Vacuum Residue Research Articles

The Use of Vacuum Residue as a Potential Rejuvenator in Reclaimed Asphalt Pavement: Physical, Rheological, and Mechanical Traits Analysis

Asphalt recycling technology with a high content of reclaimed asphalt pavement (RAP) is becoming more important as the price of paving materials rises and sustainable development and environmental conservation rules become more rigorous. Nevertheless, road authorities in numerous countries still prohibit the utilisation of RAP in asphalt mixes due to the negative impacts of RAP on the performance of asphalt mixtures. Consequently, different rejuvenators have been introduced to reinstate the original attributes of aged asphalt to resolve this issue. This study incorporated vacuum residue (VR) into mixtures with 40% RAP. The physical, rheological, and mechanical traits of the resultant samples were assessed. The results show that the 7.5% VR rejuvenator minimised the RAP asphalt ageing impact. Furthermore, the rejuvenating agent demonstrated physical and rheological rehabilitative benefits for the aged asphalt. The mechanical attributes of the rejuvenated samples were also enhanced compared to the virgin asphalt (VA) specimens.

Slurry-Phase Hydrogenation of Different Asphaltenes to Liquid Fuels on Dispersed MoS2 Nanocatalysts.

Asphaltene, the most complex and recalcitrant fraction of heavy oil, was investigated in this study to gain new insights into its structure and reactivity. Two types of asphaltenes, ECT-As and COB-As, were extracted from ethylene cracking tar (ECT) and Canada's oil sands bitumen (COB), respectively, and used as reactants for slurry-phase hydrogenation. Characterization of ECT-As and COB-As was carried out by a combination of techniques, including XRD, elemental analysis, simulated distillation, SEM, TEM, NMR, and FT-IR, to gain insights into their composition and structure. A dispersed MoS2 nanocatalyst was used to study the reactivity of ECT-As and COB-As under hydrogenation conditions. The results showed that under optimal catalytic conditions, the vacuum residue content of hydrogenation products could be reduced to less than 20%, and the products contained over 50% light components (gasoline and diesel oil), indicating that ECT-As and COB-As were effectively upgraded. The characterization results indicated that ECT-As contained a higher aromatic carbon content, shorter alkyl side chains, fewer heteroatoms, and less highly condensed aromatics than COB-As. The light components (gasoline and diesel oil) of ECT-As hydrogenation products mainly consisted of aromatic compounds with 1-4 rings, with the alkyl chains mainly composed of C1-C2, while light components of COB-As hydrogenation products were mainly composed of aromatic compounds with 1-2 rings and C11-C22 paraffins. The characterization of ECT-As and COB-As and their hydrogenation products revealed that ECT-As was an "archipelago type" asphaltene, composed of multiple small aromatic nuclei interconnected through short alkyl chains, while COB-As was an "island type" asphaltene, with long alkyl chains connected to aromatic nuclei. It is suggested that the structure of asphaltene has a significant impact on both its reactivity and product distribution.

CO2-H2O assisted co-pyrolysis of petroleum vacuum residue and polypropylene to improve asphaltene reduction and coke suppression: A statistical approach

Non-catalytic co-pyrolysis of petroleum vacuum residue (VR) and polypropylene (PP) was studied under CO2 and/or steam atmospheres in a batch condition. A statistical approach was performed to analyze the effect of temperature, CO2 initial pressure, reaction time, PP and water contents using fractional factorial design methodology. A comparison of co-pyrolysis in steam, CO2, and steam + CO2 atmospheres showed that CO2 + steam is a more effective environment for reduction of asphaltene and suppressing coke formation. In detail, steam dominated the pyrolysis process, whereas CO2 enhanced the thermal cracking reactions, thereby increasing the asphaltene conversion to maltene and decreasing coke formation. Moreover, the results indicated that the addition of PP to VR improved the yield and quality of the liquid product and diminished the coke content. The optimum conditions were the temperature of 380 °C, CO2 initial pressure of 0.6 MPa, reaction time of 90 min with PP/ VR and water/ VR ratios of 0.23, and 0.25 (g/g), respectively. Pyrolysis of VR under such conditions resulted in the 86% maltene yield, 89.7% asphaltene reduction and 6.3% coke reduction. 1H NMR analysis showed that paraffins occupy the major content of the liquid (81.07 vol%), followed by aromatics (12.28 vol%) and olefinic compounds (6.65 vol%). In addition, the upgraded oil had a remarkable °API gravity of 35.9 and a low viscosity of 5.27 ± 0.02 cP. Furthermore, heavy metals of Ni and V were removed from the liquid product by 56.1% and 65.6%, respectively. Pyrolysis of VR with PP in the CO2 + steam environment would be deemed an economically viable and environmentally friendly technique of transforming the abundant low-grade VR feedstocks to valuable liquid fuels at a milder processing condition without using any catalysts.

