Heavy oil upgrading about hydrocracking and acid reduction

Abstract

In this study, vacuum residue upgrading for liquid product conversion and acid content reduction with model compound were studied. Both experiments include various analysis technics for advanced improved study. Vacuum residue upgrading with catalyst in subcritical water was investigated. Experiments were carried out with changing temperature, catalyst amount, reaction time, and water amount. Maximum conversion of 55.5 wt. % was given at the condition of $400 ^\circ C$ of temperature, 0.5 g of MoNaph catalyst, 6 h of reaction time, and 20 g of water amount. Liquid product conversion was comparable to that of the hydrogen gas process. Liquid product conversions were supported by subcritical state water. Catalyst was dispersed on the vacuum residue and water mixture. Hydrogenation and saturation were observed by reduction of C/H ratio of liquid product. Decrease of $f_A$ and increase of $H_AU/C_A$ for liquid product are related to hydrogenation, saturation, ring opening and pyrolysis. Large accumulated mass of 61.2 wt. % under $500 ^\cir C$ for liquid product is accomplished by conversion of light products which have low boiling point. Similar aspects were observed by using synthesized $MoS_2$ nanosheet catalyst compared to that of MoNaph catalyst. Esterification and Decarboxylation experiments with model feed in various conditions for TAN reduction were investigated. SnO catalyst was used in esterification, and it resulted in about 97 % of TAN reduction at $300 ^\cir C$ . MgO and Y-zeolite were used for decarboxylation, and both resulted in over 90 % of TAN reduction. With low temperature condition under $250 ^\cir C$, TAN reduction of decarboxylation was relatively lower than esterification. Decarboxylation experiments with different model feeds revealed that reactivity of each carboxylic acid was different. Fixed-bed reactions showed deactivation and salt formation of catalysts. FT-IR analysis for esterification confirmed peak shift from carboxylic functional group peak (about $1700 cm^{-1}$ ) to ester functional group peak (about $1740 cm^{-1}$ ). In the case of decarboxylation, removal or reduction of $1700 cm^{-1}$ carboxylic functional group peak was observed. GC/MS analysis revealed that not only esterification and decarboxylation occurred in TAN reduction, but also other kinds of reactions such as ketonization arose. Product composition of decarboxylation was more complicated than that of esterification.