Hydro-treatment of a direct coal liquefaction residue and its components

Direct coal liquefaction residue (DCLR) contains a significant fraction of heavy liquids. Better use of DCLR is an important task to overall economy of direct coal liquefaction. This paper studies hydro-treatment of a DCLR and its solvent-extraction components under typical direct coal liquefaction conditions. The DCLR is found hydro-treatable, resulting in more light products and less heavy products. In one case, 40 wt% heavy fractions in the DCLR are converted into light fractions. Hexane soluble fraction (HS) is the most stable while pre-asphaltene fraction (PA) is the most active during the hydro-treatment. Some synergetic effect can be observed when DCLR is treated as whole. The fractions of DCLR, before and after the hydro-treatment, are subjected to FTIR and NMR analyses, which show increase in hydrogen content and decrease in oxygen content in HS fractions after the hydro-treatment. GPC analysis reveals that the hydro-treatment results in slight decreases in molecular weight of HS fraction. The data seem to suggest that separation and hydro-treatment of liquid fractions from a DCLR is a viable option for high oil yield.     

煤炭直接液化残渣加氢研究进展

在煤炭直接液化生产过程中,会产生占液化原煤质量30％左右的液化残渣。它是一种高碳、高灰和高硫的物质,主要由未转化的煤、液化中间产物、无机矿物质以及煤液化催化剂组成。煤炭直接液化残渣有很高的利用价值,无论从经济角度还是环保角度出发,都需要对残渣进行利用,这也是煤炭直接液化工业化必须解决的问题。综述了煤炭直接液化残渣的来源、组成、性质、加氢研究现状及应用等。     

Study of the preasphaltenes of coal liquefaction and its hydro-conversion kinetics catalyzed by SO4/ZrO2

The investigation of hydro-conversion behavior of the heavy intermediate products derived from coal direct liquefaction is advantageous to optimize the technological conditions of direct coal liquefaction and improve the oil yield. In this paper, the hydro-conversion of preasphaltenes catalyzed by SO₄²⁻/ZrO₂ solid acid was investigated based on the structural characterization of preasphaltenes and its hydro-conversion products, and the determination of products distribution and the kinetics of preasphaltenes hydro-conversion. The results indicated that the content of condensed aromatic rings increased, and the contents of hydrogen, oxygen and aliphatic side chains of preasphaltenes decreased with the increase of coal liquefaction temperature. The preasphaltenes showed higher hydro-conversion reactivity while SO₄²⁻/ZrO₂ solid acid was used as catalyst. Higher temperature and longer time were in favor of increasing the conversion and the oil + gas yield. The conversion of preasphaltenes hydro-conversion under 425 °C, for 40 min reached 81.3% with 51.2% oil + gas yield. SO₄²⁻/ZrO₂ solid acid was in favor of the catalytic cracking rather than the catalytic hydrogenation in the hydro-conversion of preasphaltenes. The activation energy of preasphaltenes conversion into asphaltenes was 72 kJ/mol. The regressive reactions were only observed at a higher temperature.     

非纯氢气氛下煤直接液化的研究

介绍了4种非纯氢气氛下煤的直接液化技术研究现状:是在甲烷气氛下进行煤的液化;二是在焦炉气下进行煤的热解和加氢及模拟焦炉气进行煤的液化;三是在合成气或合成气-水体系下进行煤的液化;四是在CO和H2O体系下进行煤的液化。分析了上述几种非纯氢气氛下煤液化的转化率和液化产物的选择性等问题,并指出发高活性和高选择性的催化剂是非纯氢气氛下煤直接液化的研究方向。     

Exfoliated MoS2 catalysts in coal liquefaction

A technique is described for the application of MoS₂ to coal particles. The method was used to determine the importance of several parameters to the performance of this direct coal liquefaction catalyst. Improved performance was obtained when MoS₂ was intercalated with lithium, then exfoliated in a mixture of tetrahydrofuran and water in the presence of coal. Performance was compared by subjecting dried coal/catalyst mixtures to uniform microautoclave liquefaction tests. Measurements of coal conversion and hydrogen consumption show that a combination of reduction of the MoS₂ stacking and improved coal/catalyst dispersion is beneficial.     

