US4008255A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovery of phthalic anhydride
Assignee: BASF SE
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Filing: 1975-06-23
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Granted: 1977-02-15
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Expires: 1995-06-23
Abstract
Abstract Process for the recovery of phthalic anhydride in which gases as obtained in the catalytic atmospheric oxidation of o-xylene or naphthalene are treated with a hydrocarbon containing C 26 - paraffins, cooling, if necessary, the hydrocarbon laden with phthalic anhydride, separating the solid phthalic anhydride followed by melting and distillation thereof.
Inventors
- 👤 Friedrich Wirth
- 👤 Wolfgang Kube
- 👤 Paul Hornberger
- 👤 Otto Leman
- 👤 Joachim Wagner
- 👤 Dieter Karau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:31
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
141 words
A process for the continous recovery of phthalic anhydride from process gases obtained in the catalytic atmospheric oxidation of o-xylene or naphthalene which comprises: washing said process gases in an absorption column at a temperature of 60° to 170° C with a solvent consisting essentially of C26-44 paraffins or with a hydrocarbon mixture having a boiling point of at least 360° C at atmospheric pressure and containing at least 55% by weight of C26-44 paraffins, whereby phthalic anhydride from said process gases is dissolved in said paraffins; cooling said paraffins ladened with phthalic anhydride to form solid phthalic anhydride, separating said solid phthalic anhydride from the major portion of the solvent by mechanical means to form a slurry of phthalic anhydride crystals, melting said crystals and distilling said phthalic anhydride from said slurry; and recycling said paraffins to said absorption column.
Claim 2
Dependent Claim
141 words
A process for the continous recovery of phthalic anhydride from process gases obtained in the catalytic atmospheric oxidation of o-xylene or naphthalene which comprises: washing said process gases in an absorption column at a temperature of 60° to 170° C with a solvent consisting essentially of C26-44 paraffins or with a hydrocarbon mixture having a boiling point of at least 360° C at atmospheric pressure and containing at least 55% by weight of C26-44 paraffins, whereby phthalic anhydride from said process gases is dissolved in said paraffins; cooling said paraffins ladened with phthalic anhydride to form solid phthalic anhydride, separating said solid phthalic anhydride from the major portion of the solvent by mechanical means to form a slurry of phthalic anhydride crystals, melting said crystals and distilling said phthalic anhydride from said slurry; and recycling said paraffins to said absorption column.
Claim 3
Dependent Claim
30 words
A process as claimed in 1, wherein washing of the process gases with said solvent is carried out in a column at a temperature of from 70° to 140° C.
Claim 4
Dependent Claim
32 words
A process as claimed in claim 1, wherein the washing of the process gases with said solvent is carried out at temperatures of from 60° to 80° C in a quenching tower.
Claim 5
Dependent Claim
45 words
A process as claimed in claim 1, wherein the washing of the process gas with said solvent is carried out in a column at temperatures of from 90° to 140° C and then in a quenching tower at temperatures of from 60° to 90° C.
Claim 6
Dependent Claim
15 words
A process as claimed in claim 1 wherein said solvent consists essentially of C26-38 paraffins.
Claim 7
Dependent Claim
32 words
A process as claimed in claim 1 wherein said solvent leaves the absorption column at a temperature of 90°-135° C laden with from 0.5 to 40% by weight of phthalic and hydride.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-15 | 1980-08-16 | 1981-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-15 | 1984-08-16 | 1985-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-15 | 1988-08-16 | 1989-02-15 | $7700.00 | Window Closed / Lapsed |