Catalytic hydrocracking of primary maceral concentrate extracts prepared in a flowing solvent reactor

Differences between the behaviour of coal macerals during liquefaction and catalytic hydrocracking were investigated. The liquefaction experiments were carried out in tetralin, using a flowing solvent reactor. The extracts were catalytically hydrocracked in a micro-bomb reactor, using a commercial catalyst. Extracts and hydrocracked products were characterised by size exclusion chromatography (SEC), UV-fluorescence spectroscopy (UV-F), probe-mass spectrometry and thermogravimetric analysis. Conversions of the vitrinite and the liptinite concentrates during liquefaction were high (∼89%), while inertinite samples yielded a little over 20% extract. For inertinites, the emerging picture was consistent with high cross-link density. Liptinite was extracted less completely at lower temperatures and more slowly at high temperatures compared to corresponding vitrinites and vitrinitic coals. Long chain aliphatics released from the liptinite concentrate between 340 and 390°C appeared likely to have originated in lower-molecular mass material occluded in the sample matrix and dissolving in tetralin prior to the onset of massive covalent bond scission. SEC chromatograms showed material of larger MMs in liptinite and vitrinite extracts than in the inertinite extract. The molecular mass distributions broadened with increasing extraction temperature. Catalytic hydrocracking experiments were carried out in a micro-bomb reactor for 10 and 120 min at 440°C, under 190 bar of hydrogen. In hydrocracking, the liptinite was the slowest extract to react at short reaction times (∼10 min). However, at longer reaction times, its products showed the smallest MM-distribution. Smaller differences were observed between the chromatograms of the 10 and 120 min hydrocracked products of the inertinite extract. Differences between spectra of the three extracts would strongly suggest the presence of larger (and apparently irreducible) polycyclic aromatic ring systems, in the hydrocracked products of the inertinite extract.     

Model for the coal hydrogenation process and its applications

A coal hydrogenation model has been formulated which incorporates both chemical and microscopic experimental data. In this generalized model, carbonization and hydrogenation are viewed as concurrent processes in the liquefaction of coal. Insufficient hydrogen availability, rapid heating rates and long reaction times at elevated temperatures can promote carbonization reactions. The model describes in detail the reaction pathways involved in the hydrogenation of both inertinite and vitrinite. When vitrinite is hydrogenated in the presence of a hydrogen donor solvent, a plastic material called vitroplast is formed. The vitroplast is either converted to liquid and gaseous products when hydrogen availability is high or becomes mesophase and then semicoke when hydrogen availability is low. Even under favourable hydrogenation conditions, the major reaction pathway in the hydrogenation of inertinite is one of initial mild carbonization followed by hydrogenation. It is evident that the difference in hydrogenation behaviour between vitrinite and inertinite is due, in part, to the ability of the hydrogen donor solvent to penetrate vitrinite but not inertinite particles. The hydrogenation model is useful for explaining various phenomena that occur during hydrogenation, such as the formation of mesophase and semicoke, and the blockage of reactors and preheaters.     

Pyrolysis behavior of vitrinite and inertinite from Chinese Pingshuo coal by TG-MS and in a fixed bed reactor

The pyrolysis behaviors of vitrinite and inertinite from Chinese Pingshuo coal were investigated by using the thermogravimetry coupled with mass spectrometry (TG-MS) and in a fixed bed reactor, respectively. The results showed that inertinite has lower pyrolysis reactivity, lower tar and gas yields, but higher water yield than vitrinite. At 650 °C, the tar and gas yield of vitrinite is 22.4% and 14.4%, respectively, obviously higher than 13.4% and 10.2% of inertinite. The TG-MS analysis also showed much difference of vitrinite and inertinite in gas evolution profile. The ultimate and XRD analyses of chars indicated that the difference in element composition of vitrinite char and inertinite char decreases with the increase of temperature, and have similar element composition and structure characteristic at 650 °C. The total sulfur removal of both vitrinite and inertinite increases with the pyrolysis temperature, and reaches to 60% at 650 °C, but the organic sulfur in inertinite seems more stable than that in vitrinite.     

