Catalytic hydroliquefaction of North Dakota lignite part II. Kinetics of dissolution

A slurry of North Dakota lignite in anthracene oil has been treated with hydrogen in a continuous stirred tank reactor in the presence of a cobalt-molybdenum catalyst. A kinetic analysis of the lignite dissolution data obtained has been carried out. The rate of dissolution has been found to be first order in initial lignite concentration and approximately four-tenths order in fractional conversion. Results indicate that the apparent activation energy increases with increasing temperature with values from 19 to 33 kcal/g mole.     

Hydrogenolysis of coal-related model compounds by carbon monoxide-water mixture

Model organic compounds have been subject to hydrogenolysis reactions using CO and H₂O under industrial conditions as used for lignite and residual oil. Twenty-eight compounds, including diphenylmethane, indane, tetralin, anthracene, diphenyl ether, indene, benzophenone and xanthene were used. The purpose is to study the hydrogenolysis behaviour of compounds with structures as found in coal and residual oil. Using a Co-Mo catalyst, scission of the CC chain connecting two aromatic rings is enhanced by increased chain length of the molecule. Ether bonds are broken more easily than CC bonds. With the exception of decalin, cyclic CC bonds are more resistant to cleavage than linear bonds. Alcohol hydroxyl, and carbonyl groups of stilbene are the easiest to reduce but phenolic hydroxyl groups are stable. The Co-Mo catalyst promoted hydrolysis of ether bonds as well as hydrogenolysis. The method of the study is considered to be more effective for hydrogenolysis of organic compounds than the reported use of alkali and tetralin because of milder reaction conditions which are required.     

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.     

Catalytic liquefaction of various coals using a mixture of carbon monoxide and water

In a batch-autoclave, twenty coals were liquefied using a cobalt-molybdenum oxide catalyst with a mixture of CO and H₂0 at 400 °C with or without vehicle oil. Furthermore, lignite and peat were liquefied on tungsten oxide catalyst at 300 °C in the absence of CO. The reactivity of coal in this liquefaction is found to depend strongly on its rank. The vehicle oil significantly influences the extent of the water-gas shift reaction, especially when bituminous coals are liquefied, by dissolving such coals. Liquefaction of coal by this process is considered to take place via three routes: hydrogenolysis by the nascent hydrogen produced from the shift reaction; dissolution of coal into the vehicle oil which is an initial stage of hydrogenolysis; and a solvolytic reaction with H₂O, such as hydrolysis.     

Recovery,fractionation and study of oils from a lignite

Oils from a lignite (Teruel, Spain) were studied. They were obtained by catalytic depolymerization, by reacting an aromatic substrate (tetralin), Lewis acid catalyst (BF₃) and the lignite (oil A) or asphaltenes (oil B) at atmospheric pressure and temperatures <220 °C. The A and B oils were fractionated on an alumina-silica gel dual column into their saturated, mono- and diaromatic, polyaromatic and polar components by elution with hexane, hexane-benzene, benzene and methanol-diethyl ether-benzene respectively. The elemental analysis, average molecular weight, i.r. and ¹H n.m.r. spectroscopy and aromaticity data of these subfractions were studied.     

Alkyl aryl ethers in lignite solubilization. 1. Study of the process

The chemistry of solubilization of a lignite has been investigated with anisole, 3-methyl anisole and 1,3-dimethoxybenzene catalysed by SbCl₃, ZnCl₂, AlCl₃ and BF₃ as boron trifluoride etherate, at atmospheric pressure and temperatures < 220 °C. 60% of lignite was solubilized in a toluene-ethanol azeotropic mixture. During the process, the solvent is incorporated as an alkylated substratum. The yield increased with activity of the aromatic ether ring and catalyst acidity.     

Optimization of Cottonseed Oil Ethanolysis to Produce Biodiesel High in Gossypol Content

Transesterification of cottonseed oil was carried out using ethanol and potassium hydroxide (KOH). A central composite design with six center and six axial points was used to study the effect of catalyst concentration, molar ratio of ethanol to cottonseed oil and reaction temperature for percentage yield (% yield) and percentage initial absorbance (%A _385nm) of the biodiesel. Catalyst concentration and molar ratio of ethanol to cottonseed oil were the most significant variables affecting percentage conversion and %A _385nm. Maximum predicted % yield of 98% was obtained at a catalyst concentration of 1.07% (wt/wt) and ethanol to cottonseed oil molar ratio of 20:1 at reaction temperature of 25 °C. Maximum predicted %A _385nm of more than 80% was obtained at 0.5% (wt/wt) catalyst concentration and molar ratio of 3:1 at 25 °C. The response surfaces that described % yield and %A _385nm were inversely related. Gossypol concentration (% wt), oxidative stability and %A _385nm of biodiesel were found to be highly correlated with each other. Hence, color %A _385nm is a measure of the amount of pigments present in biodiesel fuels that have not yet been subjected to autoxidation. High gossypol concentration also corresponds to a fuel with high oxidative stability. The fatty acid ethyl esters (FAEE) produced from cottonseed oil had superior oxidative stability to fatty acid methyl esters (FAME) produced from cottonseed oil.     

