Carbon molecular sieve membranes for water separation in CO2 hydrogenation reactions: Effect of the carbonization temperature

Carbon membranes are a potentially attractive candidate for the in-situ removal of water vapor in CO2 hydrogenation reactions. Their hydrophilicity and pore structure can be tuned by properly adjusting synthesis procedure. Herein, we assess effect carbonization temperature (450–750 °C) on performance supported CMSM terms vapor/gas separation, correlation with changes their surface functionality porous structure. FTIR spectra showed that nature functional groups evolution step, leading to gradual loss (i.e., OH stretching disappears at Tcarb ≥ 600 °C). The extent adsorption displays an optimum 500 °C, membrane carbonized 650 °C being least hydrophilic. We found size distribution strongly influences permeance. At all Tcarb, adsorption-diffusion (AD) is dominant transport mechanisms. However, as soon ultra-micropores appear (Tcarb: 600–700 molecular sieving (MS) contributes increase permeance, despites hydrophilicity. 750 MS pores disappear, causing drop Finally, permeance different gases (N2, H2, CO, CO2) mostly affected distribution, mechanism over AD, except CO2. gas permeation drastically change function content feed, indicating gas/vapor molecules need compete access membranes.