Upgrading Of Vacuum Residue Research Articles

Enhancement of hydrotreating activity of oil-soluble CoMo6 heteropolyacid for 4,6-dimethyldibenzothiophene and vacuum residue by controlling sulfurization degree

An oil-soluble CoMo6 heteropolyacid was synthesized by modifying the heteropolyacid with a surfactant dioctadecyl dimethyl ammonium chloride, and then was used to prepare highly active sulfided catalyst. The effect of sulfurization degree on the hydrotreating activity of the catalyst was investigated, and the results show that the incompletely sulfurized catalyst exhibited high reactivity for 4,6-dimethylbenzothiophene (4,6-DMDBT) and vacuum residue (VR). The unusual finding was attributed to more CoMoS species and surface oxysulfides, and the latter were probably generated in the partial replacement of O atoms with S atoms during the sulfurization. The acidic oxysulfides (SO42- groups) not only improved the activation of 4,6-DMDBT but also facilitated the cleavage of C-C bonds of the intermediate product 3,3′-dimethylcyclohexylbenzene according to the reaction data and DFT calculation. Besides, the catalysts with incomplete sulfide state exhibited outstanding catalytic performance on the upgrading of VR. The proposed incomplete sulfurization strategy provided a new way to prepare bifunctional hydrogenation catalysts with both desulfurization and cracking activities.

Morphology effect on catalytic performance of ebullated-bed residue hydrotreating over Ni–Mo/Al2O3 catalyst: A kinetic modeling study

Upgrading of vacuum residue is of prime industrial significance due to the increasing demand for light oils. Elucidating the effect of catalyst morphology on vacuum residue hydrotreating performance by kinetic modeling is therefore of great importance. Herein, kinetic analysis of hydrodemetallization (HDM) and hydrodeconradson-carbon-residue (HDCCR) performances on industrial Ni–Mo/Al2O3 catalysts with spherical and cylindrical morphologies in ebullated-bed were evaluated for more than 1600 h. It was found that the percentage of light impurities easier to be removed on spherical catalysts were 78.20% and 39.43% in HDM and HDCCR reactions, respectively, higher than 65.20% and 17.50% on cylindrical catalysts. This suggests that catalyst morphology affects the impurity removal ability and the impurity properties, resulting in better hydrotreating performance of spherical catalysts. This work not only combines catalyst morphology with impurity removal capability through kinetic modeling, but also provides new insights into the design of efficient hydrotreating catalysts.

Role of catalyst defect sites towards product selectivity in the upgrading of vacuum residue

Slurry hydrocracking is an upcoming technology which effectively upgrade residues and produces more valuable distillate products. Catalyst used in this process enhances hydrogenation and reduces coke formation. Nanoflower molybdenum sulfide (MoS2 NanoF) is synthesized by a simple hydrothermal treatment of ammonium heptamolybdate and sulfur powder. The morphology is determined by scanning electron microscopy (SEM) showing that curved nanoplates of MoS2 grow like petals of a flower. High-resolution transmission electron microscopy (HR-TEM) images reveals the arc-like and angular shape of nanorods of MoS2 fringes, proving the interlayer growth of MoS2 nanoplates. These curved plates create defects in the MoS2 sites that are highly active for a hydrogenation reaction. X-ray photoelectron spectroscopy (XPS) results suggest the presence of Mo+4 and S-2 in the synthesized catalyst. Raman analysis also supports the formation of a few layers of MoS2 phases. The activity of the synthesized catalyst is evaluated for slurry phase hydrocracking of a vacuum residue (VR) at high-temperature and high-pressure conditions. MoS2 NanoF catalyst exhibits higher hydrocracking and hydrotreating activities. It is mainly due to the presence of highly active defect structure of MoS2. Higher activities indicate the presence of higher hydrogenation sites in the synthesized MoS2 NanoF catalyst. Moreover, this hydrogenation activity substantially reduces coke formation during hydroprocessing of the residue.

SARA fractions evaluation during microwave-assisted upgrading of an oil refinery vacuum residue: effects of operational conditions

The operational conditions effects on SARA fractions during upgrading of vacuum residue using microwave irradiation were investigated. The residue was from Tehran oil refinery, Iran. The vacuum residue specifications contained API gravity: 8.79, viscosity (at 60 °C): 16391 cSt, viscosity (at 80 °C): 1910 cSt, saturates and aromatics: 52.09 wt%, resins: 34.61 wt%, and asphaltenes: 13.3 wt%. The parameters included catalysts type (Fe, MoS2, Cu, Fe2O3, and Ni), processing time, active carbon as a sensitizer, power level, catalyst, NaBH4. The best conditions of the process included time: 60 min, carbon: 20 wt%, power level: 100%, catalyst: 20 wt%, NaBH4: 3 wt%, resulted that saturates and aromatics increased from 52.09 wt% to 77.64 wt%, resins decreased from 34.61 wt% to 21.59 wt%, asphaltenes decreased from 13.3 wt% to 0.77 wt%. In the best conditions, the product was similar to a crude oil entering an oil refinery. Highlights SARA fractions during upgrading vacuum residue using microwaves are investigated. The parameters include catalysts, power level, sensitizer, NaBH4, process time. The studied catalysts are iron, nickel, copper, MoS2, iron oxide. In optimal conditions, product was similar to a crude oil entering an oil refinery.

