煤基富勒烯(C_(60))的制备与提纯

<正>富勒烯是除石墨和金刚石外碳的第三种同素异构体,其代表性分子是C_（60）和C_（70）。大量研究成果表明,富勒烯的特殊球形空心分子结构赋予了它许多奇异的物理化学性质,在超导、非线性光学、催化剂等诸多领域显示出十分诱人的应用前景。目前,国内外主要以高纯石墨电极为原料制备富勒烯,由于煤的价格低廉且来源广泛,以煤炭为原料制备富勒烯的研究备受国外学者的关注。本文以冶金焦为原料用电弧法制备富勒烯,研究了实验操作条件及冶金焦性质与富勒烯收率间的关系。粗富勒烯以活性炭为固定相,甲苯为流动相的柱色谱分离提纯,考察了活性炭的孔隙结构及柱色谱的长度对C_（60）纯度和收率的影响。     

Aromatic Production from Catalytic Fast Pyrolysis of Biomass-Derived Feedstocks

The conversion of biomass compounds to aromatics by thermal decomposition in the presence of catalysts was investigated using a pyroprobe analytical pyrolyzer. The first step in this process is the thermal decomposition of the biomass to smaller oxygenates that then enter the catalysts pores where they are converted to CO, CO₂, water, coke and volatile aromatics. The desired reaction is the conversion of biomass into aromatics, CO₂ and water with the undesired products being coke and water. Both the reaction conditions and catalyst properties are critical in maximizing the desired product selectivity. High heating rates and high catalyst to feed ratio favor aromatic production over coke formation. Aromatics with carbon yields in excess of 30 molar carbon% were obtained from glucose, xylitol, cellobiose, and cellulose with ZSM-5 (Si/Al = 60) at the optimal reactor conditions. The aromatic yield for all the products was similar suggesting that all of these biomass-derived oxygenates go through a common intermediate. At lower catalyst to feed ratios volatile oxygenates are formed including furan type compounds, acetic acid and hydroxyacetaldehyde. The product selectivity is dependent on both the size of the catalyst pores and the nature of the active sites. Five catalysts were tested including ZSM-5, silicalite, beta, Y-zeolite and silica–alumina. ZSM-5 had the highest aromatic yields (30% carbon yield) and the least amount of coke. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparison of flame propagation properties of petroleum coke and coals of different rank

Ignition and flame propagation characteristics of 18 kinds of coal and a petroleum coke were investigated through a laser ignition experiment. Flame stability was strongly influenced by amount of volatile matter and pyrolysis rate. Lean limit of flame propagation was strongly influenced by amount of volatile matter. Flame propagation was observed when pyrolized volatile matter was mixed with surrounding air or oxygen, until the concentration of pyrolized volatile matter reached a constant value. Flame propagation velocity was strongly influenced by pyrolysis rate. As the pyrolysis rate increased, the flame propagation velocity increased. The flame propagation velocity of petroleum coke was higher than that of coal with the same volatile content. The flame propagation of petroleum coke was superior to what was expected based on the volatile content, primarily because the high pyrolysis rate caused a shorter ignition delay than what would be expected given the volatile content. A database for the lean limit of flame propagation was used to develop a flame stability model to estimate lean flammability of a large-scale burner. The model could predict the effect of the coal rank, the particle diameter distribution for lean flammability limit. The estimated lean flammability limit of petroleum coke (volatile content 11.5%) was equal to that of lv bituminous coal with volatile content of about 15%.     

