Pyrolysis Of Asphaltenes Research Articles

High-Temperature Reaction Mechanism of Molybdenum Metal in Direct Coal Liquefaction Residue

In this paper, the extraction residue of direct coal liquefaction residue-DCLR(ER) was used as raw material. The high-temperature reaction mechanism of Mo compound in DCLR(ER) was investigated using a synchronous thermal analyzer and the Factsage database. The high temperature reaction of DCLR(ER)-MoO3 in an oxygen atmosphere consists of pyrolysis of organic components at 400–600 °C, molybdenum trioxide sublimation at 747–1200 °C, and a stable stage at 600–747 °C. The thermal reaction process of the DCLR(ER)-MoS2 system in the oxygen atmosphere involves the pyrolysis of unreacted coal and asphaltene, the oxidation of molybdenum sulfide at 349–606/666 °C, the diffusion of MoO3 at 606/666–85 °C, and the sublimation reaction process of MoO3 at 854–1200 °C. The results show that the lower heating rate can promote the oxidation of the Mo compound and the sublimation of molybdenum trioxide. On the other hand, the oxides of aluminum, calcium, and iron in DCLR(ER) can inhibit the oxidative pyrolysis efficiency of the DCLR(ER)-MoS2 system.

Bitumen and asphaltene derived nanoporous carbon and nickel oxide/carbon composites for supercapacitor electrodes

Asphaltenes from bitumen are abundant resource to be transformed into carbon as promising supercapacitor electrodes, while there is a lack of understanding the impact from different fractions of bitumen and asphaltenes, as well as the presence of transition metals. Here, nanoporous carbon was synthesized from bitumen, hexane-insoluble asphaltenes and N,N-dimethylformamide (DMF)-fractionated asphaltenes by using Mg(OH)2 nanoplates as the template with in-situ KOH activation, and used as an supercapacitor electrode material. All of the carbon exhibited large surface area (1500–2200 m2 g−1) with a distribution of micro and mesopores except for that derived from the DMF-soluble asphaltenes. The pyrolysis of asphaltenes resulted in the formation of nickel oxide/carbon composite (NiO/C), which demonstrated high capacitance of 380 F g−1 at 1 A g−1 discharge current resulting from the pseudocapacitance of NiO and the electrochemical double layer capacitance of the carbon. The NiO/C composite obtained from the DMF-insoluble portion had low NiO content which led to lower capacitance. Meanwhile, the specific capacitance of NiO/C composite from the DMF-soluble part was lower than the unfractionated asphaltene due to the higher NiO content resulting in lower conductivity. Therefore asphaltenes derived from nickel-rich crude bitumen is suitable for the synthesis of nanoporous NiO/C composite material with high capacitance.

Phosphorous and sulfur doped asphaltene derived activated carbon for supercapacitor application

It is important to develop alternative methods for obtaining hierarchical porous and heteroatoms-doped carbon for the fabrication of a high-performance supercapacitor that is both effective and inexpensive. In this research, asphaltene rich-sulfur derived activated carbon (As-AC) is prepared by one-step pyrolysis of asphaltene. But, further phosphorous doping Asphaltene derived activated carbon (P-As-AC) was fabricated with facile pyrolysis of As-AC at 300 °C in the presence of (NH4)2HPO4. The synthesized materials were characterized by XRD, BET, EDAX, XPS, TEM, FTIR, Raman and Zeta potential analysis. XRD diagram show two broad diffraction peaks for As-AC and P-As-AC samples were displayed at 2Ө values of around 24° and 42°, respectively. The total specific surface area (SSA) of As-AC was 425.7 m2 g−1 while that of P-As-AC that doped with phosphorus decreased sharply to 18.468 m2 g−1. The total pore volume decreased from 0.5 cm3 g−1 for As-AC to 0.023 cm3 g−1 for P-As-AC and the pore size decrease from 3.3 nm for As-AC to 2.3 nm for P-As-AC. The supercapacitive activity of As-AC and P-As-AC electrodes was studied by cyclic voltammetry (CV), Galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The mechanism of energy storage and charge storage was discussed.

