Knowledge of petroleum heavy residue potential as feedstock in refining process using thermogravimetry

In the petroleum industry, previous knowledge of the feedstock's potential to produce light material is an important aspect of refining. For the evaluation of heavy petroleum fractions, thermogravimetry (TG), a thermal analysis technique, is considered a good analytical tool to determine the thermal behavior of these fractions at high temperatures. In the present work, TG analyses were made of petroleum distillation residues from different Brazilian oils. The apparent cracking activation energy of saturates, aromatics, resins and asphaltenes was also determined by TG. Saturates and aromatics showed values of 80-120 kJmol^− 1 at low conversions (< 0.3) and of 120-220 kJ mol^− 1 at high conversions (> 0.3). The thermal cracking activation energy of resins and asphaltenes occurred between 220-300 kJ mol^− 1, i.e., at higher values than those of aromatic and saturated fractions. This paper discusses the prediction of carbonaceous residue based on thermal analysis.     

Pyrolysis kinetics of atmospheric residue and its SARA fractions

Thermal analysis of atmospheric residue from heavy crude oil and its SARA fractions was carried out and the tendency of each fraction toward coke formation was determined. The coke yield was 16.3 wt.% for atmospheric residue, 43.1 wt.% for asphaltenes, 4.6 wt.% for resins, 3.8 wt.% for aromatics, and 0.3 wt.% for saturates. Pyrolysis kinetics of residue and its fractions, i.e., asphaltenes, resins and aromatics was also investigated. The TG experiments were conducted at three different heating rates of 8, 12, and 16 °C/min from room temperature up to 800 °C under nitrogen atmosphere to verify the weight variation with reaction temperature. Isoconversional analysis to fit data assuming first order kinetics was employed. Asphaltenes was the fraction that produces coke in higher amount having a range of activation energy of 41.0–58.6 kcal mol⁻¹ whereas activation energy for atmospheric residue ranged from 11.5 to 30.0 kcal mol⁻¹.     

Transformation of petroleum asphaltenes in supercritical water

The transformation of petroleum asphaltenes in supercritical water was studied. The experiments were performed in autoclave at temperature 380 °C and pressure 226 atm with stirring for 3 h, medium density was about 0.33 g/cm³. The reaction resulted in the formation of gas products, about 4.3%, and an insoluble residue (coke) with about 48.6% yield. The remaining products were separated into fractions by consecutive dissolution in hexane (30.0%), benzene (10.6%), and chloroform (5.7%). The properties of the obtained products were studied with FT-IR spectrometry and ¹H NMR spectroscopy. The method of simulated distillation was used to demonstrate that the fractional composition of the hexane-soluble part of the products is close to the fractional composition of a mixture of the diesel fraction and vacuum gas oil of the corresponding oil in 1:1 ratio. The obtained data support the conclusion that asphaltene cracking proceeds in SCW, with most probable main processes being dealkylation of substituents in the aromatic fragments of molecules and aromatization. This leads to formation of gaseous products and hexane-soluble fraction consisting of lighter aliphatic and aromatic compounds, as well as carbonized solid residue.     

Kinetics of asphaltene thermal cracking and catalytic hydrocracking

A pentane-insoluble asphaltene was processed by thermal cracking and catalytic hydrocracking over NiMo/γ-Al₂O₃ in a microbatch reactor at 430 °C. Kinetic analysis shows that the first-order kinetics fits the data of conversion in reaction times ≤ 30 min approximately, but deviates from the data of times over 30 min significantly; whereas the second-order kinetics fits the data of the reaction times up to 60 min adequately, to give the apparent rate constants of 1.704 × 10⁻² and 9.360 × 10⁻² wt frac⁻¹min⁻¹ for the two cracking processes. Furthermore, a three-lump kinetic model is proposed to include parallel reactions of asphaltenes to produce liquid oil (k₁) and gas + coke (k₃), and consecutive reaction from liquid to gas + coke (k₂). The evaluated value of k₁ is 1.697 × 10⁻² and 9.355 × 10⁻² wt frac⁻¹min⁻¹, k₂ is 3.605 × 10⁻² and 6.347 × 10⁻³ min⁻¹ , and k₃ is 6.934 × 10⁻⁵ and 4.803 × 10⁻⁵ wt frac⁻¹min⁻¹ for asphaltenes thermal cracking and catalytic hydrocracking, respectively. Selectivity analysis shows that the catalytic hydrocracking process promotes liquid production and inhibits coke formation effectively.     

