-doped bis [3-(trimethoxysilyl) propyl] amine (BTPA) were prepared via sol-gel processing followed by coordination reactions to improve the permeability and separation performance. The evolution of silver in two phases as silver ions and as nanoparticles was observed during modification of the aminosilica networks; the silver ions coordinated with amine moieties while the silver nanoparticles developed following reduction on the aminosilica surface. The silver/amine mole ratio was evaluated against the formation of coordinated and particulate species during modification in the range of 0.1–0.5 mol mol−1. The formation of microporosity was successfully developed from 2.36 to 115 m2 g−1 by increasing the silver mole ratio. Furthermore, silver-modified aminosilica membranes showed a hydrogen (H2) permeance of 1.46 × 10−6 mol m−2 s−1 Pa−1, which was 65-fold higher than pure BTPA with excellent selectivity for H2/propane (C3H8) separation of 1500. It is evident that the proposed modification method via the two-phase structural evolution of silver coordination and nanoparticles reorganized the organosilica framework and improved the separation in the dehydrogenation of propane.