The initial addition of Ihas a dramatic effect on some uncatalyzed Belousov-Zhabotinskii (BZ) oscillators in a well-defined, narrow range of [I-],. The number of oscillations and the length of the induction period increase as [IJO increases, while the amplitude of the oscillations decreases. The oscillations disappear above a certain [I-lO. A temporary bistability exists in some cases between a steady state and an oscillatory state. A model is suggested to describe the uncatalyzed BZ system as well as its perturbation with iodide ion. A new route for Brregeneration is suggested within the framework of the FKN-OKN mechanism that is in better agreement with known bromination rates of the organic substrates and that also rationalizes both the appearance of an induction period and the exclusive formation of o-quinones among the possible quinoid reaction products. The effect of Iis explained by assuming that iodine is protected from oxidation to IO,-by BrO,-by becoming reversibly bound in an aromatic ring and that the resulting iodinated organics inhibit the HBrO, autocatalysis so that smaller amounts of the main reactants and their important derivatives are consumed in each cycle in the perturbed system as compared to the unperturbed one. Some experimental results are presented in support of these assumptions. The model adequately simulates the unperturbed oscillator and reproduces some of the major effects of I-perturbation, including the increased length of the induction period and number of oscillations, the decrease in the amplitude of the oscillations in the case of medium the inhibitory effect of high [I-lO, and the [I-], intervals over which the above phenomena occur. It fails to simulate the temporary bistability as well as quantitative behaviors at very low [I-]0.

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The DAO (maltenes) is also shown in the Kern River profile set. The prominent maximum seen in the feed profile (peak 3) is also seen here. This is also the maximum for smaller-sized sulfur-containing compounds and accounts for the majority of the sulfurcontaining molecules.The SDA separation process separates the very large sulfur-containing components from the smaller sulfurcontaining compounds, similar to the effect on the metal-containing compounds. But unlike the metal compounds, the majority of the sulfur is found in the DAO fraction. This is not necessarily a disadvantage because these molecules are very amenable to catalytic removal. Desulfurization is one the easiest aspects of refining. It should be noted, however, the distribution of compounds and heteroatoms in this type of processing can be greatly feed dependent,8 as well as separation solvent dependent.56 To provide the process with flexibility, several commercial and proposed processes use two-stage or multistage asphaltene removal,@ with multiple alkane solvents of different solubility parameters. The end result is various grades of DAO (56) Reynolds, J. G. Fuel Sci. Technol. Int. 1987,5(5), 593-620. that will be treated in different parts of the refinery depending upon the quality of the product. ConclusionsSEC-ICP has opened up several new areas of petroleum process analysis, showing the size behavior of nickel, vanadium, and sulfur in heavy crude oils and during thermal, catalytic, and SDA processing. It has offered insight into new and innovative ways of processing heavy crude oils and residua derived from them as well as helped explain the success of existing processing methods. This has only come about because of a combined, interdisciplinary effort from several fields of science-analytical, inorganic, and organic chemistry, along with chemical and petroleum engineering.

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