EP0154746A2
Expired / Lapsed
EP
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Method of recovering dewaxing aid (DWA) from mixture of wax and DWA by wax permeation through semipermeable membrane
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1984-12-03
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Granted: —
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Expires: 2004-12-03
Abstract
Abstract @ Dewaxing aids (8) used to improve the separability of wax from hydrocarbon oils (2), preferably petroleum oil, most preferably lube or transformer oils, are themselves recovered from the wax (16) and/or the dewaxed oil (24) by selective permeation of the wax (22) and/or dewaxed oil/ dewaxing solvent (28) through a semipermeable membrane (18 and/or 26) with the retained, recovered dewaxing aid (20 and/or 30) being recycled to the dewaxing process. The dewaxing aid (20 and/or 30) is recovered in an undegraded form, and is as effective in the dewaxing process as is fresh dewaxing aid. Degraded dewaxing aid, if any, passes through the membrane along with the wax (22) or oil or dewaxing solvent (28) and is thus not recovered for recycle.
Inventors
- 👤 Biddanda Umesh Achia
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 02:08
CPC Classifications
C; C10; C10G; C10G73/00; C10G73/02; C10G73/04; B; B01; B01D; B01D61/00; B01D61/02; B01D61/025
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
82 words
A method for recovering dewaxing aid in an undegraded form from a mixture of precipitated wax-dewaxing aid produced by chilling waxy hydrocarbon oil in the presence of dewaxing aid to yield precipitated wax-dewaxing aid mixture which is then separated from said chilled oil, the dewaxing aid recovery method comprising heating the separated, precipitated wax-dewaxing aid mixture to liquefy said mixture and selectively permeating said liquefied wax through a semi-permeable membrane under pressure yielding a wax permeate and an undegraded dewaxing aid retentate.
Claim 2
Independent Claim
82 words
A method for recovering dewaxing aid in an undegraded form from a mixture of precipitated wax-dewaxing aid produced by chilling waxy hydrocarbon oil in the presence of dewaxing aid to yield precipitated wax-dewaxing aid mixture which is then separated from said chilled oil, the dewaxing aid recovery method comprising heating the separated, precipitated wax-dewaxing aid mixture to liquefy said mixture and selectively permeating said liquefied wax through a semi-permeable membrane under pressure yielding a wax permeate and an undegraded dewaxing aid retentate.
Claim 3
Dependent Claim
64 words
A method as in claim 1 in which the semi-permeable membrane has an average pore size in the range of from 500 to 2,000R (500 x 10- 10 m to 2000 x 10 - 10 m) and the dewaxing aid has a molecular weight in the range of from about 1,000 to about 1,000,000, preferably in the range from about 200,000 to about 500,000.
Claim 4
Dependent Claim
44 words
A method as in claim 1 or claim 2 in which the waxy hydrocarbon oil is chilled in the presence of dewaxing aid and dewaxing solvent, and a mixture comprising precipitated wax and dewaxing aid is then separated from chilled oil and dewaxing solvent.
Claim 5
Dependent Claim
58 words
The method of claim 3 wherein the dewaxing solvent is selected from C 2 -C 10 alkane, alkene or alkyne hydrocarbons, C 3 -C 6 ketones, aromatic hydrocarbons, halogenated hydrocarbons, mixtures of C 3 -C 6 ketones and aromatic hydrocarbons and mixtures of C 3 -C 6 ketones and C 2 -C 6 alkane, alkene or alkyne hydrocarbons.
Claim 6
Independent Claim
62 words
The method of any one of claims 1 to 4 wherein the dewaxing aid comprises of one, or a mixture of more than one, of materials selected from condensation polymers of chlorinated paraffins and naphthalenes, polyalkylacrylates, polyalkylmethacrylates, alpha-olefin copolymers, ethylene-vinyl acetate copolymers, alkyl fumarate-vinylacetate copolymers, polyethylene oxides, polyvinylacetates, polyvinylpyrrolidones, polyisobutylenes, polybutadiene, polystyrene-butadiene copolymers, alkali metal stearates, polyalkylene glycols, and fatty acid glycerides.
Claim 7
Independent Claim
58 words
The method of any one of claims 1 to 5 wherein the semipermeable membrane is selected from cellulose esters, cellulose ethers, regenerated-cellulose, vulcanized or unvulcanized gum rubber and latex, polycarbonate, polypropylene, polyester, polyethylene, polybutadiene, polytetrafluorethylene, polystyrene, butadienestyrene copolymers, isoprene-isobutene copolymers, polyacrylonitrile, crosslinked or vulcanized organopolysiloxanes, polypentaerythritol, ethylenepropylene copolymers, sulfonated polyarylethersulfones, polyvinyl alcohol, nitrocellulose, polyisoprene, butadiene-acrylonitrile copolymers and poly-2-chlorobutadiene.
Claim 8
Independent Claim
34 words
The method of any one of claims 1 to 6 wherein the content of dewaxing aid in the wax or dewaxed oil fed to the membrane separation process is 0.001 to 50X by weight.
Claim 9
Independent Claim
31 words
The method as in any one of claims 1 to 7 wherein the wax which is separated from the chilled oil contains from 0.10 to 85 percent by weight of oil.
Claim 10
Independent Claim
36 words
The method of any one of claims 1 to 8 wherein at least some of the retentate containing recovered dewaxing aid is recycled to the dewaxing process for contacting with additional portions of waxy hydrocarbon oil.
Claim 11
Independent Claim
36 words
The method of any one of claims 1 to 9 wherein a portion of the retentate enriched with dewaxing aid, when withdrawn from the membrane separation zone, is recycled to the inlet of the latter zone.
Claim 12
Independent Claim
25 words
The method of any one of claims 1 to 10 wherein the membrane separation is operated in a plurality of serially arranged membrane separation stages.
References Cited (Backward Citations)
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