Addition Polyalkylnorbornenes: A Promising New Class of Si‐Free Membrane Materials for Hydrocarbons Separation

Abstract

ated petroleum gases. The realization of this process allows avoiding problems with the condensation of hydrocarbons (i.e., to reduce the dew point) and pre-detonating coking in compressor engines. [4,5] The separated C 2+ fraction will be a valuable feed for further chemical processing, or it can be used as a fuel. For a successful solution of the abovementioned task, membranes that show solubilitycontrolled permeation (i.e., which are characterized by higher permeability of heavier components of a mixture) seem to be the most attractive. For a long time, it was believed that the solubility-controlled permeation is a feature of rubbery polymers. In particular, it took place for the most permeable rubber-polydimethylsiloxane, while for convenient glassy polymers the permeability of hydrocarbons usually reduces with the size of penetrants mole cules. [5,6] At the same time, the use of glassy polymers in this process could extend frames and conditions of its application owing to high glass transition temperatures, good mechanical properties, and the promising combination of membrane characteristics of glassy polymers (glassy polymers dominate the polymers near or on the upper bound in contrast to rubbery polymers [7] ). The discovery of glassy poly(trimethylsilylpropyne) (PTMSP) and other highly permeable polyacetylenes in the last decades of the twentieth century quite unexpectedly revealed that glassy polymers indeed could possess the solubility controlled gas permeation of hydrocarbons. [8,9] Later it was shown that some other glassy polymers with large free volume polymers of intrinsic microporosity (PIM's) [10,11] and addition polynorbornenes bearing Me 3 Si-side groups [12,13] ) also exhibited the solubility controlled permeation. The main reasons for this phenomenon were the nanoporous nature of these glassy polymers and the presence of large free volume. Unfortunately, the abovementioned nanoporous polymers have not found a practical application for separation of hydrocarbons mainly due to the significant aging over time. These materials, as well as polysiloxanes, are extremely permeable membranes, so higher permeable polymers are not apparently required. Therefore, the process of hydrocarbon separation would be improved if the separation selectivity and polymers stability could be enhanced. To overcome these problems, low free volume glassy polynorbornenes [14][15][16][17] and polyacetylenes [18][19][20] have been successfully developed. The solubility-controlled permeation of hydrocarbons in these polymers Addition Poly(alkylnorbornenes) Nanoporous glassy polymers are perspective materials for the fabrication of gas separation membranes, especially for the application of gaseous hydrocarbon separation. However, the drawback of such materials is the pronounced physical aging resulting in the dramatic drop of gas transport properties due to relaxation of high-free-volume fraction in time. Herein, a novel and readily available group of such glassy polymers is reported based on 5-alkylnorbornenes. These polym...

Synthesis and Gas Transport Properties of Addition Polynorbornene with Perfluorophenyl Side Groups

“…The ageing of the membranes from APF5 was not studied in this work, and will be studied later. Nevertheless, it has recently been shown that similar addition polynorbornenes with alkyl or tri(alkoxy)silyl side groups are not prone to ageing for several months [ 25 , 29 ].…”

“…The ageing of the membranes from APF5 was not studied in this work, and will be studied later. Nevertheless, it has recently been shown that similar addition polynorbornenes with alkyl or tri(alkoxy)silyl side groups are not prone to ageing for several months [25,29]. The permeability selectivity of separation for APF5 was determined as the ratio of the permeability (P) coefficient of component i to that of component j (Equation ( 4)).…”

“…As a result, various addition polymers derived from norbornenes were successfully developed for applications such as adhesives [ 13 ], OLEDs [ 14 , 15 , 16 ], catalyst supports [ 17 , 18 ], membrane materials [ 9 , 19 , 20 ], gas storage materials [ 21 ], and dielectrics [ 22 , 23 , 24 ]. Different norbornene-based membrane materials possessing extremely high gas permeability accompanied by high C 4 H 10 /CH 4 and CO 2 /N 2 selectivities were reported [ 9 , 25 , 26 , 27 , 28 , 29 , 30 ]; in some cases, these polymers possess good long-term stability of their gas transport properties [ 25 , 29 ]. It was found that the most attractive sets of properties can be obtained by the introduction of trimethylsilyl, alkoxysilyl, siloxanyl, and alkyl side groups [ 9 ].…”

Hydrocarbon separations by glassy polymer membranes

“…[109][110][111][112] Notably, Jue and F I G U R E 7 Deconvoluting diffusion and sorption contributions to hydrocarbon permeation in sorption-selective glassy polymers. [85][86][87][88][89][90] (a) Diffusivity (D A )versus sorption coefficient (S A ) and (b) diffusion selectivity (D A /D B )versus sorption selectivity (S A /S B ). Hollow points: polyacetylenes and polynorbornenes, Solid points: PIM-1 (A: ethane, propane, n-butane; B: methane) coworkers made defect-free PIM-1 monolithic hollow fiber membranes with 3-6 μm skin layer.…”

“…[138,139] Unsubstituted addition PNBs are diffusion-selective showing low FFV ($0.11) and permeabilities. [88,140] Substitution by alkyl side groups provides sorptionselective PNBs (e.g., PDNB, Figure 14) with higher FFV and permeabilities than unsubstituted ones. Replacing alkyl side groups by bulkier Si-containing side groups further increases FFV and permeabilities.…”