Manufacture of aromatic hydrocarbons from coal hydrogenation products

The manufacture of aromatic hydrocarbons from coal distillates was experimentally studied. A flow chart for the production of benzene, ethylbenzene, toluene, and xylenes was designed, which comprised the hydrogen treatment of the total wide-cut (or preliminarily depehenolized) fraction with FBP 425°C; fractional distillation of the hydrotreated products into IBP-60, 60–180, 180–300, and 300–425°C fractions; the hydro-racking of middle fractions for increasing the yield of gasoline fractions whenever necessary; the catalytic reform of the fractions with bp up to 180°C; and the extraction of aromatic hydrocarbons.     

Characterization and utilization of hydrotreated products from the Whiterocks (Utah) tar sand bitumen-derived liquid

The bitumen-derived liquid produced in a fluidized-bed reactor from the Whiterocks tar sand was hydrotreated over a sulphided Ni-Mo/Al₂O₃ hydrodenitrogenation catalyst in a fixed-bed reactor. The process variables studied were temperature (617–680 K), pressure (11.0–17.1 MPa) and liquid hourly space velocity (0.18–0.77 h⁻¹). The feed and the hydrotreated liquid products were analysed by gas chromatography-mass spectrometry analyses. The compounds identified in the bitumen included isoprenoids; bicyclic, tricyclic, and tetracyclic terpenoids; steranes; hopanes; and perhydro-β-carotenes. Normal and branched alkanes and alkenes and partially dehydrogenated hydroaromatics were identified in the bitumen-derived liquid. Comparison of the compounds identified in the bitumen and the bitumen-derived liquid indicated that the dealkylation of long alkyl side chains 0to form - and isoolefins and the cleavage of alkyl chains linking aromatic and hydroaromatic clusters were the dominant pyrolysis reactions. Monoaromatic hydrocarbons were the predominant aromatic species in the hydrotreated product. The properties of the jet fuel fractions from the hydrotreated products met most of the jet fuel specifications. The cetane indices indicated that these fractions would be suitable for use as diesel fuels.     

蒽油加氢转化为轻质燃料油技术研究

综述了煤焦油加氢技术的现状,通过原料分析确定了蒽油加氢的工艺路线。对加氢精制催化剂和加氢改质催化剂进行了选择确定,并考察了反应温度对加氢精制产物的影响及对改质效果的影响,确定了其工艺条件。经此过程,使约97%的蒽油转化为清洁燃料油,其中石脑油馏分收率3.9%,柴油馏分收率93.0%,十六烷值为37.0,加氢改质后质量较仅加氢精制柴油馏分得到大幅提高。     

Upgrading of middle distillate fractions of a syncrude from Athabasca oil sands

Current processes for upgrading bitumen from Athabasca oil sands produce synthetic crudes which are high in aromatics and deficient in hydrogen. As a consequence, middle distillate fractions derived from these syncrudes produce diesel fuels of low cetane number and jet fuels which are hydrogen deficient. Results obtained from bench-scale hydrotreating experiments indicate that quality fuels may be produced from Athabasca syncrudes. Middle distillate fractions from this source were subjected to high-severity hydroprocessing in a continuous-flow reactor unit using conventional hydrotreating catalysts which were pre-sulphided by a mixture of $\text{H}{}_2\text{H}{}_2\text{S}$. Aromatic hydrogenation at high temperatures and pressures was affected by the approach to thermodynamic equilibrium, however, at lower temperatures, in some cases virtually 100% saturation was achieved and treated fractions were found to meet cetane number and jet fuel smoke point requirements. Data treatment in the present study includes a model for the hydrogenation kinetics and correlations between aromatic carbon and fuel combustion properties.     

Aging effects on gasoline-ethanol blend properties and composition

Blends of 75% gasoline and 25% ethanol (E25) are unique fuels used in Brazil. The natural E25 oxidation process due to aging under atmospheric conditions has been investigated. To evaluate aging effects on the properties of commercially available fuel blends, two samples of regular E25, one sample of regular E25 with additives, and one sample of high octane E25 were tested. The samples were analyzed as new and in aging periods of 30 and 180 days. Fuel density, distillation temperatures T₁₀, T₅₀ and T₉₀, motor and research octane number, as well as concentrations of ethanol, oxygen, olefins, total aromatics, benzene and saturates were evaluated. It was observed an increase of fuel density, distillation temperatures, aromatics and oxygen concentration, and a decrease of the concentration of olefins with aging. The results indicate that the use of aged fuel in automotive engines may increase fuel consumption, carbon deposits formation, carbon monoxide and hydrocarbon emissions.     

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.     