Integrated process for partial oxidation of heavy oil and in-situ reduction of red mud

RM was used for the upgrading of vacuum residue (VR) by partial oxidation (POX). The function of diverse metal oxides in RM during VR upgrading was clarified and the utilization of used RM was developed. The results show that POX of VR with RM600 (calcined RM at 600 °C) decreases the cracking temperature, and increases heavy oil conversion and light fuels yield. The active sites Fe and O are highly dispersed on RM600, and Na species doping results in the formation of sodium ferrite, creating oxygen vacancy. Large specific surface area is remained after reaction due to the presence of Al2O3, SiO2 and TiO2. Fe2O3 in RM600 is in-situ reduced to Fe3O4, which could be further reduced by deposited coke on spent RM600 to produce Fe. The spent RM600 could be reused through a chemical looping POX and the yield of light fuels remains stable during 20 cycles.

Efficient conversion of extra-heavy oil into distillates using tetralin/activated carbon in a continuous reactor at elevated temperatures

Tetralin/activated carbon was applied to the upgrading of vacuum residue (VR) in a continuous reactor. The experimental performance was evaluated at a fixed pressure of 5.0 MPa in the range of 385–470 °C, and 1.5 and 3.0 h−1 of liquid hourly space velocity. A lower space velocity, which is closely related to the reaction time, led to significantly higher conversion at the cost of forming a carbonaceous product (coke). Increasing the reaction temperature greatly affected the conversion of residue into lighter products. The application of a tetralin/activated carbon to the VR upgrading resulted in high residue conversion (74.5 wt%) and asphaltene reduction (80.8%) at 470 °C, with a small amount of coke (1.2 wt%). Additionally, the tetralin/activated carbon system led to reduction of the sulfur, nitrogen and metal concentrations in the liquid products. The hydrogen-donor solvent/carbon system acts as an attractive hydrogen-donor medium in the extra-heavy oil upgrading.

Upgrading of vacuum residue with chemical looping partial oxidation over Fe-Mn mixed metal oxides

Heavy oil upgrading to produce light fuels is an important strategy to solve the depletion of light crude oil. Partial oxidation using transition metal oxides as oxygen carrier is a potential method for heavy oil upgrading. A series of Fe-Mn mixed metal oxides were synthesized and used for partial oxidation of vacuum residue (VR) in this study. As a result, the gasoline and diesel oil yields increase on Fe-Mn mixed metal oxides. The carbonaceous residue yield decreases with the increasing Mn content. A variety of characterizations were carried out to reveal the correlation between the physicochemical properties of the mixed metal oxides and partial oxidation performance. To achieve oxygen regeneration and stable production of light fuels, a chemical looping partial oxidation process using Fe1Mn3 as carrier of oxygen was proposed. The Fe1Mn3 shows potential application in VR upgrading with partial oxidation.

Thermal cracking of atmospheric residue versus vacuum residue

Current practice subjects atmospheric residue (AR) to vacuum distillation, while feeding the vacuum residue (VR) for upgrading. This study explores the direct upgrading of AR and gauges the potential for eliminating the vacuum distillation unit, while recycling the upgraded oil to the atmospheric distillation column. Thermal cracking of Arabian AR and VR was carried out in an autoclave for 1 h at 400 °C. AR provided much higher liquid yield and quality with limited coke yield (<1 wt%). Higher temperature (420 °C) and longer residence time (2 h) were tested to further improve the quality of the liquid product. In addition, drill cuttings, previously demonstrated as an effective thermal cracking catalyst, were added to selected runs. Drill cuttings promoted the formation of short chain molecules, suppressed coke formation and significantly increased the quality of the product oil compared to control AR runs. Catalytic thermal cracking of AR at 420 °C for 2 h resulted in gas and coke yields of ~9 wt% and ~6 wt%, respectively, with the remainder being a premium quality liquid having °API gravity of 34. Upgrading of VR at the same conditions produced lower °API gravity liquid of 28 with 1.5 times more gas, 3 times more coke, and ~15 wt% less liquid yield. Simulated distillation showed that the product oil from both AR and VR upgrading contained ~20 wt% residue. Nevertheless, a mass balance of the whole refining/upgrading process revealed two times more liquified petroleum gas/light gas oil cut, with 50% less vacuum gas oil and 33% less coke yield for AR upgrading.

