Characterization and compositional study of lighter fractions from coal-derived liquids

Synfuel fractions boiling in the range IBP-150 °C and 150–250 °C have been characterized. Individual component and hydrocarbon type distributions have been carried out quantitatively employing high resolution capillary gas chromatography and mass spectrometric techniques independently. More than 180 compounds including 60 olefins have been identified and quantified in the IBP-150 °C fraction only. A comparative study of hydrocarbon structures present in synfuel and crude oil fractions has been made and revealed that the cyclic character of coal-derived oils is due to predominance of hydroaromatics and cycloolefins rather than naphthenes alone. Moreover, for most of the homologous series of cyclic and aromatic structures, parent compounds are relatively more abundant in coal-derived oil than in natural crude petroleum and cracked petroleum fractions. The fractions have been evaluated for their suitability as gasoline/kerosene blending components in view of their estimated octane number and smoke point respectively.     

Steam cracking of coal-derived oils and model compounds: 1. Cracking of tetralin and t-decalin

Cracking of tetralin and t-decalin has been investigated in the temperature range between 700 and 850 °C and with residence times between 0.08 and 0.4 s. Most of the tetralin is dehydrogenated to yield 1,2-dihydronaphthalene and naphthalene. Other main products are indene and styrene, whereas t-decalin is predominantly cracked into ethylene and BTX aromatics. The kinetics of decalin decomposition can be described by a first-order irreversible reaction, whereas the behaviour of tetralin has to be expressed in terms of a reversible reaction. The overall activation energies are determined.     

环烷基瓦斯油催化裂解反应规律及产品性质

利用提升管催化裂解实验装置研究了加拿大合成原油瓦斯油HGO和LGO的催化裂解反应规律和裂解产品性质。发现总低碳烯烃（乙烯、丙烯和丁烯）产率随反应温度和剂油比的增大存在最大值,随反应时间的延长而减小,随水油比的增大而升高。实验确定了HGO催化裂解的优化反应条件：反应温度620～640℃、剂油比16、反应时间2 s、水油比0.5左右。在此反应条件下,乙烯、丙烯和总低碳烯烃产率分别可达9.0%（质量）,15.8%（质量）和32.6%（质量）。催化裂解汽油馏分、柴油馏分和重油馏分含有大量的芳香烃,其中催化裂解汽油馏分总芳香烃含量在80%（质量）以上,主要是甲苯和C₈芳香烃;催化裂解柴油馏分总芳香烃含量在60%（质量）以上,主要是单环和双环芳香烃;催化裂解重油馏分总芳香烃含量在70%（质量）以上,主要是多环芳香烃。     

Thermal cracking of coal-derived materials to BTX and ethylene

The vapour-phase thermal cracking (i.e. non-catalytic) of a range of coal-derived materials and pure compounds using laboratory scale reactors is described. Up to 27% benzene, toluene and xylenes (BTX) and 24% ethylene were obtained by cracking hydrogenated coal extract, compared with less than 4% of each from unhydrogenated extract, anthracene oil and coal, confirming the importance of naphthenes (cyclic aliphatics) as BTX and ethylene precursors. Experiments with pure compounds showed that product yields could be predicted closely from the cracking pattern of the components and the composition of the mixtures.     

H.p.l.c. quantitation of hydrocarbon class types in cracked products

H.p.l.c. was optimized to obtain quantitative compositional data on hydrocarbon class type (saturates, olefins, aromatics plus polars) in cracked products from vacuum gas oil (370–500°C) feed over REY zeolite catalyst in a micro-activity test unit. H.p.l.c. separation was achieved using an amino column, a backflush device and nC₆ as mobile phase. An RI detector was used to obtain total saturates and aromatics and a 200 nm u.v. detector to estimate olefins and aromatic hydrocarbons by ring number. Quantitation was achieved using external standard procedure and standards were prepared from the identical petroleum products to obtain response factors. A considerable variation in the liquid product yield during cracking reactions was noticed, from 40 to 70 wt%. Cracking reactions were also favoured through hydrogen transfer, increasing substantially the aromatic content in the range 50–70 wt%. Olefins were also formed during cracking, ranging from 5 to 10 wt%.     

