Tar formation characteristic of integrated process of coal pyrolysis with dry reforming of low carbon alkane over Ni/La_(2)O_(3)-ZrO_(2)

Coal pyrolysis integrated with dry reforming of low-carbon alkane(CP-DRA)is an effective way to improve tar yield.Ni/La_(2)O_(3)-ZrO_(2) with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition and obtain high tar yield in CP-DRA.In this study,the fraction distribution and component of tars from CP-DRA and coal pyrolysis in N_(2) atmosphere(CP-N_(2))were characterized by using several methods to understand the effect of DRA on coal pyrolysis.The isotope trace method was also used to discuss the role of low-carbon alkane in CP-DRA.The results showed that the tar from CP-N_(2)is mainly composed of aliphatic compounds with more C_(al),H_(al) and CH+CH_(2),and the tar from CP-DRA contains more Car,Har,and CH_(3),and has lower weight-average molecular weight and more light tar content than CP-N_(2).A small amount of C_(2)H_(6) addition in CP-DRA will raise the ratio of H_(β) and CH+CH_(2).Electron paramagnetic resonance(EPR)analysis shows that the tar from CP-DRA has a higher radical concentration while the corresponding char has a lower radical concentration.The isotope trace experiment showed that alkanes provide·H,·CH_(3),etc.to stabilize the radicals from coal pyrolysis and result in more alkyl aromatic compounds during CP-DRA.

Influence of heating rate on reactivity and surface chemistry of chars derived from pyrolysis of two Chinese low rank coals

A series of char samples were derived from pyrolysis of two typical low-rank coals in China （Shengli lig- nite and Shenmu bituminous coal） at low, medium and fast heating rates, respectively, to the same pyrol- ysis temperature 750℃. Then these chars were characterized by means of thermogravimetric analysis and Fourier transform infrared spectrometer with the aim to investigate the influence of heating rate in pyrolysis process on gasification reactivity and surface chemistry of them. Besides, a homogeneous model was used to quantitatively analyze the activation energy of gasification reaction. The results reveal that Shengli lignite and its derived chars behave higher gasification reactivity and have less content of oxygen functional groups than Shenmu coal and chars. Meanwhile, chars derived from Shengli lignite at 50℃/min and Shenmu coal at 200℃/min have the greatest gasification reactivity, respectively. The oxygen functional groups in Shengli lignite are easily thermo-decomposed, and they are less affected by the heating rate, while that in Shenmu coal have a significant change with the variation of heating rate. In addition, there is no good correlation between the change of oxygen functional groups and that of the gasification reactivity of the derived chars from pyrolysis at different heating rates.

Co-pyrolysis characteristics and interaction route between low-rank coals and Shenhua coal direct liquefaction residue

To reasonably utilize the coal direct liquefaction residue(DLR), contrasting research on the co-pyrolysis between different low-rank coals and DLR was investigated using a TGA coupled with an FT-IR spectrophotometer and a fixed-bed reactor. GC–MS, FTIR, and XRD were used to explore the reaction mechanisms of the various co-pyrolysis processes. Based on the TGA results, it was confirmed that the tetrahydrofuran insoluble fraction of DLR helped to catalyze the conversion reaction of lignite. Also, the addition of DLR improved the yield of tar in the fixed-bed, with altering the composition of the tar. Moreover, a kinetic analysis during the co-pyrolysis was conducted using a distributed activation energy model. The co-pyrolysis reactions showed an approximate double-Gaussian distribution.

Pyrolysis Oil from the Fruit and Cake of Jatropha curcas Produced Using a Low Temperature Conversion (LTC) Process: Analysis of a Pyrolysis Oil-Diesel Blend