Kinetics and selectivity of asphaltene hydrocracking

Thermal hydrocracking and catalytic hydrocracking over NiMo/γ-Al₂O₃ of a pentane-insoluble asphaltene were conducted in a microbatch reactor at 430 °C. The experimental data of asphaltene conversion fit second-order kinetics adequately, to give the apparent rate constants of 2.435 × 10⁻² and 9.360 × 10⁻² wt frac⁻¹ min⁻¹ for the two processes respectively. A three-lump kinetic model is proposed to evaluate rate constants of parallel reactions from asphaltenes to liquid oil (k₁) and to gas + coke (k₃), and consecutive reaction from liquid to gas + coke (k₂). The evaluated k₁ is 2.430 × 10⁻² and 9.355 × 10⁻² wt frac⁻¹ min⁻¹, k₂ is 2.426 × 10⁻² and 6.347 × 10⁻³ min⁻¹, and k₃ is 5.416 × 10⁻⁵ and 4.803 × 10⁻⁵ wt frac⁻¹ min⁻¹ for asphaltenes hydrocracking in the presence or absence of the catalyst, respectively. Analysis of selectivity shows that the catalytic hydrocracking process promotes liquid production and inhibits coke formation effectively.     

Studies on thermal cracking behavior of residual feedstocks in a batch reactor

Thermal cracking of residual fractions has gained interest of refiners due to increasing demand of middle distillates and at the same time decline in demand of fuel oils. The present study is an attempt to gain deeper insight into the thermal cracking behavior of residual feedstocks in terms of certain key characteristics. Laboratory scale experiments on a 400 ml capacity stainless steel batch reactor were conducted with four residual feedstocks of Indian and Middle East origin—North Gujarat short residue (NGSR), Visbreaker feed from Mathura refinery (MVBF), Bombay High short residue (BHSR) and Asphalt from Haldia refinery (HRA), with asphaltene content varying in the range 1.85-10.15 wt%. The cracked products were separated by distillation up to 500 ^°C. The distillate (500 ^°C-) was analyzed by ASTM D2887 (SIMDIST) method and obtained data were classified into lumps, namely Gas (C₅-), Gasoline (IBP-150 ^°C), Light Gas Oil (150-350 ^°C) and Vacuum Gas Oil (350-500 ^°C) prior to detailed data analysis. The analysis of results reveals that the thermal cracking of petroleum residues follows first order kinetics. The rate constants and activation energies have also been estimated.     

Kinetics of catalytic steam gasification of bitumen coke

The catalytic steam gasification of coke from Athabasca bitumen was investigated by thermogravimetric analysis using K₂CO₃ and Na₂CO₃ as catalysts, both of which reduced the activation energy of the reaction considerably to 1.2 × 10⁵ J mol⁻¹ and 1.3 × 10⁵ J mol⁻¹, respectively, down from 2.1 × 10⁵ J mol⁻¹ for the uncatalyzed reaction. The reaction rates varied with the partial pressure of steam between 60 kPa and 85 kPa consistent with a Langmuir-Hinshelwood model, but a first order equation was also sufficient given the low partial pressures. The initial rate of gasification of the coke particles correlated linearly with the estimated external surface area of the particles, as expected from a surface reaction involving a non-porous solid. The initial reaction rate increased with increasing the catalyst loading up to 2.4 (mol potassium)/kg. A portion of the catalyst penetrated into the coke, as confirmed by secondary ion mass spectroscopy analysis, where it could not promote the reaction with steam. This result was consistent with a small increase observed in the reaction rate at low catalyst loading. The shrinking core model was successful in predicting the rates at higher conversions from the initial rate data, despite increases in BET surface area with conversion.     

Hydroconversion characteristics and kinetics of residue narrow fractions

Chinese Dagang atmospheric residue, Arabian light and medium vacuum residues were subjected to supercritical fluid extraction and fractionation (SFEF). Each residue was fractionated into eight narrow extractable fractions with increasing molecular weight (MW) and polarity, and a non-extractable end-cut. Catalytic hydroprocessing of residue SFEF fractions were carried out in a 100 ml autoclave in the presence of two crushed, commercial Ni-Mo catalysts.Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactivities decreased as the MW and/or aromaticity of residue fraction increased. Decreased HDS and HDN reactivities were due to increased diffusion resistance and decreased intrinsic reactivity, respectively. Even though the properties of residues varied, coke yield, sulfur and nitrogen removal data for all SFEF fractions correlated well with the recently proposed feedstock characteristic index, K_H. Sulfur and nitrogen removals for SFEF fractions with K_H value less than 6, were comparable to those in thermal cracking. The heavy fractions, especially the end-cut, inhibit catalytic reactivity of the light fractions. As a result, use of the bulk sample analysis for the whole residue is misleading to determine the reactivity of residue. The SFEF end-cut was the most refractory fraction of the residue, which had a much higher coking propensity than all the SFEF fractions. Product gas yields were similar for all SFEF fractions, except for the end-cut which was 50% higher. As the SFEF fractions became heavier, the coke yield increased at the expense of light and middle distillate yields. The performance of two commercial catalysts was similar.     

Crystallization of triplet alkalies (Li,K, Na)-containing fluorrichterite glasses

Crystallization characteristics of glasses based on fluoramphibole containing three alkalies were investigated. The thermal behaviour of the glass samples was studied using DTA and their heat-treated samples were characterized by XRD and SEM. Fluorophlogopite, tainiolite, fluorrichterite, roedderite, enstatite and cristobalite phases were developed in the heat-treated glasses. The high Li-containing sample shows modification of the crystalline phases and the phase transformation at each DTA exotherm. Dominance of fluorophlogopite or fluorrichterite was detected in high K- and Na-containing samples respectively with enstatite as well. Crystallization at high temperature lowered the cristobalite phase in the high alkali-content glasses, whereas all samples showed formation of roedderite and enstatite on long duration heat-treatments. The microstructure of the glass–ceramic samples tends to be fine in the case of equal triplet alkalies (Li, K, Na)- and Na-containing samples whereas it became coarse in the high K-content samples. However, it was nonhomogeneous because of dendritic growths in the high Li-content ones. The coefficient of thermal expansion of glasses showed moderate values of 76–89 × 10⁻⁷ °C⁻¹ (20–300 °C). However, in the corresponding glass–ceramics, and with exception of the highest Li-content glass–ceramic (72–78 × 10⁻⁷ °C⁻¹), these were relatively high especially for samples of highest K- and Na-contents (83–119 × 10⁻⁷ °C⁻¹). The density of the glass–ceramic samples (2.821–2.641 gm/cm³) decreased in the order GNKL > GN > GK > GL > Grich.     

Influence of asphaltenes on coke formation during the thermal cracking of different Brazilian distillation residues

This research was conducted to allow the investigation on the influence of asphaltenes on coke formation, during the thermal cracking of atmospheric distillation residues, using thermogravimetry. Asphaltenes of five refinery atmospheric distillation residues, of different API gravity Brazilian crude oils, were isolated by the IP143 methodology. The original samples and the same samples, after asphaltenes extraction, were analyzed by thermogravimetry. It was observed that the heavier the sample, the higher was the contribution of the asphaltenes to the coke formation. The extracted asphaltenes were analyzed under the same TG conditions of the atmospheric distillation residues and all asphaltenes appeared to form approximately the same amount of carbonaceous residue after the thermal cracking. Heavier and lighter atmospheric distillation residues were doped with 10%, 20% and 30% amount of asphaltenes and, again, the higher the asphaltenes amount, the higher would be the carbonaceous material formation. The same tendency was observed for both doped samples.     