Enhancing the Production of Light Olefins by Catalytic Cracking of FCC Naphtha over Mesoporous ZSM-5 Catalyst

The enhanced production of light olefins from the catalytic cracking of FCC naphtha was investigated over a mesoporous ZSM-5 (Meso-Z) catalyst. The effects of acidity and pore structure on conversion, yields and selectivity to light olefins were studied in microactivity test (MAT) unit at 600 °C and different catalyst-to-naphtha (C/N) ratios. The catalytic performance of Meso-Z catalyst was compared with three conventional ZSM-5 catalysts having different SiO₂/Al₂O₃ (Si/Al) ratios of 22 (Z-22), 27 (Z-27) and 150 (Z-150). The yields of propylene (16 wt%) and ethylene (10 wt%) were significantly higher for Meso-Z compared with the conventional ZSM-5 catalysts. Almost 90% of the olefins in the FCC naphtha feed were converted to lighter olefins, mostly propylene. The aromatics fraction in cracked naphtha almost doubled in all catalysts indicating some level of aromatization activity. The enhanced production of light olefins for Meso-Z is attributed to its small crystals that suppressed secondary and hydrogen transfer reactions and to its mesopores that offered easier transport and access to active sites.     

Upgrading coal-derived liquids to diesel fuel

Distilled fractions of a coal-derived liquid from the H-Coal process were upgraded to diesel fuel by catalytic hydrotreatment. The total hydrotreated products were distilled into naphtha (<180°C) and diesel fuel fractions (>180°C) and the diesel fractions were analysed for hydrocarbon-type composition, hydrogen content and some diesel fuel properties. GC—MS-analyses were carried out on the hydrocarbon-type fractions to identify individual chemical compounds. To investigate the effect of different distillation cut points on diesel fuel yield and properties, cut points for one hydrotreated product were varied. The diesel fuel cetane numbers were correlated with percentage hydrogen, total aromatics and saturates. Cetane numbers above 40 were obtained for diesel fuels containing (i) more than 75% saturates, (ii) less than 15% total aromatics and (iii) a hydrogen content above 12.8%. Compounds identified by GC—MS-analyses (in the diesel fractions) were typical aromatic and cycloparaffin compounds. Normal-and iso-paraffin compounds were not detected. By varying the distillation cut point from 135 to 180°C, the cetane number of the residual diesel fraction improved from 37 to 44. This increase is ascribed to the removal of aromatic compounds in the 135–180°C boiling point range.     

Characterization of coal—liquid fractions. Molar enthalpies of quinoline interaction with coal-derived asphaltenes and heavy oils

The toluene-insoluble (Tl), asphaltene (A), and heavy oil (HO) fractions were isolated from three centrifuged SYNTHOIL liquid product (CLP) samples, prepared under different process conditions at 450 °C, 27.6 MPa hydrogen pressure from the same feed coal, Kentucky hvAb, from Homestead Mine. Run FB 53 was made with CoMo catalyst, 11-min preheater residence time, and 3-min reactor residence time. The much higher viscosity of FB 53–59 compared to FB 53-1 correlates with the larger contents of its toluene-insolubles and asphaltene, larger oxygen and sulphur contents of its asphaltene and toluene-insolubles, larger molecular weight and smaller aromaticity of its asphaltene, and the larger enthalpy of interaction (ΔH^o) of its asphaltene with quinoline in benzene. The average molecular weight and percentage of heteroatoms of the heavy oil from FB 53–59 are also greater than that from FB 53-1, and the value of ΔH^o of the heavy oil with quinoline, follows the same order. Run FB 57 was made with glass pellets, 17-min preheater residence time and 6-min reactor residence-time. Since in FB 53–59 the CoMo catalyst has lost part of its activity, a comparison of FB 53–59 with FB 57 yields information on the effect of residence times on the properties. The toluene-insoluble and asphaltene contents, as well as the viscosity, of FB 53–59 is larger, while the heavy oil content of FB 53–59 is smaller than that of FB 57. This comparison indicates that a larger-residence-time preheater and reactor may, to some extent, favour conversion as well as decrease the viscosity of the product oil. The values of ΔH^o for the interaction of quinoline with the heavy oil and asphaltene fractions obtained from the three CLP samples are in the order: FB 53–59 > FB 57-42 > FB 53-1, and they are attributed to the varying degree of hydrogen-bonding effects involving largely aromatic phenols which serve as hydrogen donors to quinoline.     

