Chromatographic study of the thermal decomposition of spent sulfuric acid

One of the most widely used means of regenerating spent sulfuric acid is to decompose them to sulfur dioxide for subsequent conversion to sulfuric acid. During the thermal decomposition of spent sulfuric acid solutions containing organic and inorganic contaminants, complex reactions - in series and parallel - may occur with the formation of a multicomponent gas phase of variable composition: SO/sub 3/, SO/sub 2/, O/sub 2/, H/sub 2/O, CO, CO/sub 2/, and in specific cases NH/sub 3/ and its decomposition products and oxides. A method has been developed for analyzing SO/sub 2/, CO/sub 2/, CO, O/sub 2/, and N/sub 2/ in samples of the gas phase that enables these components to be determined on one chromatograph: SO/sub 2/ and CO/sub 2/ are separated at 100/sup 0/C on a thermostated column with MSK silica gel; CO, O/sub 2/ and N/sub 2/ are determined at room temperature on a column packed with molecular sieves connected to the gas system by a supplementary four-way valve. We present as an illustration the results of an investigation of the decomposition of spent sulfuric acid solutions from the production of methyl methacrylate.