An experimental and modeling study of vacuum residue upgrading in supercritical water

Arabian Heavy crude oil was fractionated into distillate and vacuum residue fractions. The vacuum residue fraction was treated with supercritical water (SCW) at 450°C in a batch reactor for 15–90 min. The main products were gas, coke, and upgraded vacuum residue; the upgraded residue consisted of gasoline, diesel, and vacuum gas oil range components. The molecular composition of gas and upgraded vacuum residue was analyzed using gas chromatography (GC, GC × GC). SCW treatment converted higher carbon number aliphatics (≥C₂₁) and long‐chain (≥C₅) alkyl aromatic compounds into C₁?C₂₀ aliphatics, C₁?C₁₀ alkylaromatics, and multiringed species. The concentrations of gasoline and diesel range compounds were greater in the upgraded product, compared to the feed. A first‐order, five lump reaction network was developed to fit the yields of gas, coke, diesel, and gasoline range components obtained from SCW upgrading of vacuum residue. Distillation of crude oil followed by SCW treatment of the heavy fraction approximately doubled the yield of chemicals, gasoline, and diesel, while forming significantly less coke than conventional upgrading methods. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1732–1743, 2018     

Catalytic conversion of canola oil to fuels and chemical feedstocks Part I. Effect of process conditions on the performance of HZSM-5 catalyst

The conversion of canola oil to hydrocarbons using a shape selective zeolite catalyst is reported in this work. Canola oil was passed over HZSM-5 catalyst in a fixed bed micro-reactor and the effects of reaction temperature and oil space velocity on the conversion and selectivity were studied using a statistical experimental design. The results show that 60–95 wt% of the canola oil can be converted to hydrocarbons in the gasoline boiling range, light gases and water. The gasoline fraction contained 60–70 wt% of aromatic hydrocarbons and the gases were mostly C₃ and C₄ paraffins. Furthermore, the spent catalyst could be regenerated completely at 600°C in 1 h with dry air.     

Degradation of waste High-density polyethylene into fuel oil using basic catalyst

High-density polyethylene (HDPE) has been degraded thermally and catalytically using MgCO₃ at 450 °C into liquid fraction in a batch reactor. Different conditions like temperature, time and catalyst ratio were optimized for the maximum conversion of HDPE into liquid fraction. Catalytic degradation yielded 92% liquid fraction whereas 90% wax was obtained with thermal degradation. The composition of the liquid fraction was characterized by physicochemical properties of petroleum fuel tests. The catalytic liquid fraction consisted of high concentration of C₈-C₉, C₁₃-C₁₄ and C₁₇-C₁₈ hydrocarbons. The distillation data showed that ∼50% of the fraction has boiling point in the range of gasoline and ∼50% in the range of diesel oil.     

Modeling and optimization of Fischer–Tropsch products hydrocracking

The hydrocracking behavior the product of a Fischer–Tropsch synthesis consisting of a C₄–C₃₀ mixture of paraffins and olefins on a platinum/amorphous silica–alumina catalyst has been analyzed and optimized. The influence of temperature on the selectiveness of the hydrocracking has been investigated. Time and temperature optimization was performed in order to obtain the best operating conditions for the enhancement of gasoline and diesel cuts. This work presents a mathematical model of the tubular reactor used in hydrocracking the heavy hydrocarbon fraction produced by the Fischer–Tropsch synthesis. The system was studied to optimize the operating conditions as to produce the highest amounts of diesel and/or gasoline. The hydrocarbon product distribution changes during hydrocracking were modeled considering a commercial bifunctional catalyst. The model was validated with data reported in the literature and has presented a satisfactory fitting to the experimental data with a confidence level of 95%. The production of specific cuts such as diesel and gasoline was optimized after the model has been validated. The results showed that lower temperatures (550 K) favor the cracking of heavy hydrocarbons chains into diesel and higher temperatures (650 K) favor a more effective cracking generating higher amounts of gasoline.     

Catalytic dehydromethylation of methylcyclohexane and the simultaneous transformation of fractions of straight-run gasoline and methanol with modified forms of mordenite and pentasil

Results are presented from studies of the dehydromethylation (DHM) of methylcyclohexane (MCH) and the simultaneous transformation of straight-run gasoline fractions and methanol on modified forms of mordenite and pentasil in the presence of various hydrogen acceptors (O₂, CO₂). High selectivity on xylene isomers is observed for polycationic modifications of HNa-TsVM. On such catalytic systems, the degrees of DHM and dehydrodisproportionation (DHD) of MCH grow with an increase in O₂-to-CO₂ ratio in the range of 0.05 : (1–1.5), while the degree of its dehydrogenation to toluene is virtually constant. High yields of di- and trimethylbenzenes are achieved in the reactions between methanol and gasoline fractions composed mainly of C₇–C₈ hydrocarbons at 100–140 °C. The results from this study can be used for straight-run gasoline reforming with the aim of increasing the yield of C₈-C₉ aromatic hydrocarbons.     

