Published October 2003
Sulfates such as ammonium bisulfate (ABS) and ammonium sulfate (AS) are generated in the production of a variety of chemicals including methionine, methionine hydroxy analog, caprolactam, acrylonitrile and methyl methacrylate. More stringent environmental regulation has resulted in increased emphasis on technologies for the handling of waste streams like ABS and AS.
Novus International and Degussa have developed technologies for the regeneration of sulfuric acid from the ammonium sulfate salts formed in the production of methionine and methionine hydroxy analog (MHA). In contrast to conventional sulfuric acid process that converts sulfur dioxide to sulfur trioxide over a catalyst bed which is then converted to sulfuric acid. The Degussa process converts sulfur dioxide directly to sulfuric acid by reaction with hydrogen peroxide. The sulfuric acid can be recycled to the hydrolysis portion of the MHA process.
In this review we present a technical and economic evaluation of the conversion of ammonium bisulfate (ABS) generated in methionine and MHA processes to sulfuric acid via the hydrogen peroxide route, based on the production of 130 million lb/yr (59,000 t/yr) of sulfuric acid at a U.S. Gulf Coast location. Although any source of spent acid or sulfate salts may be used as feedstock.
This review should be interested to manufacturers of chemicals that generate AS and ABS as a by-product.