DE1216316B - Improved process for the continuous production of melamine - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 40JTWW PATENT OFFICE Int. α .:

C07d

EDITORIAL

German class: 12 ρ - 10/05

Number: 1216 316

File number: St 18064IV d / 12 ρ

Filing date: July 12, 1961

Opening day: May 12, 1966

^: The invention relates to an improvement of the subject of patent 1102165 forming process for the continuous production of melamine by successive heating of urea and / or a product formed by thermal decomposition of urea with ammonia in the presence of a catalyst with a large internal surface in two separate reaction rooms wherein the urea and or or its thermal decomposition product together initially a heated to about 350 ° C catalyst fluidized bed, such as is used for the melamine synthesis per se known, is fed with ammonia and withdrawing gases and vapors through to about 330 ⁰ C. The catalyst resting layer held, whereupon the melamine formed is deposited by cooling from the gases and vapors leaving the catalyst resting layer.

This process has the disadvantage that in order to achieve the highest possible degree of conversion relatively large amounts of catalyst are required. So you need z. B. in the catalyst rest layer 1700 kg of silica grains if this layer is kept at 330 ° C by cooling and if the catalyst fluidized bed 100 kg of urea is added every hour. The degree of conversion in this case is 96%.

If the catalyst resting layer is kept at a temperature of 350 ° C., this layer must Contains 825 kg of silica grains, so with the same addition of urea a degree of conversion of 94% of Theoretically possible maximum value is reached ". At higher temperatures, the degree of conversion goes down return.

A process for the production of melamine is known from British patent specification 767 344, in which urea and / or a product formed by thermal decomposition of urea is heated to temperatures of 220 to 400 ° C. _{in the presence of NH 3 and a catalyst with a large internal surface area} .

In one embodiment of this method it has been discussed to use three different e.g. B. cascaded To apply fluidized catalyst beds with increasing temperatures, then the solid catalyst from one to the next Fluidized bed is conveyed.

This transport of solids and the swirling of the catalyst in different layers requires a large amount of energy.

According to the Invention, Big Savings Are Improved Process For Continuous
Manufacture of melamine

Addendum to the patent: 1102 165

Applicant:

Stamicarbon N.V., Heerlen (Netherlands)

Representative:

Dr. F. Zumstein,

Dipl.-Chem. Dr. rer. nat. E. Assmann

and Dipl.-Chem. Dr. R. Koenigsberger,

Patent Attorneys, Munich 2, Bräuhausstr. 4th

Named as inventor:
Johannes Joseph Steggerda,
Geleen (Netherlands)

Claimed priority:

Netherlands of July 14, 1960 (253 816)

possible in terms of catalyst and energy costs if the vapors flowed through the first Part of the catalyst rest layer or in the case of several catalyst rest layers connected in series in the layers through which the air flows first, the temperature rises from around 350 to 375 to 425 ° C leaves, followed by cooling the remaining part of the catalyst rest layer or layers the temperature of the escaping vapors is reduced to about 350 ° C or below.

If z. B. the entering with a temperature of 350 ° C vapors the temperature in the lower part Let the rest layer rise up to 400 ° C, whereupon the temperature is increased by cooling in the upper part the escaping vapors is set back to 350 ° C, the rest shift only needs kg of catalyst, but kg if the entire rest shift is kept at 350 ° C will.

The amount of catalyst saved is therefore 38%.

Of course, in the process according to the invention, instead of just a catalyst rest

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layer several, ζ. B. use two series-connected catalyst layers and in this case maintain a temperature of 375 to 425 ° C. in the catalyst layer through which the vapors first flow and a temperature of 350 ° C. (or lower) in the subsequent catalyst layer, r; ;; '; ■. \ / _! - "_'_.""-.. ■ ..; -.-.-

Claims (1)

Claim: • - - , - ■ -. ' ίο Process for the continuous production of melamine by successive heating of urea and / or a product formed by thermal decomposition of urea with ammonia in the presence of a catalyst with a large internal surface in two separate reaction rooms., ·· where the • urea and / or or its thermal decomposition product of ammonia together with a heated first to about 350 ⁰ C catalyst fluidized bed: as · five ^':; the _melamine; ;.; ' ..synthesis, which is known to be needed, is fed and the exhausting gases and vapors are passed through a catalyst resting layer kept at about 330 ° C, whereupon • the melamine formed is separated from the gases and vapors leaving the catalyst layer by cooling, according to the patent 1102165, characterized in that in the part of the catalyst rest layer through which the vapors first flow, or in the case of several series-connected catalyst ^{rest layers in the layers through which the flow passes first, the temperature is allowed to rise from about 350 to 375 to 425 °} C., whereupon the remaining part of the catalyst rest layer is cooled or the catalyst rest layers on the temperature of the exiting vapors . is lowered about 350 ° C or below ,. · Considered publications:
■ British patent specification No. 767 344 ... - ..