Statistical study on the batch conversion of estevan lignite into oils using carbon monoxide and hydrogen mixtures

Batch autoclave hydrogenolysis of a Saskatchewan lignite has been conducted with CO and H₂ mixtures. Conversion, oil yield and the carbon monoxide consumption patterns were measured as a function of reaction temperature (380 — 460°C), initial cold pressure (7.1 — 11.1 MPa), contact time (10 — 50 min), and initial CO/H₂ gas composition (1/3 — 3/1 vol. %). The experimental results were obtained following an unreplicated 2⁴ factorial design. Significant models were derived for conversion and the CO consumption patterns. A relationship seems to develop between carbon monoxide consumption and the amount of oil produced. The oil yield model however showed a lack-of-fit at the F_5% level. The highest conversion and oil yield experimentally obtained were 85.3 and 63.4% respectively, on the lignite m.a.f. basis. In general greater hydrogenation but less deoxygenation occurred at the lower temperature.     

寻甸褐煤的催化多段加氢热解过程

利用热重技术对寻甸褐煤的催化多段加氢热解过程进行了研究,考察了不同的催化剂制备方式对该过程的影响,并在固定床上研究了产物的分布和焦油组成.结果表明：催化剂的存在明显增加了自由基的生成及其被氢化饱和的速率,从而导致了总转化率的提高;与不加催化剂相比,当Mo负载量为0.2%时, 350 ℃的停留过程使转化率从26%激增到50%;不同Mo负载量下的停留对加氢热解过程中的低温峰和高温峰的影响不同;经超声处理催化剂制备的煤样,其加氢热解在任何温度下的转化率均高于用电磁搅拌制备的结果,而且热解温度越高其效果越明显;超声负载催化剂的多段催化加氢热解的总转化率远远高于通过电磁搅拌制备的煤样;催化条件下的多段加氢热解过程改变了产物的分布,并明显提高了焦油中轻质组分的含量,苯类、酚类和萘类收率分别增加了42%、37.8%和115.4%.     

Dependence of coal liquefaction behaviour on coal characteristics. 1. Vitrinite-rich samples

The liquefaction behaviour of a number of vitrinite-rich coals has been determined in batch autoclaves at temperatures of 385–425 °C and pressures of about 8.6 MPa (85 atm) of hydrogen. In one set of experiments, impregnated ammonium molybdate was used as catalyst, with no added liquid as vehicle. In a second set, a proprietary catalyst was used and anthracene oil served as vehicle. Lignites, sub-bituminous, medium-volatile and low-volatile bituminous coals gave relatively poor conversions. However, a lignite sample that had been subjected to ion-exchange treatments gave high conversion, and the viscosity and structural parameters of the products varied with the nature of the treatment. In general the highest conversions were observed for coals in the high-volatile bituminous range, but within this broad range and for the comparatively small set of samples studied neither these data nor the structural characteristics of the products show any very evident correlation with rank parameters or with the geological history of the sample. Two geologically young bituminous coals from the Pacific Coal Province gave excellent conversions; both had very high mineral-matter contents, a fact that may be very relevant.     

The investigation of coal-pyrite/lignite concentration and their separation in the artificial mixture by oil agglomeration

In this study, the concentration of coal-pyrite and lignite taken from Yozgat-Ayridam (Turkey) Coal Management was investigated by oil agglomeration.In the previous studies, the agglomeration of coal-pyrite was investigated using different bridging liquids (fuel oil, diesel oil and kerosene) and the combination of reagent (KEX, Acorga M5397)+kerosene. When using only bridging liquids, the agglomeration recovery of pyrite was very low. To increase the hydrophobicity of pyrite, KEX was used. However, the pyrite was not agglomerated with an acceptable recovery. But when using Acorga M5397, which is a chelating reagent, the agglomeration recovery of pyrite was increased. The pyrite was agglomerated with a recovery of 76.70 wt% by single-stage agglomeration.In the optimum conditions which were determined for coal-pyrite, the agglomeration recovery of lignite was investigated. It was found that the lignite could not be agglomerated with an acceptable recovery.To investigate the separation of coal-pyrite and lignite, the artificial mixture of coal-pyrite and lignite was prepared with the weight ratio of 1/4 of coal-pyrite and lignite. It was found that the pyrite could be agglomerated at a recovery of 96.54% with three-stage agglomeration process. The lignite concentrate was produced with a recovery of 73.96 wt% and the pyrite content of 0.86 wt%.These findings showed that the coal-pyrite and lignite could be separated by oil agglomeration using appropriate reagent and bridging liquid.     