Constitution of tars from the flash pyrolysis of Australian coals: 1. Separation

Separation of the maltene fraction of Millmerran flash-pyrolysis coal tar by ion-exchange and adsorption chromatography produced coal-tar resins, aromatic hydrocarbons (AH) and an alkane/alkene fraction. The coal-tar resins comprise acid, base, neutral and polyfunctional fractions. Derivatives of benzene and naphthalene are the main volatile constituents of the AH fraction, while the alkane/alkene fraction consists mainly of straight-chain hydrocarbons from C₁₀ to C₃₄ and small amounts of isoprenoid hydrocarbons, steranes and triterpanes. Fuller's Earth, used in the separation of the maltenes, suffers from the disadvantage of irreversibly adsorbing organic material.     

Synthetic diesel fuel produced from coal

The characteristics of synthetic diesel fuel are analyzed. The fuel consists of hydrocarbons C₃–C₃₂; the content of the middle fractions is 83.26 wt %. The IR spectrum of the synthetic diesel fuel contains deformational vibrations corresponding to paraffins and unsaturated hydrocarbons, as well as aromatic and heteroaromatic compounds. Synthetic fuel produced from coal is recommended as a raw material for DTZ commercial diesel fuel, suitable for use in winter.     

Semicoking of Kansko-Achinsk lignite and applications of tar fractions

The semicoking of regular lignite from the Berezovsk field in Kansko-Achinsk Basin (moisture content 1.6–19.6 wt %) at 450–550°C in a reactor with solid heat carrier is studied. The products are semicoke (up to 68.1%), tar (up to 9.5%), gas (up to 31.9%), and pyrogenetic water. The composition of the semicoking gas is quantitatively determined. Its main components are hydrogen (up to 71.7%) and methane (up to 17.2%). The heat of combustion of the semicoking gas is 12.39–16.25 MJ/m³. The yield of phenolic fractions in the semicoking tar, consisting of phenol and its alkyl derivatives with one or two short substituents (C₁–C₃), is 10.5–14.6%. After hydraulic purification of the gasoline fraction in the semicoking tar (below 180°C), gasoline with octane rating 75.8 (by the motor method) is obtained. It consists of aromatic, saturated, and unsaturated hydrocarbons (C₅–C₈). The diesel fuel derived from tar fractions distilled off at temperatures up to 350°C are of good quality, except for their low cetane rating. The high-boiling tar fractions may be used to produce lignite pitch and pitch coke. The semicoke obtained is a very effective reducing agent in the production of phosphorus. It may also be used as a lean additive in coking batch and as a component in enriched domestic coal briquets.     

Intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by redistribution of hydrogen between the units

The dehydrogenation and dewaxing of hydrocarbons of middle-distillate fractions, which proceed in the hydrogen medium, are of great importance in the petrochemical and oil refining industries. They increase oil refining depth and allow producing gasoline, kerosene, and diesel fractions used in the production of hydrocarbon fuels, polymer materials, synthetic detergents, rubbers, etc. Herewith, in the process of dehydrogenation of hydrocarbons of middle distillate fractions (C₉–C₁₄) hydrogen is formed in the reactions between hydrocarbons, and the excess of hydrogen slows the target reaction of olefin formation and causes the shift of thermodynamic equilibrium to the initial substances. Meanwhile, in the process of hydrodewaxing of hydrocarbons of middle distillate fractions (C₅–C₂₇), conversely, hydrogen is a required reagent in the target reaction of hydrocracking of long-chain paraffins, which ensures required feedstock conversion for production of low-freezing diesel fuels. Therefore, in this study we suggest the approach of intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by means of redistribution of hydrogen between the two units on the base of the influence of hydrogen on the hydrocarbon transformations using mathematical models. In this study we found that with increasing the temperature from 470 °C to 490 °C and decreasing the hydrogen/feedstock molar ratio in the range of 8.5/1.0 to 6.0/1.0 in the dehydrogenation reactor, the production of olefins increased by 1.45–1.55%wt, which makes it possible to reduce hydrogen consumption by 25,000 Nm³/h. Involvement of this additionally available hydrogen in the amount from 10,000 to 50,000 Nm³/h in the dewaxing reactor allows increasing the depth of hydrocracking of long-chain paraffins of middle distillate fractions, and, consequently improving low-temperature properties of produced diesel fraction. In such a way cloud temperature and freezing temperature of produced diesel fraction decrease by 1–4 °C and 10–25 °C (at the temperature of 300 °C and 340 °C respectively). However, when the molar ratio hydrogen/hydrocarbons decreases from 8.5/1.0 to 6.0/1.0 the yield of side products in the dehydrogenation reactor increases: the yield of diolefins increases by 0.1–0.15%wt, the yield of coke increases by 0.07–0.18%wt depending on the feedstock composition, which is due to decrease in the content of hydrogen, which hydrogenates intermediate products of condensation (the coke of amorphous structure). This effect can be compensated by additional water supply in the dehydrogenation reactor, which oxidizes the intermediate products of condensation, preventing catalyst deactivation by coke. The calculations with the use of the model showed that at the supply of water by increasing portions simultaneously with temperature rise, the content of coke on the catalyst by the end of the production cycle comprises 1.25–1.56%wt depending on the feedstock composition, which is by 0.3–0.6%wt lower that in the regime without water supply.     