Vacuum Residue Upgrading Via Catalytic Steam Cracking in Slurry Type Reactor in Presence of Mo-based Dispersed Catalyst

Vacuum Residue Upgrading Via Catalytic Steam Cracking in Slurry Type Reactor in Presence of Mo-based Dispersed Catalyst

Upgrading of petroleum vacuum residue using a hydrogen-donor solvent with acid-treated carbon

Hydrocarbon/carbon systems can be used to perform the hydrogen transfer reaction in heavy oil upgrading, as alternatives to metal catalysts and molecular hydrogen. In this study, a system comprising a hydrogen-donor solvent (tetralin) and acid-treated activated carbon was established to evaluate its ability as a hydrogen transfer agent to upgrade a vacuum residue (VR). The use of tetralin substantially decreased coke formation from 32.7 wt% to a negligible amount in VR upgrading at 450 °C because the solvent could act as a hydrogen donor and diluent for the coke precursors. The acid-treated activated carbon accelerated dehydrogenation of tetralin through hydrogen transfer in the upgrading, resulting in a higher residue conversion and moderate coke formation. In view of the phase behavior, the hydrogen transfer reaction could also be promoted by increasing the contact between the hydrogen acceptor and donor in the supercritical medium. In the VR upgrading using the activated carbon in supercritical tetralin, complete residue conversion was achieved with 47 wt% light fractions (gas and light oil) and 6 wt% coke at 450 °C and 5.33 MPa. The results indicate that the streams available in oil refinery processes, which are rich in hydrocarbons with hydrogen-donor abilities, have great potential for use in heavy oil upgrading.

Supercritical methanol as an effective medium for producing asphaltenes-free light fraction oil from vacuum residue

The upgrading of vacuum residue (VR) in supercritical methanol (scMeOH) was investigated without using catalysts. Various process parameters, including temperature (350–425°C), reaction time (30–90min), and additives (toluene and hydrogen) were explored to optimize the yield of light fraction oil (LFO) with few impurities. At a 400°C, 16.7wt% of VR in methanol for 60min, the LFO produced in scMeOH contained very low asphaltene content (0.74wt%) and a very low amount of heteroatom/metallic impurities (S, 3.58wt%;N, non-detectable; Ni, 10.4ppm;V, 36.9ppm, Fe, 7.3ppm). In addition, the naptha-to-diesel fraction increased from 1wt% (VR feed) to 15wt% and the saturate+aromatic content increased from 43.7 area% (VR feed) to 59.6 area% in the LFO. When the reaction time was extended to 90min at 400°C, a complete removal of asphaltenes could be achieved.

Effective vacuum residue upgrading using sacrificial nickel(II) dimethylglyoxime complex in supercritical methanol

The petroleum refining industry has become more profitable in recent years owing to the extraordinary value-adding processes of petroleum and petroleum-based products that generate a minimal amount of leftover. However, effectively utilizing vacuum residue (VR) to meet the rising demand for middle distillates in the near future remains a great challenge. The high-cost and low-surplus of hydrogen source in refineries complicate the application of existing slurry hydrocracking technologies at a practical scale. As such, supercritical methanol can serve as an effective and economically viable alternative to conventional VR upgrading techniques. Herein, an effective catalytic upgrading of VR using sacrificial nickel(II) dimethylglyoxime (Ni-DMG) complex in supercritical methanol is reported. The sacrificial Ni-DMG complex prevents low-temperature poisoning, which is typically caused by the heteroatoms present in asphaltenes, as well as catalyst coking. Under an optimized reaction condition of 400°C, 30.5–31.2MPa in supercritical methanol at a reaction time of 1h, a high amount of directly distillable fraction (72.2wt.%) was obtained using Ni-DMG in supercritical methanol. In the presence of low H2 pressure (initial pressure: 1MPa), the distillable fraction increased significantly to 92.2wt.% with an extremely low coke content (6.2wt.%). In addition, the upgraded oil was completely denitrogenated with noticeable desulfurization and significant demetallization activities (60.4%, 51.2%, and 85.7% reduction of nickel, iron, and vanadium, respectively).

