胜利褐煤超临界醇解反应行为研究

对胜利褐煤在甲醇、碱体系中的超临界反应行为进行了研究,考察了反应温度、反应时间和碱的种类分别对胜利褐煤转化率、产物收率和分布规律的影响.结果表明,反应温度显著影响褐煤的转化率和产物收率,产物主要为四氢呋喃可溶组分(占67%～85%)和甲苯可溶组分(占8%～22%);300℃时,胜利褐煤在甲醇-NaOH体系中转化率和收率最高(99%左右);反应时间显著影响褐煤的转化率和产物收率,80 min后褐煤的转化率和产物收率分别为99%和100%;反应过程中四氢呋喃可溶组分可转化为甲苯可溶组分、正己烷可溶组分和水溶性组分;碱的种类对褐煤超临界醇解转化率和产物收率有显著影响.     

Extraction of lignite with water in sub- and supercritical states

On a semi-continuous apparatus, Dayan lignite was extracted with water in sub- and supercritical states. The experiments were carried out to investigate the effect of temperature on extract formation rate, extract yields and product components at different pressures and end temperatures. The results indicated that the extract formation rate has a maximum with the variation of temperature. The temperature corresponding to the maximum extract formation rate, changing with the pressure, is between 400 and 450°C. The extraction yields vary with the conditions. With the increase of pressure, the conversion and extract yield increase. With the increase of end temperature, the conversion also increases, but the increment is mainly gas and light oil. The main fraction in extract is preasphaltene and the main gas component is CO₂.     

离子液体作用下褐煤与生物质在亚临界水中共液化

选用小麦秸秆和金沟褐煤作为实验原料在间歇式高压反应釜中进行液化实验,考察了不同温度、不同秸秆/煤比例下添加离子液体时小麦秸秆与褐煤共液化产物分布情况及硫的变迁行为。研究结果显示:当小麦秸秆和褐煤在亚临界水中液化时,添加离子液体1-丁基3-甲基咪唑氯盐[Bmim]Cl会降低正己烷不溶组分收率,但可以提高气体收率与总转化率。添加[Bmim]Cl后,随着样品中小麦秸秆比例减少,液化油收率、正己烷不溶组分收率、四氢呋喃可溶组分收率、气体收率与总转化率均呈下降趋势。添加 [Bmim]Cl后残渣中硫的相对含量增加,其他产物中硫的相对含量减小;添加 [Bmim]Cl后残渣中有机硫的相对含量以及气相中COS和H₂S含量都随温度升高而增加。     

Coal liquefaction using supercritical toluene–tetralin mixture in a semi-continuous reactor

Liquefaction of Banpoo coal and Mae Moh coal using supercritical toluene–tetralin mixture was performed in a semi-continuous apparatus at a temperature ranging from 370 to 490 °C and under pressures up to 12.2 MPa. The addition of tetralin to toluene increased the coal conversion and the liquid yield by the stabilization of radical fragments and inhibition of radical recombination. The effect of solvent pre-swelling treatment and catalyst impregnation on conversion and liquid yield was also examined. The combination effects of catalyst and swelling enhanced conversion and the liquid yield of sub-bituminous coal. The yield of coal liquid at the condition of 490 °C and 10 MPa with toluene–tetralin reached a maximum 45 wt.% (in daf coal) with THF as the swelling agent and ZnCl₂ as the catalyst. The coal residue, after extraction, maintained most of its heating value and had a lower sulfur content.     

Catalytic hydroliquefaction of North Dakota lignite part I. Effects of process variables on product distribution

Finely ground North Dakota lignite slurried in anthracene oil was hydrogenated in a continuous stirred tank reactor in the presence of a cobalt-molybdenum catalyst. Effects on product distribution of process variables such as H₂ pressure, temperature, space time, lignite concentration in anthracene oil, and catalyst concentration have been investigated. Results indicate that 80% of maf lignite can be converted into gaseous and liquid products with an oil yield of about 35% on the same basis.     

褐煤超临界醇解萃余物组成分析

通过工业分析、元素分析、灰成分分析和热值分析对褐煤超临界醇解萃余物进行了研究,结果表明,褐煤醇解萃余物水分含量为6.93％～11.35％,灰分含量高达22.10％～24.46％,挥发分为39.75％～45.53％,无黏结性和结焦性:褐煤醇解萃余物碳含量为66.74％～76.03％,氢含量为4.51％～5.06％,氮含量...     