Background: The LTC process is a technique that consists of heating solid residues at a temperature of 380oC - 420oC in an inert atmosphere and their products are evaluated individually: these products include pyrolysis oil, pyrolytic char, gas and water. The objective of this study was to compare the effects of the use of oils obtained by pyrolysis of Jatropha curcas as an additive for diesel in different proportions. Results: A Low Temperature Conversion (LTC) process carried out on samples of Jatropha curcas fruit and generated pyrolysis oil, pyrolyic char, gas and aqueous fractions in relative amounts of 23, 37, 16 and 14% [w/w] respectively for Jatropha curcas fruit and 19, 47, 12 and 22% [w/w] respectively for Jatropha curcas cake. The oil fractions were analyzed by FTIR, 1H NMR, 13C NMR, GCMS and physicochemical analysis. The pyrolysis oil was added to final concentrations of 2, 5, 10 and 20% [w/w] to commercial diesel fuel. The density, viscosity, sulfur content and flash point of the mixtures were determined. Conclusions: The results indicated that the addition of the pyrolysis oil maintained the mixtures within the standards of the diesel directive, National Petroleum Agency (ANP no 15, of 19. 7. 2006), with the exception of the viscosity of the mixtures containing 20% pyrolysis oil.

Evolution and organic geochemical significance of bicyclic sesquiterpanes in pyrolysis simulation experiments on immature organic-rich mudstone

Sesquiterpanes are ubiquitous components of crude oils and ancient sediments.Liquid saturated hydrocarbons from simulated pyrolysis experiments on immature organic-rich mudstone collected from the Lower Cretaceous Hesigewula Sag were analyzed by gas chromatography-mass spectrometry(GC-MS).C14 bicyclic sesquiterpanes,namely,8β(H)-drimane,8β(H)-homodrimane,and 8 a(H)-homodrimane were detected and identified on basis of their diagnostic fragment ions(m/z123,179,193,and 207),and previously published mass spectra data,and these bicyclic sesquiterpanes presented relatively regular characteristics in their thermal evolution.The ratios 8β(H)-drimane/8β(H)-homodrimane,8β(H)-homodrimane/8 a(H)-homodrimane,and 8β(H)-drimane/8 a(H)-homodrimane all show a clear upward trend with increasing temperature below the temperature turning point.Thus,all these ratios can be used as evolution indexes of source rocks in the immature-lowmaturity stage.However,the last two ratios may be more suitable than the first ratio as valid parameters for measuring the extent of thermal evolution of organic matter in the immature-low-maturity stage because their change amplitude with increasing temperature is more obvious.

Diluted low concentration electrolyte for interphase stabilization of high-voltage LiNi_(0.5)Mn_(1.5)O_(4) cathode

The Co-free Li Ni_(0.5)Mn_(1.5)O_(4)(LNMO)is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs.However,the synthesis of LNMO is generally time and energy consuming,and its practical application is hindered by the lack of a compatible electrolyte.Herein,a spray pyrolysis-based energy-saving synthesis method as well as a diluted low concentration electrolyte(0.5 M LiPF_(6) in a mixture of fluoroethylene carbonate/dimethyl carbonate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(FEC:DMC:TTE,1:4:5 by volume))are proposed to address these challenges.Owing to the unique features of the precursor prepared by spray pyrolysis,well-crystallized LNMO single-crystal can be obtained within 1 h calcination at 900℃.Besides,the fluorinated interphases derived from the diluted low concentration electrolyte not only mitigate the Mn dissolution and Al corrosion at the cathode side,but also suppresses dendritic Li deposition at the anode side,thus enabling stable cycling of both LNMO and Li metal anode.Thus,30μm Li|LNMO(1.75 m A h cm^(-2))cells achieve a high capacity retention(90.9%)after 168 cycles in the diluted low concentration electrolyte.

The Technical Analysis on Upgrade and Coupling of Low-Quality Coal

Experimental study was conducted with regard to upgrading low-quality coal by low temperature pyrolysis technology and fluidization classification technology, which laid the theoretical foundation for research and development of low-quality coal upgrading process. Firstly, a pyrolysis pilot experiment of long-flame coal was performed and the optimum pyrolysis conditions were found. When the final pyrolysis temperature was 450?C and the residence time was 10 minutes, the content of semicoke volatile dry ash-free was about 22.89% and the content of semicoke ash was about 16.1%. More than 5% of the ash needs to be removed before entering the pyrolysis fluidized bed. Thus, classification tests were carried out to pick out the coal particles with the target size of 500 μm, using a gas-solid fluidized bed coal picker. It was found that the separating effect of coal particles was the most satisfactory when the inlet velocity at the bottom was 3.27 m/s. The percentage of particles with diameters less than 500 μm was as low as 28.7% in the coarse samples. Based on the test results, a novel process of low-quality coal upgrade and coupling was proposed, which realized the sorting, grading, drying and pyrolysis of low-quality coal through the multi-stage fluidized bed integrated process.

