David E Best

US Patent:

55147976, May 7, 1996

Filed:

Jun 7, 1995

Appl. No.:

8/479003

Inventors:

David Best - Prairieville LA
Amit Gupta - Baton Rouge LA

Assignee:

Melamine Chemicals, Inc. - Donaldsonville LA

International Classification:

C07D25162

US Classification:

544203

Abstract:

A method of purifying melamine produced from urea in a high-pressure, non-catalytic, non-aqueous process is described. In the method impure melamine is heated to a temperature of from about 250. degree. to about 1000. degree. F. under a pressure from about 600 to 3000 psi in the presence of ammonia to provide melamine having a purity of 99. 0% or above. The method is economical since chemical treatment and recrystallization steps are not required.

US Patent:

45658676, Jan 21, 1986

Filed:

Jan 9, 1985

Appl. No.:

6/689921

Inventors:

Roger E. Thomas - Baton Rouge LA
David E. Best - Prairieville LA

Assignee:

Melamine Chemicals, Inc. - Donaldsonville LA

International Classification:

C07D25160

US Classification:

544201

Abstract:

This high-pressure, high-temperature anhydrous process prepares melamine from urea. It is a primary object of the present invention to provide a highly energy-efficient and improved continuous process for the production of melamine from urea which utilizes a simplified process to produce and recover a high-grade (96 to 99. 5% purity) melamine as a dry powder directly from liquid melamine melt. Molten urea is supplied to a reactor maintained at high temperature (700. degree. to 800. degree. F. ) and high pressure (1700 to 2200 psig) whereby melamine, CO. sub. 2, and NH. sub. 3 are formed. The reactor effluent stream containing liquid melamine, CO. sub. 2, and NH. sub. 3 is transferred to a gas separator where CO. sub. 2 and NH. sub. 3 containing melamine are separated and cycled to a scrubber unit for scrubbing with molten urea reactant to remove the melamine before transfer of the CO. sub. 2 and NH. sub. 3 gases at high pressure to an adjacent urea plant for utilization in producing urea.

US Patent:

55147968, May 7, 1996

Filed:

Jun 7, 1995

Appl. No.:

8/478088

Inventors:

David Best - Prairieville LA
Amit Gupta - Baton Rouge LA

Assignee:

Melamine Chemicals, Inc. - Donaldsonville LA

International Classification:

C07D25160

US Classification:

544201

Abstract:

A high-pressure, non-catalytic process for producing melamine from urea wherein the melamine is recovered directly as a dry powder without washing or recrystallization is described. In the process, liquid melamine is fed to a cooling unit where it is quenched with a liquid medium, preferably liquid ammonia. By increasing the pressure within the cooling unit to a pressure in excess of 600 psi and preferably to 1200 to 1400 psi provides melamine having a purity in excess of 99%.

US Patent:

62622617, Jul 17, 2001

Filed:

Apr 7, 2000

Appl. No.:

9/545677

Inventors:

Tjay T. Tjioe - Sittard, NL
David E. Best - Prairieville LA

Assignee:

DSM NV

International Classification:

C07D25160

US Classification:

544201

Abstract:

Process for the preparation of melamine from urea via a high-pressure process in which dry melamine powder is obtained by transferring the melamine melt leaving the reactor to a vessel in which the melamine melt is cooled by means of ammonia characterized in that the melamine melt is sprayed into a cooling vessel and cooled by droplets of evaporating liquid ammonia which is sprayed into the same cooling vessel at a pressure above 0. 1 MPa and a temperature between 50. degree. C. and the melting point of the melamine in the cooling vessel.