Chemical Reaction Engineering Studies on Cocracking of Petroleum Vacuum Residue with Coal, Plastics, and Biomass (Bagasse and Petrocrop)

In our previous article, Ahmaruzzaman and Sharma (2007), the cracking of petroleum vacuum residue (XVR) and its coprocessing with thermoplastic and biomass (Calotropis procera) has been discussed. This article deals with the studies on cocracking of XVR with thermosetting plastic, i.e., bakelite (BL), Samla coal (SC), biomass, i.e., bagasse (BG) or C. procera (CL) and their binary, ternary, and quaternary mixtures in a thermogravimetric analyzer (TGA). The kinetic studies were performed using the Coats and Redfern kinetic modeling equation. The overall activation energies obtained were 25 kJ/mole for petroleum vacuum residue, 99 kJ/mole for polypropylene, 21 kJ/mole for coal, 23 kJ/mole for Calotropis procera, and 25 kJ/mole for the combination of these four materials. However, other models, such as van Krevelan et al. and Horowitz and Metzger have also been used in some cases to compare the results with those obtained by the Coats and Redfern kinetic models. In the present work, the effect of catalysts on the cracking of Basra vacuum residue (BVR) has also been reported.     

True Boiling Point Extended Curve of Vacuum Residue Through Molecular Distillation

Molecular distillation is a separation process that explores high vacuum, operation at reduced temperatures, and low exposition of the material at the operating temperature. The term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent temperature (AET) above 540°C. For the assay of the properties of petroleum and petroleum products, the use of the true boiling point (TBP) distillation analysis is accepted as a common practice; however, for heavy petroleum fractions, some difficulties appear for determination of TBP of these petroleum fractions. The objective of this work is to develop a new and a more appropriated method to extend the TBP curve to use it for characterizing vacuum residue of heavy petroleum. The falling film molecular distillator was used. The results showed that it is possible to extend the TBP curve through molecular distillation process with very good precision.     

Thermal Hydrocracking Kinetics of Chinese Gudao Vacuum Residue

The thermal hydrocracking kinetics of Chinese Gudao vacuum residue was studied in a batch autoclave reactor. The temperature ranged in 390-435°C and the initial hydrogen pressure was 7.0 MPa at 20°C. Ammonium phosphomolybdate (APM) in its dispersed phase was the catalyst. The reaction products, gas, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and coke, were separated during and after experiments, and their yields vs. reaction time were obtained, for four reaction temperatures: 390, 405, 420, and 435°C. The activation energy was calculated from a traditional kinetic model to be 218.6 kJ/mol. A new kinetic model was proposed in this work that allows for the calculation of activation energy with a minimum number of three tests, each at a different temperature. This is comparable to the traditional model which requires a minimum of 12 tests; a minimum of four tests for one temperature and a minimum of three temperatures. The activation energy calculated from the new model with four tests is 229.6 kJ/mol, only 5% greater than that obtained from the traditional model. The reaction rate constants obtained from this model are also consistent with those from the traditional model.     

DETERMINATION OF ORGANIC SULFUR COMPOUND TYPES IN VACUUM GAS OILS USING GC-FID-SCD METHOD

The analyses of individual organic sulfur compounds in petroleum distillates are the key to understanding the kinetics of the chemistry involved in hydrodesulfurization, HDS. A sample of vacuum gas oil (VGO) produced commercially by distillation of treated atmospheric residue was analyzed by GC-FID-SCD method for individual organic sulfur compounds characterization and quantification. Dibenzothiophene and benzonaphthothiophene and their alkyl derivatives were found to constitute almost the entire organic sulfur compound range present in the VGO. Using a relationship between the total sulfur determined by “X-ray” and “Coulomax” methods and the composition of individual sulfur compounds determined by SCD, the quantity of those organic sulfur compounds present in VGO was estimated. Despite the limit in temperature raise (325°C) in the capillary column and that the range studied (346-555°C) is higher than those limits, optimum conditions were chosen to overcome those obstacles. From the analyses the behavior of refractory and unrefractory sulfur compounds in the VGO region can now be followed easily.     