Study on Fractional Separation and GC-MS Analysis of Flash Coal Tar Pyrolysed at Low Temperatures

The composition of low temperature pyrolysis coal tar has an effect on its further processing and reasomble utlization In this paper, the compeition or coal tars produced from both low temperature pyroysis in a fluidized bed aud flash pyrolysis with solid heat carrier have been investigated by the methch of fractional seperation and Gas Chromatography-Mass Spectrometry (GC-MS)- It is observed that the degree of coalification maceral and secondary reaction temperature (freeboard temperature in a fluidized bed) have some iufluence on the composition of coal tars- The main compoundes are phenol cresols,xylenols, naphthalene, alkylnaphthalenes, antbraceue, phenanthrene,acenaphthylene, fluoren, indene and so

催化剂对煤热解焦油品质的调控及其表面积炭行为的分析

以催化剂为核心和焦油提质为目的的低阶煤热解技术是保障国家能源安全和实现“双碳”目标的煤炭清洁高效转化技术。鉴于煤焦油品质调控和催化剂表面积炭行为的复杂性,阐述了金属、金属氧化物、天然矿物质、分子筛和炭基催化剂对煤和热解挥发物的催化作用及其对热解产物分布和组成的影响,并对比分析了各类催化剂的优缺点。探讨不同催化剂物理化学性质的区别及其与催化性能之间的关系,结合煤及热解挥发物中C—C、C—H、C=C、—OH、C=O、C—O和—COOH等化学键的断键行为,揭示了不同催化剂的作用机制。在此基础上,针对催化过程中存在的焦油产率低及提质效果差的问题,提出了利用金属尤其是过渡金属改性催化剂活化热解体系中的内部小分子氢供体和外部固体/气体氢供体对重质组分裂解碎片原位供氢的方法,实现焦油产率的提高及焦油品质的改善。同时,针对催化剂易积炭失活问题,分析了积炭的物理化学性质和组成以及积炭形成的原因。从催化剂设计及热解反应体系出发,分析了多种有效抑制积炭的途径,如多级孔与金属活性位点的组合效应、双金属改性调控Brønsted和Lewis酸性位点的比例、酸碱双功能催化剂的开发以及引入H_(2)O、CH_(4)、C_(2)H_(6)和CH_(3)OH等富氢小分子调控挥发物组成等,以期为低阶煤催化热解技术的发展提供理论基础。

Adsorption and Kinetic Study of Activated Carbon Produced from Post-Consumer Low-Density Polyethylene (LDPE) Wastes

Post-consumer polymeric wastes in form of low-density polyethylene (LDPE) can now be considered suitable as a precursor for the synthesis of low-cost activated carbon (AC). This study produced AC from LDPE using sulphuric acid (H2SO4) and potassium hydroxide (KOH) as the activating agent. The reaction conditions for pyrolysis were varied in the range of 0.50 - 2.00 M, 400°C - 500°C, and 45 - 60 minutes. Physico-chemical investigations reveal that AC yield is significantly dependent on both carbonization temperatures and time. The obtained optimum values of 446.50°C and 51.09 mins gave a yield of 24% for the base-activated carbon. The high iodine numbers obtained strongly indicate the presence of large surface area and pore volumes is further confirmed using the Scanning Electron Microscopy (SEM) analysis which reveals the presence of pores on the external surface of the carbons. Fourier Transform Infrared Technique (FTIR) analysis further shows that the synthesized compounds are purely carbon with rich oxy-gen-surface complexes on the surface which is as a result of the introduction of the chemical oxidizing agents. The produced carbons were found to have high adsorption affinity for selected inorganic ions which are: Mn7+, Co2+, and Cr6+. Adsorption isotherm results show the adsorption process to be favourable with the Langmuir isotherm parameter RL having values of <1, while the Freudlich adsorption model was found to perfectly fit the data at selected adsorbent dosages and adsorbate concentrations. The pseu-do-second-order model provides the best correlation for the kinetic analysis. The acid-activated carbon was found to have better adsorption capacities than the base-activated carbon.

