An attempt to alter the gas separation of mesoporous glass membranes by amine modification

Mesoporous glass membranes were synthesised and used to study the influence of an altered surface chemistry on adsorption and diffusion properties. A modification with a silane possessing high amine content was conducted to enhance the interaction with adsorbable gases. The obtained membranes were characterised by their adsorption equilibrium properties and their permeabilities for the gas pair carbon dioxide and nitrogen in single gas and binary mixture permeation experiments. The modified surface induced a reversal in the temperature dependence of the membrane selectivity. The strong adsorption on the modified surface led to a hindered carbon dioxide transport at lower temperatures and an accelerated transport at higher temperatures. Due to the limited amount of grafted adsorption sites on the modified membranes this effect was pronounced at low partial pressures of carbon dioxide.

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► Porous glass membranes were surface modified using silane with a high amine content.
► Adsorption and permeation measurements for CO2/N2 mixtures.
► Modification led to an enhanced adsorption of CO2 at high temperatures.
► A reversal in the dependence of the selectivity on temperature was observed.