Abstract: This application is directed to the field of scrubbing a sulfur dioxide-laden gas stream by a phosphate rock solution, and then regenerating that sulfur dioxide gas via acidulation, by contacting the phosphate rock solution with sulfuric acid to regenerate a high purity sulfur dioxide stream.

Abstract: A process to improve ethanol yield, decrease fermentation time and reduce byproduct formation by monitoring and controlling oxidation reduction potential (redox) of the fermentor is disclosed.

Abstract: A process is provided for producing elemental sulfur from hydrogen sulfide contained in an acid gas feed stream wherein hydrogen sulfide and sulfur dioxide are reacted in a catalytic only sulfur recovery unit comprising a single catalytic converter containing a Claus catalytic reaction zone. A sulfur dioxide-enriched gas recovered from tail gas treatment is recycled and introduced into the catalytic reaction zone as part of a feed gas mixture that also includes the acid gas feed stream. Temperatures within the catalytic reaction zone are effectively moderated by recycle of tail gas effluent to the converter so that high concentrations of hydrogen sulfide in the acid gas feed stream can be tolerated and improved process flexibility and capacity are realized. A pretreatment process including contacting the acid gas with an aqueous acid wash to reduce the concentration of unsaturated hydrocarbons in the acid gas and inhibit deactivation of the oxidation catalyst is also disclosed.

Abstract: A process for the selective removal and recovery of sulfur dioxide from effluent gases is disclosed. The sulfur dioxide is recovered in a sulfur dioxide absorption/desorption cycle which utilizes a liquid solvent to selectively absorb sulfur dioxide from the effluent gas. The liquid solvent includes an organic phosphorous compound selected from phosphate triesters, phosphonate diesters, phosphinate monoesters and mixtures thereof. Preferably, the liquid solvent includes phosphonate diesters of the formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are independently aryl or C.sub.1 to C.sub.8 alkyl. The organic phosphonate diesters are substantially water immiscible, the solubility of water in the organic phosphonate diester being less than about 10 weight percent at 25.degree. C., and have a vapor pressure less than about 1 Pa at 50.degree. C. In accordance with a preferred embodiment, the liquid solvent include dibutyl butyl phosphonate.