Humic acid-Fe as catalyst for coal liquefaction

Research to increase the activity of iron based catalysts focuses on decreasing the particle size, increasing catalyst dispersion. The chelate compound of iron with humic acid (HA), which macromolecules radii can range from 6 to 50 nm, is truly in a highly dispersed state. Fe²⁺ or Fe³⁺ were dispersed finely into the HA matrix through the ion exchange with -COOH groups or chelate with carbonyl group in humic acid macromolecules. X-ray diffraction (XRD) and FT-IR spectrophotometer were used to characterize iron species before or after chelating with humic acid. The results indicate that there exist α-FeOOH, ferrihydrite and amorphous iron in HA-Fe. Most of the work has been conducted on a laboratory scale, and the results show that HA-Fe catalyst was approved for its excellent catalytic activity in coal liquefaction, and the conversion and oil yield of coal have been greatly improved.     

Catalytic close-coupled two-stage liquefaction process development with a bituminous coal

Catalytic close-coupled two-stage processing is the state-of-the-art direct liquefaction technology for converting coal into transportation and utility fuels. Three pilot plant runs were completed at the Wilsonville pilot plant using Illinois No. 6 coal and bimodal catalysts. Product yield and product quality data are presented. Appropriate comparisons are made with previous processes. The catalyst performance is discussed in terms of process-derived activity trends, catalyst analyses, and catalyst replacement rates. The effects of coal space velocity, concentrated coal slurry, the elimination of interstage separator, ground catalyst addition, and system pressure on process performance are discussed. Finally, process economics are discussed briefly.     

工业废水和煤液化残渣制取水煤浆的研究

对工业废水和煤液化残渣制备水煤浆的特性进行了实验研究,在选取5#添加剂和添加剂加入量为0.4%的条件下,废水煤浆浓度、黏度、析水率、流动性均符合湿法气流床加压气化生产的要求。随着废水配入比例的增加,浆体黏度逐渐增大,煤浆稳定性得到改善。随着废水稀释比例的增加,最高成浆浓度逐渐升高。利用工业废水和煤液化残渣制取水煤浆,减轻了对环保的负担。     

Effect of catalyst distribution in coal liquefaction

The effect of the mode of catalyst addition in the liquefaction of eastern Kentucky Elkhorn #2 coal was studied in a continuously stirred tank reactor. Particulate addition of iron in the form of pyrite significantly catalyzed the liquefaction reaction; coal conversion increased, and oil yield was greater by more than a factor of two, both at 825 and 850°F (714 and 728 K, respectively). Although pyrite concentration had a negligible effect on product distribution, the mode of catalyst addition was significant. Impregnation and molecular dispersion with 1 wt. % iron based on coal gave either similar or improved product distribution compared to the addition of 3.5 wt. % iron in the form of particulate pyrite. Significantly lower hydrocarbon gas make and hydrogen consumption were noted with impregnation and molecular dispersion than with particulate addition. SRC sulfur content was marginally higher with impregnation, but was lower with molecular dispersion. Solvent hydrogen content increased with particulate addition, but decreased with impregnation and molecular dispersion.     

煤炭直接液化溶剂的研究

讨论了煤炭直接液化过程中溶剂的特点、作用及质量要求,煤液化溶剂具有一般溶剂的功能,同时还具有良好的供氢和传递氢的功能特点,起到溶解、分隔煤裂解生成的自由基的作用,溶剂必须具有一定的分子结构和分子大小。初步讨论了表征煤液化循环溶剂供氢性的指标,指出普通溶剂如四氢萘和二氢萘等部分饱和的芳香化合物可直接用作煤液化溶剂,多环芳烃含量较高的煤焦油和石油系重质油,经过预加氢处理提高溶剂的供氢性后,可作为煤液化过程的起始溶剂或替代溶剂。     

Effects of catalyst and vehicle in coal liquefaction

Experiments have been carried out, using a semi-batch reactor equipped with a consecutive sampling device, to clarify the effects of catalysts and vehicles in the coal liquefaction process. The results show that a vehicle has a significant effect during preheating, unlike a catalyst which is not effective at this stage. A catalyst is more effective in promoting liquefaction under reaction conditions of 450°C and ≈ 20 MPa than is a vehicle. A vehicle higher in hydrogen donation increases the yield of oil even if a catalyst is present, providing a multiplier effect. In the development of a direct coal liquefaction process, therefore, selection of a vehicle is as important as that of a catalyst.     