The variation of structural characteristics of macerals during pyrolysis

Vitrinite and inertinite were separated by DGC from Chinese Shenmu bituminous coal and the structural characteristics of the macerals, before and after pyrolysis, were analyzed by ultimate analysis, FTIR and ¹³C NMR. The results showed that vitrinite chars always had higher H and lower C content than inertinite char at the same pyrolysis temperature. The FTIR and ¹³C NMR indicated that vitrinite had more aliphatic C-H, hydrogen bonding and lower aromaticity. With increasing temperature, the aliphatic C-H decreased, aromatic C-H, aromaticity and H_ar/H_al ratio increased. At the same temperature, inertinite always had higher H_ar/H_al ratio than vitrinite, which is consistent with that inertinite had higher aromaticity than vitrinite. And the H_ar/H_al ratio was also related to the remainder volatile matter. With increasing H_ar/H_al ratio, the remainder volatile matter in vitrinite and inertinite decreased. The higher aromaticity and H_ar/H_al ratio and lower H content of the inertinite in all temperature range were correlated with its higher thermal stability and lower volatile yield than vitrinite.     

Maceral and rank influences on the morphology of coal char

Concentrates of vitrinite and inertinite macerals have been pyrolysed in a flame under conditions representative of the initial stages of pulverized coal combustion. Char was distinguished from soot by size analysis and the char yield correlated with the proximate analysis. The char morphology was studied by optical microscopy and quantitative measurements of porosity and pore size were made using image analysis. Vitrinite and inertinite produce chars of characteristic morphology. The softening behaviour of inertinite varies with coal rank and can be related to the optical reflectance. The porosity of vitrinite chars approaches that of inertinite chars at high rank.     

神木煤显微组分热解半焦CO_2活化特性研究

通过对神木煤显微组分不同温度下（500℃,700℃）热解得到的半焦和半焦CO2活化特性进行研究,发现富惰质组半焦比表面积和孔隙结构明显优于富镜质组半焦;热解半焦均存在较宽泛的中孔、大孔,从500℃到700℃,富镜质组半焦生成的微孔多于富惰质组半焦。在实验条件下,500℃和700℃的半焦CO2活化性能均是富镜质组〉原煤〉富惰质组。热解从500℃提高到700℃,富镜质组半焦的CO2反应活性明显提高。惰质组的结构疏松,在活化过程中容易造成孔壁塌陷,形成大孔,从而导致富惰质组半焦比表面积减小。     

基于显微组分化学键特征的宁夏庆华煤热解特性及动力学分析

通过X射线光电子能谱和傅里叶红外光谱表征宁夏宁东庆华煤不同显微组分的官能团种类、表面结构元素价态分布及化学键赋存特征。采用热重-质谱联用考察庆华煤镜质组和惰质组在不同热解温度下的失重行为和关键气体组分变化。进一步基于Coats-Redfern模型从化学键断裂特征和反应动力学角度探讨煤镜质组和惰质组的热解行为差异。结果表明，庆华煤显微组分的热解失重峰与相应化学键断裂信息能够很好地吻合。不同显微组分的热重曲线变化趋同，但相同热解温度下镜质组的失重率始终高于惰质组。快速热解阶段镜质组较惰质组表现出更大的失重率和最大失重速率。其主要原因在于镜质组的脂肪族官能团相对含量更高，快速热解阶段会发生更多的C_al—C_al断裂。不同热解温度下庆华煤显微组分三个主要热解阶段的活化能和频率因子大小次序为：快速热解阶段>快速缩合阶段>缓慢热解阶段。在快速热解阶段，镜质组和惰质组的平均活化能均约为75 kJ/mol，但镜质组的频率因子更高。     

Optically anisotropic fragments in a Western Canadian subbituminous coal

Large Isotropic and anisotropic, angular and rounded fragments of inertinite were found in a Canadian subbituminous coal (%R oil = 0.50). The istropic fragments included pyrofusinite, macrinite and pseudovitrinite with pre-oxidized, heat-treated fragments showing oxidation rims. The anisotropic fragments include the heat-treated residue of liptinite, e.g. resinite showing granular anisotropy, pyrolytic carbon and fragments of vitrinite showing basic anisotropy. The morphology of inertinite fragments is described and an attempt is made to correlate these particles with heat-affected coal macerals. The occurrence of pyrolytic carbon with a reflectance of 3.11% and of liptinite showing anisotropy in a coal matrix with a reflectance of 0.50% is unusual. It indicates the detrital nature of the pyrolytic carbon. The formation of isotropic and anisotropic inertinite was possibly due to a thermal event, perhaps a wood or swamp fire. The pseudovitrinite found in these coals may have been formed by heat-treatment of fossil oxidized vitrinite fragments. The anisotropic fragments in the coals (e.g. pyrolytic carbon and anisotropic vitrinite), are detrital and are grouped with inertodetrinite.     