Co-processing of heavy oil with wood biomass using supercritical m-xylene and n-dodecane solvents

Heavy oil was co-processed with wood biomass by using supercritical m-xylene and n-dodecane. The effects of the solvent, temperature, hydrogen, and catalyst on vacuum residue (VR) upgrading were evaluated using residue conversion, coke formation, and product distribution as performance parameters. VR was subjected to co-processing with microcrystalline cellulose (cellulose) or oil palm empty fruit bunch fiber (EFB), and the parameters were compared with those obtained from VR upgrading. Co-processing of VR/cellulose using a catalyst and hydrogen led to higher conversion (72.6 wt%) than co-processing of VR/EFB at 400 °C and the highest yield of light product (65.7 wt%). Using the Fe3O4 catalyst with H2 for co-processing positively influenced generation of the light product fraction. VR upgrading and co-processing using supercritical solvents could eliminate a certain amount of sulfur compounds from heavy oil. Co-processing of wood biomass with petroleum feedstocks in existing oil refineries can reduce the capital costs of bulk treatment.

A parameter study for co-processing of petroleum vacuum residue and oil palm empty fruit bunch fiber using supercritical tetralin and decalin

Co-processing of petroleum vacuum residue (VR) and oil palm empty fruit bunch (EFB) fiber was carried out through the use of supercritical solvents. The effects of solvent (tetralin and decalin), temperature (400 and 450°C), a catalyst, and hydrogen on the co-processing were evaluated according to residue conversion and product distribution analysis. The results were compared with only the VR upgrading results as well as the co-processing of VR and microcrystalline cellulose. Supercritical tetralin exhibited high reaction performance in both VR upgrading and co-processing of VR/EFB without significant coke formation, compared with the results in decalin. In the presence of H2, the Fe3O4 catalyst contributed toward suppressing coke formation. The co-processing of VR/EFB using tetralin could achieve a residue conversion of 86.4wt% with only 0.8wt% of coke formation, showing more favorable conversion than that of VR/microcrystalline cellulose. Therefore, it led to a positive effect which improved the residue conversions and yielded a great quantity of light product.

Upgrading of vacuum residue in batch type reactor using Ni–Mo supported on goethite catalyst

It is imperative to develop an efficient catalyst to convert vacuum residue (VR) into low boiling point liquid products via an environmentally benign pathway. Ni–Mo bimetal was impregnated on goethite supports and well characterized using various analytical techniques. VR hydrocracking catalytic activities were investigated in a batch reactor. The 1%Ni–4.5%Mo/Goethite catalyst showed a high yield of low boiling point liquid products, 69.8%, with 80% VR conversion at 420°C in the presence of 70bar initial hydrogen pressure in 3h. In these liquid products, 8.6% of naphtha, 51.4% of middle distillate, 9.8% of vacuum gas oil (VGO) with 28.1% of saturates, 62.5% of aromatics, 8.4% of resins and >1% of asphaltenes were confirmed by TGA and SARA analysis, respectively. The experimental findings indicated that the formation of low boiling point liquid products depends on physical parameters and chemical composition of the catalyst. This paper describes the synthesis of the supported catalysts, influences of the active metal composition, metal/support interaction, and process parameters for hydrocracking of VR into high value, low boiling point liquid products.

Upgrading Residue by Carbon Rejection in a Fluidized-Bed Reactor and Its Multiple Lump Kinetic Model

Pretreating inferior residues to provide feedstock with trace metals and a few asphaltenes for downstream processes is important for refineries to process heavier crude oils. Toward this end, the upgrading of vacuum residue (VR) over special catalysts designed for decarbonization and demetalization was investigated in a fluidized-bed reactor. The effects of operating parameters such as reaction temperature, catalyst-to-oil ratio, and weight hourly space velocity on product distribution and removals of contaminants were determined. The experimental results demonstrate that low cracking severity is favorable for obtaining the maximum liquid yield, giving rates of removal for metals, Conradson carbon residue, and asphaltenes for residue of more than 98%, 85%, and 97% respectively. In addition, a seven-lump kinetic model with a detailed product distribution was developed to describe reaction behaviors of VR upgrading. Rate constants and apparent activation energies were estimated with the improved Marquardt method. The effect tests show that the kinetic model can predict the product yields very well.

Effects of Supercritical Water in Vacuum Residue Upgrading

Vacuum residue (VR) upgrading was conducted in the environment of supercritical water (SCW) without oxygen addition in an attempt to yield a maximum of light oil. Simulated distillation of the liquid products from a set of orthogonal experiments shows that temperature should not be too high to restrict coke formation, and the most beneficial condition is found at (1) 420 °C for the temperature, (2) 0.15 g/cm3 for the water density, (3) 2 g/g for the H2O/oil ratio, and (4) 1 h for the reaction time. A simultaneous increase of the water density and H2O/oil would significantly improve the cracking behavior and the yield in light oil. Scattered coke particles between 10 and 100 μm were generated from VR cracking, which suggests the dispersion effect of SCW. The infrared spectrum analysis has indicated an increase in the H/C atomic ratio in the liquid product, which implies that hydrogen is generated from the condensation reactions rather than from water because no oxygen-containing group was detected.