Synergetic effects of Y-zeolite and amorphous silica-alumina as main FCC catalyst components on triisopropylbenzene cracking and coke formation

The synergetic effects of HY-zeolite and silica-alumina (SA), as two major components of an FCC catalyst, on the cracking activity and coking tendency during catalytic cracking of 1,3,5-triisopropylbenzene (TiPB, as a resid representative) were studied. NaY-zeolite and SA were synthesized by hydrothermal and co-precipitation methods, respectively, and ammonium exchanged for three times at 80 °C. The catalysts were characterized by XRD, XRF, SEM, BET, AAS and ammonia TPD techniques. TiPB cracking was investigated on four different catalyst configurations including SA, Y-zeolite, SA.Y and SA-Y in a fixed bed reactor. SA.Y stands for physical mixture of equal amounts of Y-zeolite and SA. For SA-Y, a bed of SA was placed upstream of the same amount of Y-zeolite. The catalysts were in-situ activated at 475 °C and evaluated by TiPB cracking at 350 °C. The coke content of the catalyst beds, after 40 min cracking of TiPB, was estimated by TPO using an FT-IR gas cell. At 3 min time on stream, 5.2 times higher yield of benzene, as a deep cracking product, is observed on SA-Y as compared to SA.Y. The TiPB conversion decreases in the order of SA-Y > SA.Y > Y-zeolite ? SA. Furthermore, as compared to Y-zeolite, 24% lower coke is formed on SA-Y. Also CO evolution during TPO of coked SA-Y catalyst is about 24% lower than that of the coked zeolite. As a result, protecting of Y-zeolite by SA from direct exposure to resid feed enhances the cracking activity, decreases the tendency to coke formation and diminishes CO emission in the catalyst regeneration process.     

Laboratory-scale coal reactivity testing for entrained gasification

A relatively simple and rapid micro-gasification test has been developed for measuring gasification reactivities of carbonaceous materials under conditions which are more or less representative of an entrained gasification process, such as the Shell coal gasification process. Coal particles of < 100 μm are heated within a few seconds to a predetermined temperature level of 1000–2000 °C, which is subsequently maintained. Gasification is carried out with either CO₂ or H₂O. It is shown that gasification reactivity increases with decreasing coal rank. The CO₂ and H₂O gasification reactions of lignite, bituminous coal and fluid petroleum coke are probably controlled by diffusion at temperatures 1300–1400 °C. Below these temperatures, the CO₂ gasification reaction has an activation energy of about 100 kJ mol^?1 for lignite and 220–230 kJ mol^?1 for bituminous coals and fluid petroleum coke. The activation energies for H₂O gasification are about 100 kJ mol^?1 for lignite, 290–360 kJ mol^?1 for bituminous coals and about 200 kJ mol^?1 for fluid petroleum coke. Relative ranking of feedstocks with the micro-gasification test is in general agreement with 6 t/d plant results.     

Study of mullite formation in porcelain stoneware applying isoconversional and IKP methods

The growth process of mullite in a porcelain stoneware body has been studied under isoconversional, isokinetic relationship and invariant kinetic parameters. Activation energy for mullite crystallisation of over 589–628 kJ mol⁻¹ and a Ln A over 50–59 min⁻¹ was obtained. The model was Johnson–Melh–Avrami with n = 1.5. The model chosen implies quick nucleation and subsequent one or three-dimensional growth. Isoconversional methods show an independent activation energy variation in mid range conversion degrees. Lower and higher conversion degrees show different reactions in mullite formation. Results obtained with the methods employed here are in agreement with a previous paper where the Kissinger non-isothermal method and Ligero et al. approximation were applied.     

