Silica Nanohybrid Membranes with High CO₂ Affinity for Green Hydrogen Purification

Abstract

An effective separation of CO2 from H2 can be achieved using currently known polyethylene oxide (PEO)‐based membranes at low temperatures but the CO2 permeability is inadequate for commerical operations. For commercial‐scale CO2/H2 separation, CO2 permeability of these membranes must be significantly enhanced without compromising CO2/H2 selectivity. We report here exceptional CO2/H2 separation properties of a nanohybrid membrane comprising polyethylene glycol methacrylate (PEGMA) grafts on an organic‐inorganic membrane (OIM) consisting of a low molecular weight polypropylene oxide (PPO)‐PEO‐PPO diamine and 3‐glycidyloxypropyltrimethoxysilane (GOTMS), an alkoxysilane. The CO2 gas permeability of this nanohybrid membrane can reach 1990 Barrer with a CO2/H2 selectivity of 11 at 35 °C for a mixed gas mixture comprising 50% CO2 ‐ 50% H2 at 3.5 atm. The transformation of the inorganic silica phase from a well‐dispersed network of finely defined nanoparticles to rough porous clusters appears to be responsible for this OIM membrane exceeding the performance of other state‐of‐the‐art PEO‐based membranes.

Recent developments in membranes for efficient hydrogen purification

“…(Fig. 29) [317]. The transformation of the inorganic phase from a well-dispersed network of finely defined fillers to rough clusters was primarily responsible for a significant improvement in CO 2 permeability [318].…”

Polymeric membranes for the purification of hydrogen

“…Gas separation membranes can be distinguished in conventional membranes that operate on the basis of gas diffusivity selectivity, i.e., size selection, and reverse-selective membranes that have solubility selectivity (Lau et al, 2011). Table 14.2 lists hydrogen permeability and H 2 /CO 2 ideal selectivity for different polymers.…”

Enhanced CO2 separation properties by incorporating poly(ethylene glycol)-containing polymeric submicrospheres into polyimide membrane

“…Numerous efforts have been devoted to explore PEGcontaining blend membranes [23], copolymer membranes [24] and hybrid membranes [25,26] for efficient CO 2 separation. Considering the moderate polarity of PEG and the favorable affinity between PEG and CO 2 , rationally designed PEG-containing fillers may act as solubility promoter without causing polymer chain rigidification in membranes.…”