Production of bio‐crude from forestry waste by hydro‐liquefaction in sub‐/super‐critical methanol

Hydro‐liquefaction of a woody biomass (birch powder) in sub‐/super‐critical methanol without and with catalysts was investigated with an autoclave reactor at temperatures of 473–673 K and an initial pressure of hydrogen varying from 2.0 to 10.0 MPa. The liquid products were separated into water soluble oil and heavy oil (as bio‐crude) by extraction with water and acetone. Without catalyst, the yields of heavy oil and water soluble oil were in the ranges of 2.4–25.5 wt % and 1.2–17.0 wt %, respectively, depending strongly on reaction temperature, reaction time, and initial pressure of hydrogen. The optimum temperature for the production of heavy oil and water soluble oil was found to be at around 623 K, whereas a longer residence time and a lower initial H₂ pressure were found to be favorite conditions for the oil production. Addition of a basic catalyst, such as NaOH, K₂CO₃, and Rb₂CO₃, could significantly promote biomass conversion and increase yields of oily products in the treatments at temperatures less than 573 K. The yield of heavy oil attained about 30 wt % for the liquefaction operation in the presence of 5 wt % Rb₂CO₃ at 573 K and 2 MPa of H₂ for 60 min. The obtained heavy oil products consisted of a high concentration of phenol derivatives, esters, and benzene derivatives, and they also contained a higher concentration of carbon, a much lower concentration of oxygen, and a significantly increased heating value (>30 MJ/kg) when compared with the raw woody biomass. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

褐煤负载有机钠盐水蒸气气化实验与动力学分析

基于模拟双马来酰亚胺工业废液,通过对负载乙酸钠和碳酸钠的褐煤水蒸气气化的实验,分别研究了反应温度、催化剂负载浓度对气化特性的影响。结果表明:碳酸钠和乙酸钠作为催化剂对褐煤水蒸气气化都具有明显的催化效果,但当碳酸钠的负载量超过10%之后会出现抑制现象,而乙酸钠作为催化剂并没有出现抑制现象;在相同温度或负载浓度的条件下,负载乙酸钠的催化效果要优于负载碳酸钠时的催化效果。对实验数据进行动力学分析发现,均相模型和缩核模型都能够有效描述本研究的实验结果。     

Coliquefaction studies of waste polymers and lignite influenced by acidic and oil‐soluble catalysts

A detailed study of postconsumer polymer coliquefaction with lignite influenced by two acidic and two oil‐soluble catalyst precursors is presented in this article. The conversion of reacting solids into gaseous and liquid products was determined in four initial series of coprocessing experiments performed with and without catalysts on a suite of four heavy organic solvents. Based on the results obtained, two newer series of experiments were also designed and carried out, aimed at the optimization of this complex transformation using this time lignite oxidatively pretreated. It was found that the mentioned hydroconversion is a promising way of hydrocarbon synthesis and that oxidatively pretreated lignite proved superior to the raw material. It was also found that the oil‐soluble catalysts employed indicated a particularly noticeable activity increase, influencing, thus, the efficacy of the conversions achieved. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1323–1330, 2000     

The Optimization of the Production of Methyl Esters from Corn Oil Using Barium Hydroxide as a Heterogeneous Catalyst

In recent years, vegetable oils, as renewable raw materials, became a promising feedstock for chemicals and biodiesel production. The main products derived from oils are esters of fatty acids, especially methyl esters, obtained by their transesterification with methanol, in presence of acid or alkaline catalysts. The use of such catalysts implies the need for washing operations, which leads to environmental pollution. In the present paper, the response surface methodology based on a central composite design, has been developed to optimize the process of transesterification of corn oil. Ba(OH)₂ in presence of diethyl ether was used as catalyst. A quadratic polynomial equation was obtained. It correlates the reaction parameters [methanol/oil molar ratio (x _r), reaction time (x _t) and catalyst concentration (x _c)] with methyl esters yield. Analysis of variance analysis showed that only methanol/oil molar ratio and catalyst concentration have had the most significant influences on the conversion. The maximum methyl esters yield was obtained using the following optimum parameters: methanol/corn oil ratio of 11.32, reaction time of 118 min and catalyst concentration of 3.6 wt%.     

