US3856673A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of spent sulfuric acid
Assignee: Air Products and Chemicals Inc
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Filing: 1973-04-02
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Granted: 1974-12-24
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Expires: 1993-04-02
Abstract
Abstract A process for purifying a spent acid stream containing organic impurities and at least 60 percent by weight of sulfuric acid comprises admixing the stream with ozone, hydrogen peroxide, peroxydisulfates or chlorates and recovering a purified acid stream containing substantially less of the organic impurities than the spent stream. The process has particular utility in the removal of the nonvolatile organic impurities contained in spent sulfuric acid from the nitration of aromatic hydrocarbons.
Inventors
- 👤 La Mater G De
- 👤 B Milligan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:20
CPC Classifications
C; C01; C01B; C01B17/00; C01B17/69; C01B17/90; C01B17/905
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
172 words
IN A SYSTEM FOR THE NITRATION OF AROMATIC COMPOUNDS, A PROCESS FOR PURIFYING A SPENT ACID STREAM FROM SAID SYSTEM AND CONTAINING ORGANIC IMPURITIES WHICH COMPRISES THE STEPS OF STRIPPING SID SPENT ACID STREAM IN A DENITRIFIER TO REMOVE A SUBSTANTIAL PORTION OF THE VOLATILE ORGANIC IMPURITIES THEREFROM, CONTACTING THE RESULTING STRIPPED SPENT ACID STREAM CONTAINING AT LEAST 50 PPM OF NONVOLATILE ORGANIC IMPURITIES SELECTED FROM THE GROUP CONSISTING OF NITROCRESOLS AND OTHER NITROPHENOLIC COMPOUNDS AND FROM 60% TO ABOUT 85% BY WEIGHT OF SULFURIC ACID FROM SAID DENITRIFIER WITH AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF OZONE, HYDROGEN PEROXIDE, CHLORATES, PEROXYDISULFATES AND MIXTURES THEREOF BY ADDING AT LEAST ONE STOICHIOMETRIC EQUIVALENT IN INCREMENTS OF ABOUT ONE-THIRD OR LESS OF SAID OXIDIZING AGENT PER EQUIVALENT OF NONVOLATILE ORGANIC IMPURITIES DURING A PERIOD OF ABOUT ONE MINUTE TO ABOUT 60 MINUTES AT A TEMPERATURE OF ABOUT 130* TO 230*C AND RECOVERING A PURIFIED ACID STREAM CONTAINING LESS THAN 50 WEIGHT OF SAID NONVOLATILE ORGANIC IMPURITIES THAN SAID STRIPPED SPENT ACID STREAM.
Claim 2
Dependent Claim
172 words
IN A SYSTEM FOR THE NITRATION OF AROMATIC COMPOUNDS, A PROCESS FOR PURIFYING A SPENT ACID STREAM FROM SAID SYSTEM AND CONTAINING ORGANIC IMPURITIES WHICH COMPRISES THE STEPS OF STRIPPING SID SPENT ACID STREAM IN A DENITRIFIER TO REMOVE A SUBSTANTIAL PORTION OF THE VOLATILE ORGANIC IMPURITIES THEREFROM, CONTACTING THE RESULTING STRIPPED SPENT ACID STREAM CONTAINING AT LEAST 50 PPM OF NONVOLATILE ORGANIC IMPURITIES SELECTED FROM THE GROUP CONSISTING OF NITROCRESOLS AND OTHER NITROPHENOLIC COMPOUNDS AND FROM 60% TO ABOUT 85% BY WEIGHT OF SULFURIC ACID FROM SAID DENITRIFIER WITH AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF OZONE, HYDROGEN PEROXIDE, CHLORATES, PEROXYDISULFATES AND MIXTURES THEREOF BY ADDING AT LEAST ONE STOICHIOMETRIC EQUIVALENT IN INCREMENTS OF ABOUT ONE-THIRD OR LESS OF SAID OXIDIZING AGENT PER EQUIVALENT OF NONVOLATILE ORGANIC IMPURITIES DURING A PERIOD OF ABOUT ONE MINUTE TO ABOUT 60 MINUTES AT A TEMPERATURE OF ABOUT 130* TO 230*C AND RECOVERING A PURIFIED ACID STREAM CONTAINING LESS THAN 50 WEIGHT OF SAID NONVOLATILE ORGANIC IMPURITIES THAN SAID STRIPPED SPENT ACID STREAM.
Claim 3
Dependent Claim
21 words
The process of claim 1 wherein said oxidizing agent is continuously added to said spent acid stream during the contacting step.
Claim 4
Dependent Claim
45 words
The process of claim 1 wherein the effluent from the contacting step is stripped to remove the volatile materials resulting from the oxidation of said organic impurities and then recovered as a purified acid stream containing less than 50 percent by weight of said impurities.
Claim 5
Dependent Claim
167 words
In a system for the nitration of toluene, a process for purifying a spent acid stream from said system and containing organic impurities which comprises the steps of stripping said spent acid stream in a denitrifier to remove s substantial portion of the volatile organic impurities, contacting the bottom containing at least 50 ppm of nonvolatile organic impurities selected from the group consisting of nitrocresols and other nitrophenolic compounds and from 60 percent to about 85 percent by weight of sulfuric acid from said denitrifier with an oxidizing agent selected from the group consisting of ozone, hydrogen peroxide, chlorates, peroxydisulfates and mixtures thereof by adding at least one stoichiometric equivalent in increments of about one-third or less of said oxidizing agent per equivalent of nonvolatile organic impurities during a period of about one mimute to about 60 minutes at a temperature of about 130* to 230*C and recovering a purified acid stream containing less than 50 percent by weight of said nonvolatile organic impurities than said bottoms.
Claim 6
Dependent Claim
167 words
In a system for the nitration of toluene, a process for purifying a spent acid stream from said system and containing organic impurities which comprises the steps of stripping said spent acid stream in a denitrifier to remove s substantial portion of the volatile organic impurities, contacting the bottom containing at least 50 ppm of nonvolatile organic impurities selected from the group consisting of nitrocresols and other nitrophenolic compounds and from 60 percent to about 85 percent by weight of sulfuric acid from said denitrifier with an oxidizing agent selected from the group consisting of ozone, hydrogen peroxide, chlorates, peroxydisulfates and mixtures thereof by adding at least one stoichiometric equivalent in increments of about one-third or less of said oxidizing agent per equivalent of nonvolatile organic impurities during a period of about one mimute to about 60 minutes at a temperature of about 130* to 230*C and recovering a purified acid stream containing less than 50 percent by weight of said nonvolatile organic impurities than said bottoms.
Claim 7
Dependent Claim
21 words
The process of claim 4 wherein said oxidizing agent is continuously added to said spent acid stream during said contacting step.
Claim 8
Dependent Claim
44 words
The process of claim 4 wherein said spent acid stream has been continuously stripped in said denitrifier to remove a substantial portion of the volatile impurities therefrom prior to continuously contacting said stream with said oxidizing agent and continuously recovering said purified acid stream.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |