Modified poly(phenylene oxide) based membranes for enhanced fluid separation
AssigneePraxair Technology, Inc.
InventorsBenjamin Bikson, Gertrud Gotz, Yurdagul Ozcayir, Joyce K. Nelson
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Abstract
The present invention relates to composite membranes and membranes which are formed from modified poly(phenylene oxide) polymers having improved film forming properties and separation characteristics. The present invention further relates to poly(phenylene oxide) polymer and modified poly(phenylene oxide) polymer, having improved membrane forming characteristics and processes for producing the same.
Claims30
A process for separating at least one gas component from a gas mixture, said process comprising bringing said gas mixture into contact with a composite membrane at a pressure sufficient to permeate said at least one gas component from said gas mixture, said composite membrane comprising a porous substrate coated with modified poly(phenylene oxide) polymer, said modified poly(phenylene oxide) polymer being prepared with poly(phenylene oxide) precursor having a number average molecular weight above 25,000, said modified poly(phenylene oxide) polymer defined by having a chemical structure with at least 10% of the polymer backbone comprised of the following recurring unit:
- ##STR3## wherein R.sub.1 and R.sub.2 are selected from the group consisting of H, SO.sub.3 H, SO.sub.3 M, sulfonyl SO.sub.2 R.sub.3, sulfonamide SO.sub.2 N(R.sub.3).sub.2, carbonyl COR.sub.3 and amide COHNR.sub.3, with R.sub.3 being a C.sub.1 to C.sub.4 aliphatic radical or aryl radical, and M being alkali metal, alkaline earth metal, transition metal, NH.sup.+.sub.4 or organic base, provided that at least one of R.sub.1 and R.sub.2 is not H.
A process for separating at least one fluid component from a fluid mixture, said process comprising:
- bringing said fluid mixture into contact with a membrane at a pressure sufficient to separate at least one fluid component from said fluid mixture, said membrane comprised of sulfonated poly(phenylene oxide) polymer which is prepared via a process comprising:
- (a) dissolving poly(phenylene oxide) polymer in an inert solvent to form a solution;
- (b) adding a sulfonation agent to said solution at a temperature sufficiently low to avoid any significant sulfonation reaction to form a substantially homogeneous reaction mixture;
- (c) raising the temperature of said substantially homogeneous reaction mixture to effect sulfonation of the dissolved poly(phenylene oxide) polymer and;
- (d) recovering the resulting sulfonated poly(phenylene oxide) polymer.
A composite membrane comprising at least one separation layer of modified poly(phenylene oxide) polymer on a porous substrate, said modified poly(phenylene oxide) polymer being prepared with poly(phenylene oxide) precursor having a number average molecular weight above 25,000, said modified poly(phenylene oxide) polymer defined by having a chemical structure with at least 10% of the polymer backbone comprised of the following recurring unit:
- ##STR4## wherein:
- R.sub.1 and R.sub.2 are selected from the group consisting of H, SO.sub.3 H, SO.sub.3 M, sulfonyl SO.sub.2 R.sub.3, sulfonamide SO.sub.2 N(R.sub.3).sub.2, carbonyl COR.sub.3 and amide CONHR.sub.3, with R.sub.3 being a C.sub.1 to C.sub.4 aliphatic radical or aryl radical, and M being alkaline metal, alkaline earth metal, transition metal, NH.sup.+.sub.4 or organic base, provided that at least one of R.sub.1 and R.sub.2 is not H.
A membrane capable of separating at least one fluid component from a fluid mixture, said membrane comprising sulfonated poly(phenylene oxide) polymer which is prepared via a process comprising:
- (a) dissolving poly(phenylene oxide) polymer in an inert solvent to form a solution;
- (b) adding a sulfonation agent to said solution at a temperature sufficiently low to avoid any significant sulfonation reaction to form a substantially homogeneous reaction mixture;
- (c) raising the temperature of said substantially homogeneous reaction mixture to effect sulfonation of poly(phenylene oxide) polymer;
- and
- (d) recovering the resulting sulfonated poly(phenylene oxide) polymer.
