Role of Hydrogen Pressure in Slurry-Phase Hydrocracking of Venezuela Heavy Oil

Abstract

The composition, structure, and colloidal stability of hydrocracked products at various hydrogen pressures were analyzed to investigate the role of hydrogen pressure in slurry-phase hydrocracking of Venezuela heavy oil. Experimental data showed that the formation of gas, naphtha, and coke was suppressed by a high hydrogen pressure during the slurry-phase hydrocracking. In addition, the maximum of light oil per coke ratio was observed at 8 MPa of hydrogen. The desulfurization and denitrogenation were promoted by the increase of hydrogen pressure. However, the influence of hydrogen pressure on the desulfurization rate was reduced at higher pressure, while the influence on the denitrogenation rate was still obvious. With the increase of hydrogen pressure, the Conradson carbon residue (CCR) of the vacuum residue (VR) product decreased. Meanwhile, the coking inducing period of the atmospheric residue (AR) product prolonged, which means that the colloidal stability of the AR product was enhanced by a high hydrogen pressure. Structural parameters of asphaltene were studied according to the reference of the Fourier transform infrared (FTIR) spectroscopy method of kerogen structure studying. The cracking and hydrogenation saturation of asphaltene were promoted by a high hydrogen pressure, which lead to the increase of the A factor (infrared absorption intensity ratio of saturated aliphatic carbon and aromatic carbon) and n CH 2 /n CH 3 of asphaltene products as well as the decrease of the Y factor (condensation index of asphaltene) and Z factor (discriminative index of the side-chain fracture situation of asphaltene).

Effect of cyclohexane as hydrogen-donor in ultradispersed catalytic upgrading of heavy oil

“…In comparison to upgrading under a nitrogen atmosphere, there was 9.5% and 41.2% further reduction in gas and coke yields. This confirmed the previous well-established findings of the role of hydrogen in suppressing coke formation, also observed by Hart et al [3,6], and also a similar decrease in gas and coke yields under hydrogen atmosphere has been reported in the literature [23,24]. Under nitrogen atmosphere, the catalytic upgrading is mainly a carbon rejection process, in which the hydrogen within the hydrocarbons is redistributed among the cracked fragments, resulting in light fractions (distillates) and deposits with lower hydrogen/carbon atomic ratio (coke).…”

“…High temperature contributes mainly to condensation of free radicals and abstraction of hydrogen to form coke [19,23,24], and is favoured by thermal cracking. However, in the presence of dispersed Ni-Mo/Al 2 O 3 catalyst hydrogen; methyl and ethyl transfer reactions were activated on the active sites of the ultrafine particles and react with the cracked fragments.…”

“…This helps to suppress the condensation of hydrocarbon free radicals due to thermal cracking; hence the yields of large molecular weight hydrocarbons and coke are reduced [19]. Hence, coke inducing period and colloidal stability of the reaction medium is improved and prolonged in the presence of hydrogen and cyclohexane [23,24].…”

Surface Modification of Nickel Sulfide Nanoparticles: Towards Stable Ultra‐Dispersed Nanocatalysts for Residue Hydrocracking

“…At the end of the experiment, the hydrocracking products were separated into gas, naphtha, diesel, vacuum gas oil (VGO), VR, and TI products through a series of processes according to previous reports . The hydrogenation effect of the NSNPs was presented by light oil (naphtha and diesel) per coke ratio calculated by Equation (1): …”

Effects of Surface Modification on the Catalytic Performances of Nickel Sulfide Nanocatalysts for Residue Hydrocracking: A Monte Carlo Simulation and Experimental Study

“…Residue is a stable colloidal system in which the micelle is combined by asphaltene (core) and the adsorbed resin (solvation layer), and the dispersion medium is composed of saturates, aromatics, and some resin . During the slurry‐phase hydrocracking process, asphaltene is considered to be the coking precursor that precipitates from the broken colloidal system of residue and condenses to generate coke because of the high reaction temperature and fraction transformation . Meanwhile, hydrogen is activated by the dispersed catalysts and then quenched with macromolecule free radicals close to the catalyst to suppress the formation of coke .…”