Bioleaching of molybdenum from coal liquefaction catalyst residues

It has been shown that the bacterium Thiobacillus ferrooxidans can solubilize MoS₂ from coal liquefaction catalyst residues. The MoS₂ is formed during the liquefaction process from a molybdenum catalyst precursor. MoS₂ is insoluble; in order to be recovered and reused, it must be converted to a soluble form. T. ferrooxidans can oxidatively solubilize the molybdenum in MoS₂ to molybdate, in which form it can be recovered as a soluble or HCl extractable material. Bioleaching experiments show that with a starting cell concentration of 1.0 × 10⁷ cells ml⁻¹, or greater, a significant amount of the molybdenum in the residue was solubilized. These experiments indicate that the amount of molybdenum biologically solubilized from the liquefaction residues is dependent on inoculum size, with all strains of T. ferrooxidans tested having equal ability, and on the particle size of the residue. An important factor in the solubilization of MoS₂ by T. ferrooxidans is the inhibitory effect of molybdate. Literature reports that as little as 10 ppm molybdate is inhibitory to growth or ferrous iron oxidation. However, leachates containing in excess of 70 ppm molybdenum (equivalent to 116 ppm molybdate) were generated as a result of bioleaching of the liquefaction residue. When cells from previous leaching experiments were used to inoculate flasks containing fresh media and additional liquefaction residue, the bacteria were able to bioleach the fresh residue. Recent experiments have focused on the ability of T. ferrooxidans to produce protective agents in the leachate that minimize the inhibitory effects of molybdate. We found that production of the protective factor(s) did not depend on previous exposure of the cells to molybdenum or liquefaction residue.     

Properties and liquefaction activities of ferrous sulfate based catalyst impregnated on two Chinese bituminous coals

Activities of ferrous sulfate based catalysts impregnated on two Chinese coals were studied in coal liquefaction, and compared with an impregnated iron sulfide catalyst. Chemical forms and particle size distribution of the impregnated ferrous sulfate based catalysts were determined using EXAFS, XRD and SAXS techniques. The impregnated ferrous sulfate shows significant activity in the liquefaction of bituminous coals, but is less active than the impregnated iron sulfide catalyst. Addition of Na₂S or urea to the ferrous sulfate in the impregnation process increases the coal conversion to the level of the impregnated iron sulfide catalyst. Addition of Na₂S does not significantly promote the formation of iron sulfide on coal surface as usually believed. The iron impregnated on the coal surface existed mainly in the form of γ-FeOOH regardless of the forms of iron and the promoters. The most probable diameter of the impregnated ferrous sulfate based catalyst determined by SAXS is around 40-50 Å.     

Improvement and characterization of an impregnated iron-based catalyst for direct coal liquefaction

An impregnation method to prepare an active iron-based catalyst for direct coal liquefaction was improved. With the same catalytic activity, the water usage in the improved method is only 1% of that used in the unmodified method. The improved method not only simplifies the impregnation procedure and reduces cost, but also generates small catalyst particle size on coal surface. Water in the coal promotes thermal liquefaction, but deactivates the impregnated catalyst (possibly due to the adsorption of H₂O molecular on the catalyst surface). Electron probe microanalysis (EPMA), X-ray diffraction (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS) analyses show that the catalyst precursors prepared by both methods are in nanometer size and highly dispersed on coal surface. The irons deposited on coal surface are not only in sulfide forms, but also coordinate with oxygen from moisture- and oxygen-containing groups of coal. The impregnated iron may be composed of FeOOH and FeS or in the forms of Fe–O–S or Fe–S–O. The iron transforms to crystalline pyrrhotite in coal liquefaction.     

强黏烟煤反火炉造气的研究

通过对烟煤反火炉造气的研究，了解了强黏烟煤在模拟反火炉中的燃烧情况，探讨了各风速与不同煤粒径之间、气体产率与风速之间的关系，为解决反火炉易断火及烟煤造气烟尘大、焦油中沥青含量及游离碳过高、烟煤制气中的“破黏”、反火炉产气效率低等问题提供了可靠的依据，也为确定烟煤反火炉造气的最佳炉型、结构及最优工艺条件和控制手段提供了可靠的依据。     

Study on coal liquefaction characteristics of Chinese coals

The New Energy and Industrial Technology Development Organization (NEDO) has implemented the collaborative research work with China Coal Research Institute (CCRI) on the liquefaction of Chinese coals for about 20 years. A total of 53 runs in a 0.1 t/d bench scale coal liquefaction plant installed at the CCRI were made on 27 kinds of coal selected among coals existing throughout China. The bench plant was operated in a direct hydrogenation (DH) mode and NEDOL mode. In the DH mode, 25 MPa of reaction pressure was employed with decrystallized anthracene oil used as the solvent, while 17 MPa of reaction pressure was employed and hydrogenated solvent was used in the NEDOL mode. This study confirmed that the NEDOL mode, which uses comparatively mild in liquefaction conditions, can liquefy each coal with the high oil yield more efficiently, and is capable of liquefying about 60% of inertinite in high inertinite coals.     