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.     

Olefins and BTX-production by thermal cracking of hydrotreated vacuum gas oil and related fractions

Aramco vacuum gas oil was catalytically hydrotreated to conversions of 20, 40 and 60%, and subsequently fractionated into naphtha, kerosene, gas oil, and hydrotreated vacuum gas oil. These fractions were thermally cracked to test their potential as feedstock for olefins and BTX production. The olefin yields from the hydrotreated vacuum gas oil obtained from hydrotreating with 40 and 60% conversion favorably compare with those of straight-run naphthas. Cracking in conventional naphtha/atmospheric gas oil units becomes possible. The naphtha, kerosene and gas oil fractions are preferably added to standard refinery streams.     

Conversion of n-Octene over Nanoscale HZSM-5 Zeolite

Transformation of n-octene has been investigated over nanoscale HZSM-5 at different reaction temperature and contact time. The results show that the main reaction was isomerization of n-octene over 200 °C. Hydrogen transfer reaction also occurred at 200 °C, but the products were alkanes and cycloolefins instead of aromatics. The aromatization was promoted by high temperature. The maximum selectivity of i-paraffins occurred between 300 and 350 °C. Propene, butene and pentene were the primary cracking products. These olefins were oligomerized and cracked to produce a wide distribution of olefins with different carbon atoms. These intermediates then were quickly transformed into aromatics and alkanes by hydrogen transfer over acid sites at high reaction temperature. Propane and butane can be transformed into methane and ethane at long contact time above 400 °C.     

动植物油生产清洁燃料和低碳烯烃的替代加工工艺

Since the production cost of biodiesel is now the main hurdle limiting their applicability in some areas, catalytic cracking reactions represent an alternative route to utilization of vegetable oils and animal fats. Hence, catalytic transformation of oils and fats was carried out in a laboratory-scale two-stage riser fluid catalytic cracking （TSRFCC） unit in this work. The results show that oils and fats can be used as FCC feed singly or co-feeding with vacuum gas oil （VGO）, which can give high yield （by mass）of liquefied petroleum gas （LPG）, C2-C4 oletms, tor example 45% LPG, 47% C2-C4 olefins, and 77.6% total liquid yield produced with palm oil cracking. Co-feeding with VGO gives a high yield of LPG （39.1%） and propylene （18.1%）. And oxygen element content is very low （about 0.5%） in liquid products, hence, oxygen is removed in the form of H2O, CO and CO2. At the same time, high concentration of aromatics （C7-C9 aromatics predominantly） in the gasoline fraction is obtained after TSRFCC reaction of palm oil, as a result of large amount of hydrogen-transfer, cyclization and aromatization reactions, Additionally, most of properties of produced gasoline and diesel oil fuel meet the requirements of national standards, containing little sulfur. So TSRFCC technology is thought to be an alternative processing technology leading to production of clean fuels and light olefins.     