Thermal cracking and combustion kinetics of asphaltenes derived from Fosterton oil

Thermal behavior of crude oil (Fosterton) asphaltenes mixed with reservoir sand was investigated using thermogravimetric analysis (TGA), in nitrogen and air atmospheres for different heating rates up to 800 °C. In this study, four sets of TGA runs were performed to examine the thermal behavior of Fosterton asphaltenes and the coke derived from the asphaltenes. The parameters studied were heating rate (10, 15 and 20 °C min^− 1) and the type of purge gas (N₂ and air) employed for the process of thermal degradation of asphaltenes. Distributed activation energy model (DAEM) has been applied to study the asphaltene pyrolysis kinetics. It was observed that the activation energy was distributed from 46.16 to 72.17 kJ/mol, for the conversion range of 0.1 to 0.4. The general model for nth order reaction was used to obtain the kinetic parameters of coke oxidation reaction from the TGA data. From the model, the calculated activation energy, E, was 93.46 kJ/mol and the pre-exponential factor was 9.59 × 10⁵ min^− 1 for the coke combustion. The apparent order of combustion reaction gradually increased from 0.7 to 0.8 for different temperatures.     

Removal of Zn(II) from aqueous solution with natural Chinese loess: Behaviors and affecting factors

The Chinese loess was proved a promising adsorbent for Zn(II) removal from aqueous solution with adsorption capacities at 70.2-83.2 mg g^− 1 at 15-45 °C. Batch tests were conducted to evaluate the factors affecting the removal efficiency, of which the pH, temperature and initial Zn concentration all found in positive relevance to the increase of Zn(II) removal efficiency except for the slurry concentration. The uptake of Zn(II) on Chinese loess was considered as ion-exchange adsorption based on the calculated adsorption energy at − 12.8 to − 16.18 kJ mol^− 1 by D-R isothermal adsorption model. The adsorption kinetics follows the pseudo-second-order kinetics and the equilibrating duration was found to be > 24 h. Thermodynamic investigation shows that the enthalpy and entropy changes during adsorption are in the range of 18.27-47.83 kJ mol^− 1 and 52.7-129.6 J mol^− 1 K^− 1, respectively. The predicted Gibb's free energies were in the range of − 5.97-3.09 kJ mol^− 1, indicating that the adsorption was in favor of higher temperature and lower initial Zn(II) concentration. The optimal Zn(II) removal efficiency could be obtained under the following conditions: low or intermediate Zn(II) concentration, long reaction time, high temperature and initial pH > 3.0.     

Possible CO2 mitigation via addition of charcoal to coking coal blends

Processes involving biomass oxidation are considered to be CO₂ neutral since the replenishing of the biomass by normal growth will remove CO₂ from the atmosphere. Thus the use of charcoal in the production of metallurgical coke, to be used as a reducing agent in the formation of iron, would be a strategy for the reduction of CO₂ in the overall ironmaking process. This paper describes experimental attempts to produce industrial grade coke from coking coal blends to which are added amounts of charcoal up to 10%. Coking experiments were carried out partly in a 30 lb coke oven and partly in a sole heated oven. The influence of blend composition, heating rates and charcoal particle size was investigated. Cokes made using fine charcoal addition (− 60 mesh) were considerably weaker than cokes made from the base blend. This is interpreted to be the effect of the ash constituents in the charcoal which, among other things, contains much higher calcium than the coals used. However, carefully sized fractions of coarse charcoal (− 3/8 + 1/4 in) produced much higher quality coke, possibly the result of a different dispersion of the charcoal mineral components.     

Study of the preasphaltenes of coal liquefaction and its hydro-conversion kinetics catalyzed by SO4/ZrO2

The investigation of hydro-conversion behavior of the heavy intermediate products derived from coal direct liquefaction is advantageous to optimize the technological conditions of direct coal liquefaction and improve the oil yield. In this paper, the hydro-conversion of preasphaltenes catalyzed by SO₄²⁻/ZrO₂ solid acid was investigated based on the structural characterization of preasphaltenes and its hydro-conversion products, and the determination of products distribution and the kinetics of preasphaltenes hydro-conversion. The results indicated that the content of condensed aromatic rings increased, and the contents of hydrogen, oxygen and aliphatic side chains of preasphaltenes decreased with the increase of coal liquefaction temperature. The preasphaltenes showed higher hydro-conversion reactivity while SO₄²⁻/ZrO₂ solid acid was used as catalyst. Higher temperature and longer time were in favor of increasing the conversion and the oil + gas yield. The conversion of preasphaltenes hydro-conversion under 425 °C, for 40 min reached 81.3% with 51.2% oil + gas yield. SO₄²⁻/ZrO₂ solid acid was in favor of the catalytic cracking rather than the catalytic hydrogenation in the hydro-conversion of preasphaltenes. The activation energy of preasphaltenes conversion into asphaltenes was 72 kJ/mol. The regressive reactions were only observed at a higher temperature.     

