Petroleum Residues Research Articles

Catalytic cracking of heavy petroleum residue in supercritical water: Study on the effect of different metal oxide nanoparticles

Cracking of heavy petroleum residue obtained from the vacuum distillation unit in supercritical water (SCW) was performed with and without catalysts. First, different nanoparticles, including CeO2, Co3O4, and MnO2 were synthesized in a batchwise SCW reactor; then, the abilities of aforementioned nanocatalysts to convert vacuum residue (VR) into the lighter fractions as well as their stability under severe condition of supercritical water were examined. The X-ray diffractometery (XRD) and transmission electron microscopy (TEM) images indicated that the obtained nanoparticles with a satisfactory size and morphology were synthesized under supercritical condition. VR cracking experiments were also conducted in a batchwise reactor under operating condition, namely temperature: 450°C, reaction time: 60min, catalyst/oil ratio (g/g): 1/5, and water/oil ratio (g/g): 80/3. The performance of different nanocatalysts was compared based on the yield of maltene, coke, and asphaltene obtained from VR cracking. As a result, it was determined that the efficiency of nanocatalysts in VR cracking diminishes in the order of CeO2>Co3O4>MnO2, while the non-catalytic cracking or SCW pyrolysis attained the lowest rank with a slight difference with the case of MnO2. Moreover, the XRD was utilized to investigate the stability of different catalysts. The results demonstrated that only CeO2 was stable, whereas the other catalysts were reduced to the lower oxidation states during the reaction. Nevertheless, the scanning electron microscopy (SEM) image and the Brunauer–Emmett–Teller (BET) surface area of spent CeO2 showed the agglomeration of nanoparticles after the reaction.

Utilization of petroleum residues under microwave irradiation

This paper presents the results of tar conversion under microwave irradiation (MWI). It is established that carbon adsorbents produced from natural mineral row possess by high microwave energy absorption coefficients; which characterized by high value of dielectric losses. Non-liner dynamics of carbon adsorbents heating at different current density from 80 till 200μA/cm2 indicates that plasma generation occurs during microwave irradiation. It is found that the mechanism of tar conversion which preliminary adsorbed in the pores of the carbon sorbents under microwave irradiation and convective heating is different. The C–H bond is mainly activated and decomposed under microwave treatment with predominant formation of hydrogen. In case of C–C bonds, they are mainly subjected to thermolysis under convective heating and methane is the main product of degradation. To confirm the difference in the mechanism of tar destruction under microwave influence and convective heating the experiments with individual hydrocarbons adsorbed in the pores of hydrophobic sorbents were carried out.

Physicochemical aspects of petroleum coke formation (review)

The current status and development of petroleum residue upgrading via coking in Russia and over the world have been surveyed with an emphasis on the role of the process in salving the problem of increasing the refining depth. Theoretical concepts of thermal conversion of heavy petroleum feedstock and the structure of asphaltenes as principal coke-forming compounds have been discussed, the results of studies on the formation of coke as either a byproduct or (to a greater extent) the desired product have been considered, and models of the coke structure have been proposed. The characteristic features of the coking process for petroleum residues of various chemical compositions have been addressed, as well as means for controlling the feedstock thermal stability and the yield and quality of coke with the use of external factors.

Identification of vanadyl complexes structure in asphaltene molecules present in petroleum residues by pulsed EPR spectroscopy

Identification of vanadyl complexes structure in asphaltene molecules present in petroleum residues by pulsed EPR spectroscopy

USE OF A LOW-COST TEMPLATE-FREE ZSM-5 FOR ATMOSPHERIC PETROLEUM RESIDUE PYROLYSIS

To understand the physicochemical properties and catalytic activity during the pyrolysis of atmospheric petroleum residue, a template-free ZSM-5 zeolite was synthesized using a direct method without additional seeds or an organic structure director and compared with conventionally synthesized ZSM-5. The crystallinities of the two zeolites were evaluated by XRD and FTIR and were quite similar; however, structural analyses using SEM and argon physisorption revealed that the zeolites diverged in particle diameter and in the external surface area of the micropores. The synthesis procedure without a template incorporated additional aluminum into the crystalline network, according to ICP-AES and TPD NH3 experiments. The catalytic pyrolysis performed over the template-free ZSM-5 generated results comparable to those for pyrolysis performed over the conventional ZSM-5 according to its hydrocarbon distribution. The selectivity to aromatics compounds was exactly the same for both ZSM-5 zeolites, and these values stand out compared to thermal pyrolysis. The template-free ZSM-5 produced 20% of light hydrocarbons (C4-C6), where such compounds are olefins and paraffins of great interest to the petrochemical industry. Therefore, template-free ZSM-5 is promising for industrial use due to its lowered synthesis time, low-cost and significant distribution to light hydrocarbons.