催化裂解反应条件对产物收率的影响

增产低碳烯烃、轻质芳烃等产物是催化裂解技术发展的趋势,反应条件是影响催化裂解产物分布的关键因素。介绍催化裂解过程涉及的反应机理,概述反应温度、剂油质量比、停留时间(空速)、水油质量比等反应条件,裂解装置和原料油性质对产物收率的影响,结合工业实例分析反应条件对产物收率的影响。     

Two-stage pyrolysis of heavy oils. 3. Pyrolysis of tar-sand bitumens. Relation between ethylene yield and structural characteristics of heavy oils

Thermal cracking of tar-sand bitumens has been carried out using a two-stage pyrolysis reactor with temperature zones of 440°C and 750–800°C, respectively. Feedstocks were pyrolysed in the first stage into cracked oils, which were carried to the second stage for subsequent pyrolysis. Only 12–14 wt% of ethylene was obtained from tar-sand bitumens at the residence time of 1.2 s in the second stage, although 27 and 16 wt% were obtained from Taching and Iranian heavy vacuum residues, respectively. The tar-sand bitumens contain shorter paraffinic straight-chains and have more branched molecules than the vacuum residues of petroleum. A straight-chain paraffin index is proposed, with which a good correlation was obtained between ethylene yield and the fraction of straight-chain paraffin carbons in the heavy oil.     

Separation of coal-derived liquids by gel permeation chromatography

Coal-derived liquids, obtained from pilot plants and bench-scale reactors, have been separated by gel permeation chromatography into aromatic, phenolic, and asphaltenic fractions, where asphaltenes and long-chain hydrocarbons are in the same fraction. The Chromatographie system uses 10 nm μStyragel columns and solvents such as tetrahydrofuran (THF) and toluene. The separation is reasonably clean and almost devoid of overlapping. The saturated hydrocarbons are separated from the asphaltenes by vacuum distillation. Aromatic, phenolic and aliphatic fractions are characterized by high-resolution gas chromatography—mass spectrometry. The phenolic fraction contains alkylated phenols, indanols, and naphthols. The aromatic fraction is composed of alkylated benzenes, indans, naphthalenes and small amounts of multi-ring aromatics such as alkylated fluorenes and pyrenes. Most of the long-chain hydrocarbon fraction is of straight-chain alkanes ranging from tetradecane to tetratetracontane. Some branched alkanes, such as pristane and phytane, are also present. If olefins are present in the sample they also separate with the long-chain hydrocarbon fraction. Although various analytical data such as i.r., n.m.r., molecular size distribution and elemental composition of asphaltenes have been obtained, the chemical characterization is not complete. The gel permeation Chromatographie separation technique, as discussed in this paper, is very useful for fast analysis of any coal-derived liquid.     

Thermal degradation of shale oils: 1. Kinetics of vapour phase oil degradation

As vertical modified in-situ retorts (VMIS) have been scaled up and tested, the overall oil yield has declined and is generally lower than that observed in an above-ground process. This reduced oil yield could adversely affect the economics of VMIS retorting. Diminished yields are attributed to a combination of factors associated with scale-up such as in complete rubblization, wide particle size distributions (large blocks of shale), and poor flow distributions. Additionally, oil losses can occur by comparatively long exposure of the oil vapours to high temperatures, by exposure to successive condensation and revaporization of the oil as it travels down the retort, and finally by long time thermal exposure of the condensed oil retained in the bottom portion of large VMIS retorts. To study such vapour phase degradation of shale oil using oil produced from Occidental Petroleum's No. 6 VMIS retort, a tubular continuous flow reactor, with an on-line gas chromatograph for gas composition monitoring was used to study thermal degradation of shale oil under retorting conditions. Oil and a combination of gases including steam were metered into the preheater and then the vapours passed into a quartz tubular reactor where the temperature and residence time of the gaseous mixture were controlled. Complete mass balances were performed giving the weight fraction of oil converted to noncondensable hydrocarbon gases and coke. This experimental design is novel because high temperature thermal degradation of shale oil was studied for the first time under steady state flow conditions with carefully controlled residence time and temperature. A range of temperatures (425–625 °C) and residence times (2–10 s) were used in a series of factorial-designed experiments (3²) to accurately determine the effects of these variables. Results of the study showed that the addition of steam to the carrier gas did not reduce oil degradation losses but did react with the coke thereby changing the product gas composition and quantity. A first-order oil degradation rate expression was used to model the rate of oil loss. The calculated activation energy was 17.3 kcal mol^?1. Chemical analyses of the product liquids and gases confirmed previously reported findings that the oil loss indices (alkene/alkane, ethylene/ethane, naphthalene/(C₁₁ + C₁₂), and gas/coke) increase with increasing oil degradation.     

