US4387224A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Melamine quality by reactivation of the melamine synthesis catalyst
Assignee: BASF SE
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Filing: 1982-09-20
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Granted: 1983-06-07
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Expires: 2002-09-20
Abstract
Abstract In the synthesis of melamine by conversion of urea in a fluidized catalyst bed, the melamine quality is improved by reactivating the catalyst by treating it, in the fluidized bed, with gases containing steam, in the absence of oxygen, at from 250° to 450° C.
Inventors
- 👤 Dieter Fromm
- 👤 Ernst-Juergen Schier
- 👤 Hans H. Schneehage
- 👤 Wolfgang Vodrazka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:14
CPC Classifications
C; C07; C07D; C07D251/00; C07D251/02; C07D251/12; C07D251/26; C07D251/40; C07D251/54; C07D251/56; C07D251/60; B; B01; B01J; B01J21/00; B01J21/20; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/584
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
60 words
A process for improving the quality of melamine by reactivating the catalysts, which have been employed in the synthesis of melamine by thermal conversion of urea in a fluidized catalyst bed, through treatment with gases containing steam, wherein the catalyst in the fluidized bed is treated with steam-containing gases in the absence of oxygen at from 250° to 450° C.
Claim 2
Dependent Claim
60 words
A process for improving the quality of melamine by reactivating the catalysts, which have been employed in the synthesis of melamine by thermal conversion of urea in a fluidized catalyst bed, through treatment with gases containing steam, wherein the catalyst in the fluidized bed is treated with steam-containing gases in the absence of oxygen at from 250° to 450° C.
Claim 3
Dependent Claim
19 words
A process as claimed in claim 1, wherein the treatment is carried out at from 350° to 450° C.
Claim 4
Dependent Claim
18 words
A process as claimed in claim 1 or 2, wherein the treatment is carried out during the synthesis.
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) | 1986-06-06 | 1986-12-06 | 1987-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-06 | 1990-12-06 | 1991-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-06 | 1994-12-06 | 1995-06-07 | $7700.00 | Window Closed / Lapsed |