低阶煤热解过程中铬的迁移释放特性研究

我国低阶煤储量丰富,重金属在低阶煤热解过程中会迁移到热解产物和环境,既影响产物品质又污染环境。为研究低阶煤热解过程中重金属的迁移特性,以新疆淖毛湖煤(NMH)和内蒙古高硫煤(GL)为实验样品,以重金属铬为研究对象,利用逐级化学提取研究了铬的赋存形态,对原煤进行热解,研究了热解终温和升温速率对铬(Cr)迁移行为的影响,利用逐级化学提取制备了单组份,并对它进行热解,研究了单组份Cr的热稳定性。结果表明,NMH和GL中Cr的赋存形态主要包括硅铝酸盐结合态FC_(2)(34.8%和26.4%)、有机结合态FC_(4)(32.9%和35.7%)、碳酸盐结合态FC_(1)(29.8%和34.3%)、二硫化物结合态FC3(2.5%和3.6%)。热解过程中,Cr的释放率随着升温速率的增大而增大;NMH中Cr在800℃的释放率为8.53%,远低于GL的25.24%。

多段移动床干馏炉集气结构的优化研究

为考察移动床干馏炉内部集气结构对串气率的影响,以陕北低阶碎煤为试验对象,搭建移动床冷态试验装置,在不同进气流量下测定各层气量的流量分配比例,研究在不同位置增设集气结构对气体分布的影响。结果表明:气体经布气伞进入移动床后,有10%的气量无法通过集气主伞流出,而从卸料口泄漏导致串气。在布气伞下部0.6 m和1.2 m处、集气主伞上部0.6 m处分别增设一层集气伞,均可以降低串气比例。同时在上部与中部或中部与下部增加两层集气伞时,可以使串气率降低为0。当中部集气伞与主伞内的压差由0 Pa增加至80 Pa时,串气率由2.80%升高至5.22%,设计炉内结构时应考虑降低沿程阻力损失或者加设集气通道。

富油煤原位热解地质环境影响与地质保障技术

【目的】富油煤作为一种集煤、油、气为一体的特殊非常规油气资源,通过原位热解可转化为高附加值焦油、可燃气及半焦固体燃料等,具有解决传统煤炭工业发展过程中绿色开发、清洁低碳利用难题的潜力。在减少煤炭开采污染、提高能效利用等方面,为碳达峰碳中和(“双碳”)目标的实现提供了新的解决方案,也为我国寻求油气资源战略依赖突围提供了重要路径参考。然而,目前国内富油煤地下原位热解的研究仅限于少数先导性试验研究,对于富油煤原位热解的地质环境影响研究与全生命周期地质保障技术探索亟待开展。【方法】基于富油煤开发原位热解的地质环境扰动响应特征,重点探讨了富油煤原位热解对热解区岩体变质、覆岩损伤变形、地下水扰动、地表沉降及地表生态环境等方面的影响,总结了富油煤原位热解地质条件评价与过程监测主要内容和测试技术,梳理了富油煤原位热解地质保障面临的挑战。同时,结合理论研究、技术方法、感测装备、传感单元、数据解译、多源信息融合和工程实践等内容认识,提出了构建富油煤原位热解地质保障技术体系的思考。【结果和结论】分析认为,在富油煤原位热解的新型资源转化利用模式条件下,迫切需要研发与之相匹配的地质保障技术,制定完整的开发、设计、施工、评价方法和标准,以规范和引导富油煤热解技术的发展与应用。此外,还需要在充分挖掘和利用富油煤油气资源固有优势的基础上,积极推动富油煤清洁利用技术的研发创新、安全生产标准的提升以及生态环境保护的深度融合,为煤炭工业实现绿色转型和高效可持续发展提供全面的战略对策与保障。