煤基油中芳烃组分的分离及其鉴定研究进展

芳烃组分的分离是实现煤基油分质利用的关键技术之一，掌握芳烃组分在煤基油中的分布及其组成结构有助于促进芳烃组分分离技术的开发。本文分别针对蒸馏法、溶剂萃取法、柱层析法等煤基油中混合芳烃组分的分离方法及精馏法、结晶法、超临界萃取法、膜分离法、化学法、吸附法等单一芳烃组分的精制技术进行了系统介绍，指出了各分离方法的优势及不足；同时综述了气相色谱法、液相色谱法、多维色谱联用法、紫外分光光度法等主要的芳烃组分组成及结构鉴定方法；进而探讨了煤基油中芳烃组分分离及其鉴定的发展趋势，认为芳烃组分的精细分离应深入研究各组分间的相互作用，将低能耗、环保型新型分离技术与传统方法相结合，芳烃组分的鉴定应将多种表征手段相结合，多层次、全方位地分析其组成结构。     

Application of the DEPT pulse sequence for the generation of 13CHn subspectra of coal-derived oils

The application of the recently developed DEPT pulse sequence for the generation of ¹³CH_n subspectra of coal-derived oils is determined. The technique is able to generate subspectra with accurate cancellation of signals of unwanted multiplicity for complex oil mixtures containing broad and overlapping resonances. However, the use of signal intensities in DEPT subspectra to determine quantitatively the amounts of CH_n groups present in oil mixtures suffers in accuracy due to variable polarization transfer and relaxation rates.     

Aromatic gas oil cracking under realistic FCC conditions in a microriser reactor

A paraffinic hydrowax feed spiked with naphthalene, anthracene, and phenanthrene was cracked in a once-through microriser reactor at 575 °C and with a catalyst-to-oil (CTO) ratio of 4.8 g_cat g_oil⁻¹. The conversion by cracking reactions is limited to the paraffinic fraction of the feed and the alkyl groups associated with the benzene ring in aromatic compounds; the aromatic probes did not crack under the applied conditions, and in fact an additional amount of naphthalene was formed by complex dealkylation and hydrogen transfer reactions. The ‘uncrackabilty’ of aromatics was directly demonstrated by processing an aromatic gas oil, containing 33.3 wt% aromatics. Experiments were performed with residence times between 0.05 and 8.2 s, keeping the temperature (525 °C) and CTO ratio (5.5 g_cat g_oil⁻¹) constant. The data was interpreted with a simplified first-order five-lump kinetic model, where approximately 19 wt% of the feed was found to be uncrackable. HCO (feedstock) conversion took mainly place during the first two seconds and coke was only formed during the first 50 ms of catalyst-oil contact. Gasoline was not overcracked to gas. Approximately 50 wt% of the LCO fraction was formed during this 50 ms and did not change thereafter.     

Simulation Study of a Novel Process Co‐Producing Synthesis Gas and Light Olefins

There are abundant resources of heavy hydrocarbons worldwide, and their utilization is becoming more widespread as time progresses. The present paper proposes a process that combines coke gasification and heavy hydrocarbon pyrolysis, producing synthesis gas and light olefins. Simulation studies on the process are carried out by using Aspen Plus. The results show that the temperature of the gasification‐pyrolysis can be controlled by changing the feed rate of O₂ and steam. In addition, the coke jam problem can be solved by increasing the gasification‐pyrolysis temperature or residence time. The maximum amount of light olefins can be acquired by controlling the gasification‐pyrolysis residence time. More than 37 wt % heavy hydrocarbons are changed to synthesis gas with more than 15 wt % changed to light olefins in the case studied.