Property-composition relationships for diesel and kerosene fuels

A range of 18 diesel fuels and 21 kerosene fuels from mainly Australian petroleum and synthetic fuel sources, including coal, shale and peat, was investigated. Compositional details were defined as the weight per cent abundances of n-alkanes, branched plus cyclic saturates, single-ring aromatics, doublering aromatics and polynuclear aromatics, using both h.p.l.c. and ¹³C n.m.r. techniques. Relationships between fuel composition and a range of fuel properties were sought. Simple linear relationships between property values and compositional data were used. Explicit correlative expressions were derived using multiple linear regression analysis, with the coefficient of multiple determination, R², indicating the quality of the fit between observed and calculated property values. In most cases good correlations were achieved. For diesels the properties investigated, with R² values in parentheses, were: inverse specific gravity (0.99); ¹³C n.m.r. aromaticity (0.99); ¹H n.m.r. aromaticity (0.88); cetane index (0.97); aniline point (0.96); diesel index (0.98); and FIA-measured aromatics content (0.77). For kerosenes the properties, with R² values in parentheses, were: ¹³C n.m.r. aromaticity (0.98); ¹H n.m.r. aromaticity (0.97); smoke point (0.88); and FIA-measured aromatics content (0.94). The results are shown to be of value in assessing the potential and limitations of hydrotreating as a process for upgrading synfuels.     

劣质催化裂化柴油综合利用技术研究进展

催化裂化柴油硫含量高,芳烃含量高,十六烷值低,是较为劣质的柴油组分。通过加氢方法一般可以实现催化裂化柴油的大幅改质,但芳烃加氢饱和对提高中间馏分油的十六烷值有限。催化裂化柴油已成为限制企业柴油质量升级的关键。针对国内外车用柴油质量升级趋势,以劣质催化裂化柴油高值化和清洁化利用为出发点,综述劣质催化裂化柴油综合利用技术的研究进展,分析劣质催化裂化柴油加氢改质后调和柴油的劣势,重点介绍由劣质催化裂化柴油生产低碳芳烃或高辛烷值汽油的工艺技术,提出利用催化裂化柴油富含芳烃的特点,加氢后生产高辛烷值汽油或轻质芳烃是最具竞争力的加工路线。下一步的工作重点是进一步提高现有技术芳烃加氢饱和与侧链断裂选择性,提高低碳芳烃产率,减少低值副产物,使经济效益最大化。     

Structural characterization of Saudi Arabian heavy crude oil by n.m.r. spectroscopy

Saudi Arabian heavy crude oil was separated into six fractions, including five distillate fractions (<93, 93–204, 204–260, 260–343 and 343–454 °C) and a >454 °C distillation residue. Each fraction was analysed by ¹H and ¹³C n.m.r. spectroscopy, and combined gained information from these analyses provided reliable average structural parameters. These included estimation of aliphatic and aromatic content, average paraffinic chain length, and estimation of hydrogen, methyl and alkyl bearing aromatic carbons for each of the six fractions. The extent of branching in paraffinic chains and amount of aromatic bridgehead carbons were also calculated.     

Properties of rapeseed oil for use as a diesel fuel extender

Chemical and thermal analyses were carried out on degummed and filtered (5 μm) rapeseed oil (referred to as SRO, i.e., semirefined rapeseed oil) to determine its suitability as a diesel fuel extender. The upper rate for inclusion of SRO with diesel fuel is 25%. This fuel blend had a phosphorus level of 2.5 ppm, which was comparable to rape methyl esters (1.0 ppm phosphorus). Thermogravimetric analyses were used to estimate the cetane ratings of the fuels. A 25% SRO/diesel blend had an estimated cetane index of 32.4 compared to 38.1 for diesel fuel only. Differential scanning calorimetry and thermogravimetric analyses were used to compare the volatility ranges of the fuels. SRO needed higher temperatures for volatilization (i.e., 70–260°C for diesel fuel vs. 280–520°C for SRO). This indicated poorer cold-starting performance of SRO compared with diesel fuel. SRO fuel is a low-sulfur, high-oxygen fuel giving SRO a more favorable emissions profile than pure diesel fuel.     