Selective preparation of light aromatic hydrocarbons from catalytic fast pyrolysis vapors of coal tar asphaltene over transition metal ion modified zeolites

The catalytic cracking of coal tar asphaltene (CTA) pyrolysis vapors was carried out over transition metalion modified zeolites to promote the generation of light aromatic hydrocarbons (L-ArHs) in a pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) micro-reactor system. The effects of ultra stable Y (USY), Co/USY and Mo/USY on the selectivity and yield of L-ArHs products and the extent of deoxygenation ( E deoxygenation ), lightweight ( E lightweight ) from CTA pyrolysis volatiles were investigated. Results showed that the yields of L-ArHs are mainly controlled by the acid sites and specific surface area of the catalysts, while the deoxygenation effect is determined by theirs pore size. The E lightweight of CTA pyrolysis volatiles over USY is 9.65%, while the E deoxygenation of CTA pyrolysis volatiles over Mo/USY reaches 20.85%. Additionally, the modified zeolites (Mo/USY and Co/USY) exhibit better performance than USY on L-ArHs production, owing to the synergistic effect of metal ions (Mo, Co) and acid sites of USY. Compared with the non-catalytic fast pyrolysis of CTA, the total yield of L-ArHs obtained over USY (4032 mg∙kg −1 ), Co/USY (4363 mg∙kg −1 ) and Mo/USY (4953 mg∙kg −1 ) were increased by 27.03%, 38.19% and 54.78%, respectively. Furthermore, the possible catalytic conversion mechanism of transition metal ion (Co and Mo) modified zeolites was proposed based on the distribution of products and the characterizations of catalysts.

Evaluation and comparison of thermodynamic and kinetic parameters for oxidation and pyrolysis of Yarega heavy crude oil asphaltenes

The processes of pyrolysis in atmosphere of nitrogen and oxidation in air were compared for asphaltenes extracted from Yarega heavy crude oil and its atmospheric and vacuum residues. Thermogravimetry, differential scanning calorimetry and kinetic studies were applied to estimate kinetic parameters of the asphaltenes samples. Different stages of pyrolysis and oxidation were determined and their temperatures were estimated. The steps of pyrolysis and oxidation obtained through different methods were compared. The asphaltenes from atmospheric residue and heavy parent oil showed two pyrolysis stages. Only one stage was distinguished for vacuum residue asphaltenes. Three stages were described for oxidation process. The values of rate of mass loss, heat flow, heat consumption and activation energy were calculated for conversion stages. Data from conversion studies was interpreted through physical processes. The obtained results can contribute to the development of methods for asphaltenes processing in petroleum refineries.

Identification and Implications of Trimethyl-n-Alkylbenzenes in Marine Oils from the Deep Tarim Basin

The source of marine oils from the deep Tarim Basin is still in debate due to several alteration processes of source indicators. A series of trimethyl-alkylbenzenes has been detected in marine oils from this old, composite basin, besides the reported aryl isoprenoids with 2,3,6-trimethyl substitution (AIPs). They are characterized by regular gas chromatography elution pattern, which is similar to that of n-alkylbenzenes, and suggest a strong possibility of n-alkyl side chains. C15 trimethyl-n-alkylbenzenes were synthesized by Friedel–Crafts acylation of trimethylbenzene isomers to determine their structures. Based on the chromatography and mass spectra data and the coinjection of synthesized compounds, this series of compounds has been assigned as the 2,4,5-trimethyl-n-alkylbenzenes that coeluted with 2,3,5-trimethyl-n-alkylbenzenes, and other trimethyl-n-alkylbenzene isomers were also detected. This series of trimethyl-n-alkylbenzene (AAs) shows much higher relative abundances in light and waxy oils than in normal and heavy oils, which is opposite to the variation in relative abundances of aryl isoprenoids. The ratios of these trimethyl-n-alkylbenzenes to the aryl isoprenoids (AA/AIP ratio) generally show a good correlation with the maturity indicators for most of studied oils despite of some outliers (mainly condensates). The pyrolysis of asphaltenes has confirmed these trends. These results support an important control of thermal stress on the molecular compositions of marine oils from the deep Tarim Basin, besides other secondary alteration processes (such as oil mixing and migration fractionation, among others). These factors should be given a full consideration for the source determination of deep and ultradeep oils.

Pyrolysis of Asphaltenes Derived from Residual Oils and Their Thermally Treated Pitch.

