The upgrading of petroleum residuum and coal in catalytic coprocessing

The combined catalytic reactions using different types of petroleum residuum and coal were performed at 425°C and 60 minutes in the presence of hydrogen to upgrade both materials to high quality synthetic fuels. In order to improve this coprocessing technology, the effect of the chemical and physical properties of both materials on the coprocessing product yields was investigated through a parametric study. In all reaction combinations, substantial increase in maltene production and high coal conversions of over 84% were observed regardless of petroleum residuum type and coal rank. The petroleum residuum properties of specific gravity and conradson carbon residue had effects on asphaltene production and coal conversion. The results of quantitative analysis for the amount of coal upgraded during coprocessing lead to conclude thata large amount of coal converted to maltene fraction due to high catalytic activity and reactive hydrogen donor richness of coprocessing system. However, most of the heavier fractions were formed primarily from coal regardless of the type of residuum used.     

Catalytic coprocessing of coal and petroleum residues with waste plastics to produce transportation fuels

Coprocessing reactions with waste plastics, petroleum residues and coal were performed to determine the individual and blended behavior of these materials using lower pressure and cheaper catalysts. The plastic used in this study was polypropylene. The thermodegradative behavior of polypropylene (PP) and PP/petroleum residues/coal blends were investigated in the presence of solid hydrocracking (HC) catalysts. A comparison among various catalysts has been performed on the basis of observed temperatures. The higher temperatures of initial weight loss of PP shifted to lower values by the addition of petroleum residues and coal. The catalysts were also tested in a fixed-bed micro reactor for the pyrolysis of polypropylene, petroleum residues and coal, alone and blended together in nitrogen and hydrogen atmosphere. High yields of liquid fuels in the boiling range 100-480 °C and gases were obtained along with a small amount of heavy oils and insoluble material such as gums and coke. The results obtained on the coprocessing of polypropylene with coal and petroleum residues are very encouraging as this method appears to be quite feasible to convert plastic materials into liquefied coal products and to upgrade the petroleum residues and waste plastics.     

The effect of coal rank on flash hydropyrolysis of Chinese coal

Fourteen kinds of Chinese coal were flash hydropyrolysed in a small entrained reactor at 750°C and hydrogen atmosphere. The results indicated that carbon content and yields of liquid hydrocarbon, H/C and yields of gaseous hydrocarbon, oxygen content and yields of CO, CO₂ and H₂O show better corresponding relations. The correlations between yields of CH₄, C₂ and C₂H₆ and H/C can be expressed as Y_CH4=−42.2+100(H/C)(0.51<0.59), Y_CH4=15.8+1.67(H/C)(0.59<1.11), Y_C2=0.347+4.78(H/C), Y_C2H6=0.352+4.74(H/C); The correlations between yields of CO₂ and water and oxygen content can be expressed as: Y_CO2=−0.0437+0.0355(O); Y_H2O=0.726+0.467(O). The cutoff points of flash hydropyrolysis for coal are that H/C is 0.6 and carbon content is 85%. The coal which H/C is lower than 0.6 and carbon content is higher than 85% is usually not good for flash hydropyrolysis. It is found that influence of coal rank on yields of liquid, gas product and total yields of product in flash hydropyrolysis can be expressed as of H/C in coal.     

XRD evaluation of KOH activation process and influence of coal rank

Three Japanese coals with different rank (Ohmine, Miike and Taiheiyo coals) were activated with KOH from 300 to 850 °C. Higher rank coal with lower oxygen content showed a high yield and also a large specific surface area determined by N₂ adsorption isotherms. X-ray diffraction (XRD) patterns of the activated carbons were measured to characterize stacking structure of aromatic layers by standardized analysis of coal by XRD method, considering the presence of slit-shaped micropores among the stacking structure. Structural parameters obtained by this method were related to the yield and the surface area in order to discuss the feature of micropores developed during the activation.     