Evaluation of Atmospheric and Vacuum Residues Using Molecular Distillation and Optimization

The term atmospheric residue describes the material at the bottom of the atmospheric distillation tower having a lower boiling point limit of about 340°C; the term vacuum residue (heavy petroleum fractions) refers to the bottom of the vacuum distillation, which has an atmospheric equivalent boiling point (AEBP) above 540°C. In this work, the objective is to evaluate the behavior of different kinds of Brazilian atmospheric and vacuum residues using molecular distillation. The Falling Film Molecular Distillator was used. For the results obtained through this process, a significant range of temperature can be explored avoiding the thermal decomposition of the material. So these results are very important to the refinery decisions and improvements. The Experimental Factorial Design results showed that the temperature has more influence on the process than the feed flow rate, when a higher percentage of distillate is required.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal-derived slurry oil at 90 bar initial pressure for temperatures of 380-460^° C and residence time of 15-60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂-pressure of 60-150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂-pressure of 90-150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂-pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

委内瑞拉减压渣油的热解特性及其动力学研究

采用热重 质谱(TG-MS)联用对委内瑞拉减压渣油在不同升温速率下进行热解实验,研究其热解反应特性,并采用3种等转化率法和分布活化能模型(DEAM)求取减压渣油热解反应的动力学参数。实验结果表明,委内瑞拉减压渣油的热解主要反应温度区间为179~490 ℃,总质量损失率为77.54%,质量损失峰值在446 ℃达到最大,最大质量损失速率为317.38μg/min。Flynn-Wall-Ozawa(FWO)法比其他2种等转化率法能更好地描述减压渣油的热解过程,由其计算得到的热解活化能为56.77~178.91 kJ/mol。进一步采用DEAM模型将减压渣油分为4个假定组分,对升温速率为10 ℃/min条件下的热重分析(TG-DTG)数据进行分峰拟合,求得饱和分、芳香分、胶质和沥青质四组分动力学参数,并据此获得减压渣油总活化能分布曲线。结果表明,委内瑞拉减压渣油活化能主要集中在100~250 kJ/mol范围内,通过加权求和获得平均活化能为190.11 kJ/mol。     

AN EVALUATION OF OIL PRODUCED FROM ASPHALT RID (UTAH) TAB SAND AS A FEEDSTOCK FOR THE PRODUCTION OF ASPHALT AND TURBINE FUELS

In this article an evaluation is made of the potential end uses of an oil produced from Asphalt Ridge tar sand by wet forward combustion. The oil is evaluated with respect to its potential to produce a specification-grade asphalt and aviation turbine fuels. To accomplish this the oil was vacuum distilled to produce a distillate and a residue. The distillation residue meets all of the ASTM D 3381 Table 1 specification tests for an AC-10 asphalt. However, the viscosity at 135°C (275°F) is low when compared with the more stringent D 3381 Table 2 requirements. This indicates that the residue has a higher temperature susceptibility than allowed for by Table 2. The residue also has an unusually low aging index. This indicates that it may not set properly. However, it may also mean that it may be resistant to rapid age hardening. The results from successive freeze-thaw cycling indicate that the residue, when coated on appropriate aggregates, is comparable to or better than some petroleum asphalts coated on the same aggregates. Freeze-thaw cycling to failure is an indirect measure of the resistance of an asphalt-aggregate mixture to moisture-induced loss of strength

The distillate of the thermally-produced oil which represents about 50 wt % of the whole oil was also evaluated as a feedstock for the production of transportation fuels. The chemical and physical properties of the distillate are improved with respect to those of the original bitumen and the thermally-produced oil. Combined gas chromatographic/mass spectral analysis of the neutral fraction from the distillate indicates it is composed of predominantly aromatic structures. The aromatic structures are primarily of the 2- and 3-     

Improved Purification of Petroleum Coke for Grease Lubricants by a Flotation Process

The surface and thermodynamic properties of the anionic surfactant were studied together with its efficiency on being used as a collector in the flotation of petroleum coke. The surface tension of the aqueous solution was measured at 25°C and the surface excess concentration as well as the critical micelle concentration of the mixtures were investigated. There was a good relationship between the adsorption effectiveness of the phase transfer catalyst (cationic) and the efficiency of the collector. A synergistic effect was observed for the phase transfer catalyst and the anionic collector reducing the surface tension of the aqueous solution in the purification of petroleum coke. The results showed the best mole fraction of mixture (anionic/ cationic)which is preferable to be used as the flotation collector. The optimum conditions for purification of petroleum coke were determined so as to acceptably use this coke for the lubricating grease.     

Kinetics of thermolysis of vacuum tower bottoms mixed with pine sawdust

Basic features of thermal degradation of mixtures of vacuum tower bottoms with pine sawdust have been studied by dynamic thermogravimetry. The kinetic parameters of the process have been determined using the integral model-free Ozawa–Flynn–Wall method. The enthalpies and ethropies of activation of the thermal degradation of the vacuum residue, the sawdust, and their mixtures have been calculated on the basis of the transition state theory. It has been shown that pine sawdust and its degradation products have an activity to enhance the kinetic parameters and the rate of thermal degradation of vacuum tower bottoms. It has been found that the E value of thermolysis of the heavy petroleum residue substantially decreases with an increase in the proportion of sawdust in the vacuuum resid to 225.0 kJ/mol for the mixture containing 18.0 wt % pine sawdust at a degree of conversion of the mixture of 0.8.     

