Effects of the Temperature and Initial Hydrogen Pressure on the Isomerization Reaction in Heavy Oil Slurry-Phase Hydrocracking

Abstract

Thermal hydrocracking and slurry-phase hydrocracking of Karamay vacuum residue (KLVR) were studied, and the hydrocracked products were analyzed by gas chromatography (GC) and a paraffins, olefins, naphthalenes, and aromatics (PONA) composition analysis system. The effects of the temperature and initial hydrogen pressure on the isomerization reaction in heavy oil slurry-phase hydrocracking were investigated. Experimental data revealed that the conversion of KLVR increased as the temperature and initial hydrogen pressure increased in both thermal hydrocracking and slurry-phase hydrocracking. Hydrogen consumption of slurry-phase hydrocracking increased with the increase of the temperature and initial hydrogen pressure, while hydrogen consumption in thermal hydrocracking was negligible. Two impact indexes R G ′ and R N ′ were proposed to study the isomerization reaction in heavy oil slurry-phase hydrocracking. The results indicated that a high temperature and high initial hydrogen pressure enhanced the isoparaffin restraining effect of a dispersed Mo catalyst. Under a certain reaction temperature, the linear relation between impact indexes and hydrogen consumption was observed, indicating that the isomerization reaction was inhibited by hydrogen participating in a free-radical reaction.

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

“…The main function of dispersed catalysts in the SZVR hydrocracking process is to accelerate hydrogen activation, thus the suppression of the excessive thermal cracking and condensation of SZVR is realized . The product distribution from SZVR hydrocracking without and with different types of dispersed Ni catalysts is shown in Figure a.…”

“…During the hydrocracking reactions, the reaction pressure increased as high as around 18 MPa. 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): …”