Vanadium of petroleum asphaltenes and source kerogens (La Luna Formation, Venezuela): isotopic study and origin

High-resolution mass spectrometry indicates that the isotopic abundance of ⁵⁰vanadium (V) of the Late Cretaceous La Luna petroleum asphaltenes and related source kerogens of marine origin (both highly enriched with V>2000 ppm) is higher by about 3.5% than that of inorganic source (VOSO₄·5H₂O, Merck). Similar results are obtained with the isotopic analysis of the asphaltenes (containing high V) extracted from the floating asphalts (Dead Sea, Israel). We propose that the difference in the ⁵⁰V/⁵¹V values between the La Luna petroleum asphaltenes/source kerogens and inorganic source can be best ascribed to the biological processing of the seawater V. The fact that the isotopic composition of V of the vary over a very narrow range (2.46-2.52) suggests an essentially same (or similar) and fixed (micro)biological source of V. Isotopic analysis was also extended to the methanol-soluble fractions of the La Luna asphaltic petroleums (DM-119/-120/-124) highly enriched with extractable (alkyl) vanadyl-porphyrins (VO²⁺-P). This analysis shows that the isotopic abundance of ⁵⁰V for the methanol-soluble fractions agrees (within the limits of experimental error) with those of the asphaltenes/kerogens.     

Thermodynamics,kinetics, and isotherms studies for gold(III) adsorption using silica functionalized by diethylenetriaminemethylenephosphonic acid

A novel hybrid material silica gel chemically modified by diethylenetriaminemethylenephosphonic acid GH-D-P has been developed and characterized. The results of the adsorption thermodynamics and kinetics of the as-synthesized GH-D-P for Au(III) showed that this high efficient inorganic–organic hybrid adsorbent had good adsorption capacity for Au(III), and the best interpretation for the experimental data was given by the Langmuir isotherm equation, the maximum adsorption capacity for Au(III) is 357.14 mg/g at 35 °C. Moreover, the study indicated the adsorption kinetics of GH-D-P could be modeled by the pseudo-second-order rate equation wonderfully, and the adsorption thermodynamic parameters ΔG, ΔH and ΔS were −20.43 kJ mol⁻¹, 9.17 kJ mol⁻¹, and 96.24 J K⁻¹ mol⁻¹, respectively. Therefore, the high adsorption capacity make this hybrid material have significant potential for Au(III) uptake from aqueous solutions using adsorption method.     

Corrosion protection of sol–gel coatings doped with an organic corrosion inhibitor: Chloranil

Hybrid sol–gel films have been prepared with diethoxydimethylsilane (DEODMS), methyltriethoxysilane (MTEOS) as a source of hydrolysable silane and tetra-propoxyzirconium (TPOZ) as a source of hydrolysable zirconium. In order to improve corrosion protection, an organic corrosion inhibitor: tetrachloro-p-benzoquinone (chloranil), has been incorporated into the sol–gel matrix. The effect of chloranil, added with various concentrations from 3 to 12 × 10⁻⁴ M, on the sol–gel film morphology and composition has been examined by atomic force microscopy (AFM) and glow discharge optical emission spectroscopy (GDOES), respectively. Addition of high additive concentrations (>9 × 10⁻⁴ M) strongly disorganised the sol–gel network. The anticorrosion properties of the doped sol–gel films have been characterised by electrochemical impedance spectroscopy (EIS) in chloride solution and have been compared to salt spray observations. Chloranil additions (<9 × 10⁻⁴ M) have significantly increased the corrosion protection of the sol–gel layers for a long term.