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Hydrocracking of solvent deasphalted (SDA) pitch was performed in batch and semi-batch systems, at different reaction temperatures (380–430 °C) with varying amounts of Mo-octoate precursor (0–1,000 ppm Mo) under 70–130 bar of H2 pressure. The reusability of the catalyst was also examined. Coke formation was unavoidable in the hydrocracking of the asphaltene-rich feed. The coke induction period was prolonged when the catalyst was introduced. Increasing the Mo catalyst concentration decreased the coke yield and improved the product quality. The catalytic hydrocracking of the SDA pitch under high H2 pressure suppressed coke formation, promoted desulfurization, and increased the H/C ratio of the liquid products. At least 500 ppm of Mo catalyst and H2 pressur above 110 bar were required for the hydrocracking of SDA pitch with controllable coke generation in the semi-batch system. Sufficient hydrogen supply and moderate catalyst concentration were essential for the slurry-phase hydrocracking of asphaltenerich feedstocks to enhance the product quality and suppress coke formation. [ABSTRACT FROM AUTHOR]

Thermal cracking of C5-deasphalted oil (C5-DAO) was performed in a batch reactor at 410°C in the absence and presence of H2 gas and catalysts. Coke was formed during the thermal cracking of C5-DAO even though the feed contained no asphaltenes. Although H2 suppressed asphaltene formation and decreased the coke yield, coke was still formed in the absence of a catalyst. A slurry-phase dispersed catalyst inhibited the transformation of resins into heavier fractions and facilitated <1 wt % asphaltene yield with no coke formation even under high conversion conditions. The main function of the catalyst was the facilitation of hydrogenation reactions and the stabilization of free radicals, leading to liquid production by inhibiting coke formation. Consequently, the product quality, in terms of hydrogen to carbon ratio and microcarbon residue and S contents, was enhanced by catalytic hydrocracking. [ABSTRACT FROM AUTHOR]

Non-catalytic and catalytic hydrocracking of C5-isolated asphaltene and its subfractions were performed in batch and semi-batch reactors at various temperatures. Catalyst and H2 played an important role in the hydrocracking of asphaltenes. In the batch system, the catalyst enhanced asphaltene conversion to light liquid products and suppressed coke formation. The coke formation was controlled at a low reaction temperature, but the reaction rate was too low. Light liquid products were also formed at the beginning of the reaction even at high temperatures, but the coke formation was predominant as the reaction time went on due to the decrease in H2 amount in the reactor. To solve these problems, H2 was continuously supplied during the reaction using the semi-batch system. Sufficient supply of H2 improved the conversion of asphaltenes to light liquid products while inhibiting the coke formation. The lightest asphaltene fraction was easily cracked into light products by inhibiting the coke formation, while the heaviest fraction tends to form coke. The lightest asphaltene fraction prolonged the coke induction period of the heaviest fraction during the catalytic hydrocracking because the lightest fraction contained a significant amount of heavy resin close to that which could prevent aggregation of the heaviest asphaltenes. [ABSTRACT FROM AUTHOR]