Abstract
Urea, which is synthesized directly by reacting ammonia and carbon dioxide under high temperature and high pressure, is at times tinged pale yellow when stored for some time. The cause of this coloration has not been clarified. It was observed that carbon dioxide, when compressed during urea synthesis, attained its supercritical state in the compressor. Extraction of a compressor oil with supercritical carbon dioxide was carried out under actual plant operating conditions, and found that the compound extracted was 2, 6-di-tert-butyl-p-cresol (BHT). In addition, it was confirmed that urea containing a small amount of BHT developed coloration when it was exposed to sunlight.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