Characteristics and composition of lignites and boiler ashes and their relation to slagging: The case of Mae Moh PCC boilers

In order to examine the cause of occasional slagging problems, a dedicated 7-day sampling and data collection were carried out on two 300-MWe units of Mae Moh power plant owned by the Electricity Generating Authority of Thailand. The properties of feed lignite varied from low (∼11% in ash) to medium (∼18% in ash) CaO content during the sampling period. The elemental content was measured for collected fly ashes, bottom ashes and slags, and compared with those of the feed lignite. The analysis and operational data obtained during the 7-day sampling period were compared with those obtained from the additional laboratory-scale investigation of high Ca lignites and those obtained from one of the units during another period when slagging problem was experienced. The study found that, apart from Ca, the concentration of three other elements and their compounds - Fe, Al and Si, plays a very important role in slag formation and its control while these lignites are used in large utility units. The flue exit gas temperatures (FEGT) of the unit experiencing slagging were also found to approach the initial deformation temperatures (IT) of the lignite ash. The solution appears to be the monitoring of the concentration of four elements, i.e. oxides of Ca, Fe, Al and Si in the feed lignite, and in ensuring through proper mining or blending that concentration of CaO, Fe₂O₃ and Al₂O₃ is kept <20%, ∼15% and >15%, respectively, at all times. Also, it is important that the FEGT during operation is kept sufficiently below the IT of the ash of feed lignite at all times.     

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。     

Production of coal pitch by the oxidation of coal extracts in anthracene oil

If anthracene oil is used to produce extracts from 2B, D, 2G, GZh coal, coal pitch may be produced by oxidation of the extracts using atmospheric oxygen. The resulting pitch is characterized by higher yield and by a greater coke residue than is observed in pitch produced from anthracene oil without added coal in analogous conditions. Ultrasound treatment for 3 h on an IL10-0.63 unit ensures complete solution of the coal (4–9%) in the anthracene oil. The mineral component of the coal also enters the solution and is then concentrated in the pitch formed. To reduce the ash content of the pitch, ash must preliminarily be removed from the initial coal. For the example of 2B and D coal, it is found that reducing the ash content of the coal to ~1% and subsequent solution in the anthracene oil to a coal concentration of 5–8% yields a coal extract such that pitch with no more than 0.4% ash and up to 41% coke residue is formed on oxidation by atmospheric oxygen.     

Comparative performance of impregnated molybdenum-sulphur catalysts in hydrogenation of Spanish lignite

Hydrogenation of a Spanish lignite of 12% sulphur content was conducted using three molybdenum-containing catalysts impregnated into the lignite: ammonium tetrathiomolybdate, a sulphided ammonium heptamolybdate, and molybdenum disulphide. The conversions to liquids and hydrodesulphurization were investigated for a series of residence times and temperatures. At 275 °C, the ammonium salts provide no greater conversion or sulphur removal than obtained in the absence of catalyst, because these salts have not decomposed to an active catalyst at this temperature. However, lignite impregnated with molybdenum disulphide does experience greater conversion and desulphurization than lignite reacted without catalyst. At 325 °C, the lignite impregnated with the ammonium salts gives conversions and desulphurization substantially superior to that achieved with molybdenum disulphide or without catalyst. This is attributed to the superior dispersion that can be achieved by impregnation using a solution of a soluble salt rather than a slurry of the insoluble disulphide. The best conversions, liquid yield, and desulphurization are achieved using impregnated sulphided ammonium heptamolybdate.     

Effect of solvent on molecular composition in coal liquefaction

The product from uncatalysed liquefaction of lignite using synthesis gas (CO-Steam process) was examined by column chromatography, high-resolution mass spectrometry, gas chromatography-mass spectrometry, and low-voltage mass spectrometry. The nature of the vehicle solvent affected the type and distribution of compounds in the product oil. Anthracene oil and recycle oil as solvents gave mainly aromatics and phenols. When tetralin was used as solvent, the product showed larger amounts of oxygen compounds, more hydroaromatic compounds, and a greater degree of alkylation in high-molecular-weight aromatics. Tetralin, therefore, appears to be a more powerful hydrogen donor than anthracene oil or recycle oil in stabilizing intermediate fragments that would otherwise repolymerize. Carbon-number analysis data for liquids prepared using three different solvents are presented.