煤显微组分的性质及燃烧特性研究

本文根据元素分析、工业分析以及差热分析等数据研究了平朔煤、红阳煤、大同煤和东胜煤的显微组分的性质及燃烧特性。结果表明，壳质组具有最大Ｈ／Ｃ比和最高挥发分含量，镜质组的Ｈ／Ｃ比和挥发分含量高于隋质组；显微组分的粘结性，镜质组大于惰质组；镜质组和惰质组相比较，镜质组的着火点低、燃尽温度也低，具有较窄的燃烧区间；壳质组的着火点最低，但是燃尽温度要高于镜质组。     

Comparative behaviour of coal and maceral concentrates during artificial coalification

A series of experiments were performed in cold-seal autoclaves (confined-pyrolysis) to characterize the behaviour of individual macerais (vitrinite, inertinite, exinite) extracted from the same Lorraine Basin coal during artificial coalification. Rock-Eval pyrolysis, elemental analysis and weight loss determination provided the simple maturation indexes required. Emphasis was laid on the timing of hydrocarbon generation and on the possible similarities existing between inertinite and vitrinite of higher rank. Hydrocarbon potential and hydrocarbon yield were found to increase from inertinite to vitrinite and exinite, but similar mechanisms were involved during the thermal degradation of both inertinite and vitrinite.     

宁夏庆华煤镜质组和惰质组显微组分的分子结构及对比分析

使用密度梯度离心法对宁夏庆华煤的显微组分进行分离，获得煤的镜质组和惰质组。通过元素分析、X射线光电子能谱（XPS）、固体¹³C核磁共振（¹³C NMR）技术、傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）技术等表征手段对不同显微组分进行物性表征。进一步基于统计平均的分子结构近似结合分子模拟计算，确定庆华煤镜质组和惰质组显微组分的分子结构可分别表示为C₂₆₉H₁₉₆N₄O₁₃S和C₂₅₅H₁₇₉N₃O₁₄S。通过FTIR光谱与¹³C NMR光谱验证，从而实现了不同显微组分的分子结构描述。对两种显微组分的分子模型和结构参数进行了系统对比分析，发现镜质组的芳碳百分数为51.95，惰质组的芳碳百分数为62.16。镜质组模型中芳碳结构数目较少，脂肪碳结构丰富，不饱和度较小，还原度最大。惰质组模型中芳碳结构数量最大，脂肪碳结构数目少，不饱和度最大，煤化程度高。镜质组在原煤中含量高，是原煤的主要组成。惰质组的含量少且大分子结构缩合度高，分布在镜质组构成的基体中。     

Study on the structure and gasification characteristics of selected South African bituminous coals in fluidised bed gasification

The gasification characteristics of three South African bituminous coals were investigated in a bubbling fluidised bed reactor. The three coals are similar in rank, but two are inertinite-rich coals and the third has a high vitrinite content. The microstructural characteristics of the parent coals and their resultant chars were determined using XRD, FT-IR, Raman and petrographic analysis. The microstructural changes that occurred in the organic (maceral) and the inorganic (mineral) fractions of the selected coals were evaluated. The change in the carbon structure was correlated to the proportions of inertinite and vitrinite macerals in the coals. High vitrinite content resulted in an increase in the order of the disordered carbon structure after gasification and this leads to greater graphitised ordered carbon structures. While a high inertinite content resulted in low or no structural transformation of the chemical structure. The transformation of inorganic mineral constituents of the coal was correlated to the amount of inertinite present in the selected coals. Higher proportions of inertinite macerals and inertinitic chars resulted in higher proportions of melted minerals. Char samples with low proportions of organic matter resulted in higher proportion of melted minerals covering the char surface.     

