Ultra-Selective CMSMs Derived from Resorcinol-Formaldehyde Resin for CO2 Separation

Abstract

A resorcinol-formaldehyde precursor was synthesized to fabricate the CO2 selective Carbon Molecular Sieve Membranes (CMSMs) developed in this study. The degree of polymerization (DP) was analyzed via Gel Permeation Chromatography (GPC) and its effect on the CO2/N2 perm-selectivity and CO2 permeance was investigated. The membrane that was polymerized at 80 °C (named R80) was selected as the best performing CMSM after a preliminary test. The post treatment with oxidative atmosphere was performed to increase the CO2 permeance and CO2/N2 perm-selectivity on membrane R80. The gas permeation results and Pore Size Distribution (PSD) measurements via perm-porometry resulted in selecting the membrane with an 80 °C polymerization temperature, 100 min of post treatment in 6 bar pressure and 120 °C with an oxygen concentration of 10% (named R80T100) as the optimum for enhancing the performance of CMSMs. The 3D laser confocal microscopy results confirmed the reduction in the surface roughness in post treatment on CMSMs and the optimum timing of 100 min in the treatment. CMSM R80T100 exhibiting CO2/N2 ideal selectivity of 194 at 100 °C with a CO2 permeability of 4718 barrier was performed higher than Robeson’s upper bound limit for polymeric membranes and also the other CMSMs fabricated in this work.

Carbon Molecular Sieve Membranes for Selective CO2/CH4 and CO2/N2 Separation: Experimental Study, Optimal Process Design, and Economic Analysis

“…Pore size distribution (PSD) of fabricated CMS membranes was measured via permporometry and reported in previous work. 50,51 CMS membranes for the selective separation of CO 2 from CH 4 were also successfully fabricated and tested in permeation experiments. Results higher than the Robeson's upper bound limit of CO 2 /CH 4 perm-selectivity and CO 2 permeance were observed in all fabricated CMS membranes.…”

“…CO 2 permeance increases generally with increasing temperature as a function of the dominant molecular sieving transport mechanism in ultramicropores. Pore size distribution (PSD) of fabricated CMS membranes was measured via permporometry and reported in previous work. , …”

“…The permeation results from the experimental measurements were used to calculate perm-selectivities and permeances at each operational pressure and temperature. More details regarding the treatment of permeation data and calculations could be found in our previous work . The CMS membranes, which were developed to separate CO 2 from N 2 , exhibited extremely high perm-selectivities and permeances compared to Robeson’s upper bound limit for polymeric membranes at all operating temperatures and pressures.…”

“…In the next step, coated membranes were moved to a drying/polymerization rotary oven, and finally cured membranes were placed in a tubular carbonization oven for pyrolysis at 500 °C for a duration of 3 h with a heating rate of 1 °C/min in N 2 atmosphere. All the details regarding the synthesis of the precursor, characterization, and fabrication steps, are reported in our previous work . For CMS membranes that were fabricated for CO 2 /N 2 separation, the oligomer synthesis was carried out at 90 °C for 3 h, while for CO 2 /CH 4 separation, the polycondensation reaction was performed at 85 °C for 4 h. The renaming of the membranes is based on the polymerization temperature after dip coating and the weight percentage of the ethylene diamine used in their dipping solution.…”

“…All the details regarding the synthesis of the precursor, characterization, and fabrication steps, are reported in our previous work. 50 For CMS membranes that were fabricated for CO 2 /N 2 separation, the oligomer synthesis was carried out at 90 °C for 3 h, while for CO 2 /CH 4 separation, the polycondensation reaction was performed at 85 °C for 4 h. The renaming of the membranes is based on the polymerization temperature after dip coating and the weight percentage of the ethylene diamine used in their dipping solution. As an example, R80E1, is the carbon membrane for which the coated support was polymerized at 80 °C and the dipping solution contained 1 wt % of the ethylene diamine.…”