System for mixing a catalyst precursor into heavy oil using a high boiling hydrocarbon diluent to form a diluted precursor mixture, which is mixed with the heavy oil to form a conditioned feedstock, which is heated to decompose the precursor and form dispersed metal sulfide catalyst particles in situ. The high boiling hydrocarbon diluent is at a temperature above the decomposition temperature of the catalyst precursor and is first fed through a cooler and/or mixed with a cooler diluent to reduce its temperature and avoid premature decomposition of the catalyst precursor. The high boiling hydrocarbon diluent may include a portion of the heavy oil feedstock, a portion of the conditioned feedstock, a vacuum tower bottoms product, or other high boiling hydrocarbon material having a boiling point higher than 524 C. A portion of the diluent may optionally include a medium boiling hydrocarbon material having a boiling point less than 524 C.

System and method for mixing a catalyst precursor into heavy oil using a high boiling hydrocarbon diluent to form a diluted precursor mixture, which is mixed with the heavy oil feedstock to form a conditioned feedstock, which is subsequently heated to decompose the precursor and form dispersed metal sulfide catalyst particles in situ. Because the high boiling hydrocarbon diluent is typically at a temperature above the decomposition temperature of the catalyst precursor, it is first feed through a cooler to reduce its temperature to avoid premature decomposition of the catalyst precursor. The high boiling hydrocarbon diluent may include a portion of the heavy oil feedstock, a portion of the conditioned feedstock, a vacuum tower bottoms product, or other high boiling hydrocarbon material having a boiling point higher than 524 C. A portion of the diluent may optionally include a medium boiling hydrocarbon material having a boiling point less than 524 C.

System and method for mixing a catalyst precursor into heavy oil using a high boiling hydrocarbon diluent to form a diluted precursor mixture, which is mixed with the heavy oil feedstock to form a conditioned feedstock, which is subsequently heated to decompose the precursor and form dispersed metal sulfide catalyst particles in situ. Because the high boiling hydrocarbon diluent is typically at a temperature above the decomposition temperature of the catalyst precursor, it is first feed through a cooler to reduce its temperature to avoid premature decomposition of the catalyst precursor. The high boiling hydrocarbon diluent may include a portion of the heavy oil feedstock, a portion of the conditioned feedstock, a vacuum tower bottoms product, or other high boiling hydrocarbon material having a boiling point higher than 524 C. A portion of the diluent may optionally include a medium boiling hydrocarbon material having a boiling point less than 524 C.

Processes and systems for upgrading hydrocracker unconverted heavy oil are provided. The invention is useful in upgrading unconverted heavy oil such as resid derived from hydrocracking processes and may be used to upgrade such resids to form fuel oils such as low sulfur fuel oil for marine use. A combination of solutions is applied in the invention including applying a separation process for unconverted heavy oil comprising hydrocracker resid, combining an aromatic feed with the unconverted heavy oil, followed by subjecting the unconverted heavy oil to a hydrotreating process.

Processes and systems for upgrading hydrocracker unconverted heavy oil are provided. The invention is useful in upgrading unconverted heavy oil such as resid derived from hydrocracking processes and may be used to upgrade such resids to form fuel oils such as low sulfur fuel oil for marine use. A combination of solutions is applied in the invention including applying a separation process for unconverted heavy oil comprising hydrocracker resid, combining an aromatic feed with the unconverted heavy oil, followed by subjecting the unconverted heavy oil to a hydrotreating process.