A kinetic model for pyrolysis of petroleum residue under nonisothermal conditions

Kinetic study on pyrolysis of petroleum residue was carried out by an accurate Arrhenius type equation at heating rate of 0.5–30.0°C/min under nonisothermal conditions. The influence of some critical parameters including temperature, heating rate and activation energy on mass conversion was evaluated. The apparent activation energies for during the pyrolysis process were in the range of 198–361 kJ/mol at various mass conversions of 5–94%. The reaction temperature was introduced as the most important parameter for the improvement of mass conversion, compared to that of other parameters. The pyrolysis of petroleum residue was occurred in a broad temperature range, from 150–650°C, yielding 33 wt% unpyrolyzed residue. It also was found that an increase in heating rate has a minor impact in the process. Model predictions were compared with experimental data, which showed fully good agreement.     

AN EVALUATION OF ASPHALT RIDGE (UTHA) TAR SAND BITUMEN AS A FEEDSTOCK FOR THE PRODUCTION OF ASPHALT AND TURBINE FUELS

The purpose of this study was two-fold. The first was to produce vacuum distillation residues and determine if their properties met ASTM asphalt specifications. The second was to determine if the distillates could serve as potential feedstocks for the production of aviation turbine fuels. The bitumen used for this study was the oil produced during an in situ steamflood project at the Northwest Asphalt Ridge (Utah) tar sand deposit.

Two distillation residues were produced, one at +316 °C (+600°C)and one at +399°C (+750°F). However, only the lower boiling residue met ASTM specifications, in this case, as an AC-30 asphalt. The original oil sample met specifications as an AC-5 asphalt. These residue samples exhibited some unique properties with respect to aging. It is suggested that the low aging indexes and high flow properties of the samples may be beneficial for pavements that require good low-temperature performance.

Two distillate samples were produced, one at IBP-316°C (IBP-600°F) and one at IBP-399°C (IBP-750°F). The chemical and physical properties of these samples were determined, and it was concluded that both samples appear to be potential feedstocks for the production of conventional and high-density aviation turbine fuels.     

STUDY ON COKING KINETICS OF CHINESE GUDAO VACUUM RESIDUE

Using a molten metal bath as heat source of reaction, the coking kinetics of Gudao vacuum residue in temperature ranges of 400 - 440°C and 460-500°C were studied and kinetic models were developed. The order of reaction, pre-frequency factor and apparent activation energy of thermal-cracking were determined as 1.0, 7.853 × 10¹⁰ min^-1 and 175.3KJ/mol respectively. The results laid a solid foundation for technological computation, reconstruction and design of the tubular furnace using the residuum as its feedstock.     

CHANGE OF PHYSICAL AND THERMAL DECOMPOSITION PROPERTIES OF IN SITU HEAVY OIL WITH STEAM TEMPERATURE

Ikiztepe crude oil was subjected to four different steam temperatures during steam injection which was applied as an enhanced oil recovery process on a linear limestone model saturated with oil. Produced oils were characterized using density, viscosity measurements, pyrolysis experiments utilizing TGA and elemental analysis runs. Results showed that produced crude oils change in measured characteristics as compared to the original oil. These changes include an increase in H/C, and cracking activation energy, decrease in density, viscosity and amount of residue remaining after cracking (coke). Also, decrease in asphaltene amount, changes in the elemental composition of asphaltenes and increase in the cracking activation energies were observed at 225 °C run. These measurements show that the produced oils get lighter and differ compositionally from the original oil as steam temperature increases. Decrease in elemental sulphur amount is one of the major changes when environmental considerations are concerned. Residual oil left in the limestone pack on the other hand shows an increase in the low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO) activation energies as determined from TGA combustion experiments on the samples taken from the pack after steam injection experiments.     

废聚乙烯塑料与减压渣油混合延迟焦化的研究

在实验室将废聚乙烯塑料、减压渣油以及它们的混合物，在反应温度455－495℃、氢气压力0．1－0．4MPa和反应时间2－8h的临氢条件下进行延迟焦化反应。结果表明，由于废聚乙烯焦化的液体产物组成主要为链烷烃和链α－烯烃，占10％的废聚乙烯塑料和减压渣油混合原料的延迟焦化加工过程，可以得到性质较好的焦化柴油馏分。废聚乙烯塑料的加入，还可以减少焦化炉管的生焦，延长装置的运转周期，有望成为回收废塑料减少环境污染的一种途径。     

ISOMERIZATION OF n-HEXANE AND n-PENTANE MIXTURE ON Pt-ALUMINA CATALYST

A mixture of n-hexane and n-pentane (1:1) by volume was isomerized on commercial Pt-alumina catalyst in a continuously fixed-bed reactor at atmospheric pressure. The effect of temperature, LHSV, hydrogen/hydrocarbon molar ratio and chlorine concentration were studied.