Additive effect of tyre constituents on the hydrogenolyses of coal liquefaction residue

A numerous amount of waste tyre is landfilled or dumped all over the world, which causes environmental problems. The coal liquefaction residue (CLR) produced in 30% yield through the process supporting unit of the NEDOL coal liquefaction process. As one of the effective method for processing both CLR and waste tyre, simultaneous hydrogenolyses of these materials was carried out. The synergistic effects to upgrading, such as the increase of oil yield and the decrease of asphaltene yield, were appeared on the hydrogenolyses. However, the interaction between tyre and CLR to synergistic effects was not clarified. In this study, the effects of hydrogen donatable solvent (tetralin) and pressurized gas on the hydrogenolyses of CLR and tyre constituents are discussed. As a result, it was clarified that both tetralin and the pressurized H₂ gas were necessary for the simultaneous hydrogenolyses of CLR and tyre. The hydrogen shuttling from H₂ gas and tetralin was enhanced by the aromatic compounds derived from tyre rubber constituents (styrene-butadiene rubber and natural rubber). The hydrogenation of the heavy oil constituent in CLR was enhanced by carbon black and the inorganic constituents in tyre, such as zinc oxide and sulfur. Accordingly, the synergistic effects on the simultaneous hydrogenolyses of CLR and tyre were appeared because the hydrogen shuttling occurred by the aromatics from tyre rubber constituents, and the hydrogenation was enhanced by carbon black and the inorganic constituents in tyre.     

芳香族溶剂对低阶煤轻度加氢改质的影响

为考察溶剂供氢性对加氢改质的影响,以四氢萘与甲基萘为溶剂,对低阶煤进行轻度加氢,考察不同反应条件对转化率、气产率、氢耗及产物分布的影响。结果表明,温度对转化率及气产率的影响显著,在360~430℃,随着温度升高,转化率及气产率增加显著;在氢压低于4 MPa时,脱氢反应体现较为显著,体系中有大量萘生成,压力对转化率及气产率的影响不明显,低压条件下,四氢萘供氢起主导作用;气相氢并不直接参与煤的反应,而是与溶剂发生加氢反应,进而由溶剂向煤供氢;低阶煤轻度加氢改质是一个快速反应的过程,反应时间不宜过长,30~60 min为宜;对改质后产物进行分析,黏结指数G75,灰分0.3%,硫含量0.3%。     

Thermal and catalytic coprocessing of waste tires with coal

Thermal and catalytic coprocessing of waste tires and coal was performed using waste tires from two sources and coals of three different ranks. Bituminous coals yielded higher conversions than either subbituminous coal or lignite when coprocessed with waste tire. In this study waste tires from tire buffing processes were used. One of these materials provided by Rouse Rubber represented the typical composition of most automotive tires while the other material supplied by Uniroyal contained a substantial amount of mineral fillers because the material obtained from buffing the white lettering on the sidewall of the tire. Each of these waste tires when used as a solvent in coprocessing had different solvent qualities; the Rouse waste tire was typically a much better solvent for coal than Uniroyal waste tire. Catalytic coprocessing of waste tires with coal using slurry phase hydrogenation catalysts increased total and coal conversions compared to thermal reactions. Addition of carbon black to the coprocessing system had minimal effect on the conversion or product distributions, while the addition of the heat-treated residue from the liquefied waste tires resulted in enhanced conversion and hexane solubles production from coprocessing systems. The mineral-rich Uniroyal residue was more active than the carbon black-rich Rouse residue. Combining the residues with slurry phase hydrogenation catalysts enhanced their activity even further.     

Kinetics of tyre char oxidation under combustion conditions

Combustion of tyre char particles with diameters between 102 and 212 μm was performed in an experimental laboratory reactor, at temperatures between 750 and 850 °C, in an oxidative atmosphere with up to 10 vol.% O₂ at 1 bar. The observed char combustion time varied from about 9 s at 750 °C to about 4 s at 850 °C. Under these conditions the experimental data indicated increasing mass transfer resistance with temperature. A diffusion reaction model was employed to study the effects of simultaneous mass transfer and kinetics in the experiments. An intrinsic reaction rate for tyre char combustion was estimated and comparison with literature data revealed good agreement.     