Effect of Shear Stress on Crude Oil Fouling in a Heat Exchanger Tube Through CFD Simulations

This work presents the effect of shear stress on deposit formation caused by the heavy petroleum residues in the crude oil. The investigation is based on a three dimensional study through Computational Fluid Dynamics approach. Fouling process is simulated using asphaltenes precipitation and chemical reaction routes. The asphaltenes phase deposition and coke formation rates were predicted through Volume-of-Fluid (VoF) multiphase model and thermal cracking due to chemical reactions, respectively. The aging process of the fouling layer was studied through a transient state numerical approach. Grid dependence study has been performed to confirm the accuracy of the performed mesh. It was observed that, wall shear stress enables the removal of fouling precursors and thus reduce the deposit formation.

Study on Colloidal Model of Petroleum Residues through the Attraction Potential between Colloids.

The samples of DaGang atmospheric residue (DG-AR), Middle East atmospheric residue (ME-AR), TaHe atmospheric residue (TH-AR), and their thermal reaction samples were chosen for study. All the samples were fractioned into six components separately, including saturates plus light aromatics, heavy aromatics, light resins, middle resins, heavy resins, and asphaltenes. The dielectric permittivity of the solutions of these components was measured, and the dielectric permittivity values of the components can be determined by extrapolation, which increased steadily from saturates plus light aromatics to asphaltenes. Moreover, the Hamaker constants of the components were calculated from their dielectric permittivity values. The Van der Waals attractive potential energy between colloids corresponding to various models could be calculated from the fractional composition and the Hamaker constants of every component. It was assumed that the cores of colloidal particles were formed by asphaltenes and heavy resins mainly; the other fractions acted as dispersion medium. For the three serials of thermal reaction samples, the Van der Waals attraction potential energy between colloids for this kind of model was calculated. For TH-AR thermal reaction samples, the Van der Waals attraction potential energy presented the maximum as thermal reaction is going on, which was near to the end of coke induction period.

Seasonal variation of carbonaceous pollutants in PM2.5 at an urban ‘supersite’ in Shanghai, China

Multiple PM2.5 samples collected through different seasons from October 2011 to August 2012 at an urban site in Shanghai, China were analyzed for carbonaceous pollutants. Data from this site, a 'super' air quality monitoring station at Fudan University, has been used by researchers to investigate the formation mechanism of haze episodes. The characteristics and concentrations of organic carbon (OC), elemental carbon (EC), n-alkanes, as well as relative abundances of hopanes, in these samples were determined. The concentrations showed a pronounced annual cycle with higher values in cold seasons (spring and winter, mean: 8.6 μg/m(3), 3.3 μg/m(3) and 136.4 ng/m(3) for OC, EC and n-alkanes, respectively) and lower values in warm seasons (fall and summer, mean: 6.6 μg/m(3), 2.6 μg/m(3) and 73.8 ng/m(3) for OC, EC and n-alkanes, respectively). EC generally displayed a common source with that of OC in all seasons. Petroleum residue was the major source of n-alkanes, contributing 71.4% to the targeted C14-C33n-alkanes over four seasons. Principal components analysis and the composition of hopanes showed that emissions from vehicle exhaust contributed more carbonaceous aerosols than coal combustion. These data could provide important information for measures to reduce carbonaceous pollutant emissions and improve air quality in Shanghai, and other urban centers across China.

Structural characteristics of petroleum sludge

The structural characteristics of dewatered petroleum sludge and the fraction boiling above 350°C are compared, on the basis of physicochemical research methods. The structure of the residue boiling above 350°C is more aromatic than the initial sludge and resembles that of heavy petroleum residues. This suggests that hydroconversion of the >350°C fraction and the heavy petroleum residues will also be similar. Hence, the sludge component boiling above 350°C may prospectively be processed by hydroconversion in the presence of ultrafine catalysts.

Radiotracer investigations in pilot-scale soakers

This paper describes a radiotracer investigation carried out to measure residence time distribution (RTD) of petroleum residues in pilot-scale soakers. The main objectives of the investigation were to evaluate the feasibility of using bromine-82 as dibromobiphenyl (DBBP) for tracing the petroleum residues (organic phase) as a radiotracer at elevated temperature and pressure, and to investigate the flow dynamics of the phase in the soaker at different operating and process conditions. The measured RTD was treated and mean residence times (MRTs) were determined. Tanks-in-series with backmixing model (TISBM) was used to simulate the measured RTD data. The results of model simulation indicated a high degree of backmixing in the soaker without baffles i.e. without sectionalizing the soaker. However, the introduction of perforated plates at various axial locations inside the soaker i.e. sectionalizing the soaker, reduces the extent of backmixing thus tending the flow towards plug flow.

Mesophase formation behavior in petroleum residues

Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally- benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oil s (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380°C to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.

