| 摘要 |
<p>314,443. Lamb, A. B., (Assignee of Krase, H. J., and Hetherington, H. C.). June 27, 1928, [Convention date]. Urea is produced by heating ammonium carbamate or compounds of ammonia, carbon dioxide and water such as ammonium carbonate or bicarbonate in an autoclave, in the presence of an excess of ammonia equal to at least 15 per cent of the weight of the combined ammonium, to temperatures of from 150 to 200‹ C. When the reaction has proceeded to the desired extent the temperature may be lowered, for example to 60- 100‹ C., and the uncombined ammonia distilled off and used again. The process may be made continuous, for example, by leading carbon dioxide and excess of ammonia into an autoclave, and working by the continuous process described in Specification 335,913. An example is given. Specification 241,123 also is referred to.</p> |