Hydrothermal dewatering of lower rank coals. 2. Effects of coal characteristics for a range of Australian and international coals

A range of lower rank coals from Australia, Indonesia, and the USA have been dried under hydrothermal dewatering conditions at 320 °C for 30 min in a 500 ml autoclave using a 1:3 dry coal/water mixture. The hydrothermally dewatered (HTD) products were characterised by elemental analysis (both organic and inorganic components), volatile matter determinations, moisture holding capacity, calorific value and mercury porosimetry. The total organic carbon (TOC) and the concentrations of inorganics in the waste waters were also determined. The coals fell into two broad groups, the lower rank Australian brown coals with gross calorific values in the range 10-16 MJ/kg (afm) and the higher rank Indonesian and US coals with gross calorific values in the range 18-25.5 MJ/kg (afm). Rank was the major factor influencing the properties of the HTD products but lithotype was also important. TOC values of the waste water from drying of the low rank Australian coals were much higher than those of the waste water from the higher rank coals. Important variations in the amount of leached calcium, magnesium, and iron were noted.     

Model for predicting catalytic and non-catalytic liquefaction of coal

Based on the non-uniform constitution of coal, coal liquefaction is conveniently described by a mathematical model, in which the overall liquefaction is achieved in two stages. Both stages consist of a series of parallel irreversible reactions, of which the activation energies obey normal distribution. When catalysts exist in the reaction system, they can decrease the activation energies of the second stage, but have little effect on the reactions of the first stage. This model improves the understanding of why some coal constituents are easy to liquefy while others are not. It successfully predicts that apparent activation energies increase with conversion. The predicted conversion values derived from this model show good agreement with our experimental data as well as with the data reported in the literature.     

Relationship between properties and conversions of North Bohemian coals during coal/oil coprocessing

Eleven low rank coals from North Bohemian mines were comprehensively characterized by using a number of analytical methods. Along with common proximate and ultimate analysis, spectroscopic techniques, porosity measurement, extractability and swelling in organic solvents were used. Although coals were of similar geological origin, some of their characteristics largely differed from one coal to another. Coals were coprocessed with petroleum vacuum residue at 440°C for 1 h and yields of reaction products and coal conversions were determined. Despite the differences in composition and properties, the coals provided similar conversions and yields of distillable reaction products. A small positive effect on coal conversion was found for ash content and microporosity of coals. However, a small negative effect was found for carbon content, optical reflectance and solvent extractability of coals.     

The use of coal liquefaction catalysts for coal/oil coprocessing and heavy oil upgrading

The catalytic hydrogenation of heavy oil and mixed coal-heavy oil (coprocessing) systems has been the focus of a recent study at the Federal Energy Technology Center (FETC). The intent of this effort was to extend the use of coal liquefaction technologies to heavy oil upgrading and coprocessing systems. Specifically, new dispersed molybdenum-based catalysts developed at FETC and a novel silica-doped hydrous titanium oxide (HTO : Si)-supported NiMo catalyst developed at Sandia National Laboratories (SNL) were tested in these systems. The results indicate the potential of coal liquefaction catalysts for use in coprocessing and heavy oil upgrading. High conversions of coal–oil mixtures were observed with dispersed catalyst loadings as low as 100 ppm Mo. Similar results were observed in heavy oil systems. Also, the novel NiMo/HTO : Si catalyst was at least as effective as commercially-available supported catalysts (e.g. Amocat 1C) for conversion of high boiling point material to distillable products and aromatics removal.     

