Polymers With Intrinsic Microporosity Research Articles

Metal ion modified PIM-1 and its application for propylene/propane separation

Polymers with intrinsic microporosity (PIMs) have attracted much attention from the membrane community due to the nature of high fractional free volume and high gas permeability. To explore their potential for C3H6/C3H8 separation, PIM-1 was hydrolyzed and incorporated with various metal ions such as Zn2+, Mg2+ and Ag+. Experimental results reveal that the pristine PIM-1 has poor C3H6/C3H8 separation. Analyses from positron annihilation lifetime spectroscopy suggest that hydrolyzed PIM-1 possesses a smaller free volume size and a less fractional free volume resulting in a higher C3H6/C3H8 selectivity of α=9.12 and a lower C3H6 permeability of 421 Barrer. The Ag+ ion treated membrane shows weak facilitated transport with a moderately improved C3H6 permeability of 759 Barrer and C3H6/C3H8 selectivity of 11.69. The Mg2+ ion treated membrane exhibits affinity to the π-orbital of olefin. It has a higher C3H6/C3H8 selectivity of 15.23 but a lower C3H6 permeability of 568 Barrer. The Zn2+ ion treated membrane displays the highest C3H6 permeability of 837 Barrer but a lower selectivity of 9.12. In addition, the results of pressure-dependent permeation tests indicates that the Zn2+ ion treated membrane has better plasticization resistance than other membranes.

High performance membrane materials for gas separation

The use of membranes in various gas separations has increased significantly in recent times. This review presents some of the recent noteworthy advances in the field of membranes materials for these applications. A description of the most promising groups of high free volume polymers, including polyimides, thermally rearranged (TR) polymers, substituted polyacetylenes, perfluoropolymers, and polymers with intrinsic microporosity (PIM) is provided. High performance, rubbery, polyethers and polyether based copolymers are shown as another important class of polymer membrane materials. The development of inorganic membranes, which are not bound to the trade-off limitations between permeability and selectivity exhibited by polymers is also presented. The attention is focused on zeolitic materials, metal organic frameworks (MOF), and carbon molecular sieves (CMS). The field of mixed matrix membranes composed of inorganic particles embedded in a polymer matrix is also briefly outlined.

High-productivity gas separation membranes derived from pyromellitic dianhydride and nonlinear diamines

Two new polyimides have been obtained from commercial and inexpensive pyromellitic dianhydride and two affordable meta-substituted diamines bearing ortho methyl substituents (i.e., 2,4,6-trimethyl-1,3-phenylene diamine (TMPD) and 5,7-diamino-1,1,4,6-tetramethylindane (TMID)). Due to a combination of dianhydride rigidity and meta substitution, in addition to the influence of the ortho substituents on the orthogonal placement of the amine and imide planes, the two polyimides exhibited a high fractional free volume and a high rigidity. Therefore, these polyimides were able to produce gas separation membranes with an excellent balance between permeability and selectivity, and these membranes performed similar to many polymers with intrinsic microporosity (PIMs) and surpassed the 1991 Robeson upper bound for all gas pairs. The behavior is more favorable than that for similar polyimides based on 6FDA, which is considered to be the best dianhydride for gas separation polyimides.

Advances in high permeability polymeric membrane materials for CO2separations

Global CO2 emissions have increased steadily in tandem with the use of fossil fuels. A paradigm shift is needed in developing new ways by which energy is supplied and utilized, together with the mitigation of climate change through CO2 reduction technologies. There is an almost universal acceptance of the link between rising anthropogenic CO2 levels due to fossil fuel combustion and global warming accompanied by unpredictable climate change. Therefore, renewable energy, non-fossil fuels and CO2 capture and storage (CCS) must be deployed on a massive scale. CCS technologies provide a means for reducing greenhouse gas emissions, in addition to the current strategies of improving energy efficiency. Coal-fired power plants are among the main large-scale CO2 emitters, and capture of the CO2 emissions can be achieved with conventional technologies such as amine absorption. However, this energy-consuming process, calculated at approximately 30% of the power plant capacity, would result in unacceptable increases in power generation costs. Membrane processes offer a potentially viable energy-saving alternative for CO2 capture because they do not involve any phase transformation. However, typical gas separation membranes that are currently available have insufficiently high permeability to be able to process the massive volumes of flue gas, which would result in a high CO2 capture. Polymer membranes highly permeable to CO2 and having good selectivity should be developed for the membrane process to be viable. This perspective review summarizes recent noteworthy advances in polymeric materials having very high CO2 permeability and good CO2/N2 selectivity that largely surpass the separation performance of conventional polymer materials. Five important classes of polymer membrane materials are highlighted: polyimides, thermally rearranged polymers (TRs), substituted polyacetylenes, polymers with intrinsic microporosity (PIM) and polyethers, which provide insights into polymer designs suitable for CO2 separation from, for example, the post-combustion flue gases in coal-fired power plants.

Characterization of the Gas Transport in Mixed Matrix Membranes Based on Polymers with Intrinsic Microporosity (PIMs)

Characterization of the Gas Transport in Mixed Matrix Membranes Based on Polymers with Intrinsic Microporosity (PIMs)

95/04993 Electrostatically atomized hydrocarbon sprays

Polymers with intrinsic microporosity (PIMs) have attracted much attention from the membrane community due to the nature of high fractional free volume and high gas permeability. To explore their potential for C3H6/C3H8 separation, PIM-1 was hydrolyzed and incorporated with various metal ions such as Zn2+, Mg2+ and Ag+. Experimental results reveal that the pristine PIM-1 has poor C3H6/C3H8 separation. Analyses from positron annihilation lifetime spectroscopy suggest that hydrolyzed PIM-1 possesses a smaller free volume size and a less fractional free volume resulting in a higher C3H6/C3H8 selectivity of α=9.12 and a lower C3H6 permeability of 421 Barrer. The Ag+ ion treated membrane shows weak facilitated transport with a moderately improved C3H6 permeability of 759 Barrer and C3H6/C3H8 selectivity of 11.69. The Mg2+ ion treated membrane exhibits affinity to the π-orbital of olefin. It has a higher C3H6/C3H8 selectivity of 15.23 but a lower C3H6 permeability of 568 Barrer. The Zn2+ ion treated membrane displays the highest C3H6 permeability of 837 Barrer but a lower selectivity of 9.12. In addition, the results of pressure-dependent permeation tests indicates that the Zn2+ ion treated membrane has better plasticization resistance than other membranes.