Because the trend toward heavier feedstocks is expected to continue, it is likely that catalysts such as S-703 will find increasing application in hydrocrackers in the future. To date, the commercial results have confirmed the laboratory results in terms of the superior, heavy-feedstock processing performance of the new catalyst in all respects. Commercial experience with the new catalyst has now been obtained in several units. Further, the new catalyst exhibits enhanced stability.Įxtensive laboratory testing of the S-703 catalyst has been carried out under single-stage, stacked-bed, two-stage-flow, and series-flow conditions. Laboratory testing and commercial use show it has significantly improved performance with respect to gas make and middle-distillate selectivity in processing heavy feedstocks when compared to a Shell catalyst, S-753, developed earlier. Maxwell, Wim StorkĪ new zeolite-Y-based, second-stage hydrocracking catalyst, designated S-703, has been developed by Shell. To circumvent these problems, a multi-stage process has been developed in which the undesired by-products, ammonia and hydrogen sulfide, are removed in a special reactor before entering the actual cracking process.Arend Hoek, Tom Huizinga, A.A. Additionally, the activity of the catalysts is lowered by the ammonia formed in the process. The disadvantages of this process are moderate yields ( ca. The single-stage process employs bi-functional systems consisting of metal sulfides (cobalt, molybdenum and nickel) and aluminum oxide as catalysts. Reaction conditions in the hydrocracking process are very drastic with pressures of 80 - 200 bar and temperatures in the range of 270 - 450 ☌. Hydrocracking does not generate any alkenes because hydrogen reacts with the generated radicals forming alkanes with low boiling points instead. In this process, catalytic cracking is carried out in an atmosphere of hydrogen (300 - 500 m 3 hydrogen per ton of hydrocarbon) with the advantage that impurities, such as sulfur and nitrogen, can be removed from the product easily as hydrogen sulfide and ammonia, respectively. For technical reasons, hydrocracking was only made possible in the late Fifties of the last century.
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