SAR-AD Method to Characterize Eight SARA Fractions in Various Vacuum Residues and Follow Their Transformations Occurring during Hydrocracking and Pyrolysis

Model compounds were used to provide some chemical boundaries for the eight-fraction SAR-ADTM characterization method for heavy oils. It was found that the Saturates fraction consists of linear and highly cyclic alkanes; the Aro-1 fraction consists of molecules with a single aromatic ring; the Aro-2 fraction consists of mostly 2 and 3-ring fused aromatic molecules, the pericondensed 4-ring molecule pyrene, and molecules with 3–5 rings that are not fused; and the Aro-3 fraction consists of 4-membered linear and catacondensed aromatics, larger pericondensed aromatics, and large polycyclic aromatic hydrocarbons. The Resins fraction consists of mostly fused aromatic ring systems containing polar functional groups and metallated polar vanadium oxide porphyrin compounds, and the Asphaltene fraction consists of both island- and archipelago-type structures with a broad range of molecular weight variation, aromaticity, and heteroatom contents. The behavior of the eight SAR-ADTM fractions during hydrocracking and pyrolysis was investigated, and quantitative relations were established. Intercriteria analysis and evaluation of SAR-ADTM data of hydrocracked vacuum residue and sediment formation rate in commercial ebullated bed vacuum residue hydrocracking were performed. It showed that total asphaltene content, toluene-soluble asphaltenes, and colloidal instability index contribute to sediment formation, while Resins and Cyclohexane-soluble asphaltenes had no statistically meaningful relation to sediment formation for the studied range of operation conditions.

Lattice-strained Pt nanoparticles anchored on petroleum vacuum residue derived N-doped porous carbon as highly active and durable cathode catalysts for PEMFCs

High cost and poor durability of Pt-based cathode catalysts for oxygen reduction reaction (ORR) severely hamper the popularization of proton exchange membrane fuel cells (PEMFCs). Tailoring carbon support is one of effective strategies for improving the performance of Pt-based catalysts. Herein, petroleum vacuum residue was used as carbon source, and nitrogen-doped porous carbon (N-PPC) was synthesized using a simple template-assisted and secondary calcination method. Small Pt nanoparticles (Pt NPs) with an average particles size of 1.8 nm were in-situ prepared and spread evenly on the N-PPC. Interestingly, the lattice compression (1.08%) of Pt NPs on the N-PPC (Pt/N-PPC) was clearly observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), which was also verified by the shift of (111) crystal plane of Pt on N-PPC to higher angles. The X-ray photoelectron spectroscopy (XPS) results suggest that the N-PPC support had a strong effect on anchoring Pt NPs and endowing surface Pt NPs with lowered d band center. Thus, the Pt/N-PPC as a catalyst simultaneously boosted the ORR activity and durability. The specific activity (SA) and mass activity (MA) of the Pt/N-PPC at 0.9 V reached 0.83 mA cm−2 and 0.37 A mgPt−1, respectively, much higher than those of the commercial Pt/C (0.21 mA cm−2 and 0.11 A mgPt−1) in 0.1 M HClO4. The half-wave potential (E1/2) of Pt/N-PPC exhibited only a minimal negative shift of 7 mV after 30,000 accelerated durability tests (ADT) cycles. More importantly, an H2–O2 fuel cell with a Pt/N-PPC cathode achieved a power density of 866 mW cm−2, demonstrating that the prepared catalyst has a promising application potential in working environment of PEMFCs.