Thermogravimetric analysis (TGA) was employed to investigate the thermal stability of asphaltenes at different environments (inert and oxidizing atmosphere) and identify their refractory nature. TGA and differential scanning calorimetry were carried out at a temperature range of 50–700 °C, for asphaltene samples obtained from atmospheric residues, vacuum residues (VRs), and aromatic petroleum pitch samples, which were obtained from the cracking of VRs at different temperatures. The TGA results clearly indicate that thermal degradation of asphaltene takes place in a single process that starts around 350 °C and ends at 500 °C, giving ash contents of less than 2%. The derivatives of the TGA for the asphaltene samples suggest that the weight loss of composite material took place in two steps. The first step corresponds to the degradation of aliphatic side chains or easily oxidized hydrocarbons, while the second step corresponds to the degradation of the aromatic sheets or the stacked layers. TGA of asphaltenes in oxidizing atmosphere showed considerable changes in heat flow due to the destructive oxidation of the asphaltene molecular structure. The thermal stability or refractory nature of these asphaltenes have been calculated as heat of energy or enthalpy of the molecule, which corresponds to the π–π interaction between the aromatic ring, hydrogen bonding, and alkyl chain size of the asphaltene molecule.

Characteristics of gaseous hydrocarbons generated from asphaltene pyrolysis and the geochemical significance

ABSTRACTIn order to study the mechanism of gas generation from the asphaltene, the thermal pyrolysis simulation experiment of the asphaltene is carried out by using high temperature and high pressure closed system. During asphaltene pyrolysis, the amount of methane is constantly increased but those of ethane, propane, and butane + pentane are all first increased and then decreased and eventually go to zero with the increase of the experiment temperature. And the dynamic parameters of gaseous hydrocarbon generation can be used to analyze the dynamic procedure of the asphaltene pyrolysis at the geological scale. The experimental results can perfect the theory of the origin of natural gas and provide an evidence for source judgment and resource evaluation of natural gas in marine strata in China.

Thermal Analysis Coupled to Ultrahigh Resolution Mass Spectrometry with Collision Induced Dissociation for Complex Petroleum Samples: Heavy Oil Composition and Asphaltene Precipitation Effects

Thermal desorption and pyrolysis of various heavy oils and asphaltenes (precipitated with different paraffinic solvents) were studied. For this purpose evolved gas analysis was realized by hyphenation of a thermobalance to ultrahigh-resolution mass spectrometry (FT-ICR MS). The chemical pattern was preserved by applying soft atmospheric pressure chemical ionization (APCI). Collision induced dissociation (CID) was performed for deeper structural insights. Viscous or solid petroleum samples and fractions can be easily measured by the setup. The SARA fractions (maltenes, C7-asphaltenes, aromatics, saturated, and resins), deployed for evaluation purposes, revealed a very complex molecular pattern, and fractionation drastically increased the number of assigned elemental compositions. Species from m/z 150 to m/z 700 and two main phases (desorption and pyrolysis), which transits at roughly 300–350 °C, are observed. Both phases overlap partially but can be separated by applying matrix factorization. The heavy oil...

Sources of organic matter in the Eocene Maoming oil shale in SE China as shown by stepwise pyrolysis of asphaltene

Eocene Maoming oil shale was extracted and the precipitated asphaltene was subjected to stepwise pyrolysis carried out in seven temperature steps from 310°C to 610°C at 50°C intervals. The pyrolyzate at 310°C included n-alkanes and botryococcanes in a distribution similar to the extractable lipids. Long chain n-alkanols, fatty acids (FAs) and C29 steroids were also relatively abundant. The pyrolyzate released at 360°C was comparable with that at 310°C, but had a relatively high content of a steradiene (C29 Δ3,5-steradiene) and several C29 unsaturated steroid ketones derived from the pyrolysis of sterols by loss of –OH and –H. FAs were not present in the pyrolyzate at 410°C. Among the steroid ketones, the diones made a greater contribution, indicating that these ketones were formed as secondary products during the pyrolysis. A full suite of aliphatic hydrocarbons made its first appearance at 460°C, but steroid ketones still dominated the pyrogram. Prist-1-ene, which is frequently detected in the pyrolysis of geological macromolecules, was only a minor component, as were four unknown isomers tentatively labelled as monounsaturated C15 isoprenoid ketones. The pyrolyzates at 510 and 560°C were dominated by n-alkene/n-alkane doublets which had a bimodal distribution and carbon numbers up to C37 (at 510°C). Only trace amounts of n-alkene/n-alkane doublets were produced from the 610°C pyrolysis step. The results show that stepwise pyrolysis can be a fast overview tool for studying components of the asphaltene fraction and can provide useful information on the sources of organic matter (OM) in the oil shale, including polar molecules such as sterols, ketones, and fatty acids. An obvious advantage is the avoidance of complicated pre-treatments before detection using gas chromatography-mass spectrometry (GC–MS). The data confirm the importance of algal OM in the Maoming oil shale as well as the terrigenous plant contribution.

