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101.
This research presents the results of an experimental study on the determination of pyrolysis behaviour and kinetics of six
crude oils by differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). Crude oil pyrolysis indicated two main
temperature ranges where loss of mass was observed. The first region between ambient to 400°C was distillation. The second
region between 400 and 600°C was visbreaking and thermal cracking. Arrhenius-type kinetic model is used to determine the kinetic
parameters of crude oils studied. It was observed that as crude oils gets heavier (°API decreases) cracking activation energy
increases. Activation energy of cracking also show a general trend with asphaltene content.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
102.
Investigation of pyrolysis of chinese coals using thermal analysis/mass spectrometry 总被引:2,自引:0,他引:2
Li X. Matuschek G. Herrera M. Wang H. Kettrup A. 《Journal of Thermal Analysis and Calorimetry》2003,71(2):601-612
TA/MS (thermal analysis coupled with mass spectrometry) was applied to the pyrolysis of Chinese coals with different ranks.
A total of 13 Chinese coals were investigated. The samples were deliberately chosen to represent the 13 types of Chinese coals
according to the Chinese coal classification system. The experiments were carried out in an argon atmosphere with a flow rate
of 150 ml min-1. The samples were heated from 40 up to 1200°C with a constant heating rate of 10 k min-1. The main evolved pyrolysis products were identified through the on-line recorded mass spectra. The thermal and evolution
behavior was compared between the coals. The results showed a strong thermal and evaluation behavior dependence on the coal
rank. Different aliphatic fragments and also some aromatic substances, which are of environmental concern (BTX, PAHs), were
found to be released depending on the different types of coal.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
103.
104.
铁岭煤中重金属元素的赋存形态及其在热解过程中的挥发行为研究 总被引:3,自引:4,他引:3
采用密度分离、脱灰处理和逐级化学提取等间接方法,考察了铁岭煤中Pb, Cr, Co, Ni, V五个重金属元素的宏观结合形态,并在Φ25mm小型石英流化床反应装置上考察了上述五个重金属元素在热解过程中的挥发行为。研究发现,铁岭煤中Pb, Cr, Co, Ni, V均主要与非黄铁矿类矿物质相伴生, 且高达40%~60%赋存在硅酸盐类矿物质中。Pb的碳酸盐结合态和有机束缚的离子可交换态600℃前即可分解转化,而其硫化物和硫酸盐结合态在较高的热解温度下才能分解挥发;Co、Ni的硫化物和硫酸盐结合态在高温下可部分转换为有机结合的离子可交换态;而Cr、V的硫化物和硫酸盐结合态在高温下部分转化生成了新的热稳定相。在500℃~900℃范围内,Pb属半挥发性元素,Cr, Co, Ni, V属难挥发性元素。微量元素的挥发性极大地受其伴生环境、共存活泼元素等的影响,硅铝酸盐类矿物质对重金属元素的挥发有一定的抑制作用。 相似文献
105.
F-doped TiO2 (FTO) powders were synthesized by spray pyrolysis (SP) from an aqueous solution of H2TiF6. The resulting FTO powders possessed spherical particles with a rough surface morphology and a strong surface acidity. The fluorine concentrations in the FTO powders calculated from XPS spectra significantly depended on SP temperature and ranged from 2.76 to 9.40 at.%. The FTO powder prepared at SP temperature of 1173 K demonstrated the highest photocatalytic activity for the decomposition of gas-phase acetaldehyde under both ultraviolet (UV) and visible light (vis) irradiations, and it was higher than that of commercial P 25. This high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: enhancement of surface acidity, creation of oxygen vacancies, and increase of active sites. It was interesting to point out that the vis photocatalytic activity of FTO powders was achieved by the creation of surface oxygen vacancies rather than the improvement of optical absorption property of bulk TiO2 in vis region. 相似文献
106.
反应条件对煤加氢热解产物分布的影响 总被引:2,自引:3,他引:2
本文以内蒙古红庙煤为研究对象,在温度450-650℃和氢氯压力2-5MPA的范围内,在加压固定床反应器上考察了各种因素包括传质作用对煤加氢热解产物分布的影响。研究表明,转化率和焦油收率随最终反应温度,氢气压力和流速的升高而升高,随加速速率的增大而降低。 相似文献
107.
Two microbial cultures—ML-13 (aCandida sp.) and LSC (a fungal isolate from the University of Arkansas)—have been employed in the direct liquefaction of Louisiana
lignite. Lignite samples were pretreated with nitric acid and microbial culture broths at elevated temperatures and pressures.
Subsequent treatment with active cultures and culture derivatives resulted in significant solubilization of the lignite. Up
to 50% liquefaction of pretreated coal (20% HNO3 at ambient temperature and pressure) was observed in 4 d with ML-13 cultures, whereas almost 80% liquefaction occurred in
a similar time period when exposing pretreated lignite to an autoclaved, cell-free culture broth. 相似文献
108.
煤焦在燃烧过程中孔隙结构变化的模拟 总被引:4,自引:1,他引:4
煤焦在燃烧过程中的物理特性,如比表面积和孔径分布会发生连续变化,直接测量煤焦在燃烧过程中的孔隙结构变化很困难,但可以通过合适的数学模型来观察,二维的圆柱孔模型已大量用来对煤焦气化与燃烧过程中表面积和孔隙结构的变化进行模拟,这个模型把孔隙分成两大部分--大孔与小孔,因为小孔构成比表面的绝大部分,所以在反应过程中比表面积的变化可以由单一小孔模型来拟合,本文采用了用Tseng和Edgar提出的孔模型对几 相似文献
109.
煤显微组分分子结构模型的量子化学研究 总被引:4,自引:3,他引:4
采用分子力学和半经验量子化学方法,研究了神木煤显微组分的分子结构模型,比较了镜质组和惰质组分子模型的能量构成、不同类型键的键长和键裂解能。研究结果表明,扭转能和范德华能是分子中的主要作用力,取代基对体系能量有明显影响,烷基取代基使体系能量增加,而苯基取代基使体系能量降低;脂肪C—C键长比芳香C—C键长长,说明脂肪C—C在受热过程中比芳香C—C更容易断裂分解。对各键裂解能的计算结果表明,Car—Cal键的裂解能高于Cal—Cal,Car—O醚键的裂解能高于Cal—O醚键。而惰质组结构模型中除C—O醚键外,各键的裂解能均高于镜质组,说明惰质组结构模型比镜质组有较高的热稳定性。 相似文献
110.
A solid ion-pair material produced from ammonium tetraphenylborate (ATPB) and naphthalene has been used for the preconcentration of uranium from the large volume of its aqueous complex samples. Uranium reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) to form a water insoluble, coloured complex. This complex is quantitatively retained on the ATPB-naphthalene adsorbent filled in a column in the pH range 7.0–9.5 and at a flow rate of 2 ml/min. The solid mass from the column is dissolved with 5 ml of dimethylformamide (DMF) and uranium is determined by fourth-derivative spectrophotometry. The calibration curve is linear over the concentration range of 0.13–15.0 g of uranium in 5 ml of the final DMF solution. Seven replicate determinations of 6 g of uranium gave a mean peak height (peak-to-peak signal between 592 nm and 582 nm) of 1.02 with a relative standard deviation of 0.95%. The sensitivity is 0.8419 (d4A/d4)/(g ml–1) found from the slope of the calibration curve. The interference of a large number of anions and cations on the estimation of uranium has been studied and the method applied for the determination of uranium in coal fly ash, Zr-base alloy and some synthetic samples corresponding to standard alloys. 相似文献