Influence of a coking additive from oil refining on coke properties (CRI and CSR)

The influence of DK coking additive from oil refining—specifically, the solid product from the slow coking of heavy petroleum residues—in coal batch on the quality of the coke produced is studied in laboratory conditions. In comparison with coal concentrates, DK coking additive is characterized by lower ash content (Ad = 1.1%) and higher sulfur content (Std= 3.7%); the yield of volatiles Vdaf = 18.2%. The DK coking additive is added to the batch in doses of 4.8%, 9.1%, and 13%, with proportional decrease in the batch components. In other cases, DK coking additive is added to the batch in doses of 10%, in place of coal of the clinkering and coke groups. Coke is produced from the batch in the laboratory. The coal charge is 2 kg; the piece size is ≤3 mm. With increase in the content of DK coking additive to 13%, the strength of the coke after reaction (CSR) increases linearly from 49.2 to 54.9%, while the reactivity CRI declines linearly from 37.9 to 33.8%. The improvement in coke quality is greatest when GZh coal (a clinkering component) is replaced by the DK additive: CSR rises to 59.2% and CRI falls to 30.8%. The most promising approach is to replace the scarcest and most expensive coal—OS coal (the coke group) and KS coal (the lean group)—with DK additive, with 3.8% increase in CSR and 3.3% decrease in CRI.

Predictive correlations for thermal upgrading of petroleum residues

Predictive correlations are presented for thermal conversion of petroleum residues employing a large number of data points obtained from the literature. The proposed correlations include equations adopted in terms of three operating variables of temperature, reaction time, and pressure and three main characteristics of a residuum including API, sulfur content, and CCR to predict upgrading conversion, liquid yield, gas yield, sulfur content of the liquid product, and yield of heavy gas oil. The expressions employed in these correlations were carefully chosen from a large group of functions with a minimum number of regression variables. The trends of the dependent variables in terms of the six independent modeling variables are discussed. Satisfactory statistical results were achieved for all correlation models presented, indicating their applicability to different types of residues over a wide range of operating conditions.

Polydisperse Size Distribution of Monomers and Aggregates of Sulfur-Containing Compounds in Petroleum Residue Fractions

Dimension of sulfur-containing compounds in a residue is crucial to hydrodesulfurization catalyst design. Size distributions of sulfur compounds in fractions of Venezuela atmospheric residue were determined from the bulk-phase diffusion coefficients, which were measured at 298 K by a diaphragm cell by using 200 nm polycarbonate membranes. Sulfur compounds in all fractions show obvious size polydispersity. The size of four narrow SFEF (supercritical fluid extraction and fraction) fractions varies slightly with the concentrations of 1 g/L to 40 g/L. However, maltenes and asphaltenes from the end-cut showed significant variation in size over concentrations of 0.1 g/L to 40 g/L, which indicates a coexistence of various monomers and aggregates. The monomers are dominated in maltenes, whereas aggregates dominated in asphaltenes. The hydrodynamic diameter of sulfur-containing monomers of four SFEF fractions ranges from 0.74 to 1.45 nm at a concentration of 1 g/L. The size of maltene monomers spans a range of 1.8...

Current status and prospects of demetallization of heavy petroleum feedstock (Review)

Comparative assessment of the prospects of development of heavy petroleum feedstock (HPF) upgrading technologies in terms of the possibility of removal and recovery of metals contained in the feedstock is presented. It has been shown that HPF demetallization with different efficiencies can be achieved as a result of destructive thermal conversion of the feedstock and nondestructive mass transfer processes. Solvent deasphalting is characterized by simplicity of engineering design and operating flexibility and makes it possible to remove both asphaltenes and metals, whose deposition leads to irreversible deactivation of oil refining catalysts. Promising lines in demetallization by destructive feedstock conversion are associated with processes that provide the highest degree of HPF conversion and the lowest yield of the unconverted residue, in which the feedstock metals are concentrated. In this regard, the development and implementation of petroleum residue upgrading technologies based on the slurry hydrocracking, fluid coking or flexicoking, and supercritical fluid extraction processes creates real prerequisites for the organization of high-conversion comprehensive processing of heavy oils with the isolation of a metal concentrate.

An assessment of human influences on sources of polycyclic aromatic hydrocarbons in the estuarine and coastal sediments of China

Sediments collected from the coastal area of China, embracing west coast of Bohai Sea, south coast of Shandong Peninsula, and the Changjiang estuary (listed in order of decreasing north latitude), were analyzed for polycyclic aromatic hydrocarbons (PAHs). ∑PAH (Sixteen US EPA priority PAHs) were 2.7–350.9ng/g. Petroleum residue was the major contributor of PAHs in the coastal sediments of China due to oil leakage from ships and offshore oil fields. The contribution of vehicular emissions in coast of North China was significantly lower than that in the Changjiang Estuary, and the reverse was true for coal combustion. PAH concentrations in the sediment core of the Changjiang estuary steadily increased upward and the variation was primarily due to economic development and severe floods. The impact on PAHs by vehicular emissions (37.2%) and petrogenic sources (45.8%) overwhelmed combustion sources (17.0%).