Commercial Ebullated Bed Vacuum Residue Hydrocracking Performance Improvement during Processing Difficult Feeds

The Urals and Siberian vacuum residues are considered difficult to process in the ebullated bed hydrocracking because of their increased tendency to form sediments. Their achievable conversion rate reported in the literature is 60%. Intercriteria analysis was used to assess data from a commercial vacuum residue hydrocracker during processing blends from three vacuum residues: Urals, Siberian Light, and Basra Heavy. The analysis revealed that the main contributors to conversion enhancement is hydrodemetallization (HDM) and the first reactor ΔT augmentation. The increase of HDM from 40 to 98% and the first reactor ΔT (ΔT(R1)) from 49 to 91 °C were associated with a vacuum residue conversion enhancement of 62.0 to 82.7 wt.%. The developed nonlinear regression prediction of conversion from HDM and ΔT(R1) suggests a bigger influence of ΔT(R1) enhancement on conversion augmentation than the HDM increase. The intercriteria analysis evaluation revealed that the higher first reactor ΔT suppresses the sediment formation rate to a greater extent than the higher HDM. During processing Basrah Heavy vacuum residue, a reduction in hydrodeasphaltization (HDAs) from 73.6 to 55.2% and HDM from 88 to 81% was observed. It was confirmed that HDM and HDAs are interrelated. It was found that the attainment of conversion of 80 wt.% and higher during processing Urals and Siberian Light vacuum residues is possible when the HDM is about 90% and LHSV ≤ 0.19 h−1.

Highly active and stable CoWS2 catalysts in slurry phase hydrocracking of vacuum residue: XAFS studies

The bimetallic CoWS2 catalysts were prepared in situ during the slurry phase hydrocracking (HCK) of vacuum residue (VR) using W(CO)6 and Co-octoate as oil soluble precursors to investigate the promotional effect of Co promoters on the dispersed WS2 catalyst for the VR HCK. The morphologies and structural properties of dispersed catalysts were characterized by transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). The bimetallic CoWS2 catalyst was observed to form well-dispersed monolayers in the size range of 7–11 nm, which showed higher turn-over frequency values (TOF) and C7-asphaltene (C7-ASP) conversions than monometallic WS2 or Co9S8 catalysts in the VR HCK at 693 K and 10.0 MPa H2. Moreover, the extended X-ray fine absorption structure spectroscopy (EXAFS) coupled with the density functional theory (DFT) calculations successfully verified the formation of the Co-W-S phase.

An oil-soluble precursor with strong feedstock adaptability and excellent product selectivity for heavy oil hydrocracking

The feedstock adaptability and product selectivity of catalyst are very important for heavy oil hydrocracking. Considering that the components of heavy oil are mainly composed of aromatic compounds and alkyl compounds, Mo aryl-alkyl-dithiophosphate (Mo-Ar/R) with both benzyl and n-butyl was efficiently prepared based on the preparation method of Mo dialkyl-dithiophosphate (Mo-R) with only n-butyl whose high hydrogenation activity has been proved to improve the structural similarity to feedstock. Fourier transform infrared (FTIR) analysis, elemental analysis and oil solubility study were carried out on Mo-Ar/R and Mo-R. X-Ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and polarized microscope were used to obtain the structural and morphological information of MoS2 catalysts. Mo-Ar/R and Mo-R were evaluated in the hydrocracking of atmospheric residue ultra heavy oil (feedstock A), high sulfur vacuum residue (feedstock B) and coal tar oil (feedstock C) at 430 ℃ with an initial hydrogen pressure of 7 MPa for various reaction times, respectively. The results showed that the coexistence of benzyl and n-butyl led to better oil solubility of Mo-Ar/R, smaller size, lower stacking number and shorter slab length of the resulting MoS2 catalysts. Compared with Mo-R, Mo-Ar/R increased the valuable product yields during hydrocracking of feedstock A, feedstock C and feedstock B by 1.33 wt%, 3.53 wt% and 3.97 wt%, decreased the coke yields by 0.21 wt%, 0.40 wt% and 0.51 wt% and decreased the gas yields by 0.65 wt%, 0.97 wt% and 1.19 wt%, respectively. The initial hydrogen consumption rates and TOFs obtained in the presence of Mo-A/R are higher than that obtained in the presence of Mo-R. The performance difference between Mo-Ar/R and Mo-R seemed to be related to the contents of saturates of the different feedstocks. The coexistence of benzyl and n-butyl was proved to lead to the better feedstock adaptability and product selectivity of Mo-Ar/R compared with Mo-R due to the better structural similarity.

