Abstract
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.
Highlights
The slurry-phase hydrocracking of heavy oil is the process for converting residual feedstocks to lower boiling products [1,2]
The reduction in deasphalted oil (DAO) yield was greater than the increase in gas yield, indicating that the DAO was cracked into gas products and converted into heavier fractions such as asphaltenes and coke
It was observed that light liquid products were formed from asphaltenes at the beginning of the hydrocracking 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
Summary
The slurry-phase hydrocracking of heavy oil is the process for converting residual feedstocks to lower boiling products [1,2]. The effect of asphaltenes on the refinery process is that asphaltene molecules lose their alkyl side chains through thermolysis, which results in the aggregation and precipitation of polyaromatic sheets into coke [11,12,13], causes fouling, rapid catalyst deactivation, and decrease of reaction rate [14,15,16,17,18,19,20,21]. In our previous study [22], the effect of asphaltene contents on hydrocracking of heavy feedstocks was investigated. A study on asphaltene upgrading would benefit the hydrocracking processes
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