04445925 is referenced by 57 patents and cites 11 patents.

Stable concentrated solutions of urea and sulfuric acid containing mono- and/or diurea sulfates and less than 35 weight percent water, free of sulfamic acid and/or ammonium sulfamate, are produced by a unique process that involves the simultaneous and separate addition of urea, sulfuric acid and optionally water to a reaction zone at controlled rates and in stochiometric proportions equivalent to the composition of the desired product, and maintaining reaction temperatures below the incipient decomposition temperature for the particular composition. The heat generated by the highly exothermic reaction can be removed by cooling the liquid phase during the course of the reaction by direct air heat exchange with only nominal, if any, atmospheric emissions.

Title
Methods of producing concentrated urea-sulfuric acid reaction products
Application Number
6/318629
Publication Number
4445925
Application Date
November 5, 1981
Publication Date
May 1, 1984
Inventor
Donald C Young
Fullerton
CA, US
Agent
Michael H Laird
Gregory F Wirzbicki
Dean Sandford
Assignee
Union Oil Company of California
CA, US
IPC
C05C 9/00
View Original Source