煤液化残渣制浆研究

对某煤液化残渣进行湿法成浆性实验研究,通过对煤液化残渣料浆在表观黏度、稳定性和流变特性方面的考察,认为在选取合适的添加剂和添加剂加入量的条件下,具备合理粒度分布的煤液化残渣能够制备出高质量分数符合湿法气流床气化工艺要求的料浆。     

Fe/CaO催化剂对脱灰徐州烟煤热解特性的影响

煤热解是一种重要的煤炭分质利用技术,但热解过程中产生的副产物焦油危害极大,催化改质是高效清洁利用煤焦油的方法之一。本文采用溶胶凝胶法制备Fe/CaO催化剂,在管式炉反应器上对脱灰徐州烟煤进行了催化热解实验,对研究催化裂解煤焦油具有重要的意义。结果表明：Fe/CaO催化剂可以明显促进热解气的产生,热解气中CO₂、CO和CH₄的产量均不断增加。Fe/CaO催化剂促进了液体产物的催化裂解,导致液体产率明显下降。Fe/CaO催化剂促进焦油中的稠环芳烃向脂肪烃和轻质芳烃转化,此外,Fe/CaO催化剂还对萘类化合物的产生有促进作用。Fe/CaO催化剂催化后焦油中两环化合物的含量增多,三环及以上的化合物含量减少,焦油分子量呈减少的趋势。     

Kinetics and reaction scheme of coal liquefaction over molten tin catalyst

Rates of formation of gases, oils, asphaltenes and preasphaltenes during non-solvent liquefaction of coal over molten tin catalyst have been measured. A probable reaction scheme and the rate constants for the pathways comprising the scheme have been presented. The results show that the catalyst greatly accelerates the conversion of preasphaltenes to asphaltenes. It also accelerates two other reactions, i.e., coal to preasphaltenes and coal to asphaltenes. By contrast, the catalyst does little to promote gasification and formation of oils.     

煤间接液化技术的现状及工业应用前景

介绍了煤间接液化技术的发展历程,详细阐述了当前间接液化技术的现状,并分析其工业化前景。     

煤液化催化剂多级逆流浆态反应器流体分布与传质研究

以煤为载体的煤直接液化高效催化剂的制备需要在湍动剧烈的环境中分散和合成,气液固三相反应器的设计是其核心技术。主要从反应器的设计要求、气相含率及体系氧传质系数来研究此反应器的流体力学与传质特性。此反应器能满足催化剂制备时的要求,而且可以大幅度的减少气液相的传质阻力的影响。     

煤液化残渣软化点测定方法研究

采用环球法测定煤直接液化残渣的软化点,利用正交实验确定了实验的最佳分析条件为：样品粒度0.35 mm,热浴介质为甘油,热浴初始温度70℃,升温速率（5±0.5）℃/min。研究表明,升温速率是影响软化点测定结果准确度的关键因素,在实验过程中需严格控制。     

提高煤直接液化油品收率研究

本文针对目前煤直接液化项目煤转化油品收率偏低、煤直接液化项目经济性相对较差的问题,提出从煤粉原料、催化剂活性组分、溶剂油供氢性、反应条件、减底油品拔出等方面研究,调整操作,摸索最佳工艺条件。通过摸索研究,固化最佳工艺条件,煤转化油品收率显著提高,提高煤直接液化项目经济性。     

Performance indices for coal liquefaction solvents

Most coal liquefaction processes are based on the thermal cleavage of activated bonds giving reactive carbon and oxygen radicals which abstract hydrogen atoms from the donor solvent. The role of oil is approximated in this study by using a simple standard reaction. A series of five representative solvents react with phenyl and phenyloxy radicals generated by thermolysis of benzoyl peroxide at 87 °C in tetrachloroethylene. The n.m.r. analysis of the reacting mixture defines four performance indices, i.e. the hydrogen-donor, the efficiency, the recycle and the scavenger indices, which characterize the ability of these solvents as efficient recycle oils in coal liquefaction processes. 9,10-dihydrophenanthrene proves to be by far the most appropriate solvent for this purpose.