Performance studies of various cracking catalysts in the conversion of canola oil to fuels and chemicals in a fluidized-bed reactor

Studies were conducted at atmospheric pressure at temperatures in the range of 400–500°C and fluidizing gas velocities in the range of 0.37–0.58 m/min (at standard temperature and pressure) to evaluate the performance of various cracking catalysts for canola oil conversion in a fluidized-bed reactor. Results show that canola oil conversions were high (in the range of 78–98 wt%) and increased with an increase in both temperature and catalyst acid site density and with a decrease in fluidizing gas velocity. The product distribution mostly consisted of hydrocarbon gases in the C₁–C₅ range, a mixture of aromatic and aliphatic hydrocarbons in the organic liquid product (OLP) and coke. The yields of C₄ hydrocarbons, aromatic hydrocarbons and C₂–C₄ olefins increased with both temperature and catalyst acid site density but decreased with an increase in fluidizing gas velocity. In contrast, the yields of aliphatic and C₅ hydrocarbons followed trends completely opposite to those of C₂–C₄ olefins and aromatic hydrocarbons. A comparison of performance of the catalysts in a fluidized-bed reactor with earlier work in a fixed-bed reactor showed that selectivities for formation of both C₅ and iso-C₄ hydrocarbons in a fluidized-bed reactor were extremely high (maximum of 68.7 and 18 wt% of the gas product) as compared to maximum selectivities of 18 and 16 wt% of the gas product, respectively, in the fixed-bed reactor. Also, selectivity for formation of gas products was higher for runs with the fluidized-bed reactor than for those with the fixed-bed reactor, whereas the selectivity for OLP was higher with the fixed-bed reactor. Furthermore, both temperature and catalyst determined whether the fractions of aromatic hydrocarbons in the OLP were higher in the fluidized-bed or fixed-bed reactor.     

Identification of large polycyclic aromatic hydrocarbons in carbon particulates formed in a fuel-rich premixed ethylene flame

Large polycyclic aromatic hydrocarbons were identified in carbon particulate sampled in a fuel-rich premixed ethylene flame. The particulate was extracted with dichloromethane (DCM) in order to separate the soluble organic species (DCM-extract) from the solid carbon (soot). After DCM extraction soot was re-extracted with N-methyl pyrrolidone (NMP) obtaining the NMP-extract. Both the DCM-extract and NMP-extract were further fractionated by size exclusion chromatography in selected molecular weight (MW) ranges. Large polycyclic aromatic hydrocarbons obtained by regular incorporation of C₂ and/or C₂H₂ unit (24/26 rule) occurring in both odd and even series of carbon atom number of polycyclic aromatic hydrocarbons, were identified by laser desorption ionization–mass spectrometry (LDI–MS) analysis of the lighter MW fractions of both the DCM-extract and NMP-extract (100–400 u MW of the DCM-extract and 200–600 u fractions of the NMP-extract). The LDI–MS spectra of the heaviest MW fractions of DCM-extract and NMP-extract (600–2000 u and 600–5000 u fraction) showed a continuous spectrum of masses typical of polymeric structures. The UV–visible absorption and emission spectral analysis corroborated the assignment of lighter and of heavier fractions of DCM-extract and NMP-extract to PAH and to polymeric aromatic structures, respectively.     