Coalification paths of exinite,vitrinite and inertite

Coalification is a burial metamorphic process fundamental to understanding the origin and nature of coals and petroleum. Accurate assessment of Coalification requires removal of the variation in coal properties owing to differences in coal type. This is best achieved by assessing the coal rank of the maceral groups exinite, vitrinite and inertinite (and ultimately the macerals within each group) in terms of maximum reflectance. The mean maximum reflectances of exinite (R?_E max), vitrinite (R?_v max) and inertinite (R?_I max) are highly correlated over the rank range, soft brown coals to low-volatile bituminous coals. A single exinite Coalification break is identified at 0.4 to 0.5% R?_V max. Thereafter, exinite coalification occurs at an increasing rate (R?_E max relative to R?_V max) over the rank range 0.5–2.0% R?_V max, crossing the vitrinite Coalification path at 1.55% R?_V max. A phase of rapid inertinite Coalification (0.7–2.0% R?_I max) occurs between 0.2 and 0.9% R?_V max. Since exinite is a major land-plant source of hydrocarbons, and R?_E max is a sensitive indicator of organic maturation over the range 0.2–1.1% R?_E max, which corresponds to the main phase of oil generation, R?_E max can be a most useful indicator of petroleum generation. The inertinite lnkohlungsprung represents a dramatic compositional change which should be taken into account when considering the origin of inertinite, its utilization properties and the general processes of rank change and organic maturation.     

陕北低阶烟煤显微组分结构特征及分子结构模型

为了更好地利用我国丰富的低阶煤资源,以变质程度较低的陕北低阶烟煤镜质组、惰质组富集物作为研究对象,采用常规的煤质分析、傅立叶变换红外光谱、高分辨固体13C核磁共振、X射线衍射等分析表征手段,对样品结构进行全面分析,得到了陕北低阶烟煤显微组分分子结构特征及结构参数,建立了镜质组和惰质组的部分分子结构模型。结果表明,陕北低阶烟煤镜质组和惰质组氧含量均较高,硫含量很低,所选镜质组的芳碳率为0.634,平均缩合环数约为2.98个;惰质组的芳碳率为0.734,平均缩合环数约为3.15个;相对于镜质组,惰质组的缩合程度更高,芳核尺寸更大,排列也更加规则有序。今后低阶烟煤加工转化工艺的研究应从分子层面揭示其不同显微组分结构特征的差异性,为低阶烟煤清洁高效利用新工艺的开发奠定基础。     

Skeletal Isomerization of Linear Butenes on Ferrierite: Effect of the Presence of Lower Olefins in the Feed and of Operating Conditions

The skeletal isomerization of linear butene on ferrierite, at atmospheric pressure and 0.15 atm 1-butene partial pressure, was studied by feeding 1-butene streams with different ethene and propene concentrations and exploring several operating conditions. At short time-on-stream (5 min), the strongest acid sites govern the catalytic behavior, independent of the operating conditions in the studied ranges. At longer times, the reaction temperature mainly defines the conversion level. The higher the temperature, the larger the linear butene conversion. Temperature also has a strong influence over the nature of the carbonaceous deposit formed during reaction. At 400 °C, the deposit mainly shows an aromatic nature. The presence of lower olefins as impurities in the feed modifies both catalytic activity and by-product distribution. By decreasing the ethene concentration, the C⁺ ₅ fraction in the product stream increases and a lower carbonaceous deposit is formed. Using a nitrogen stream saturated with water during both pretreatment and reaction, the catalytic activity increases and the coke amount slightly diminishes, but the isobutene production is unfavored.     

Hydrogenation of the inertinite macerals of Bayswater coal

Yields of products from the hydrogenation of the inertinite and vitrinite+exinite macerals of the Bayswater (New South Wales, Australia) coal in a batch autoclave were investigated. Samples were hydrogenated for 1 h at 400 and 450 °C with tetralin as vehicle, hydrogen as charge gas and no added catalyst. The results show that the inertinite macerals contributed significantly to the liquid hydrogenation products, in particular to the oil yield obtained at 450 °C.     