A process for making composite membranes comprising at least one Separation layer of modified poly(phenylene oxide) polymer on a porous substrate, with such polymer defined as having chemical structure with at least 10% of the polymer backbone comprised of the following recurring unit:
- ##STR5## wherein R.sub.1 and RR.sub.2 are selected from the group consisting of H, SO.sub.3 H, SO.sub.3 M, sulfonyl SO.sub.2 R.sub.3, sulfonamide SO.sub.2 N(R.sub.3).sub.2, carbonyl COR.sub.3 and amide COHNR.sub.3, with R.sub.3 being a C.sub.1 to C.sub.4 aliphatic radical or aryl radical, and M being alkali metal, alkaline earth metal, transition metal NH.sup.+.sub.4 or organic base, provided that at least one of R.sub.1 and R.sub.2 is not H, said process comprising:
- (a) purifying poly(phenylene oxide) polymer to remove low molecular weight fractions;
- (b) chemically modifying the purified poly(phenylene oxide) polymer to form said modified poly (phenylene oxide ) polymer;
- (c) dissolving said modified poly(phenylene oxide) polymer in a solvent to form a solution;
- and
- (d) coating said porous substrate with said solution.
The process according to claim wherein said purification of poly(phenylene oxide) in step (a) is carried out by:
- (i) bringing poly(phenylene oxide) polymer containing low molecular weight fractions and/or polymerization catalyst in contact with solvent having a solubility parameter value of about 9.1 to about 9.7 [cal/cm.sup.3 ].sup.1/2 to form a slurry;
- (ii) filtering said slurry to recover purified poly(phenylene oxide) polymer in solid form and to remove low molecular weight fractions as the filtrate;
- and
- (iii) washing said purified poly(phenylene oxide) polymer in solid form with an inert solvent to remove additional low molecular weight fractions.
A process for making composite membrane, said process comprising:
- (a) dissolving modified poly(phenylene oxide) polymer in an inert solvent, said modified poly(phenylene oxide) polymer being defined as having a chemical structure with at least 10% of the polymer backbone comprised of the following recurring unit:
- ##STR6## wherein:
- R.sub.1 and R.sub.2 are selected from the group consisting of H, SO.sub.3 H, SO.sub.3 M, sulfonyl SO.sub.2 R.sub.3, sulfonamide SO.sub.2 N(R.sub.3).sub.2, carbonyl COR.sub.3 and amide CONHR.sub.3, with R.sub.3 being a C.sub.1 to C.sub.4 aliphatic radical or aryl radical, and M being alkali metal, alkaline earth metal, transition metal, NH.sup.+.sub.4 or organic base, provided that at least one of R.sub.1 and R.sub.2 is not H;
- (b) subjecting the dissolved modified poly(phenylene oxide) polymer to ultrafiltration, diafiltration and/or dialysis to obtain purified modified poly(phenylene oxide)polymer;
- (c) dissolving the purified modified poly(phenylene oxide) polymer in a solvent to form a coating solution;
- and
- (d) coating a porous substrate with said coating solution.
A process for producing poly(phenylene oxide) polymer having a number average molecular weight above 25,000, said process comprising:
- (i) bringing poly(phenylene oxide) polymer containing low molecular weight fractions and/or polymerization catalyst in contact with solvent having a solubility parameter value of about 9.1 to about 9.7 [cal/cm.sup.3 ].sup.1/2 to form a slurry;
- (ii) filtering said slurry to recover purified poly(phenylene oxide) polymer in solid form and to remove said low molecular weight fractions as the filtrate;
- and
- (iii) washing said purified poly(phenylene oxide) polymer in solid form with an inert solvent to remove additional low molecular weight fractions.
A process for preparing a membrane forming material capable of forming a membrane useful for separating at least one fluid component from a fluid mixture, said process comprising:
- (a) dissolving poly(phenylene oxide) polymer in an inert solvent to form a solution;
- (b) adding a sulfonation agent to said solution at a temperature sufficiently low to avoid any significant sulfonation reaction to form a substantially homogeneous reaction mixture;
- (c) raising the temperature of said substantially homogeneous reaction mixture to effect sulfonation of the dissolved poly(phenylene oxide) polymer and;
- (d) recovering the resulting sulfonated poly(phenylene oxide) polymer.
Dependencies are inferred from the claim text.