Neutral lipids from the temporal gland of the African elephant,Loxodonta africana

Lipids from inactive and active temporal glands of the African elephant,Loxodonta africana, were isolated and fractionated. The inactive gland had a much higher total lipid content per gram of fresh tissue than the active gland. Lipids from the inactive gland consisted predominantly of neutral lipids while the active gland contained large quantities of phospholipids. Neutral lipids from the active gland contained much more hydrocarbons, cholesterol, and alkoxy glycerides than neutral lipids from an inactive gland. The alkoxy glyceride fraction did not contain any alkenyl glycerides. The hydrocarbons consisted of a mixture containing predominantly straight chain even numbered saturated and unsaturated hydrocarbons from C₁₈–C₃₀. Fatty acids from various fractions were investigated by gas liquid chromatography. Those from the active gland were characterized by a higher percentage of unsaturated acids. The change, from inactive to the active state involves mainly a reduction in palmitic and an increase in oleic acid content.     

Evaluation of two different scrap tires as hydrocarbon source by pyrolysis

The main objective of the present study is to investigate the effect of the polymer types in scrap tires on the pyrolysis products. Two different types of scrap tires (passenger car tire, PCT and truck tire, TT) have been pyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under N₂ atmosphere. Pyrolysis products (gas, oil and carbon black) obtained from PCT and TT were investigated comparatively. The gaseous products were analyzed by GC–TCD. The psychical and chemical properties of pyrolytic oils were characterized by means of GC–FID, GC–MS, ¹H NMR. In addition, boiling point distributions of hydrocarbons in pyrolytic oils were determined by using simulated distillation curves in comparison with commercial diesel fuel. The production of activated carbon from pyrolytic carbon blacks (CBp) was also carried out. The composition of gaseous products from pyrolysis of PCT and TT were similar and they contained mainly hydrocarbons (C₁–C₄). Pyrolytic oils were found lighter than diesel but heavier than naphtha. The physical properties of pyrolytic oils from PCT and TT were similar at the same temperature. However, the composition of aromatic and sulphur content from pyrolysis of PCT was higher than that of TT. Furthermore, TT derived pyrolytic carbon black was found more suitable for the production of activated carbon due to its low ash content.     

More unsaturated,cooking-type hydrocarbon-like organic aerosol particle emissions from renewable diesel compared to ultra low sulfur diesel in at-sea operations of a research vessel

The aerosol particle emissions from R/V Robert Gordon Sproul were measured during two 5-day research cruises (29 September–3 October 2014; 4–7 and 26–28 September 2015) at four engine speeds (1600 rpm, 1300 rpm, 1000 rpm, and 700 rpm) to characterize the emissions under different engine conditions for ultra low sulfur diesel (ULSD) and hydrogenation derived renewable diesel (HDRD) fuels. Organic aerosol composition and mass distribution were measured on the aft deck of the vessel directly behind the exhaust stack to intercept the ship plume. The ship emissions for both fuels were composed of alkane-like compounds (H/C = 1.94 ± 0.003, O/C = 0.04 ± 0.001, C_nH_2n) with mass spectral fragmentation patterns consistent with hydrocarbon-like organic aerosol (HOA). Single-particle mass spectra from emissions for both fuels showed two distinct HOA compositions, with one HOA type containing more saturated alkane fragments (C_nH_2n+1) and the other HOA type containing more monounsaturated fragments (C_nH_2n?1). The particles dominated by the C_nH_2n?1 fragment series are similar to mass spectra previously associated with cooking emissions. More cooking-type organic particles were observed in the ship emissions for HDRD than for ULSD (45% and 38%, respectively). Changes in the plume aerosol composition due to photochemical aging in the atmosphere were also characterized. The higher fraction of alkene or aromatic (C_nH_2n?m, m ≥ 3) fragments in aged compared to fresh plume emissions suggest that some of the semivolatile alkane-like components partition back to the vapor phase as dilution increases, while alkene or aromatic hydrocarbons contribute more mass to the particle phase due to continuing photochemical oxidation and subsequent condensation from the vapor phase.

Copyright © 2017 American Association for Aerosol Research     

Differential thermal analysis,thermal gravimetric analysis,and solid phase micro-extraction gas chromatography analysis of water and fuel absorption in diesel soot

An experimental investigation was conducted to analyze the absorption characteristics of deposited diesel soot by differential thermal analysis, thermal gravimetric analysis, and solid phase micro-extraction gas chromatography analysis. The results showed that dry diesel soot contained 2–3%w (percent by weight) of water and a maximum of 5%w hydrocarbons. Water wetted soot contained up to 40%w water, while diesel wetted soot contained up to 60%w hydrocarbons. The hydrocarbons extracted from the soot were primarily hydrocarbons higher than C₁₂H₂₆ with little evidence of lighter hydrocarbons.     