Property of upgraded solid product from low rank coal by thermal reaction with solvent

The upgrading process for the production of clean solid fuel from subbituminous and brown coals is receiving current attention. We propose upgrading of low rank coal with solvent at 350–450 °C under 2 MPa of initial nitrogen atmosphere. Upgrading of German Fortuna brown coal (heating value: 25.4 MJ/kg, daf) at 440 °C in the presence of t-decalin gave 66 wt.% of solid products with heating value of 35.4 MJ/kg, daf. Gaseous product consisted of mainly carbon dioxide (80 wt.%) and methane. Therefore, cracking of carboxylic functional group took place effectively in this condition. Ignition temperature of the upgraded solid product, measured by thermogravimetry under airflow, increased to higher than 400 °C, while raw brown coal showed corresponding temperature of 290 °C. From the XRD patterns by X-ray diffractometry for the upgraded product, distribution of aromatic stacking layer number (N) shifted to larger N by upgrading with solvent. It is obvious that the effective carbonization occurs under these conditions. This suggests the possibility to produce value-added solid fuel or carbonaceous liquid and solid chemicals, from low rank coal, whose quality is comparable to the bituminous coal.     

Effect of process conditions on co-liquefaction kinetics of waste tire and coal

Thermal and catalytic liquefactions of waste (recycled) tire and coal were studied both separately and using mixtures with different tire/coal ratios. Runs were made in a batch tubing bomb reactor at 350–425°C. The effect of hydrogen pressure on the product slate was also studied. Mixtures of tire components and coal were used in order to understand the role of the tire as a solvent in co-liquefaction. In the catalytic runs, a ferric-sulfide-based catalyst impregnated in situ in the coal was used. Both the tire components and the entire tire exhibit a synergistic effect on coal conversion. The extent of synergism depends on temperature, H₂ pressure and the tire/coal ratio. Experiments with coal and tire components show that the synergistic effect of tire is due to the rubber portion of the tire and not the carbon black. The synergism mainly leads to an increase in the yields of asphaltenes, which are nearly double those in the coal-only runs at 400°C. The conversion of coal increases dramatically using the catalyst, but the catalytic effect is attenuated somewhat in the presence of tire, especially at high tire/coal ratios. The data were analyzed using a consecutive reaction scheme for the liquefaction of coal to asphaltenes and thence to oil+gas, both reactions being of second order; a second-order conversion of tire to oil+gas; and an additional synergism reaction when both coal and tire are present, first-order in both coal and tire. Parallel schemes were assumed for thermal (uncatalyzed) and catalyzed reactions. The uncatalyzed liquefaction of coal has a low apparent activation energy, 36 kJ/mol, compared to those for the synergism reaction (84 kJ/mol) and the catalytic coal liquefaction (158 kJ/mol). The conversion of asphaltenes to oil+gas is relatively independent of temperature and of the presence of the catalyst. The catalyst appears to play a significant role in the conversion of coal to asphaltenes, but a negligible role in the synergism reaction.     

废轮胎与煤共焦化焦油分析

用色谱-质谱联检技术(GC-MS)检测配煤与废轮胎及其共焦化焦油,研究废轮胎对煤焦油收率和质量影响。研究表明:废轮胎单独焦化焦油主要由C6～C11的脂肪烃、脂环烃和苯类物质所组成,比首钢炼焦配煤单独炼焦焦油质轻;在配煤中添加3%废轮胎共焦化时,两者间有协同效应,使焦油收率提高,对焦油组分中酚类、酯类物质影响最为显著,使焦油轻质化;同条件下废轮胎粒度影响焦油收率及焦油中的各组分,但影响力度不一。     

Effects of solvent composition on coprocessing coal with petroleum residua

The effect of solvent composition on coprocessing of coal and petroleum solvents is examined under a variety of reaction conditions. The effects of solvent modification procedures on enhancing methylene chloride/methanol (MeCl/MeOH) soluble coal conversion and pentane soluble oil production are studied. Solvent modification procedures performed prior to coprocessing reactions include pentane deasphalting, catalytic hydrotreatment, H-donor addition, and blending of coal-derived liquids with petroleum solvents. Oil production and coal conversion were variously affected by the different solvent modifications. Prior hydrotreatment of petroleum solvents generally enhanced coal conversion, as did H-donor addition. The presence of a hydrotreating catalyst exerted a leveling effect on the effects of solvent modification. Blending of coal liquids and petroleum solvents resulted in complex and not readily predictable interaction. Solvents yielding the highest MeCl/MeOH soluble coal conversion were not generally the optimal solvents for pentane soluble oil production.     