我国非炼焦煤综合利用方案的探讨

我国非炼焦煤中的不粘煤、弱粘煤分别的占煤炭总储量的11.80%和3.90%。这两种煤具有低灰、低硫、高挥发分、高发热量、燃点低、反应性好的特点。除极少数可用作炼焦配煤外,目前大多数用作动力煤。本文就这些煤种提出了几个加工利用方案,旨在提高这些煤的应用价值。     

生物质型焦生产工艺的研究

用生物质做粘结剂以干法冷压成型生产生物质型煤,再经炭化制得生物质型焦．研究了生物质（玉米秸、稻杆）配入量、成型压力、烟煤种类（气煤、气肥煤、肥煤、焦煤）及配入量对型煤和型焦的抗压强度的影响．实验结果表明,烟煤配入量和成型压力对型焦的抗压强度有显著影响,适宜的工艺条件为生物质配入量１８％,肥煤与无烟煤配比１：２,成型压力４６０ｋＮ．此外,分析了型焦和热解挥发物的组成和性质．     

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.     

影响焦炭热态性质的因素探讨

对皖北17种煤样进行了性质分析及40kg小焦炉炼焦试验,结果表明,灰分中的碱性氧化物对焦炭的溶损反应起着正催化作用,其含量越大,焦炭的反应性越大;挥发分含量在20%～24%、镜质组反射率在1.3～1.8之间的煤,焦炭的反应性和反应后强度较好;硫的存在能抑制焦炭的CO2反应性,随着硫含量的增高,焦炭的反应后强度有所提高.建立的预测模型具有一定的可靠性与稳定性.     

Statistical analyses and prediction of coking properties of coal

Using regression analyses between the properties of coals and the strengths of their cokes several significant correlations are derived, which are useful to evaluate coals in the making of metallurgical coke. Slight but significant modification was necessary for their application to coal blends. For example, plasticities of the coal blends required a different equation from that derived for the single coals. The region of high coke-strength in the diagram of volatile matter vs. total dilatation was expanded considerably towards coals of lower caking properties by blending of coals, suggesting that the blending may serve to increase the coking properties of component coals. The coke strength, especially after the gasification was found to increase with the increasing inert maceral content in the parent coals up to 30 wt %. The high level of strength was maintained even above 35 wt % of inert content.     

Optical properties of vitrinite carbonized at different pressures

The effect of pressure on the optical properties of cokes from a medium volatile bituminous coal (carbon = 87.9 wt% daf), some carbonized at atmospheric pressure and others under hydraulic pressure (21–310 MPa), over temperatures ranging from 350 to 600 °C at 50 °C intervals, has been studied. The cokes formed at atmospheric pressure developed fine grained mosaics, while medium-flow type mosaics formed in coke carbonized under hydraulic pressure. The thermal decomposition stage began at lower temperatures with increasing hydraulic pressure, resulting in a prolonged devolatilization phase for coke formed at a pressure of 21 MPa. Hence the fluidity of samples carbonized under pressure decreases with increasing hydraulic pressure. Pressure promotes the optical anisotropy apparent from the level of bireflectance. The reflectance of coke formed at atmospheric pressure is higher than that of cokes carbonized under hydraulic pressure, perhaps due to the inhibitory effect of entrapped volatile matter during carbonization under hydraulic pressure. The morphological features of vitirinite carbonized under pressure resemble those of coals naturally affected by heat.     

炼焦煤与焦炭间硫转化关系的研究

取武钢炼焦生产用煤56种,进行实验室坩埚炼焦实验,研究煤与焦炭间硫的转化关系,以降低焦炭的硫分并合理用煤。研究结果表明,对于单种炼焦煤,煤焦间硫的转化率(ΔS)随挥发分(Vd)的增加而降低,且有较好的相关性;焦炭硫分与炼焦煤硫分的比例系数(ΔS/K)也随挥发分(Vd)的增加而降低。不管是单种炼焦煤还是其配合煤,其焦炭的硫分均随炼焦煤硫分的增加而增加,且有很好的相关性。     

锦州石油焦性能及其生产普通石墨电极的质量

通过对锦州焦与大庆焦的对比实验，分析了锦州焦的特性。与大庆焦相比，锦州焦的灰分偏高，挥发分偏低、硫含量稍高，煅后焦颗粒强度大，堆积密度大；用锦州焦制造的各种规格石墨电极，其CTE、体积密度、强度、电阻率均比大庆焦的高。     