Application of Ebullated-Bed Vacuum Residue Hydrocracking at Lukoil Neftohim Burgas

Application of Ebullated-Bed Vacuum Residue Hydrocracking at Lukoil Neftohim Burgas

Impacts of support properties on the vacuum residue slurry-phase hydrocracking performance of Mo catalysts

To deeply understand the effects of support properties on the performance of Mo-based slurry-phase hydrocracking catalysts, four Mo-based catalysts supported on amorphous silica alumina (ASA), γ-Al2O3, ultra-stable Y (USY) zeolite and SiO2 were prepared by the incipient wetness impregnation method, respectively, and their catalytic performances were compared in the vacuum residue (VR) hydrocracking process. It is found that the Mo/ASA catalyst exhibits the highest VR conversion among the different catalysts, indicating that both the appropriate amount of acid sites, especially B acid sites and larger mesoporous volume of ASA can enhance the VR hydrocracking into light distillates. Furthermore, Mo catalysts supported on the different supports show quite different product distributions in VR hydrocracking. The Mo/ASA catalyst provides higher yields of naphtha and middle distillates and lower yields of gas and coke compared with other catalysts, it is attributed to the highest MoS2 slab dispersion, the highest sulfuration degree of Mo species, and the most Mo atoms located at the edge sites for the Mo/ASA catalyst, as observed by HRTEM and XPS analyses. These features of Mo/ASA are beneficial for the hydrogenation of intermediate products and polycyclic aromatic hydrocarbons to restrict the gas and coke formation.

Atomic coordination structural dynamic evolution of single-atom Mo catalyst for promoting H2 activation in slurry phase hydrocracking

Development of efficient catalysts with high atomic utilization and turnover frequency (TOF) for H2 activation in slurry phase hydrocracking (SPHC) is crucial for the conversion of vacuum residue (VR). Herein, for the first time, we reported a robust and stable single atoms (SAs) Mo catalyst through a polymerization-pyrolysis-in situ sulfurization strategy for activating H2 in SPHC of VR. An interesting atomic coordination structural dynamic evolution of Mo active sites was discovered. During hydrocracking of VR, the O atoms that coordinated with Mo were gradually replaced by S atoms, which led to the O/S exchange process. The coordination structure of the Mo SAs changed from pre-reaction Mo-O3S1 to post-reaction Mo-O1S3 coordination configurations, promoting the efficient homolytic cleavage activation of H2 into H radical species effectively. The evolved Mo SAs catalyst exhibited robust catalytic hydrogenation activity with the per pass conversion of VR of 65 wt%, product yield of liquid oils of 93 wt%, coke content of only 0.63 wt%, TOF calculated for total metals up to 0.35 s−1, and good cyclic stability. Theoretical calculation reveals that the significant variation of occupied Mo 4d states before and after H2 interaction has a direct bearing on the dynamic evolution of Mo SAs catalyst structure. The lower d-band center of Mo-O1S3 site indicates that atomic H diffusion is easy, which is conducive to catalytic hydrogenation. The finding of this study is of great significance to the development of high atom economy catalysts for the industrial application of heavy oil upgrading technology.