神华上湾煤恒温阶段直接液化反应动力学

为考察神华上湾煤的直接液化性能及反应动力学,以加氢蒽油-洗油混合油作为溶剂、负载型FeOOH作为催化剂,在0.01 t·d^-1煤直接液化连续实验装置上考察了不同反应温度（435~465℃）、不同停留时间（7~110 min）下液化产品组成的演变规律。研究发现,随着煤的裂解及加氢反应的进行,煤及沥青类物质（PAA）收率不断减小,重质液化产物逐步向轻质液化产物转化。当反应温度为455℃、停留时间为90 min时,煤转化率为90.41%（质量分数（,油收率为61.28%（质量分数（。随着反应条件进一步苛刻,油收率下降。基于上湾煤直接液化反应特性及其产物收率变化规律建立了11集总煤直接液化反应动力学候选模型,以BFGS优化算法对实验数据搜索、选优,确定了动力学模型参数。检验结果表明所建立的动力学模型可用于恒温阶段直接液化行为的模拟计算。     

煤直接液化制油技术研究现状及展望

煤直接液化制油技术是促进煤炭清洁高效利用、缓解石油供需矛盾、保障我国能源安全的重要途径。为全面了解煤液化反应机理、动力学、催化剂及工艺的全过程,促进煤直接液化技术基础研究的快速进步和新工艺的开发,笔者综述了国内外在煤加氢液化反应机理、反应动力学、催化剂以及液化工艺方面取得的研究成果,重点介绍了德国IGOR、日本NEDOL和我国的神华煤液化工艺,分析了这些典型煤液化工艺的开发历程和特点;指明了煤直接液化制油技术发展趋势。煤的加氢液化反应是自由基反应机理,是一系列顺序反应和平行反应的综合结果,包含煤的热解、自由基加氢、脱杂原子和缩合反应等,总体上以顺序反应为主。借助同位素示踪、原位实时检测、等离子体技术以及微波快速加热技术等现代分析方法和试验手段,重点研究自由基的产生速率、活性氢产生速率及定量传递机理,有助于深入认识和精准阐明煤加氢液化反应机理。各国学者利用不同的研究方法,针对不同煤种、催化剂、工艺条件和供氢溶剂等,建立了各种各样的动力学模型。动力学模型从单组分到双组分和多组分,从连续反应、平行反应到复杂的网络反应,从最初的一步反应到后来较为合理的多段反应,模型越来越复杂,越来越接近工业应用。根据反应阶段不同进行分段处理的多组分"集总"反应动力学模型将是今后煤加氢液化反应动力学发展的主要方向。借助先进分析手段及科学的处理方法,建立真正揭示不同条件下煤液化动力学规律的通用型动力学模型是未来的发展趋势。借助纳米合成、等离子体等高新技术,调控组分配伍、降低催化剂粒径、优化制备方法是制备高活性催化剂的有效手段。强化系统合理配置和优化集成,重视煤的温和液化和分级转化,优化产品结构,发展直接液化-间接液化耦合技术是煤直接液化未来的发展趋势。     

超声波辐射溶胀对煤炭直接液化性能的影响

为探讨超声波辐射溶胀在煤炭直接液化过程中的积极作用,以吡啶为溶胀剂对神华煤进行了超声波辐射条件下的溶剂溶胀处理,通过对溶胀过程中不同溶胀时间煤样的溶胀度与质量损失情况测定以及超声波辐射溶胀煤与自然溶胀煤的液化实验比较,发现超声辐射有助于煤的溶胀作用,煤液化转化率提高了3%~4%.实验表明,超声溶胀能够进一步提高煤催化加氢直接液化的反应性能.     