以不同沥青焦为原料制备活性炭的特性分析

以沥青焦、煤沥青以及氧化沥青为原料，采用KOH活化法制备高比表面积活性炭。试验分别考察了不同原料及预处理工艺对活性炭孔径分布与比表面积的影响。发现采用不同原料所制备活性炭的孔径分布呈现出正态分布的特点，孔径分布范围介于0～5．0nm之间，峰的位置介于1．0～1．5nm附近。活性炭主要由1-1．5nm范围的微孔构成，大于2nm的中孔很少。在煤沥青不熔化处理过程中，其挥发分与H／C原子比要适中，挥发分过高与过低均不利于制备高比表面积活性炭。     

Preparation of porous carbons from petroleum coke by different activation methods

Porous carbons were prepared from Shengli petroleum coke (SPC) and Minxi petroleum coke (MPC) by different activation methods with H₂O, KOH and/or KOH+H₂O as active agents. The porous carbons were characterized by nitrogen adsorption at 77 K. It has been found that activation method and component of petroleum coke, of which different kinds of transitional metals on petroleum coke are crucial for preparing high quality porous carbons. Under the identical experimental conditions, the co-activation with KOH and H₂O as active agents in the same activation process, which has been rarely reported in literature, is the easiest method for the preparation of porous carbons with high surface area. The sequence of active agents in terms of difficulty in the preparation of porous carbons with high surface area is as follows: KOH+H₂O>KOH>H₂O. A drawback of KOH+H₂O activation in the preparation of porous carbon in this work is found to be its low carbon yield in comparison to KOH activation. Compared with the SPC coke, the MPC coke with higher contents of transitional metal and carbon and lower content of nitrogen is more suitable for making high surface area porous carbons, which is believed to be mainly due to the difference in the contents of transitional metals. Porous carbon with surface area around 2500–3000 m²/g and carbon yield about 25–30% has been obtained from MPC coke by KOH+H₂O activation with less KOH and shorter activation time in comparison to the traditional methods.     

Mechanism of coal pyrolysis in relation to industrial practice

The validity of our earlier postulates of the mechanism of primary pyrolysis (at and up to 600 °C) is critically examined and it is indicated that the mechanism is strictly followed only under ideal conditions, e.g. in thin beds at rapid rates of carbonization, as in fluidbed and transport reactors. The departure of the Gray-King assay (600 °C) from the ideal path of pyrolysis, e.g. by yielding 20–30% less tar than the yield corresponding to hydroaromatic carbon content, is shown to be due to interaction between the potential tar-forming constituents and the incipient coke-forming substance. This appears to be a function of the thickness of the coal bed, the rate of heating, etc. The greater the thickness, the greater is the degree of interaction and consequent inhibition of tar formation, resulting in a proportionate increase in coke yield. Coke and tar yields are thus partly interconvertible, and the proportions of such interaction have virtually no effect on the proportion of carbon appearing as gas. In industrial high-temperature carbonization, the higher yields of coke and lower yields of tar are due to the same interaction, which occurs to a greater extent primarily because of the greater thickness and/or depth of the coal bed in coke ovens. The fixation of up to 75% of the ‘tar-forming’ carbon (hydroaromatic carbon according to the theory) does not appear to be due to cracking of tar after its formation, but is shown to be foreshadowed well within the primary stage of pyrolysis (below 600 °C), perhaps through condensation-polymerization reactions within the formative coke mass, the mechanism of which is ill-understood at present. The process appears to be very different from the cracking mechanism hitherto believed to explain it. This conclusion is also supported by a study of the distribution of carbon in the gas. Further, such comparative studies between laboratory and industrial conditions do not indicate any significant cracking of methane, hitherto believed to occur in coke ovens. Correspondingly, the reasons for carbon deposition on the exposed hot walls and other regions of coke ovens are discussed and doubt is thrown on the belief that it derives from the cracking of tar and gas.     