Catalytic hydroprocessing of oil residues for marine fuel production

The study is devoted to the tests of hierarchical meso-macroporous catalysts for three-stage atmospheric and vacuum residues hydroprocessing. A special attention is paid to properties of fresh and spent catalysts, the results of experiments on the selection of the optimal parameters (T, p and LHSV) for the three-stage hydroprocessing of residues, as well as the properties of petroleum products produced under optimal conditions. Catalysts were characterized with XRD, nitrogen adsorption–desorption, Hg-intrusion, SRXRF, TPD-NH3 and SEM. The proposed technology of the hydroprocessing of residues over the catalysts with hierarchical porosity makes it possible to obtain valuable oil products and MARPOL marine fuel, which meets modern technical and environmental requirements. Based on the laboratory experiments, a pilot setup for three-stage hydroprocessing of residues has been developed, and is tested at the moment.

Cenosphere Formation and Combustion Characteristics of Single Droplets of Vacuum Residual Oils

ABSTRACT The ignition, combustion characteristics, and cenosphere formation of single droplets combustion of four vacuum residues (VRs) from different refineries with various asphaltene contents were studied experimentally. The single droplets of VRs were suspended at the tip of a silicon carbide fiber and heated in air at temperatures of 973 and 1023 K, respectively, in an electrically heated tube furnace. The ignition and combustion behavior of the VRs were recorded using a CCD camera, which enabled the determination of droplet size, ignition delay time, flame duration, and cenosphere size. The effect of initial droplet size, gas temperature, and asphaltene content on the ignition delay time, flame duration, cenosphere morphology, and particle size were investigated. The whole ignition and combustion process of single droplets of the VRs consisted of five stages in succession: (1) pre-ignition, mainly involving the evaporation of highly volatile components from the droplet surface; (2) steady combustion of fuel vapors evaporated from the droplet surface; (3) splashing combustion of fuel vapors evaporated from droplet interior; (4) disruptive combustion due to thermal decomposition of asphaltene; and (5) solid residue ignition and combustion. A visible and sooty flame was formed upon ignition and lasted during stages 2–4. The droplet size increased sharply in the stage 4 due to the thermal decomposition of asphaltene, which was more profound for VRs with higher asphaltene content and at higher gas temperatures. The ignition delay time increased with increasing initial droplet size and gas temperature but varied little as the asphaltene content in the VRs increased, suggesting that the ignition process of VRs was controlled by the vaporization of high volatile components on the droplet surface. The thermal decomposition of asphaltene produced solid residue, which was in the form of a cenosphere with the shell thickness being ca. 20 μm and a number of blowholes presented in the shell. The VRs with higher asphaltene content had more and bigger blowholes. The ratio of cenosphere particle size to initial droplet size is independent of the initial droplet size but almost increased linearly with the asphaltene content in the VRs.

Correlations of HTSD to TBP and Bulk Properties to Saturate Content of a Wide Variety of Crude Oils

Forty-eight crude oils with variations in specific gravity (0.782 ≤ SG ≤ 1.002), sulphur content (0.03 ≤ S ≤ 5.6 wt.%), saturate content (23.5 ≤ Sat. ≤ 92.9 wt.%), asphaltene content (0.1 ≤ As ≤ 22.2 wt.%), and vacuum residue content (1.4 ≤ VR ≤ 60.7 wt.%) were characterized with HTSD, TBP, and SARA analyses. A modified SARA analysis of petroleum that allows for the attainment of a mass balance ≥97 wt.% for light crude oils was proposed, a procedure for the simulation of petroleum TBP curves from HTSD data using nonlinear regression and Riazi’s distribution model was developed, and a new correlation to predict petroleum saturate content from specific gravity and pour point with an average absolute deviation of 2.5 wt.%, maximum absolute deviation of 6.6 wt.%, and bias of 0.01 wt.% was developed. Intercriteria analysis was employed to evaluate the presence of statistically meaningful relations between the different petroleum properties and to evaluate the extent of similarity between the studied petroleum crudes. It was found that the extent of similarity between the crude oils based on HTSD analysis data could be discerned from data on the Kw characterization factor of narrow crude oil fractions. The results from this study showed that contrary to the generally accepted concept of the constant Kw characterization factor, the Kw factors of narrow fractions differ from that of crude oil. Moreover, the distributions of Kw factors of the different crudes were different.

