Hydrocarbon/hydrogen mixed gas permeation in poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends

Abstract

The gas permeation properties of poly(1‐trimethylsilyl‐1‐propyne) (PTMSP), poly(1‐phenyl‐1‐propyne) (PPP), and blends of PTMSP and PPP have been determined with hydrocarbon/hydrogen mixtures. For a glassy polymer, PTMSP has unusual gas permeation properties which result from its very high free volume. Transport in PPP is similar to that observed in conventional, low‐free‐volume glassy polymers. In experiments with n‐butane/hydrogen gas mixtures, PTMSP and PTMSP/PPP blend membranes were more permeable to n‐butane than to hydrogen. PPP, on the other hand, was more permeable to hydrogen than to n‐butane. As the PTMSP composition in the blend increased from 0 to 100%, n‐butane permeability increased by a factor of 2600, and n‐butane/hydrogen selectivity increased from 0.4 to 24. Thus, both hydrocarbon permeability and hydrocarbon/hydrogen selectivity increase with the PTMSP content in the blend. The selectivities measured with gas mixtures were markedly higher than selectivities calculated from the corresponding ratio of pure gas permeabilities. The difference between mixed gas and pure gas selectivity becomes more pronounced as the PTMSP content in the blend increases. The mixed gas selectivities are higher than pure gas selectivities because the hydrogen permeability in the mixture is much lower than the pure hydrogen permeability. For example, the hydrogen permeability in PTMSP decreased by a factor of 20 as the relative propane pressure (p/psat) in propane/hydrogen mixtures increased from 0 to 0.8. This marked reduction in permanent gas permeability in the presence of a more condensable hydrocarbon component is reminiscent of blocking of permanent gas transport in microporous materials by preferential sorption of the condensable component in the pores. The permeability of PTMSP to a five‐component hydrocarbon/hydrogen mixture, similar to that found in refinery waste gas, was determined and compared with published permeation results for a 6‐Å microporous carbon membrane. PTMSP exhibited lower selectivities than those of the carbon membrane, but permeability coefficients in PTMSP were nearly three orders of magnitude higher. © 1996 John Wiley & Sons, Inc.

Silica filled poly(4-methyl-2-pentyne) nanocomposite membranes: Similarities and differences with poly(1-trimethylsilyl-1-propyne)–silica systems

“…Polyacetylene-based polymers, and especially poly(1-trimethylsilyl-1-propyne) (PTMSP) membranes have been studied intensively for applications in this field [1][2][3]. PTMSP has a glassy nature at room temperature (T g > 200 °C) and is characterized by high permeabilities, which are attributed to the high free volume content of the polymer matrix [4,5].…”

A Novel Poly(4‐methyl‐2‐pentyne)/TiO2 Hybrid Nanocomposite Membrane for Natural Gas Conditioning: Butane/Methane Separation

“…13 C spectra were recorded on a Bruker MSh-300 spectrometer operating at 75.47 MHz (with an acquisition number of 12 000). The content of cis-and trans-units in PMP samples was quantified from the 13 C NMR spectra using a Bruker 1D WinNMR program for treating poorly resolved spectra.…”

“…[1][2][3][4][5][6][7][8] After the 1980s, among the polymeric membranes (membranes with rubbery selective layer) for use for the separation of hydrocarbon mixtures, as well as the removal of organic components from permanent gas streams, great attention was afforded to the disubstituted polyacetylenes, which are glassy polymers that have the highest known gas permeability. [7][8][9][10][11][12][13][14][15][16][17][18] Polyacetylenes such as poly(4-methyl-2-pentyne) (PMP), [7,8,16] poly(1-trimethylsilyl-1-propyne) (PTMSP), [12,13,15] and poly(1-trimethylgermyl-1-propyne) (PTMGP) [17,18] are more permeable for large organic molecules (condensable gases) than for permanent gases. This property has been attributed to an extremely high fractional free volume that results from an unusually loose packing of stiff polymer chains that contain carbon-carbon double bonds and bulky side-chain groups.…”

Polymer nanosieve membranes for CO2-capture applications

“…Previously, this phenomenon has only been observed in hydrocarbon (condensable gas)/light gas separation (for example, n-butane/H 2 ) using highly permeable PTMSP (ref. 28) and PIM-1 membranes 29 . In such high free-volume glassy polymers, condensable large gases such as butane occupy the sorption sites by a strong sorption interaction, and then exclude the sorption or passage of lighter gases.…”