Very high methane uptake on activated carbons prepared from mesophase pitch: A compromise between microporosity and bulk density

Two petroleum residues were pyrolyzed under two different conditions to obtain pitches with low or high mesophase content. The effect of the KOH: precursor ratio and the activation temperature on the packing density and porous texture of the carbons have been studied and optimized. Activated carbons combining high micropore volume (>1cm3/g) and high packing density (0.7g/cm3) have been successfully prepared. Regarding excess methane adsorption capacities, the best results (160cm3 (STP)/cm3 at 25°C and 3.5MPa) were obtained using the pitch with the higher content of the more organized mesophase, activated at relatively low temperature (700°C), with a medium KOH: precursor ratio (3:1). Some of the activated carbons exhibit enhanced adsorption capacity at high pressure, giving values as high as 175cm3 (STP)/cm3 at 25°C and 5MPa and 200cm3 (STP)/cm3 at 25°C and 10MPa (the same amount as in an empty cylinder but at half of the pressure), indicating a contribution of large micropores and narrow mesopores to adsorption at high pressure. The density of methane in pores between 1 and 2.5nm at pressure up to 10MPa was estimated to understand their contribution to the total adsorption capacity.

Sulfuric Acid Assisted Extraction and Fractionation of Porphyrins From Heavy Petroleum Residuals With a High Content of Vanadium and Nickel

Primary porphyrin extracts were obtained from carbon tetrarchloride solutions of different heavy oil residuals with assistance of sulfuric acid. According to data of chromatographic separation of extracts porphyrinic fractions appear in amount of 13.0–24.2%. Based on UV/visible absorption spectroscopy the presence of porphyrins of etio and phyllo types mostly with rhodo and deoxophylloerythroetioporphyrins in lower amount was established. The content of porphyrins in obtained fractions was determined at the level of 15.3–44.8% of the total weight. It was shown that a higher concentration of porphyrins in sulfuric acid extracts occurs for the case of the high vanadium and nickel content and low amounts relation of asphaltenes to resins.

Characterization of carbonaceous aerosols over the East China Sea: The impact of the East Asian continental outflow

Seventy-five paired PM2.5 (aerodynamic diameter less than 2.5 μm) and TSP (total suspended particle) samples collected from a pristine island in the East China Sea (ECS) between October 2011 and August 2012 were analyzed for organic carbon (OC), elemental carbon (EC), and n-alkanes. The island lies in the pathway of continental outflow from Mainland China to the northwest Pacific Ocean driven by the East Asian Monsoon. The concentrations of OC, EC (in μg/m3), and n-alkanes (in ng/m3) were highest in winter (means: 4.7, 1.3, 140.1, respectively) and lowest in summer (means: 1.1, 0.3, 17.0, respectively). PM2.5 contained approximately 88% of the OC, 80% of the EC, and 61% of the n-alkanes in TSP. Petroleum residue was the dominant contributor to the n-alkanes. C12–C22n-alkanes with strong even-to-odd predominance observed in winter were attributed to the microbial contribution from sea spray aerosol (SSA) driven by the higher wind speed. There was a higher secondary organic carbon (SOC)/OC ratio in warm seasons (summer and fall) than that in cold seasons (spring and winter). The dominance of primary organic carbon (POC) and EC in cold seasons was possibly mainly due to the influence of the East Asian continental outflow. Three episodes of high concentrations of carbonaceous aerosols were observed, and we focused on the impact of these pollutants from East Asia on the air quality over the ECS. Carbonaceous pollutants were more concentrated in PM2.5 during the fall episode triggered by biomass burning in East China. The winter haze associated with intensive indoor heating in North China brought substantial carbonaceous pollutants, with a minor influence on their size distribution. The dust episode in spring was related to coarse particles (i.e., TSP–PM2.5), yielding a distinctly different size distribution.

Experimental Study of a Pilot Plant Deasphalting Process in Ethanol Sub and Supercritical Phase

The authors aimed to study the deasphalting process on laboratory scale through the design and development of a subcritical and supercritical extraction experimental unit. The experimental unity used in tests is composed by a pump, an extractor with useful volume of 3 L and one separator vessel. Extractions in sub- and supercritical conditions were carried out using petroleum residue (vacuum residuum) as feedstock and ethylic alcohol as solvent. Temperature and pressure were manipulated in order to maintain the solvent in the required conditions, thus facilitating the extraction process and avoiding sharp changes in the system. In both phases, the products in the deasphalted oil stream present adequate characteristics for the production of lubricant oils and those in the asphalt residue stream present an elevated concentration of asphalt molecules.