Extraction of bitumen with sub- and supercritical water

The sub- and supercritical water extractions of Athabasca oil sand bitumens were studied using a micro reactor. The experiments were carried out in the temperature range of 360–380 °C, pressure 15–30 MPa and water density 0.07–0.65 g/cm³ for 0–2 hrs. The extraction conversion of bitumens increased with solvent power and temperature. A maximum conversion of 24% was obtained after 90 min extraction at the supercritical condition. Hydrogen and carbon mono-oxide were not detected in sub-critical region but in the supercritical region. The supercritical condition was favorable to the hydrogen formation for bitumen extraction. The extraction products were upgraded relative to the original bitumens due to direct hydrolysis of low-energy linkage and H₂ formed by water gas shift reaction in supercritical condition. 18% of initial sulfur in bitumen can be removed at maximum conversion condition. The asphaltene contents of the residue were significantly higher than that of original bitumen due to preferential extraction of aromatic compounds in supercritical condition.     

Synergies in co-pyrolysis of Thai lignite and corncob

The results from TGA experiments at the temperature range of 300–600 °C evidently distinguished the different pyrolysis behaviours of lignite and corncob; however, no clear synergistic effects could be observed for the mixture. The investigation of co-pyrolysis in a fixed-bed reactor, however, found significant synergies in both pyrolysis product yields and gas product compositions. The solid yield of the 50:50 lignite/corncob blend was much lower (i.e. 9%) than expected from the calculated value based on individual materials under the range of temperatures studied, and coincided with the higher liquid and gas yield. The synergistic effect in product gas composition was highly pronouncing for CH₄ formation, i.e. three times higher than the calculated value at 400 °C. Possible mechanisms were described including the interaction between corncob volatiles and lignite particles, and the effect of the heat profiles of lignite and corncob pyrolysis on the temperature dependent reactions. The enhanced devolatilisation of the blend was explained by the transfer of hydrogen from biomass to coal as well as the promotion of low-temperature thermal decomposition of lignite by exothermic heat released from corncob pyrolysis. Moreover, water, which was one of the major components in corncob volatiles produced mainly at around 200–375 °C, can also be expected to act as a reactive agent to promote the secondary tar cracking producing more CH₄.     

Direct thermochemical liquefaction of microcrystalline cellulose by sub- and supercritical organic solvents

Direct thermochemical liquefaction of microcrystalline cellulose was carried out using sub- and supercritical solvents in a batch reactor. The decomposition efficiency of dodecane and m-xylene widely used in petrochemical industries was compared to that of methanol and 1,4-dioxane. At 400 °C, the conversion in methanol was the highest (92 wt% including gaseous products), but the operating pressure was too high. m-Xylene at the same temperature showed the conversion of 71.5 wt% with a lower number of products and milder pressure. Hydrogen contributed to the increase of the total conversion by 3–8% in m-xylene and methanol, compared with the results without adding any additional gas or with nitrogen pressurization. An acid-modified silica catalyst led to a significant increase of conversion in the supercritical methanol, but its effect was negligible in the aprotic solvents. The product compounds and property of solid residue depended on the supercritical solvents applied. The thermal-treated char after liquefaction in m-xylene, dodecane and 1,4-dioxane was an effective adsorbent for CO₂ adsorption, showing the level comparable with activated carbons.     

锡林郭勒褐煤在超临界水和不同气氛下的液化性能

研究了锡林郭勒褐煤在超临界水和N₂气氛下,以及K₂CO₃,FeS+S和KOH三种催化剂分别作用下的液化性能,并与其在供氢溶剂四氢萘和H₂气氛下的液化性能进行比较。结果表明:锡林郭勒褐煤在供氢溶剂四氢萘和H₂气氛下具有较高的液化活性,在420℃、无催化剂条件下褐煤的液化转化率和油水气收率分别为76.8%和51.0%;而在相同温度、添加5%甲酸的超临界水和N₂气氛下,褐煤的液化转化率和油水气收率分别降为32.0%和29.2%,且褐煤液化主要转化为附加值高的油气部分。K₂CO₃,FeS+S和KOH三种催化剂对锡林郭勒褐煤在超临界水中液化都具有较好的催化活性,按催化活性由高到低排序为K₂CO₃,FeS+S,KOH;420℃时K₂CO₃对锡林郭勒褐煤具有最好的催化效果,褐煤的液化转化率和油水气收率最高,分别为46.5%和42.2%。气氛对锡林郭勒褐煤在超临界水中的液化性能具有较大的影响,在CO气氛下锡林郭勒褐煤的液化活性最高,420℃时褐煤的液化转化率和油水气收率最高,分别为52.2%和44.4%。这是由于在CO气氛下能够发生水煤气变换反应,可以为液化过程提供原位活性H,从而促进了油气收率和液化转化率的提高。     