Liquefaction mechanism of Wandoan coal using tritium and 14C tracer methods: 2. Liquefaction using 3H labelled gaseous hydrogen

Tritium labelled gaseous hydrogen was used to clarify the role of gaseous hydrogen in coal liquefaction. Wandoan coal was hydrogenated under 5.9 MPa (initial pressure) of ³H-labelled hydrogen and in unlabelled solvents such as tetralin, naphthalene and decalin at 400 °C and for 30 min in the presence or absence of NiMoAl₂O₃ catalyst. Without a catalyst, liquefaction proceeded by addition of the hydrogen from donor solvent. The NiMoAl₂O₃ catalyst enhanced both hydrogen transfer from gas phase to coal and hydrocracking of coal-derived liquids. With NiMoAl₂O₃ catalyst, liquefaction in naphthalene solvent proceeded through the hydrogen-donation cycle: naphthalene → tetralin → naphthalene. The amount of residues showed that this cycle was more effective for coal liquefaction than the direct addition of hydrogen from gas phase to coal in decalin solvent. The ³H incorporated in the coal-derived liquids from gas phase was found to increase in the following order: oil < asphaltenes < preasphaltenes < residue.     

神华煤直接液化项目工程示范性的思考

煤直接液化是煤炭转化的高技术产业,介绍了神华煤直接液化项目进展情况,阐述了神华煤直接液化工艺流程和技术特点以及项目采用的先进技术,结合项目对煤炭液化技术的产业化进行了分析,指出神华煤直接液化项目是煤炭液化产业化发展的典范。     

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.     

Catalytic hydrotreating of 1-methylnaphthalene as a screening test

Catalytic hydrotreating of 1-methylnaphthalene, a component of most recycle vehicles in coal liquefaction processes, can provide a useful screening test for three catalytic functions: ring hydrogenation, hydrodemethylation (HDM), and ring hydrocracking to give substituted benzenes. Detailed information is obtained from the pressure change on reaction and from gas chromatographic analyses of both the product gas and the product liquid. A commercial Co/Mo/Al₂O₃ catalyst tested at 450°C shows very little incremental HDM compared with a no-catalyst control, no ring hydrocracking, but subtantial ring hydrogenation. At 500°C, all reactions are more extensive. A low-temperature ash from Kentucky coal is relatively inactive at 450°C except for HDM.     

高分散度固体酸催化剂的液化试验研究

研制的高分散度固体酸催化剂应用于神华上湾3层煤液化试验。物料平衡在102％－106％,灰平衡在80％－82％。1^#催化剂具有很高的催化活性和选择性,获得了接近高限油收率的试验油收率。酸强度很高的Broensted酸性中心数量是显著提高液化油收率的主要固体酸。高压釜液化试验的物理升温阶段与物理－化学升温阶段分界点对应的温度,就是加氢液化反应的起始温度,首次建立了通过确定加氢液化反应起始温度来识别催化剂活性的试验方法。     

Catalytic hydrotreatment of coal-derived residua

An investigation was conducted to determine the activities of various coal-liquefaction residua during catalytic hydrotreatment. Residua produced at low- and high-severity coal-liquefaction conditions were employed, as well as a nondeashed residuum produced at low-severity conditions. All experimental runs were performed in a continuous-flow hydrotreating unit using Shell 324M catalyst. Except for hydrogenation activity, catalyst activity declined with a typical S-shaped deactivation curve. The properties of the spent catalysts do not depend significantly upon prior processing of the feedstock; however, the prior processing history of the feedstocks affected their reactivity and the rate of catalyst deactivation. The results indicate beneficial effects of conducting coal liquefaction at low-severity conditions and of product deashing prior to catalytic hydrotreatment.     

Economic evaluations of direct, indirect and hybrid coal liquefaction

The various geopolitical problems associated with oil have rekindled interest in coal, with many countries working on projects for its liquefaction. This study established the feasibility of coal liquefaction through a technical and economic examination of direct coal liquefaction (DCL), indirect coal liquefaction (ICL) and hybrid coal liquefaction (HCL) processes. An economic efficiency analysis was prepared involving costs of initial investment, annual operating and raw coal purchase and revenues from the sale of major products as key variables. For the raw materials, products and investments, analyses of net present value (NPV), internal rate of return (IRR) and sensitivity were carried out. The processes?? IRRs were found to be 22.26% (DCL), 18.43% (ICL) and 20.90% (HCL). NPVs were $4.720m (DCL), $3.811 m (ICL) and $4.254 m (HCL), and payback periods were DCL 3.3 years, ICL 4.2 years, and HCL 3.6 years. As a result of the sensitivity analysis, factors greatly affecting the earning potential of coal liquefaction included product prices, raw coal prices, and construction costs, which showed similar effects in each process.     

