Patent US3657236A successfully refreshed from Google Patents.
US3657236A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of melamine
Assignee: BASF SE
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Filing: 1969-11-19
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Granted: 1972-04-18
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Expires: 1989-11-19
Abstract
Abstract TO PRODUCE MELAMINE, UREA AND/OR ITS THERMAL DECOMPOSITION PRODUCTS ARE REACTED AT 220* TO 400*C. IN CONTACT WITH AN ALUMINUM OXIDE HAVING A LARGE SURFACE AREA IN THE PRESENCE OF AMMONIA. THE ALUMINUM OXIDE USED HAS BEEN OBTAINED BY TREATMENT OF HYDROXIDES OF ALUMINUM (WHICH HAVE NOT BEEN PREVIOUSLY CALCINED) WITH UREA AND/OR ITS THERMAL DECOMPOSITION PRODUCTS AT TEMPERATURES OF FROM 150* TO 400*C. THE AVERAGE OF ALUMINUM OXIDE ACTIVATED IN THIS MANNER OVER ALUMINUM OXIDE OBTAINED BY CALCINING ALUMINUM HYDROXIDE CONSIST IN INCREASED UREA CONVERSION AND GREATER ATTRITION RESISTANCE.
Inventors
- 👤 Hermann Dieter Fromm
- 👤 Karl Wilhelm Leonhard
- 👤 Rudolf Mohr
- 👤 Matthias Schwarzmann
- 👤 Horst Woehrle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:30
CPC Classifications
C; C07; C07D; C07D251/00; C07D251/02; C07D251/12; C07D251/26; C07D251/40; C07D251/54; C07D251/56; C07D251/60
Claims Analysis
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-18 | 1975-10-18 | 1976-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-18 | 1979-10-18 | 1980-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-18 | 1983-10-18 | 1984-04-18 | $7700.00 | Window Closed / Lapsed |