胜利褐煤超临界乙醇脱氧实验研究

为有效脱除褐煤中含氧官能团,采用超临界乙醇工艺处理胜利褐煤,研究温度、停留时间和醇煤质量比对胜利褐煤脱氧效果的影响,并利用FT-IR和GC/MS对固液相产物进行表征。结果表明,胜利褐煤超临界乙醇脱氧的最佳工艺条件为:温度270℃,停留时间90 min,醇煤质量比5∶1,此时煤样总氧含量为9.29%,脱氧率为61.40%,固相产率为89.62%。在220℃得到的液相产物中,80%左右为芳香族类化合物,酚类和酯类含氧化合物体积分数低于5%,其他含氧类化合物11.29%。270℃得到的液相产率中芳香族类化合物体积分数降低31.69%,含氧类化合物体积分数增加2.81%,酚类和酯类含氧化合物增至35%左右。褐煤经超临界醇解后,乙醇与煤分子作用发生了醚氧桥键的断裂反应,煤分子发生了脱羧反应,液相产物中含有大量酚类(主要为苯酚及其取代物)和酯类(主要为乙酯类)。     

The influence of temperature on the yields of compounds existing in bio-oils obtained from biomass samples via pyrolysis

The influence of temperature on the compounds existing in liquid products obtained from biomass samples via pyrolysis were examined in relation to the yield and composition of the product bio-oils. The product liquids were analysed by a gas chromatography mass spectrometry combined system. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiacol and their alkylated phenol derivatives. Thermal depolymerization and decomposition of biomass structural components, such as cellulose, hemicelluloses, lignin form liquids and gas products as well as a solid residue of charcoal. The structural components of the biomass samples mainly affect the pyrolytic degradation products. A reaction mechanism is proposed which describes a possible reaction route for the formation of the characteristic compounds found in the oils. The supercritical water extraction and liquefaction partial reactions also occur during the pyrolysis. Acetic acid is formed in the thermal decomposition of all three main components of biomass. In the pyrolysis reactions of biomass: water is formed by dehydration; acetic acid comes from the elimination of acetyl groups originally linked to the xylose unit; furfural is formed by dehydration of the xylose unit; formic acid proceeds from carboxylic groups of uronic acid; and methanol arises from methoxyl groups of uronic acid     

Chemical reduction of sulphur dioxide to free sulphur with lignite and coal. 1. Steady-state reaction chemistry and interaction of volatile components

The chemical reduction of SO₂ with North Dakota lignite has been discovered to be a facile reaction which occurs at a relatively low temperature of 600–650 °C. Under optimum conditions, the reaction chemistry can be controlled to allow 85–90% conversion of SO₂ to free sulphur in a single-stage reaction. Major by-products of the reaction are CO₂, H₂O and a free-flowing ash. The high sulphur yield from this reaction exceeds the calculated thermodynamic gas phase equilibrium value of 66–70%. The higher experimental yield was found to be due in part to a catalysed re-equilibration of the gaseous products in the exit line. With lignite and low-rank coals, the mechanism of SO₂ reduction appears to involve reaction of hydrocarbons within the pores structure and thus allows complete conversion of the volatile matter with no tar formation. Volatilization and tar formation successfully compete with SO₂ reduction in bituminous coals under the same reaction conditions.     

Supercritical gas extraction of Victorian brown coals: The effect of coal properties

A selection of fifteen Victorian brown coals, which varied in lithotype but only slightly in rank, were subjected to supercritical gas extraction with toluene. Seven of these coals were also extracted with 5% tetralin/toluene under the same conditions of temperature and pressure (400 °C and 10 MPa). The overall conversion, the extract yield and the yield of toluene solubles (oil and asphaltene) were correlated with more easily obtained coal properties using simple linear regression analysis. Good correlations were obtained between the total conversions and the volatile matter content of the coals, and for the toluene extractions between both the extract yield and the yield of toluene solubles and the H/C atomic ratio. For the toluene solubles from the toluene extractions, the aromaticity decreased and the molecular weight increased as the H/C atomic ratio of the coal increased. Inorganic constituents of the coals did not appear to have a marked effect on total conversion and liquid yields. Removal of the cations from two coals increased conversion and liquid yields in one case and decreased these in the other, but in both instances the changes were not large.     

