Carbon nanofiber doped alumina (Al-CNF) supported MoCo catalysts in hydrodesulfurization (HDS), and/or boron doping, e.g., up to 5 wt % of total catalyst weight, can improve catalytic efficiency. Al-CNF-supported MoCo catalysts, (Al-CNF-MoCo), can reduce the sulfur concentration in fuel, esp. liquid fuel, to below the required limit in a 6 h reaction time. Thus, Al-CNF-MoCo has a higher catalytic activity than AlMoCo, which may be explained by higher mesoporous surface area and better dispersion of MoCo metals on the AlCNF support relative to alumina support. The BET surface area of AlMoCo may be 75% less than Al-CNF-MoCo, e.g., 166 vs. 200 m.sup.2/g. SEM images indicate that the catalyst nanoparticles can be evenly distributed on the surface of the CNF. The surface area of the AlMoCoB5% may be 206 m.sup.2/g, which is higher than AlMoCoB0% and AlMoCoB2%, and AlMoCoB5% has the highest HDS activity, removing more than 98% sulfur and below allowed levels.

Carbon nanofiber doped alumina (Al-CNF) supported MoCo catalysts in hydrodesulfurization (HDS), and/or boron doping, e.g., up to 5 wt % of total catalyst weight, can improve catalytic efficiency. Al-CNF-supported MoCo catalysts, (Al-CNF-MoCo), can reduce the sulfur concentration in fuel, esp. liquid fuel, to below the required limit in a 6 h reaction time. Thus, Al-CNF-MoCo has a higher catalytic activity than AlMoCo, which may be explained by higher mesoporous surface area and better dispersion of MoCo metals on the AlCNF support relative to alumina support. The BET surface area of AlMoCo may be 75% less than Al-CNF-MoCo, e.g., 166 vs. 200 m.sup.2/g. SEM images indicate that the catalyst nanoparticles can be evenly distributed on the surface of the CNF. The surface area of the AlMoCoB5% may be 206 m.sup.2/g, which is higher than AlMoCoB0% and AlMoCoB2%, and AlMoCoB5% has the highest HDS activity, removing more than 98% sulfur and below allowed levels.

Carbon nanofiber doped alumina (AlCNF) supported MoCo catalysts in hydrodesulfurization (HDS), and/or boron doping, e.g., up to 5 wt % of total catalyst weight, can improve catalytic efficiency. AlCNF-supported MoCo catalysts, (AlCNFMoCo), can reduce the sulfur concentration in fuel, esp. liquid fuel, to below the required limit in a 6 h reaction time. Thus, AlCNFMoCo has a higher catalytic activity than AlMoCo, which may be explained by higher mesoporous surface area and better dispersion of MoCo metals on the AlCNF support relative to alumina support. The BET surface area of AlMoCo may be 75% less than AlCNFMoCo, e.g., 166 vs. 200 m.sup.2/g. SEM images indicate that the catalyst nanoparticles can be evenly distributed on the surface of the CNF. The surface area of the AlMoCoB5% may be 206 m.sup.2/g, which is higher than AlMoCoB0% and AlMoCoB2%, and AlMoCoB5% has the highest HDS activity, removing more than 98% sulfur and below allowed levels.

Carbon nanofiber doped alumina (AlCNF) supported MoCo catalysts in hydrodesulfurization (HDS), and/or boron doping, e.g., up to 5 wt % of total catalyst weight, can improve catalytic efficiency. AlCNF-supported MoCo catalysts, (AlCNFMoCo), can reduce the sulfur concentration in fuel, esp. liquid fuel, to below the required limit in a 6 h reaction time. Thus, AlCNFMoCo has a higher catalytic activity than AlMoCo, which may be explained by higher mesoporous surface area and better dispersion of MoCo metals on the AlCNF support relative to alumina support. The BET surface area of AlMoCo may be 75% less than AlCNFMoCo, e.g., 166 vs. 200 m.sup.2/g. SEM images indicate that the catalyst nanoparticles can be evenly distributed on the surface of the CNF. The surface area of the AlMoCoB5% may be 206 m.sup.2/g, which is higher than AlMoCoB0% and AlMoCoB2%, and AlMoCoB5% has the highest HDS activity, removing more than 98% sulfur and below allowed levels.

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 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.