Sulfur reservoir distribution

As seen from Fig. 4.5, the reservoir distribution of SO2 strongly depends on the aqueous phase pH. The sulfurous acid H2SO3 is not known as a pure substance several isomeric forms have been spectroscopically detected. Therefore, the symbol SO2 aq is often used the equihbrium (5.281) lies full on the left-hand side ( 5 281 10 ). Sulfurous acid, however, is largely dissociated with x>K, 2 2 — 2.2 and P 5.283 7.0, ks,2 2 — 3.1 10 S. ... 

Solutions in reservoirs A and B are permanently renewed by pumps and vigorously stirred, ensuring constant and uniform feed conditions at the A and B boundaries. Chemicals are distributed in reservoirs in such a way that neither of the solutions A nor B is reactive on its own. Iodide is present in both tanks. Chlorite is fed in basic solution only in tank A, while malonic acid, in sulfuric acid solution, is fed only in tank B. Chemicals diffuse from the edges into the gel where they meet and react. Concentration gradients of chemical species naturally settle between the feed boundaries. Isoconcentration lines naturally form parallel to these boundaries. The oxidation capacity due to chlorite decreases from A to B. The typical time for stationary concentration profiles to establish is 3 hours. 

The chemical system used for our study is a chlorite-iodide-malonic acid (CIMA) reaction in an acidic (sulfuric acid) aqueous solution. The CIMA reaction exhibits a rich variety of phenomena oscillations in a batch reactor or in a CSTR [26], transient target waves in a closed Petri dish [26], bistability in a CSTR [26, 27], front structures in a Couette reactor [27-30], and Turing patterns in open gel reactors [7-10]. In our two-side-fed reactor. Figure lb, components of the reaction are distributed in the two compartments in such a way that neither compartment is separately reactive. Chlorite is only in compartment A , and malonic acid is only in compartment B thus there are opposing chemical concentration gradients in the direction normal to the plane of the gel. The other chemical species are contained in equal amounts in both reservoirs, except for sulfuric acid, which is more concentrated in compartment B than in compartment A. Note that chlorite and iodide in compartment A are at a low acid concentration they would react rapidly at high acid conditions. 

Each refinery has its own range of preferred crude oil feedstock for which a desired distribution of products is obtained. The crude oil usually is identified by its source country, underground reservoir, or some distinguishing physical or chemical property. The three most frequently specified properties are density, chemical characterization, and sulfur content. 

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