It was found that the yield of isohexanes and isopentane increases with increasing the chloride added up to 0.1 and 0.2 mole % CCl₄ respectively. The rate of isomerization became slower at higher concentrations.

Isomerization activity of the catalyst increases with increasing temperature ranging between 350-400°C. The yield of isomers decrease with increasing temperature above 400°C.

The relative conversion of n-hexane in the mixture was found to be more than the conversion of pure n-hexane at the same conditions.     

Kinetic Modeling of Hydrocarbon Conversion to Asphaltenes in Sulphur-treated Asphalts

A study was made of the kinetics of the conversion of the hydrocarbon constituents of residual asphalts to asphaltenes at temperatures of 210-250°C. The reactions occurring led to the manifold increases in the composition of asphaltenes. Kinetic rate parameters were determined at different temperatures and the temperature effect was correlated by Arrhenius dependency. The reaction order was found to vary with temperature, increasing from 1.60 and yielding a maximum order of 4.2 at 250°C, thus confirming other results obtained in the literature. An activation energy of 266.0 kJ/mol was also recorded which is quite lower than 373 kJ/mol reported for the noncatalytic reaction. The overall effect of the catalyst employed was the reduction of the temperature at which maximum asphaltene yield could be obtained.     

THERMAL REACTIVITIES OF SOME TURKISH LIGNITES

A DTA study has been made to investigate the thermal reactivities of five Turkish lignites (Elbistan, Ilgin, Karliova, Xangal, Yatagan) in an air atmosphere. The coal samples exhibited thermal reactivity at temperatures starting from 20 °C and continuing up to 671 °C. Endothermic peaks were observed at the lower end of the temperature range, the highest endothermic peak temperature being 146°C for Elbistan lignite. Exothermic peaks appeared at around 260, 360 and 600 °C. These temperatures are considered to signify the release and combustion of single benzene ring structures and combustion of condensed aromatic rings respectively. Corresponding stages are observed in the TGA traces. After correcting for differences in methodology, the overall heat effects measured by DTA are within greater than 90% of the calorific values of the coal samples determined by bomb calorimetry.     

IR and HNMR Analysis of Asphaltic Materials Present in Some Indian Crude Oils of Gujarat Region

The structure and composition of asphaltic materials present in three crude oils produced from three reservoirs situated at Viraj, North Kadi, and Santhol in north Gujarat region in western India have been studied using IR and HNMR spectroscopy. The asphaltenic substances were obtained by Soxhlet extraction of the 200°C+ residue of each crude oil with n-pentane, n-heptane, petroleum ether (40-60°C), and ethyl acetate, following the standard IP 143/78 method. The variations in chemical nature and composition of all solvent-insoluble asphaltenic components have been discussed. All insolubles constitute mainly highly substituted aromatics having ether linkages, ketone and pyrrolic N-H functions, and large number of methyl and methylene groups in alkyl chain substituents.     

EFFECT OF INTER-MOLECULAR ASSOCIATION ON BITUMEN OXIDATION

The hypothesis that inter-molecular associations between species in petroleum bitumens affects the rate of air oxidation of the bitumens was examined using infrared spectroscopy, gel permeation chromatography and viscosity measurements. Experiments were carried out in which the rate of oxidation of two different bitumens and their fractions (maltenes, resins, asphaltenes) were measured in terms of carbonyl group formation. In THF solution at 30°C the rates of reaction of the maltene and asphaltene fractions were the same when oxidised separately or as a mixture. Although the presence of inter-molecular associations were confirmed by gel permeation chromatography, the results indicated that such effects were unimportant to the rate of the reaction. Further experiments were performed in which neat bitumen, resin and maltene (n-heptane) factors and reconstituted mixtures were oxidised under 2069 kPa of oxygen or air at 40°C or 60°C. Again, no evidence for the effect of inter-molecular association on oxidation rate was obtained. Another experiment in which a bitumen, rejuvenating oil (RO), and a mixture of the two was oxidised (2069 kPa air, 60°C) again showed that the reaction rate of the bitumen and RO were the same when oxidised separately or in the mixture. However, in contrast, the rate of increase of viscosity of the bitumen was significantly affected by the RO and was attributed to dispersal of polar oxidation products by the RO.