Interaction mechanism of flocculants with coal waste slurry

Coal tailings are the inevitable by-product of coal mining and preparation plants, and often are problematic in terms of dewatering and solid-liquid separation. The interaction of multi-component fine coal tailings with various coagulants and flocculants are important in dewatering processes. Tunçbilek coal preparation plant wastes are composed of 81% inorganic solids with negative surface charges dominating at all pHs. The highest settling rate and turbidity values without flocculant are obtained at natural pH of 8.3 due to the presence of inorganic ions in the suspension particularly Mg²⁺and Ca²⁺that act as natural coagulants. Additon of medium and low charge density anionic flocculants with high molecular weight at natural pH produced higher settling rates at lower dosages than nonionic and cationic flocculants. It shown that the charge density of anionic flocculants has a significant effect on both settling rate and supernatant turbidity, also the settling rate increases with increasing the degree of anionicity. Anionic flocculants having high molecular weight and high anione charge density produced flocs at sufficient size necessary for settling conditions, yet anionic flocculants having low charge density were more effective in the clarification of suspensions containing clay minerals of high stability. The multivalent ions act as a bridge between negatively charged coal, quartz and clay minerals with anionic groups (-CH₂-(CH-CO)-COO groups) of the polymer. Non-ionic flocculants required higher dosages than other flocculants to achieve equivalent settling rates; though excellent turbidity values were obtained in most common pH values. Cationic flocculants of higher charge densities (%70) achieved good settling rates and low supernatant turbidities (9.9 NTU) at natural pH for a dosage of 119.7 g/t-solids flocculant. An interaction mechanism of each polymer type with different components of the tailings is proposed.     

低阶煤预处理技术的研究进展

简述了低阶煤的利用现状及热转换过程中存在的问题,总结了水热预处理、酸预处理、溶剂溶胀、热预处理、氧烷基化及加氢预处理等预处理技术对低阶煤的结构、热解反应性和焦油品质及收率的影响。提出了合适的预处理技术可以降低煤的液化条件,提高煤的热转换效率,改善焦油品质,实现低阶煤的清洁高效利用。     

Fundamental ash deposition characteristics in pulverized coal reaction under high temperature conditions

Three types of coal with the different melting temperature and ash content were burned under the condition of high-temperature air pulverized coal reaction. A water-cooled tube was inserted into the furnace to make the ash adhere. Particle size and composition distributions of ash particles in both reacting coal particles and depositing layer were analyzed, using a Computer Controlled Scanning Electron Microscope, to study the deposition behaviors of ash particles. As a result, quantity of the ash deposition on the tube surface increases with a decrease of the melting temperature of coal ash. Index of fraction of the ash deposition depended on the coal type. For structure of the deposit layer, fine particles of size less than 3 μm mainly consisted of the initial layer for three types of coal, and the thickness was about 30 μm. Deposition of fine particulates of about 3 μm became a trigger of initial deposition at the stagnation point of tube even if irrespective of coal type is burned. The chemical compositions of ash particles in the reacting particles differed from those in the initial deposition layer. The deposition phenomenon relates to the particle size distribution of ash formed, the flow dynamics surrounding the probe, the chemical compositions in each ash particle and so forth.     

低阶煤提质技术现状及完善途径

为实现低阶煤的清洁利用,分析了国内外低阶煤提质技术研究现状,重点介绍了以移动床、回转窑、流化床、气流床为反应器的典型热解技术。针对低阶煤热解技术焦油收率低,焦油重质组分和粉尘含量高等技术难题,提出了低阶煤提质技术完善途径。应根据不同粒径的煤料选择适宜的热解工艺,粉煤一般采用固体热载体加热;延长煤颗粒在低温区的停留时间可降低焦油的二次反应,提高焦油收率;内热式热解技术容易导致焦油含尘量高。应依据不同煤质煤的不同组分而分级转化,通过反应调控抑制重质组分生成,实现热解产物定向,最大程度获得轻质油气产品,开发新型反应器抑制粉尘产生及夹带,实现低阶煤的清洁高效利用。