D/H ratio analysis of pyrolysis-released n-alkanes from asphaltenes for correlating oils from different sources

When oil has been greatly altered by severe biodegradation, asphaltene pyrolysis is commonly conducted to obtain intact n-alkanes for carbon isotope analysis, through which oil source characterization and oil–oil correlations can be performed. The ratio of hydrogen isotopes deuterium and hydrogen (D/H ratio) in the individual n-alkanes of oil maltenes has been shown to indicate differences between the depositional environments of the oil sources. The utility of the D/H ratio analysis of n-alkanes from the asphaltene pyrolysis for oil correlation need to be demonstrated. In this study, 18 asphaltene samples from different sources were collected and isothermally pyrolyzed in sealed gold tubes. Effects of the pyrolysis temperature were first illustrated for molecular ratios of alkanes and aromatic compounds and for D/H ratios of pyrolysis-yielded n-alkanes. In the case of n-alkanes in oil maltenes being unavailable for analysis after severe biodegradation, the D/H ratio range of the n-alkanes from the asphaltene pyrolysis was found to be consistent both in normal and biodegraded oils from the same source, indicating that biodegradation has had little effect on their hydrogen isotope signatures. In addition, n-alkanes yielded by asphaltenes from different sources possess clearly different D/H ratios, enabling n-alkane correlation between maltenes that are otherwise very similar. However, relatively large differences of D/H ratios can exist between n-alkanes in the asphaltene pyrolyzates and in maltenes, once the oil was altered by oil mixing formed at different maturity levels. The proposed method is thus helpful in oil–oil correlation for significantly biodegraded oil and oil from a mixed origin.

Pyrolysis of Asphaltenes in Subcritical and Supercritical Water: Influence of H-Donation from Hydrocarbon Surroundings

The pyrolysis of asphaltenes under hydrothermal environments covering the subcritical and supercritical regions of water was applied, and the influence of the presence of H-donors was surveyed by a reaction kinetics analysis based on the lumping approach. Under hydrothermal environments, the pyrolysis of asphaltenes consisting mainly of condensation to coke and decomposition to maltenes is significantly faster than that under a N2 environment. The H-donors introduced, decalin or maltenes, may provide nonaromatic H atoms, capping the carbon radicals essential to pyrolysis. Accordingly, the apparent activation energies of the condensation and the decomposition of asphaltenes both increase to varying degrees. The pyrolysis of asphaltenes in the presence of a small quantity of decalin is seriously retarded in subcritical water but recovers rapidly in supercritical water owning to the promoted initiation efficiency at high temperature. Accompanied by a large amount of maltenes, the decomposition to maltenes in...

Single Particle Asphaltene Pyrolysis in a Drop-Tube Furnace

Oil sands in the Athabasca and Cold Lake regions of Northern Alberta form Canada’s primary source of energy reserves. Asphaltenes, a significant part of bitumen, are often considered to be the least valuable component of crude oil due to various factors such as difficulty in transporting and processing. Very few studies have been carried out on the pyrolysis of asphaltenes in entrained flow conditions. Single particle investigations are useful since they are conducted in a well-controlled environment allowing for the elimination of complexities arising from particle–particle interactions. Char is an intermediate of the gasification process, and the structural and morphological behavior of char plays a pivotal role in determining the rate of gasification. In this work, the pyrolysis of pulverized asphaltene feedstock was carried out in a tube furnace maintained at atmospheric pressure. The effects of furnace temperature and particle size on char formation and char characteristics were investigated. Chars o...

Carbon isotope analyses of n-alkanes released from rapid pyrolysis of oil asphaltenes in a closed system.