Strategies for adding tetralin in thermal processing of heavy oil

The strategy of adding tetralin as a H-donor in the thermal processing of heavy oil was investigated by experimental characterization and theoretical calculations. According to the experiments, the timing of adding 1 wt% of tetralin has a great influence on the visbreaking performance of heavy oil. Calculations based on density functional theory showed that benzyl radicals released from the thermal cracking of tetralin accelerate the dealkylation that determines the heavy oil upgrading. Meanwhile, Hα provided by tetralin is able to selectively saturate aromatic C radicals which are essential for condensation. Compared with the conventional H-donor addition, i.e., pre-mixing of tetralin with heavy oil, a similar viscosity reduction rate of about 98% can be obtained during the visbreaking with delayed tetralin addition. Furthermore, the addition of tetralin before the significant occurrence of condensation further increases the conversion of vacuum residue fraction by 3.4% and reduces the asphaltene content of the product by 2.6 wt%.

TG-DSC and TG-FTIR analysis of heavy fuel oil and vacuum residual oil pyrolysis and combustion: characterization, kinetics, and evolved gas analysis

TG-DSC and TG-FTIR analysis of heavy fuel oil and vacuum residual oil pyrolysis and combustion: characterization, kinetics, and evolved gas analysis

Estimation of the gas hold up and flow regime of a bubble column reactor for the slurry phase hydrocracking of heavy oil

This study investigated gas hold up and flow regimes according to operating conditions (temperature, pressure, superficial gas velocity) for the design of a slurry phase hydrocracking reactor for heavy oil. Heating medium oil, vacuum residue (VR) and hydrocracking products were used in a bubble column reactor which had a diameter of 0.05 m and a height of 2.3 m. The results confirmed that the gas hold up increased and the flow regime transition point was delayed as VR was converted to a hydrocracking product (change in physical properties), and pressure also affected the flow regime transition. Using the dynamic gas disengagement method, the flow regime transition was observed in the actual hydrocracking reaction, and at the same time, it was confirmed that the hydrocracking reaction performance decreased. A VR slurry phase hydrocracking flow regime map is proposed by modifying the existing correlations, and a guide for reactor design and operation is suggested.

Влияние гидрокрекинга тяжелых остатков перегонки нефти на производственную эффективность АО «ТАИФ-НК»

The article is devoted to the experience of the TAIF-NK JSC in the application of the process of combined thermal and hydrocracking for deep processing of heavy residues of oil distillation - vacuum residue and vacuum gasoil. The Veba Combi Cracker (VCC) process was taken as a basis and during the commissioning and pilot tests it was significantly improvedby the specialists of TAIF Group, as a result of which the Heavy Residue Conversion Complex of TAIF-NK JSC is the only one in the world, which allows heavy residues conversion with maximum recovery of high-quality light oil products. The implementationof the technology of combined thermal and hydrocracking at TAIF-NK JSC ensured 85.1% achievement of the refining depth and 80.7% yield of light oil products in 2021. A retrospective of the dynamics of indicators of the depth of oil refining and the yield of light oil products from the implementation of the project is showny.

Применение гидрокрекинга вакуумного остатка в кипящем слое на предприятии «ЛУКОЙЛ Нефтохим Бургас»

This paper summarises the experience gained over seven years of operating the H-Oil hydrocracking technology with an ebullated vacuum residue bed. Four factors have been identified as major contributors to improved H-Oil performance: feedstock quality; catalyst condition; hydrocracking unconverted vacuum residue loading and utilisation. The optimum combination of all these factors made it possible to achieve a vacuum residue conversion rate of about 90%. It remains a challenge to find the correct use of the unconverted vacuum residue produced at higher conversion rates.

Глубокая переработка гудрона на базе комплекса глубокой переработки тяжелых остатков АО «ТАИФ-НК»

The article is devoted to the processing of vacuum residue and vacuum gasoil based on the Veba Combi Cracking (VCC) technology and covers aspects of the formation of the process from the first research in the field of coal hydrocracking to the world's largest complex for deep processing of heavy oil refining residues of TAIF-NK JSC.