Abstract: A process for manufacturing high purity anhydrous hydrogen fluoride (HF) having low levels of arsenic impurity by contacting anhydrous hydrogen fluoride product, or an intermediate product obtained during the manufacture of HF, with hydrogen peroxide in the presence of a catalyst which comprises effective amounts of molybdenum or an inorganic molybdenum compound and a phosphate compound. The volatile trivalent arsenic impurity in the anhydrous hydrogen fluoride is oxidized to a non-volatile pentavalent arsenic compound and the resultant mixture is distilled to recover high purity anhydrous hydrogen fluoride with reduced levels of arsenic impurity. In one embodiment, an oxidizing agent such as nitric acid or a nitrate salt is added to the reaction mixture to oxidize organic contaminants.

Abstract: An improved cyclic process for the alkylation of isoparaffins with olefins in the presence of a circulating concentrated sulfuric acid catalyst is disclosed. Improvement in the octane rating of the product alkylate is achieved by periodic fortification of the sulfuric acid catalyst with a sulfur trioxide-bearing fortifying agent under conditions wherein the harmful effects caused by contact of the sulfur trioxide with the hydrocarbons in the alkylation zone are minimized. The acid catalyst is fortified during less than about 15% of the cycles of the circulating acid catalyst through the alkylation system to maintain the water content of the acid catalyst in the range of above about 1% and below about 4% by weight. The process effects not only essentially 100% utilization of the fortifying agent for water removal but also improves the octane rating of the product alkylate while simultaneously extending the service life of the acid catalyst by allowing use of the catalyst having higher organic content.

Abstract: An improved process for the alkylation of isoparaffins by olefins in the presence of a sulfuric acid catalyst is disclosed. Improvement in the octane rating of the product alkylate is achieved by the periodic fortification of the sulfuric acid catalyst with sulfur trioxide-bearing fortifying agents and the incorporation of a holding time to delay the return of the fortified acid to the alkylation zone. Fortification is employed less than 6% of the time the catalyst is in contact with the hydrocarbons and a preferred water content of between 1.5% and 2.5% is maintained in the acid. By maintaining an optimum water content and fortifying less frequently, lower water and organic build-up rates are observed than previously thought possible. By incorporation of a holding time before the acid is returned to the alkylation reactor, there is essentially complete utilization of the fortifying agent for water removal and no free SO.sub.3 is available for harmful side reactions with the hydrocarbon feeds in the reactor.

Abstract: Improvement in the method for recovering sulfur values in the form of sulfur dioxide from spent sulfuric acid by decomposing the spent sulfuric acid at elevated temperature in the presence of elemental sulfur to generate a sulfur dioxide-containing gas stream, which involves: (a) introducing the spent sulfuric acid into a pool of molten sulfur maintained at temperature of at least about 250.degree. C. to thereby generate a gaseous stream comprising sulfur dioxide, vaporous elemental sulfur, and water; (b) cooling said gaseous stream to temperature above the melting point of the sulfur but below about 160.degree. C. to condense elemental sulfur therefrom, separating the condensed elemental sulfur and returning it to the pool of molten sulfur; followed by (c) further cooling the gaseous stream from which elemental sulfur has been condensed to condense water therefrom, and separating the condensed water from the gaseous stream.

Abstract: Process for transforming water-soluble metal sulfate residue obtained from spent sulfuric acid containing inorganic impurities, such as pickle liquors or acid wastes from hydrometallurgical processes, into substantially water-insoluble form suitable for disposal which comprises introducing the residue into a pool of molten sulfur maintained at temperature of at least about 250.degree. C. to thereby generate a gaseous stream comprising sulfur dioxide and to transform the metal sulfate residue into corresponding reduction products, and recovering sulfur dioxide and reduction products associated with sulfur in solid form suitable for disposal.