焦炭热性能的影响因素探讨

通过对梅山焦炭反应性、反应后强度和配煤质量指标进行的试验分析,结果表明:焦炭灰分、配煤挥发分和胶质层最大厚度Y值是影响焦炭热性能的重要因素,而焦炭的冷强度M40和M10与焦炭热性能没有明显的相关关系。     

炼焦精煤氧化性质的研究

测试了5种露天堆放的炼焦煤在不同时间的各指标变化情况,结果表明：高挥发分高粘结性的炼焦煤在氧化初期结焦性略有上升,然后逐步下降;中等及低挥发分的炼焦煤随着煤质的氧化其结焦性越来越差;煤的挥发分随堆放时间延长而下降,灰分则略有上升。     

一种无烟煤型焦洁净生产技术

介绍一种符合国家可持续发展战略的洁净型焦生产系统－以无烟粉煤为主要原料的型煤竖炉炼焦技术,并对其社会效益和经济效益进行初步评估。该型焦技术是以无烟粉煤为主要原料（占70％）,添加少量烟煤及粘合剂生产型煤,型煤进入连续运行的竖炉炼焦,所产煤气经净化后用作焦炉及型煤干燥的热源。其炼焦生产全过程密闭、连续、焦化时间短、无污染,产品块度及挥发分等主要指标调整灵活。     

Benzyl diethyl phosphite as a coke inhibitor during naphtha pyrolysis. tubular reactor studies

The effectiveness of benzyl diethyl phosphite as a coke inhibitor during naphtha pyrolysis was investigated in a tubular reactor at 1073 K and atmospheric pressure. Significant reduction in the coking rate was achieved by adding benzyl diethyl phosphite to the feed. The effect of toluene, methylcyclohexane, l-octene and carbon disulfide on the rate of coke formation was also investigated. Toluene enhanced the rate of coke formation significantly, whereas with methylcyclohexane and l-octene the increase was less appreciable. Carbon disulphide decreased the amount of coke deposited initially, but with increasing run time the asymptotic coking rates were found to be higher than for straight-run naphtha. The yields of propylene, 1,3-butadiene and butenes increased on addition of carbon disulphide.     

沛城煤矿天然焦的热解特性

天然焦是一种热值在18～28 MJ·kg-1 的化石燃料,虽储量丰富,但多被弃用,有待于开发利用。采用TG-FT-IR联用技术在Thermax500 型加压热重分析仪上比较徐州沛城煤矿天然焦与徐州韩桥烟煤的热解过程,并利用VECTOR 22 型红外分析仪对热解产物进行了分析。考察了升温速率、热解终温、颗粒尺寸和压力对天然焦热解特性的影响。结果表明,与煤的热解过程不同,天然焦的热解没有半焦形成阶段,只包括了2 个不同的脱气阶段;随升温速率的提高,TG曲线向高温区偏移,升温速率对天然焦挥发分的析出量几乎没有影响;热解终温对试样挥发分析出量的影响较为明显,高温时,试样颗粒在显微镜下呈现出丰富的微孔结构,有利于挥发分的析出和还原活性的提高;颗粒粒度的减小有利于挥发分的析出;低于某特定温度,热解压力的影响较弱,当温度继续升高,压力的影响逐渐明显。     

Gasification reactivities of cokes derived from athabasca bitumen

Gasification reactivities of cokes obtained from Athabasca bitumen by delayed coking and fluid coking were compared in fixed and fluidized bed systems. In both systems the C + O₂ reaction accounted for the most of converted carbon. The C + H₂O reaction proceeded to a smaller extent. The bulk reactivity of the fluid coke was higher than that of delayed coke, when comparing ?20 to +60 mesh particles in fluidized bed and ?14 to +20 mesh particles in fixed bed, respectively. However, the reactivity of the delayed coke expressed per unit of surface area was markedly higher than that of the fluid coke.