Defect-Patching of Zeolite Membranes by Surface Modification Using Siloxane Polymers for CO₂ Separation

Abstract

Grain boundary defects are normally formed in zeolite membranes during membrane preparation and calcination processes. In this work, a siloxane polymer coating with the imidazole group was grafted on the surface of defective SSZ-13 membranes by chemical liquid deposition to seal the defects. The parameters such as silanization time, polymerization time, monomer type and concentration were optimized.Characterizations including Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDX), showed that siloxane polymers were coated on the surfaces of SSZ-13 crystals and membrane. Six modified membranes showed decreased CO 2 permeance by only 21±5% [average CO 2 permeance of 1.9×10 -7 mol/(m 2 s Pa)] and increased CO 2 /CH 4 selectivity by a factor of 9±3 (average CO 2 /CH 4 selectivity of 108) for an equimolar CO 2 /CH 4 mixture at 298 K. CO 2 /CH 4 and CO 2 /N 2 selectivities of the modified membrane decreased with pressure and temperature. Membrane stability was investigated for a long-time test and exposures to water vapor at temperatures up to 378 K and to some organic solutions. This modification method is also effective in sealing the defects of other zeolite membranes such as AlPO-18 membranes.

Defects-healing of SAPO-34 membrane by post-synthesis modification using organosilica for selective CO2 separation

“…8b), thus improving the separation performance (regarding The developed VAD-SO-3-SAPO-34 membrane was compared with other small-pore CHA/AEI zeolite membranes (e.g. SAPO-34, SSZ-13, AlPO-18) with respect to their ability to separate the equimolar CO 2 /CH 4 mixture [23,31,34]. Table 2 shows that the VAD-SO-3-SAPO-34 membrane demonstrated good CO 2 permeance (which was comparable to that of the original SAPO-34 membrane), while enhancing the CO 2 /CH 4 separation selectivity by ca.…”

“…The presence of boundary defects between zeolite crystals, which are much larger than the pore opening of SAPO-34 zeolite (i.e. 0.38 nm), has a significant negative impact on the separation selectivity [31]. Therefore, in order to improve the separation performance of zeolite membranes, it is crucial to develop strategies to eliminate these defects in the membrane [18,23,[31][32][33][34][35][36].…”

“…grafted a siloxane polymer coating with imidazole group on the surface of defective SSZ-13 membranes by CLD [31]. The modified membranes showed increased CO 2 /CH 4 selectivity by a factor of ca.…”

CO2 capture using membrane contactors: a systematic literature review

“…[447][448][449][450][451]453,454,456,458,459,[463][464][465][466][467]472,473,475,[478][479][480]482,483,[484][485][486][487][488][489]496,497,[500][501][502]505,506,508,513,514,516,517,519,521,523,524,528,533,538,543]. One of the reasons for the low popularity of hydrophilic membranes is the low thermal and chemical stability of membranes, which in turn has an effect on the flux, demonstrated in Table…”

Fabrication and molecular transport studies of highly c-Oriented AFI membranes

“…Zeolite membranes have been studied intensively over the last 30 years [1,2]. Due to their well-defined and highly stable porous structure, zeolite membranes are able to achieve sharp molecular sieving with high transport rates and thus have shown excellent performance in many challenging separation systems such as dehydration [3,4], CO 2 capture [5,6], and hydrocarbon mixtures with close-boiling points [7,8]. However, it is still a considerable challenge to synthesize defect-free membranes over large areas with controllable microstructures.…”