基于热重-质谱分析的榆木/低阶煤共热解特性研究

为了研究烘焙对共热解行为的影响,以榆木(E)、250℃烘焙后榆木(E_(T250))和低阶煤(L)为原料,利用热重-质谱联用分析仪(TG-MS)进行榆木/低阶煤不同质量比例下(1∶1、1∶3、3∶1)的共热解实验。TG分析结果表明,相比E和E_(T250),L热解需要更高的温度和更长的时间;但当将生物质与低阶煤共热解后,共热解所需的温度和时间都随着生物质质量比的增加而减小;在共热解过程中,E与L的失重特性曲线相互影响,而E_(T250)在热解过程中与L的失重特性基本一致,说明经250℃烘焙后榆木与低阶煤的品质相似。

基于ReaxFF MD模拟的低阶煤热解产物演化规律及反应机理

热解是实现煤炭资源清洁高效利用的重要途径,深入认识煤热解过程中挥发分自由基的变化规律对调控热解产物至关重要,但实验方法难以捕捉其细节。本文选用经典的褐煤分子模型,结合反应分子动力学(ReaxFF MD)模拟探究了低阶煤热解过程中挥发分自由基的演化规律及反应机理。ReaxFF MD模拟结果表明,挥发分产物的收率随升温速率的增大而增加,较高的升温速率抑制了气体产物的生成、提高了焦油产物的收率,但焦油的重质化严重。含氧官能团的裂解是煤热解的触发机制,热解过程主要分为活化(800~1200K)、热解(1200~2400K)和缩聚(2400~2800K)三个阶段。在高温缩聚阶段,焦油片段之间更容易交联,进而发生缩聚反应形成焦炭,并伴随着气体生成,导致焦油收率降低,气体和焦炭产率增加。因此,改善焦油收率和品质的关键是促进焦油片段的裂解,抑制其缩聚。分析了气相产物的形成机理,CO_(2)主要来自羧基和酯基的裂解;甲氧基侧链和桥键裂解形成·CH_(3)和·CH_(2)自由基并捕获·H,最终形成CH_(4)分子;焦油的二次热解和缩聚释放大量·H和H_(2),·H之间进一步反应生成H_(2);而煤中的硫醚结构与含氮支链裂解后,进而被·H自由基稳定为H_(2)S和NH_(3)。这些从分子层面获得的机理认识,可为实验或工业调控热解产物提供重要的参考依据。

低阶煤热溶萃取物的配煤炼焦性能

目前,使用黏结性添加物进行配煤炼焦,降低焦/肥煤的使用比例,是焦化行业降本增效的重要途径。国内外学者已经在实验室阶段初步证明了低阶煤热溶萃取物替代焦/肥煤炼焦的可行性,工业化应用需要开展大规模的萃取物炼焦实际验证。基于此,本文搭建了低阶煤热溶萃取装置,并与多家焦化厂展开合作,完成了萃取物替代焦/肥煤的小焦炉实验验证。结果表明:萃取物取代20%肥煤或10%焦煤时能够明显降低焦炭的灰分,保持焦炭冷热性能基本不变。并且萃取物在炼焦过程中有72%~77%的留存率,不会造成焦炭产量的明显降低。因此,本研究明确了低阶煤热溶萃取物取代焦/肥煤炼焦方案的可行性,为焦化行业的降本增效提供了新选择,并进一步推动了低阶煤热溶萃取技术的工业化进展。

淖毛湖煤和棉秆共热解协同效应分析

煤和生物质共热解过程中,填料方式会显著影响挥发分之间相互作用及产物分布。分析分隔放置(Case 1)、机械混合(Case 2)、煤在棉秆上层(Case 3)和煤在棉秆下层(Case 4)4种填料方式下淖毛湖煤(NMH)和棉秆(CS)共热解产物的分布、组成及性质,并结合分形理论研究共热解半焦的孔隙特征,探究共热解协同效应。结果表明,NMH和CS协同作用因填料方式不同而变化,填料方式对共热解产物分布及性质影响大。用Case 4方式时,共热解焦油产率最高,为15.94%,较理论计算值增加3.89%,正协同效应最显著。此时,CS热解产生的富氢组分及时与NMH热解挥发物发生交互作用,导致H_(2)、CH_(4)和C_(2)~C_(4)产量较理论值降低,共热解焦油产率增加。不同填料方式对共热解焦油中轻油馏分均产生负协同作用。含氧化合物相对含量减少可能是因为共热解过程促进脱氧反应(如脱羧和脱羰基化等),进一步生成脂肪烃,减少含氧官能团发生交联反应;在共热解中,·H自由基与活性含氧基团产生正协同作用,促使焦油中O、N、S原子向固体或气体产物转移。由半焦分形结果可知半焦分形维数D_(1)和D_(2)均在2~3间,说明半焦粗糙度和孔结构均满足分形结构基本特征。对于Case 3和Case 4方式,位于下层样品半焦的表面更粗糙。用Case 3方式所得CS-C孔隙更小;而Case 4方式所得NMH-C孔隙更不均匀,孔结构更复杂。