低温条件下微波对钾长石溶出性能影响的微观机理分析

目前利用钾长石提钾的工艺研究多为过程复杂且能量损耗较大,本文提出了一种利用微波辐射协助水热反应提钾的新方法。采用微波辐射预处理钾长石粉末,加热迅速,再通过低温条件下的水热反应体系溶出钾离子,对此过程中微波辐射时间,微波辐射功率因素对钾溶出率的影响进行研究,并通过SEM、XRD等表征手段对反应后滤渣进行微观分析。优化工艺条件可以得出,在微波辐射功率600W、微波辐射时间15min、水热反应时间180min、水热反应温度180℃时效果最佳。研究结果表明:最优条件下,钾的溶出率达92%;微波辐射使钾长石预处理后表面发生变化,生成K_0.85Na_0.15AlSiO₄等产物,提高了钾长石的溶出性能;反应生成水羟方钠石[Na₈Al₆Si₆O₂₄(OH)₂(H₂O)₂];有效节约了反应时间和反应过程中的能量损耗。     

矿物质对高碱煤显微组分热解特性的影响

利用固定床热解炉和热重分析仪研究了沙尔湖煤显微组分的热解特性和产物产率,考察了酸洗处理对热解产物和动力学参数的影响。结果表明：经浮沉实验发现镜质组富集于S2（密度为1.4～1.5g/cm³浮选煤样）中,惰质组富集于S3（密度为>1.5g/cm³浮选煤样）中,其中S3所含硅铝酸盐类矿物显著高于S2。且碱及碱土金属（alkali and alkaline earth metals, AAEM）多以可溶性形式存在,经酸洗处理后剩余矿物质主要为石英、高岭土及硅酸盐类。在选用不同煤样进行热解特性分析发现,碱及碱土金属的存在会抑制热解主反应阶段的挥发分释放,而在二次脱气阶段,AAEM矿物质则会提高挥发分的释放速率。且在热解实验中发现,AAEM在热解中会充当煤大分子结构的交联点,降低热解焦油产率。对比不同显微组分发现,惰质组热稳定性更强,镜质组中烷烃侧链较多,芳香度较小,更易受热断裂。采用Doyle积分法确定了沙尔湖煤热解反应的动力学参数。     

Reaction behavior of quartz in gibbsite-boehmite bauxite in Bayer digestion and its effect on caustic consumption and alumina recovery

A high content of quartz is usually present in Australian gibbsite-boehmite bauxite. The reaction between quartz and sodium aluminate solution at high temperatures in the Bayer process can lead to loss of alumina and sodium oxide. Therefore, to improve alumina recovery, the reaction of quartz needs to be avoided. The digestion behavior of Australian gibbsite-boehmite bauxite and pure quartz in the Bayer process at 230–250 °C was systematically studied in this paper. The mineral composition and morphology of the reaction products were characterized and the kinetics of the quartz dissolution process was studied in detail. It was shown that boehmite in gibbsite-boehmite bauxite can be completely digested at high temperature (250 °C) with a short digestion time (5 min). A short digestion time results in a low reaction rate of quartz in bauxite, and is ideal for alumina recovery at high temperatures. The quartz reaction rate rapidly increases with longer digestion times. The apparent activation energy of the dissolution of quartz in bauxite in the caustic solution is 151.9 kJ mol^?1, and the rate-controlling step of this reaction process is the interfacial chemical reaction. By controlling the particle size of bauxite, the digestion temperature, and the digestion time, the reaction rate of quartz in bauxite can be inhibited, which is beneficial for improving alumina recovery and reducing caustic consumption. Therefore, based on the above theoretical research, a process for digesting gibbsite-boehmite bauxite is proposed using high digestion temperature (250 °C), short digestion time (5 min) and large mineral size. An economic benefit of about US$101.9 million for a refinery with the annual output of 2 million tons of alumina can be created by the proposed process.     

Coal flash pyrolysis: 4. Polymethylene moieties in coal macerals

An analysis for polymethylene moieties in purified coal macerals has shown the (CH₂)_n (wheren?5) content, by a liquefaction—¹ H n.m.r. method, to be highest in exinite macerals and lower in vitrinite and inertinite macerals. From any particular coal, the (CH₂)_n content of the vitrinite was higher than the inertinite but lower than the exinite. Pyrolysis of these macerals gave ethylene yields proportional to the (CH₂)_n content.