分形学在煤直接液化催化剂表征中的应用

采用表面分散维Ｄ表征浸渍前后煤样的表面不均匀性的变化,并进一步关联助剂的添加,干燥温度对催化剂前驱体在煤样表面上分散性和反应活性的影响作用。结果表明,适量添加助剂可以有效地防止前驱体在煤表面的局部聚集,提高浸渍煤样的表面分数维和反应性,较低的干燥有利于催化剂前驱体在煤表面分散均匀。     

神华煤液化残渣的加氢反应动力学

在微型反应管中,以神华煤液化残渣为原料,四氢萘为溶剂,在氢初压6 MPa、反应温度425～485℃、反应时间为0～30 min条件下,进行了煤液化残渣加氢实验,研究了煤液化残渣的加氢动力学特性。将氢化产物分为油气、沥青质和四氢呋喃不溶有机质,根据集总概念建立了煤液化残渣的加氢动力学模型,所建模型与实验值吻合程度高。在实验条件下,四氢呋喃不溶有机质向沥青质转化的活化能为147.41 kJ·mol^-1,沥青质向油气转化的活化能为34.81 kJ·mol^-1,沥青质缩合为四氢呋喃不溶有机质的活化能为173.48 kJ·mol^-1。     

煤直接液化工业化示范装置操作预案的试验研究

为探索和积累神华处理能力为6000t／d的煤直接液化示范装置的操作经验,在6t／d的工艺开发装置（PDU）上分别进行了模拟催化剂、助催化荆硫供应减少或中断等异常情况下的操作预案研究。研究结果表明当催化剂供应量减少一半或助催化剂硫供应中断时,对煤直接液化操作的影响可以通过采取适当提高煤浆预热炉负荷的措施加以克服;尽管催化剂供应全部中断时可以维持装置操作,但对煤液化产品质量有较严重影响。     

Effects of Lewis acid catalysts on the hydrogenation and cracking of two-ring aromatic and hydroaromatic structures related to coal

Little is known about the hydrogenation of fused aromatic nuclei during the liquefaction of coal under the influence of Lewis acid catalysts. This study was conducted to establish the effects of catalyst acidity on the activity and selectivity of Lewis acid catalysts, the sources of hydrogen involved in hydrogenation and cracking, and the relations between reactant structure and reactivity. Two-ring aromatic and hydroaromatic compounds were used to simulate some of the structural units present in coal. The catalysts examined were ZnCl₂ and AlCl₃. ZnCl₂ is less active than AlCl₃ for both hydrogenation and cracking but it does not promote the formation of tars via Scholl condensation: Methyl or hydroxyl substitution of the reactants greatly enhances their reactivity towards hydrogenation and cracking. The source of hydrogen consumed during hydrogenation depends on the choice of catalyst. In the presence of AlCl₃, Scholl condensation of aromatic nuclei serves as the principal source of hydrogen. Molecular hydrogen is used exclusively, though, when hydrogenation is catalysed by ZnCl₂. The formation of reaction products and the trends in reactant reactivity can be interpreted on the basis of carbonium ion mechanisms. The results of this study provide a basis for assessing the extent of hydrogenation occurring during the liquefaction of coal using ZnCl₂ or AlCl₃.     

煤直接液化技术发展的化学脉络及化学工程挑战

从对煤直接液化的化学本质的分析入手,讨论了煤直接液化技术发展的化学脉络及所面临的化学工程挑战。作者认为,煤直接液化技术的化学本质是煤大分子结构在热场中裂解产生自由基碎片的速率和自由基碎片加氢的速率的匹配,这两个速率的差异决定了煤浆预热、煤液化反应,甚至高温条件下产物分离等过程的特征,决定了油收率、系统中物料结焦、物料输送等行为。