Carbon isotope analysis of n-alkanes produced by the pyrolysis of oil asphaltenes is a useful tool for characterizing and correlating oil sources. Low-temperature (320-350°C) pyrolysis lasting 2-3days is usually employed in such studies. Establishing a rapid pyrolysis method is necessary to reduce the time taken for the pretreatment process in isotope analyses. One asphaltene sample was pyrolyzed in sealed ampoules for different durations (60-120s) at 610°C. The δ(13) C values of the pyrolysates were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The molecular characteristics and isotopic signatures of the pyrolysates were investigated for the different pyrolysis durations and compared with results obtained using the normal pyrolysis method, to determine the optimum time interval. Several asphaltene samples derived from various sources were analyzed using this method. The asphaltene pyrolysates of each sample were similar to those obtained by the flash pyrolysis method on similar samples. However, the molecular characteristics of the pyrolysates obtained over durations longer than 90s showed intensified secondary reactions. The carbon isotopic signatures of individual compounds obtained at pyrolysis durations less than 90s were consistent with those obtained from typical low-temperature pyrolysis. Several asphaltene samples from various sources released n-alkanes with distinct carbon isotopic signatures. This easy-to-use pyrolysis method, combined with a subsequent purification procedure, can be used to rapidly obtain clean n-alkanes from oil asphaltenes. Carbon isotopic signatures of n-alkanes released from oil asphaltenes from different sources demonstrate the potential application of this method in 'oil-oil' and 'oil-source' correlations. Copyright © 2016 John Wiley & Sons, Ltd.

Particle-scale modeling of asphaltene pyrolysis in thermal plasma

Thermal plasma technique is proposed as a potential approach to pyrolyze asphaltenes to useful chemicals at ultrahigh temperature. Thermal plasma pyrolysis experiments show that acetylene is the major gaseous product with concentration up to 45wt.%, together with some hydrogen and methane as well as the solids residue as by-products. To predict such a millisecond process, a particle-scale heat transfer model coupled with a modified competition kinetic model has been proposed, in which the heat exchange between the plasma gas and the particles as well as the heat transfer inside the particles are taken into account. Typical results indicate that the pyrolysis temperature would remarkably increase the heating rate. The heating rate would exceed 107K/s at 2000K in H2 thermal plasma and the devolatilization process would complete in 0.4ms for 50μm asphaltene particles, H2 thermal plasma provides better heating exchange efficiency between the plasma and particles than He, N2 or Ar. Linear relationship is found between the heating rate and the devolatilization time under bi-logarithm coordinates at a certain temperature, regardless of the plasma gas compositions and pulverized sub-millimeter particle size, which gives powerful guidance for process optimization of the asphaltene pyrolysis.

Distribution of Vanadium, Nickel, and Other Trace Metals in Soot and Char from Asphaltene Pyrolysis and Gasification

Vanadium (V) and nickel (Ni) are the most abundant and troublesome metals present in oil sands. During upgrading of the oil sand bitumen, these metals become concentrated in the heavier fraction asphaltenes. Any thermochemical conversion of asphaltene causes the release of these trace metals, and their distribution in the products poses concerns with toxicity, corrosion, and fouling. The pyrolysis, partial oxidation, and steam gasification experiments of asphaltene were carried out in an electrically heated atmospheric entrained-flow reactor, and the products char and soot are analyzed for the trace metal content. It is observed that the main metals present in the char and soot are V and Ni. During pyrolysis, with an increase in the temperature, the quantity of V and Ni present in char decreases as a result of the increased liberation into the gas phase. However, more liberated V and Ni were not captured by soot formed in the same experiment. During partial oxidation of asphaltenes, an increase in the sto...

Kinetic modeling of deoiled asphaltene particle pyrolysis in thermogravimetric analysis

The pyrolysis behavior of deoiled asphaltene particles was experimentally studied by thermogravimetric analysis. Considering that the activation energy would change with the evolution of pyrolysis reactions, a modified competition model was proposed to appropriately describe the pyrolysis kinetics. The model parameters were fitted with experimental results. Compared with the original two-stage model, the modified competition model showed the capability of predicting the asphaltene pyrolysis at various heating conditions using fixed kinetic parameters. The results exhibited that the modified competition model can well simulate the asphaltene pyrolysis in the main mass loss temperature range from 500 to 900 K as well as the slow decomposition at the temperatures greater than 900 K during the devolatilization process of asphaltene particles at hundred micrometer size. The modified competition model was further coupled with a heat transfer model at particle scale, including the heat exchange between the particle and the surrounding atmosphere as well as the heat transfer inside the particle. It is found that during the thermogravimetric analysis, the particle surface temperature was close to that of atmosphere, and the heat transfer effect inside the particle could be ignored for hundred-micron-sized particles. However, the temperature gradient inside particles should be considered for millimeter-sized particles. Thus, the particle samples should be sieved to hundred micron sized or smaller when studying the basic pyrolysis behaviors in order to acquire kinetic parameters for asphaltene pyrolysis by thermogravimetric analysis.

