Ammonia-Ammonium Bisulfate process

The oxime is converted to caprolactam by Beckmann rearrangement neutralization with ammonia gives ca 1.8 kg ammonium sulfate per kilogram of caprolactam. Purification is by vacuum distillation. A no-sulfate, extraction process has been described, but incineration of the ammonium bisulfate recovers only sulfur values and it is not practiced commercially (14). 

SAROX A process for utilizing the waste ammonium bisulfate from the manufacture of methyl methacrylate. High-temperature pyrolysis yields ammonia and sulfur trioxide. Developed by ICI and Air Liquide. 

This is in an unscrubbed plume. Now, concerning ammonia, you ae not really talking about ammonia as a catalyst for sulfate formation. The actual process is SO2 to sulfuric acid, followed by ammonia neutralization. The theory about SO2, water, ammonia catalysis is being questioned. The real process seems to be SO2 to sulfuric acid, then reaction with ammonia to form ammonium sulfate or ammonium bisulfate. In fact, in scavenging the sulfate, as the particle size increases, the scavenging efficiency also increases. Sulfuric acid aerosols are submicron particulates for which scavenging is very inefficient (Marsh, Atmos. Environ. 12 401-406, 1978). So what you are finding in a rain droplet is perhaps what is below the cloud or before the condensation nucleus stabilizes. 

The resulting liquor is Stripped with air or steam to remove the SO2 and is then fed to a crystallizer for the production of ammonium sulhite crystals. The crystals are then decomposed by heating to approximately 700°P. The deconqtosition reaction produces ammonium bisulfate for acidulation and ammonia for recycle to the process in accordance with the following reaction ... 

Breed, C. E., and Hollinden, G. A., 1974, TVA-EPA Pilot Plant Study of the Ammonia Absorption/Ammonium Bisulfate Regeneration Process, Proceedings EPA Symposium on Flue Gas Desulfurfyation, Atlanta, GA, Nov. 4-7, Vol. II, EPA-650/2-74-126b, Dec., pp. 1069-1108. 

In an industrial process, the ammonia generated in this reaction is neutralized with an acid such as H SO. The net result is the generation of a large amount of ammonium sulfate and bisulfate, which are unwanted solid wastes. 

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