小麦秸秆制备热解型煤黏结剂的实验研究

以生物质和低阶粉煤为原料制备热解型煤是实现低阶粉煤高效清洁分质利用的重要技术之一。该研究以小麦秸秆水解残渣(WSR)为黏结剂主要成分,分别复配3种无机黏结剂成分和5种有机黏结剂成分,考察了黏结剂组成对型煤落下强度、热强度和热稳定性的影响规律,优选了膨润土、碱性淀粉、腐植酸钠(HA-Na)等3种黏结剂成分,采用正交试验对复合黏结剂的组成进行了优化。在最优复合黏结剂配比(WSR 12.5%,膨润土3%,HA-Na 3%,碱性淀粉1%)条件下,制备的型煤落下强度为98%,冷压强度3 161 N/个,热强度1 231 N/个,热稳定性99%。

中低温煤焦油沥青组分的热解特性及动力学研究

中低温煤焦油沥青(MLP)为人造炭材料的重要原料,研究其组分的热解特性及动力学对高品质中低温煤焦油沥青基炭材料的制备具有重要意义。以中低温煤焦油沥青为原料,分别采用正丁醇(BA)和二甲基亚砜(DMSO)为萃取剂以获得4种沥青组分,通过热重分析仪对中低温煤焦油沥青和4种族组分的热解行为进行研究,利用Flynn-Wall-Ozawa法、Kissinger-Akahira-Sunose法和Satava-Sestak法计算热解活化能以及热解动力学参数。结果表明:MLP、DMSOS、BAI组分的热解反应机理符合随机成核及其后续增长模型,最佳热解机理函数分别为G(α)=[-ln(1-α)]^(4/3)、G(α)=[-ln(1-α)]^(4)、G(α)=[-ln(1-α)]2,活化能分别为73.99、180.20、46.09 kJ/mol,lg A分别为5.82、13.57、3.32;BAS组分的热解反应机理符合二维扩散模型,最佳热解机理函数为G(α)=α+(1-α)ln(1-α),E=85.36 kJ/mol,lg A=6.18;DMSOI组分的热解反应机理符合二维扩散或三维扩散模型,最佳热解机理函数为G(α)=[1-(1-α)^(1/3)]^(2),E=64.42 kJ/mol,lg A=4.00。

酚醛树脂基复合材料传热-热解模型构建与试验研究

针对现有酚醛树脂基复合材料传热-热解模型忽略产物气体渗流可压缩效应的问题,建立了考虑热解气体可压缩流动的酚醛树脂基复合材料传热-热解模型。通过可压缩压力耦合方程组半隐式方法,求解完整的Navier-Stocks方程,以实现对热解气体可压缩流动的模拟,而非现有模型普遍采用的不可压缩Darcy方程;改进了热解度的计算方式,提高了孔隙动态演化时热解区域材料物性插值的准确性。以一种酚醛树脂基复合材料——酚醛气凝胶复合材料为例,通过热质量试验数据,推导了热解动力学模型。测量了完全热解前后材料的关键计算输入参数。通过10 kPa低气压热试验测得了1000℃加热下材料的背温。结果表明:酚醛气凝胶复合材料存在200~550℃、550~800℃、800~1200℃共3个主要热解区间;完全热解前、后,材料孔隙率分别为0.568、0.484,渗透率分别为10^(-13)、10^(-12) m^(-2)。计算模型与试验结果吻合较好,最大相对误差为9.2%;热解气体向舱内渗流形成富集区域的现象对材料隔热有负面影响,但低导热系数和产物气体热阻塞作用仍使材料具备优异的防隔热性能。