On-site low-pressure diesel HDS for fuel cell applications: Deepening the sulfur content to ?1 ppm

This work investigates the feasibility of ultra-deep hydrodesulfurization (i.e. ?1 ppm of sulfur content) of several diesel feedstocks, viz., regular (R), premium (P) and hydrotreated straight-run (HSR) at low pressures, i.e. 10 bar, to lower significantly the operation costs. The premium and regular diesel contain additive packages with several components such as cetane boosters, antioxidants that show to negatively affect the sulfur conversion at low pressures. In the hydrotreated straight-run diesel fuel, which does not contain an additive package, total desulfurization can be obtained at 10 bar, T = 340 °C and LHSV = 1 h⁻¹. As a model for the additive package, FAME (fatty acid methyl ester), an ingredient that encounters the demands of a sustainable future, was added to the hydrotreated straight-run diesel (HSR + FAME) in order to check its influence on the total sulfur conversion. Results show that this biofuel component hindered tremendously the sulfur removal process by lowering the sulfur removal from 98% to zero at 10 bar, probably by competitive adsorption. At higher pressures, e.g. 30 bar, when FAME was present, new sulfur compounds were formed during the HDS process and the effective sulfur removal was very low.     

Nitrogen compound distributions in hydrotreated shale oil products from commercial-scale refining

The distributions of nitrogen compounds in crude and hydrotreated shale oil products have been determined. About 11600 m³ (73000 bbl) of Paraho retorted shale oil were hydrotreated by The Standard Oil Company of Ohio at their Toledo refinery. A hydrotreated whole product, a jet fuel, a diesel fuel, and a residuum were produced and individually separated into compound-type fractions by adsorption chromatography. The nitrogen compound types in these fractions were characterized by i.r. spectroscopy, differential potentiometric titration, and high-resolution m.s. The distributions of nitrogen compound types and nitrogen base types in the hydrotreated products are compared with those in the Paraho retorted shale oil feedstock used in the hydroprocessing. The nitrogen compound types that were readily hydrodenitrogenated during commercial-scale refining are similar to nitrogen compound types removed during one-pass, bench-scale hydroprocessing.     

Physical-chemical properties of waste cooking oil biodiesel and castor oil biodiesel blends

This work presents the physical-chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T₁₀ and T₅₀ are higher than those of diesel oil, while the distillation temperature T₉₀ is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.     

Effects of air/fuel combustion ratio on the polycyclic aromatic hydrocarbon content of carbonaceous soots from selected fuels

Patterns of polycyclic aromatic hydrocarbon (PAH) content were observed from GC/MS analysis of the extracts of soots at various air/fuel combustion ratios of three commonly used fuels: n-hexane, JP-8 (Jet fuel), and diesel. With increasing air/fuel ratio, from a simple diffusion flame up to an air/fuel ratio of 3.94, there is a significant loss of high molecular weight PAHs and an increasing abundance of oxidized lower molecular weight aromatics. The formation of high molecular weight PAHs is favored for JP-8 and diesel fuels at higher air/fuel combustion ratios than is the case with n-hexane, probably due to the aromatic content in JP-8 and diesel fuels acting as centers for large aromatic and soot nucleation. The efficiency and reproducibility of two techniques, Soxhlet and supercritical fluid extraction (SFE), used for extraction of PAHs from soot were compared. Electron paramagnetic resonance (EPR) measurements were performed on the soot both before and after supercritical fluid and Soxhlet extraction, and a substantial decrease in the spin density of soot following extraction indicates that extractable molecules are associated with 40–50% of the unpaired electrons in soot. This analysis generally supports trends observed in our earlier work for surface oxidation, surface area, unpaired electron spin density, hydration, and ozone oxidation.     

Upgrading of LCO by partial hydrogenation of aromatics and ring opening of naphthenes over bi-functional catalysts

Available options to upgrade LCO to diesel fuel are: i) aromatic saturation (ASAT) ii) mild hydrocracking and iii) aromatic saturation followed by selective ring opening (SRO) of naphthenic structures. Although the above mentioned routes lead to significant product quality enhancement, they suffer from several disadvantages. Hydrocracking leads to significant yields in gasoline-range products, ASAT is characterized by a relatively high consumption of hydrogen with only limited improvement of product quality in terms of density and cetane properties, ASAT + SRO route leads to higher improvements of product quality but it requires a very high hydrogen consumption which strongly affects the economics of the process.An alternative upgrading route consists in partial polyaromatic compound saturation and selective opening of both naphthenic and benzo-naphthenic structures to produce less condensed naphthenic structures and alkyl-benzenes respectively. In this case the hydrogen needed to improve product quality at the same level, of cetane properties and density, is lower in comparison with ASAT.This paper reports the results obtained during a research program aimed at upgrading LCO via selective ring opening. The hydroconversion of a low sulfur hydrotreated LCO has been studied over iridium and platinum loaded on different supports. The results of this study indicate that the properties of products heavily depend on the characteristics of the support and the metal used. The data obtained with the Ir/amorphous silica-alumina (MSA) show the possibility to get a clear increase of CN and decrease of density in comparison with the mere aromatic saturation. The practical consequence of this result is the possibility of producing products with CN and density similar to products obtained by complete dearomatization but still containing a significant percentage of aromatic structures so allowing a consistent saving of hydrogen.     