Intra- and inter-field compositional changes of oils from the Misoa B4 reservoir in the Ceuta Southeast Area (Lake Maracaibo, Venezuela)

Here we analyzed oil samples from 35 wells in the Ceuta Southeast Area (Lake Maracaibo Basin, northwestern Venezuela) in order to evaluate lateral intra-reservoir continuity in the Misoa B4 unit. Biomarkers, isotopic signature, and also V and Ni were examined using gas chromatography–mass spectrometry (GC–MS), isotope ratio mass spectrometry (IRMS), and inductively-coupled plasma atomic emission spectroscopy (ICP-AES). Multivariate statistical analysis was also applied to obtain useful information from geochemical data. On the basis of the characterization of these samples, we conclude that they all fall into various oil families derived from two pulses of hydrocarbon generation, migration and accumulation from the calcareous La Luna source rock, deposited in an anoxic marine environment under reducing conditions. Thus, these oils are a mixture of an earlier biodegraded, less mature oil charge and a later fresh non-biodegraded oil recharge. In addition, we applied asphaltene pyrolysis to one (LG-62) of the three “anomalous” oils. The LG-62 sample was confirmed as an almost “pure” paleobiodegraded end-member, whereas the VLF-3020 oil was tentatively classified as the unaltered end-member oil-type. Finally, the GC fingerprints and Fourier Transform Infra Red (FTIR) spectroscopic indices of the oils were used to detect minor variations in composition that are indicative of reservoir compartmentalization.

Analysis of Soot Formed during the Pyrolysis of Athabasca Oil Sand Asphaltenes

Asphaltenes are formed during the primary upgrading process of bitumen. Gasification is considered as a good option for conversion of the low-value asphaltenes into syngas. Syngas can later be used in the generation of steam for steam-assisted gravity drainage, and the hydrogen from the syngas can be used for upgrading. Understanding the decomposition of asphaltenes, the subsequent formation of soot, and the properties of soot enables optimization of the process of asphaltene gasification. In this work, the effects of feed particle size, temperature, and residence time on the formation of soot particles during the pyrolysis of Athabasca oil sand asphaltenes were investigated. Morphological, structural, and elemental properties of collected soot were also investigated. The experiments were carried out in an atmospheric entrained-flow reactor that was electrically heated to a range of set temperatures between 800 and 1400 °C, and the residence time was varied between 5 to 12 s by controlling the carrier gas nitrogen flow rate. The pyrolysis products were air-cooled in the collection probe after the reactor and passed through a cyclone to separate out particles larger than 10 μm. The particles smaller than 10 μm were subsequently passed through a cascade impactor for segregation of soot and ash particles in the size range from 0.03 to 3 μm. It was found that asphaltenes devolatilize to produce char, light gases, and tar. The different feed particle size ranges used in this study had a negligible effect on the analyzed properties of the soot. The yield of soot formed increased with the pyrolysis temperature. It was observed that the average size of primary soot particles decreases with an increase in temperature. The sulfur and hydrogen contents of soot decrease with temperature as a result of the liberation of sulfur as hydrogen sulfide during the pyrolysis reactions. With increasing residence time, the average size of the primary soot particles increases.

The temporal variation of asphaltene structure during Raman crude oil pyrolysis

In this study, the investigation of pyrolysis reactions of heavy oil was aimed. Heavy oil that was provided from Raman field in the southeastern part of Turkey to use in our study, was subjected to pyrolysis at temperatures of 350, 400 and 450°C for holding times ranging from 10 to 120min using sand bath. Product fractions were separated as gas, maltene, light maltene, asphaltene and coke. The time and temperature dependence of product distributions were determined. Molecular structure of asphaltenes are characterized by elemental analysis, proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC). The effect of the heavy oil environment on the asphaltene pyrolysis was also investigated in this study.