Polymer-Derived Amorphous Aluminosilicate Nanomembranes for H₂ Purification.

Abstract

Aluminosilicate zeolite membranes with robust microporous crystalline structures are attractive for the molecular separation of H₂ from light gases, but their large-scale fabrication is complicated and costly, hindering their practical applications. Herein, we present polymer-derived amorphous aluminosilicate nanomembranes that combine the exceptional processability of polymers with the superior gas separation properties of aluminosilicates. Specifically, thin-film composite membranes comprising 150 nm polydimethylsiloxane were first treated with oxygen plasma to generate 10 nm polyorganosilica (POSi) on the surface, which were then subjected to few-cycle atomic layer deposition (ALD) using trimethylaluminum as a metal precursor and water vapor as a coreactant. This scalable two-step process yields few-nanometer amorphous aluminosilicates with strong size-sieving ability. For example, three-cycle ALD treatment of POSi increases H₂/CO₂ selectivity from 39 to 200 and H₂/CH₄ selectivity from 190 to 500, while decreasing H₂ permeance from 990 to 210 GPU at 150 °C, superior to the state-of-the-art membranes. Rapid and scalable manufacturing of amorphous aluminosilicate nanolayers can also be of interest for catalysis and adsorption applications.