Biocatalytic oxidation of fuel as an alternative to biodesulfurization

A biotechnological method for fuel desulfurization is described. The method includes the steps of biocatalytic oxidation of organosulfides and thiophenes, contained in the fuel, with hemoproteins to form sulfoxides and sulfones, followed by a distillation step in which these oxidized compounds are removed from the fuel. Straight-run diesel fuel containing 1.6% sulfur was biocatalytically oxidized with chloroperoxidase from Caldariomyces fumago in the presence of 0.25 mM hydrogen peroxide. The reaction was carried out at room temperature and the organosulfur compounds were effectively transformed to their respective sulfoxides and sulfones which were then removed by distillation. The resulting fraction after distillation contained only 0.27% sulfur. Biocatalytic oxidation of fuels appears as an interesting alternative to biodesulfurization.     

The aromatization of linoleic acid with palladium catalyst

Summary Hydrogen transfer catalysts are known to promote the elaidinization and conjugation of unsaturated fatty acid derivatives. More extensive reactions were indicated when palladium was tried as a polymerization catalyst. A subsequent study showed that methyl linoleate could be readily cyclized and aromatized in the presence of palladium. Methyl linoleate was heated in an evacuated ampule for 6 hrs. at 270°C. with 5% of a 10% palladium on charcoal. The iodine value was lowered to 43.9 and the apparent linoleate content to less than 2%. The products were separated by urea segregation and distillation. They consisted of approximately 7% polymer, 18% methyl stearate, 40% monoolefins, and 30% of a methyl ester of an aromatic fatty acid (handling loss 5%). The aromatic material was readily oxidized to orthophthalic acid. The mechanism by which aromatics, mono-olefins, and saturates are produced through cyclization and hydrogen transfer is not known, but possible routes are suggested. Paper No. 199, Journal Series, Research Laboratory, General Mills Inc.     

Storage stability of marine diesel fuels

The cause of instability in marine diesel fuels was investigated by ageing several fuels at 65 °C for various periods. Aged and unaged fuel samples were chromatographically separated into acid, base and neutral fractions, and the fractions were analysed in detail to obtain a clearer understanding of the mechanism of colour change and sediment formation. The results suggest that oxidation of neutral compounds to polar intermediates may be a major pathway for sediment formation and darkening of marine diesel fuels. Considerable loss of polar compounds, both those originally present and those newly formed, to sediment was also found. Within a compound class, the more aromatic higher molecular weight members were observed to be the most active in sediment formation.     

Fuel constituent effects on fuel reforming properties for fuel cell applications

The effect of different types of compounds commonly found in diesel fuel (e.g., paraffins, naphthenes, and aromatics), as well as their chemical structure (e.g., branched versus linear paraffins) on fuel reforming has been investigated. Diesel reforming is very complicated because diesel is a complex mixture of hundreds of compounds with greatly different reactivities. The syngas production rates at the same conditions were observed in this order: paraffins > naphthenes ? aromatics. Additionally, the type of reforming performed (OSR, CPOX, or SR) as well as the process parameters (space velocity and reaction temperature) significantly affected the syngas production rates as well as carbon formation. The reactivity of one fuel component can affect the conversion pattern of others, e.g., overall yields from the reforming of a fuel mixture are not additive of yields from individual fuel components, rather the more reactive component is consumed first. Furthermore, the type of substituent in aromatics and naphthenes, the carbon chain length in n-paraffins, branching in paraffins, and degree of aromatic saturation affect the overall hydrocarbon conversion, syngas selectivity, and carbon formation. The presence of sulfur compounds in the fuel caused significant drops in H₂ yields compared to CO yields.     

New method for obtaining the distillation curves of petroleum products and coal-derived liquids using a small amount of sample

Based on thermogravimetric principles a new distillation method for petroleum products and coal-derived liquids has been developed. The boiling point distributions of five petroleum fractions (kerosene; 128–228 °C; light gas oil, 178–298 °C; middle gas oil, 200–360 °C; vacuum gas oil, 268–565 °C; and high vacuum gas oil, 305–604 °C) and one highly aromatic coal-tar fraction (wash oil, 180–310 °C) were obtained. The results are in good agreement with those obtained by standard (ASTM) distillation methods. The amount of sample required is very small (≈10 mg) and can be solid or liquid. The experiments at normal pressure were carried out using a specially designed sample holder made of quartz. In the case of high-boiling-point fractions (distillation under reduced pressure) a normal sample holder can be used. The results are automatically recorded as temperature versus weight loss.