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Patent US4908134A successfully refreshed from Google Patents.
US4908134A
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Ultrafiltration polyamide membrane and its use for recovery of dewaxing aid (OP-3454)
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1989-02-16
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Granted: 1990-03-13
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Expires: 2009-02-16
Abstract
Abstract Polyimide ultrafiltration membranes made using a single solvent and containing a pore forming agent have been produced and have been found to be useful for recovering dewaxing aid used in dewaxing process.
Inventors
- 👤 Bryce P. Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:13
CPC Classifications
B; B01; B01D; B01D61/00; B01D61/14; B01D61/145; B01D71/00; B01D71/06; B01D71/58; B01D71/62; B01D71/64; C; C10; C10G; C10G73/00; C10G73/02; C10G73/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
200 words
A method for recovering dewaxing aids used in the solvent dewaxing of waxy hydrocarbon oils wherein the dewaxing aid is present in a dewaxed oil stream, a precipitated wax stream or both and wherein the dewaxing aid present in said dewaxed oil stream, precipitated wax stream or both is recovered by heating said stream so that the wax is in the liquid state and contacting said heated stream with an ultrafiltration polymeric membrane to selectively permeate through said membrane the oil or wax component of said heated stream while producing retentate containing the dewaxing aid which retentate can be recycled to the solvent dewaxing process wherein the ultrafiltering polymeric membrane comprises a polyimide membrane made by dissolving a fully imidized polyimide polymer in a pro solvent or mixture of pro solvents and a pore forming agent characterized by having at least about 50% more molar volume than the solvent or solvent mixture used, a solubility parameter equal to a greater than that of the solvent and a polar end and substantial hydrocarbon character, to produce a casting solution, using said casting solution to produce a thin layer of said polyimide polymer/solvent/pore former, and quenching the layers in a quenching solvent.
Claim 2
Independent Claim
200 words
A method for recovering dewaxing aids used in the solvent dewaxing of waxy hydrocarbon oils wherein the dewaxing aid is present in a dewaxed oil stream, a precipitated wax stream or both and wherein the dewaxing aid present in said dewaxed oil stream, precipitated wax stream or both is recovered by heating said stream so that the wax is in the liquid state and contacting said heated stream with an ultrafiltration polymeric membrane to selectively permeate through said membrane the oil or wax component of said heated stream while producing retentate containing the dewaxing aid which retentate can be recycled to the solvent dewaxing process wherein the ultrafiltering polymeric membrane comprises a polyimide membrane made by dissolving a fully imidized polyimide polymer in a pro solvent or mixture of pro solvents and a pore forming agent characterized by having at least about 50% more molar volume than the solvent or solvent mixture used, a solubility parameter equal to a greater than that of the solvent and a polar end and substantial hydrocarbon character, to produce a casting solution, using said casting solution to produce a thin layer of said polyimide polymer/solvent/pore former, and quenching the layers in a quenching solvent.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein the ultrafiltration dewaxing aid recovery process is performed at a temperature of about 70° to 250° C. and an applied pressure of about 5 to 200 psi.
Claim 4
Dependent Claim
20 words
The method of claim 1 or 2 wherein the polyimide polymers used to produce the membrane is based on 5(6)-amino-l-(4,-aminophenyl)-l,3,3-trimethyindane.
Claim 5
Dependent Claim
36 words
The method of claim 3 wherein the solvent used to produce the membrane casting solution is selected from methylene chloride, ethylene chloride, chloroform, tetrachloroethane, acetophenone, cyclohexanone, m-cresol, dimethylformamide, N-methylpyrrolidone (NMP) or dimethylacetamide (DAMC) and mixtures thereof.
Claim 6
Dependent Claim
11 words
The method of claim 4 wherein the poreformer is epsilon caprolactam.
Claim 7
Dependent Claim
30 words
The method of claim 5 wherein the casting solution contains 14 to 22 wt % polymer, about 6 to 20 wt % pore former and the balance is the solvent.
Claim 8
Dependent Claim
11 words
The method of claim 6 wherein the solvent is dimethyl formamide.
Claim 9
Dependent Claim
32 words
The method of claim 3 wherein the mixture of dewaxing aid and wax or dewaxing aid and oil which is subject to the ultrafiltering process comes from an autorefrigerative solvent dewaxing process.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |