Basf Aktiengesellschaft

Casale Chemicals Sa

Willi Ripperger

Walter Herrmann

Wolfgang Ruehenbeck

Manfred Dressel

Herbert Geierhaas

Heinrich Eberle

Werner Zwick

Process for cooling and crystallizing solid melamine from the gaseous phase or from melamine melts as they develop in technical processes used to produce melamine, characterized in that the melamine-containing process gases or melamine melts are introduced into liquid, organic phase at high pressure, said phase comprising polyvalent alcohols such as ethylene glycol, glycerine or their homologous series or of amines such as ethanol amines or a mixture of both groups. The advantage this process is that the hot melamine is cooled very quickly without forming thermal decomposition products and that during quenching no reaction of the melamine with the solvent occurs, the formation of higher deammoniation products such as melam and melem is prevented and higher deammoniation products of the melamine such as melam and melem, are partially converted back into melamine.

Process for gently cooling and crystallizing melamine from a melamine melt or from the gaseous phase

A method for purifying melamine comprising impurities like ureido-melamine, oxotriazines, melam, melem, comprises the step of putting into contact at a temperature comprised between 340&#xb0; C. and 410&#xb0; C. and at a pressure comprised between 8 and 17 MPa a melamine melt with a bed of a catalyst thus obtaininig melamine with a purity of at least 99%.

Process for the production of high purity melamine from urea

In the preparation of ammonium carbamate by reacting ammonia with carbon dioxide, the reactants are introduced into a layer of ammonium carbamate which is kept in the fluidized state by gaseous ammonia or carbon dioxide. The temperature is kept below 25.degree. C. by removing the heat of reaction.

Preparation of ammonium carbamate

Spherical refining catalysts containing cobalt and/or nickel together with molybdenum on aluminum oxide are prepared in closed mixers provided with mixing elements from spray-dried powders such as catalyst preparations or carriers using peptizing agents. The catalysts thus prepared have a bulk density much higher than that of extrudates of similar composition. Their surface and pore size distribution make them suitable for use in the catalytic refining of hydrocarbon fractions containing metal and asphalt, and particularly for refining vacuum distillates and residues from atmospheric distillation.

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Frankenthal, Germany

Willi Ripperger