反应温度对催化裂化汽油芳构化的研究

以中国石油兰州炼油石化公司催化汽油为原料,采用小型固定流化床为芳构化反应装置,考察了反应温度对芳构化产物收率、转化率、马达法和研究法辛烷值、气体产品组成和液体产品组成的影响规律。实验结果表明,随着反应温度的升高,干气、液化气和焦炭收率呈上升趋势,而汽油和柴油收率呈下降趋势,FCC汽油的转化率都在94%左右,且随反应温度的升高先增大后减小;乙烯、丙烯、丁烯、乙烯和总低碳烯烃收率单调增加,而乙烯、丙烯、丁烯、乙烯和丙烯和总低碳烯烃收率的增加幅度各不相同;异构烷烃和烯烃收率随着反应温度的升高逐渐减少,而芳烃的收率和选择性随着反应温度的升高逐渐增加,正构烷烃和环烷烃的收率随着温度的增加先增加后减少。     

Improvement of oil yield and its distribution from coal extraction using sulfide catalysts

Extraction of Mae Moh lignite using toluene-tetralin mixture was performed in a batch reactor at a temperature range from 370 to 490 °C and under initial hydrogen pressure up to 12 MPa. Experiments were carried out to investigate the effects of temperature and initial hydrogen pressure on coal conversion, liquid yield and liquid composition. The effect of catalysts Fe₂S₃, Fe/Ni and Ni/Mo impregnated into activated carbon was also studied. In the absence of a catalyst, the oil yield decreased with temperature above 410 °C and the content of naphtha and kerosene increased while light gas oil and gas oil decreased with increasing temperature. The presence of catalyst would benefit the formation of lighter components, kerosene and light gas oil. Extraction in the presence of Ni/Mo catalyst, the liquid yield reached 64.6 wt% (daf) which included naphtha 2%, kerosene 72.8%, light gas oil 14.9%, gas oil 2.4% and long residue 7.9%. For GC-MS analysis, the fraction of kerosene was composed of tetralin, naphthalene, dodecamethyl-cycloheptasiloxane, methyl dodecanoate, tetradecamethyl-cycloheptasiloxane, ethyl dodecanoate, methyl tetradecanoate and dibutyl phthalate.     

The effect of supercritical water on the hydroconversion of Tahe Residue

The effect of supercritical water (SCW) on the hydroconversion of Tahe residue has been investigated at different temperatures and hydrogen pressures. It was demonstrated that introduction of water into the reaction could reduce the amount of coke formed and increased the yield of liquid product. The isotopic tracer method was used to determine quantitatively the extent of hydrogen exchange between water and the liquid product. The results indicated that the degree of hydrogen exchange of the liquid product with water decreased slightly with increasing hydrogen pressure. About 40% of the water molecules involved in hydrogen exchange with the oil residue as the concentration of water in the reaction mixture was 10 wt %. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Aromatic Compounds from Lignin Liquefaction over ZSM‐5 Catalysts in Supercritical Ethanol

A systematic research about the liquefaction of alkali lignin in supercritical ethanol using ZSM‐5 zeolite catalysts is reported, which includes the synergistic effect of temperature, catalytic content, and reaction time on product yield and distribution. Fourier transform infrared and gas chromatography‐mass spectrometry analysis were carried out to evaluate the compositions of bio‐oil and solid residue. Under moderate condition, maximum conversion and yield of bio‐oil were satisfactorily high. With the help of ZSM‐5 catalyst, lignin could be successfully converted into aromatic compounds.     

Fischer‐Tropsch Synthesis Over Co‐Ru/γ‐Al2O3 Catalyst in Supercritical Media

The Fischer‐Tropsch synthesis (FTS) in gaseous and supercritical phases was examined in a continuous, high‐pressure fixed‐bed reactor by employing a cobalt catalyst (Co‐Ru/γ‐Al₂O₃). The kinetic modeling of the FTS was investigated in the reactor over a 60–80 mesh cobalt catalyst. The Langmuir‐Hinshelwood kinetic equation was used for both the Fisher‐Tropsch (FT) and water gas shift (WGS) reactions. The kinetic model was applied for simulation of the reactor with 16–20 mesh cobalt catalyst. The simulation results showed a good agreement with the experimental data. The experimental data showed that higher CO conversion and lower CH₄ and CO₂ selectivities were achieved in supercritical media compared to the gaseous phase. The BET surface area and pore volume enhancement results provided evidence of the higher in situ extraction and greater solubility of heavy hydrocarbons in supercritical media than in gaseous phases. Furthermore, the effects of supercritical solvent such as n‐pentane, n‐hexane, n‐heptane and their mixtures were studied. Moreover, the influence of reaction temperature, H₂/CO ratio, W/F_(CO+H2) and pressure tuning in the supercritical media FT synthesis were investigated, as well as the effect of the supercritical fluid on the heat transfer within the reactor. The product carbon distribution had a similar shape for all types of solvents and shifted to lighter molar mass compounds with increasing temperature, H₂/CO ratio, and W/F_(CO+H2). Finally, the product distribution shifted to higher molar mass hydrocarbons with increasing pressure. As a result, one may conclude that a mixture of hydrocarbon products of the FTS can be used as a solvent for supercritical media in Fischer‐Tropsch synthesis.