Four-lump kinetic model for fluid catalytic cracking process

In the fluid catalytic cracking reactor heavy gas oil is cracked into more valuable lighter hydrocarbon products. The reactor input is a mixture of hydrocarbons which makes the reaction kinetics very complicated due to the involved reactions. In this paper, a four-lump model is proposed to describe the process. This model is different from others mainly in that the deposition rate of coke on catalyst can be predicted from gas oil conversion and isolated from the C₁–C₄ gas yield. This is important since coke supplies heat required for endothermic reactions occurring in the reactor. By this model we can also conclude that the C1–C4 gas yield increases with increasing reactor temperature, while production of gasoline and coke decreases.     

Group structure characteristics of the liquid thermolysis products of vitrinites of different ranks

The results of the group structure analysis of asphaltenes, resins, and hydrocarbons in the liquid products obtained upon the thermolysis of vitrinites of different ranks are presented. The molecular weights of components decreased with the degree of vitrinite conversion: aromatic structures were predominant among ring compounds, and the lengths of alkyl substituents decreased. The molecules of asphaltenes predominantly consisted of two-block structures, whereas tars and oils mainly exhibited a single-block organization; in all cases, the alkyl substituents of aromatic rings had a length of C₁–C₄.     

Determination of paraffin and aromatic hydrocarbon type chemicals in liquid distillates produced from the pyrolysis process of waste plastics by isotope-dilution mass spectrometry

Isotope dilution mass spectrometry was developed for the determination of composition of paraffins, olefins, naphthenes and aromatics in distilled oil produced from the pyrolysis reaction of mixed waste plastics using labeled hydrocarbon internal standards including octane-d₁₈, dodecane-d₂₆, hexadecane-d₃₄, benzene-d₆, toluene-d₈, ethylbenzene-d₁₀, 1,3,5-trimethylbenzene-d₁₂ and naphthalene-d₈. This technique made it possible to thoroughly quantify more than three hundred peaks in plastic-derived pyrolysis oil, classify pyrolysis oil into four hydrocarbon groups of paraffin, olefin, naphthene and aromatic, and determine the weight percent of each hydrocarbon group simultaneously. Compared with commercially available petroleum oil, distilled plastic-derived pyrolysis oil contained much more aromatics amounting to 60-82 wt% of whole hydrocarbons. Toluene (C7-benzene) and trimethylbenzenes (C9-benzenes) were the predominant species amounting to 40-50% of whole hydrocarbons in pyrolysis oil with a gasoline range boiling point and 25-35% of whole hydrocarbons in pyrolysis oil with a diesel range boiling point, respectively.     

Paraffinic hydrocarbon composition of earthworms (Lumbricus terrestris)

The paraffinic hydrocarbon fraction of the lipids extracted from earthworms (Lumbricus terrestris) contains ca. 88%n-alkanes and 12% branched alkanes and other hydrocarbons. Then-alkanes range from C₁₃ through C₃₃, and their most interesting feature is the even-over-odd carbon number predominance in the C₁₃−C₂₄ range. The nonnormal hydrocarbons consist primarily of monomethyl-substituted alkanes. Other hydrocarbons that have been identified include the C₁₆. C₁₈, C₁₉ and C₂₀ isoprenoids and the C₁₈, C₂₀ and C₂₂ n-alkylcyclohexanes.     

Analysis of coal-derived liquid obtained by mild hydrogenation: 1. Neutral oil distilling at 186–343 °C

Taiheiyo coal (77% C) was hydrogenated under mild conditions to preserve the unit structure of the parent coal as far as possible. The n-hexane-solubles (yield, 49.8 wt% daf coal) were washed with acid and base and the neutral material separated into 7 fractions by vacuum distillation. The three lower boiling fractions, DS01 (7.3 wt% neutral oil), DS02 (3.6 wt%) and DS03 (4.8 wt%), were further separated by liquid chromatography into hydrocarbon subfractions which were analysed by g.c. and g.c.-m.s. Saturates are most abundant, especially the n-alkanes which comprise ≈9–13 wt% of each fraction. The saturates also contain isoprenoids (C₁₅, C₁₆, C₁₈, C₁₉ and C₂₀), branched alkanes, n-alkyl cyclohexanes, terpanes and others. With increasing boiling point, smaller amounts of monoaromatic ring hydrocarbons and more di- or triaromatic ring hydrocarbons are found. The alkyl side-chains of aromatic nuclei have a large carbon number, especially in the smaller rings. The existence of phenyltetralin or phenylnaphthalene shows a feature of bonding between aromatic nuclei.