胜利褐煤超临界乙醇脱氧实验研究

为有效脱除褐煤中含氧官能团,采用超临界乙醇工艺处理胜利褐煤,研究温度、停留时间和醇煤质量比对胜利褐煤脱氧效果的影响,并利用FT-IR和GC/MS对固液相产物进行表征。结果表明,胜利褐煤超临界乙醇脱氧的最佳工艺条件为:温度270℃,停留时间90 min,醇煤质量比5∶1,此时煤样总氧含量为9.29%,脱氧率为61.40%,固相产率为89.62%。在220℃得到的液相产物中,80%左右为芳香族类化合物,酚类和酯类含氧化合物体积分数低于5%,其他含氧类化合物11.29%。270℃得到的液相产率中芳香族类化合物体积分数降低31.69%,含氧类化合物体积分数增加2.81%,酚类和酯类含氧化合物增至35%左右。褐煤经超临界醇解后,乙醇与煤分子作用发生了醚氧桥键的断裂反应,煤分子发生了脱羧反应,液相产物中含有大量酚类(主要为苯酚及其取代物)和酯类(主要为乙酯类)。     

H_2O_2氧解对褐煤腐植酸及含氧官能团的影响

采用H_2O_2氧解褐煤,研究了氧解条件对褐煤腐植酸含量的影响。通过Boehm滴定和FTIR分析研究了氧解条件对含氧官能团含量和基团结构的影响。结果表明,H_2O_2可有效提高褐煤中腐植酸含量、腐植酸含氧官能团含量和褐煤活性;最佳氧解条件为:氧解时间24 h,H_2O_2浓度20%,液固比0.8 m L/g,在此条件下,褐煤中总腐植酸含量增加了12.53%;氧解反应仅使褐煤中含氧官能团含量增加,腐植酸含量增大。     

H_2O_2氧解对褐煤腐植酸及含氧官能团的影响

采用H_2O_2氧解褐煤,研究了氧解条件对褐煤腐植酸含量的影响。通过Boehm滴定和FTIR分析研究了氧解条件对含氧官能团含量和基团结构的影响。结果表明,H_2O_2可有效提高褐煤中腐植酸含量、腐植酸含氧官能团含量和褐煤活性;最佳氧解条件为:氧解时间24 h,H_2O_2浓度20%,液固比0.8 m L/g,在此条件下,褐煤中总腐植酸含量增加了12.53%;氧解反应仅使褐煤中含氧官能团含量增加,腐植酸含量增大。     

褐煤含氧官能团对腐植酸产率的影响

空气作为氧化剂对胜利褐煤进行预氧化,采用碱溶酸析法提取褐煤腐植酸.研究氧化温度和氧化时间对褐煤含氧官能团质量摩尔浓度及腐植酸析出规律的影响,拟合了含氧官能团质量摩尔浓度和腐植酸析出量之间的关系.结果表明:随着氧化温度的升高,胜利褐煤表面含氧官能团质量摩尔浓度先增加后减少,褐煤中羧基质量摩尔浓度在150℃时达到最大值;随着氧化时间的增加,褐煤含氧官能团质量摩尔浓度逐渐增加;腐植酸产率随着氧化温度和氧化时间的增加而增大,随着含氧官能团质量摩尔浓度的增加而上升,酸性含氧官能团含量与腐植酸析出量之间的拟合关系式为y=32.36x-168,R~2=0.67.     

N_2保护下热预处理对胜利褐煤热解产物分布的影响

采用管式炉反应器在惰性气氛下对胜利褐煤进行脱氧预处理,研究了热预处理对褐煤热解产物半焦产率、焦油产率及气态产物的影响。结果表明:热预处理使得煤半焦产率明显降低,焦油产率升高,气体生成量大于原煤。在600℃热解时,半焦产率最小,焦油产率最大。褐煤中含氧官能团之间的氢键会使得交联反应增加。     

炭黑改性及其在橡胶中的应用研究进展

炭黑由碳氢化合物在高温下(1400℃～1800℃)脱氢和重缩合反应形成。其层状类石墨微晶基本粒子结构中含95%～99%的碳,及少量氢、氧、硫、灰分等成分,各碳原子位于正六角形顶角上,形成六角形平面层,层面边缘有自由基、氢和含氧基团等功能团。其中,表面含氧基团依其结合或解离质子能力不同而呈现酸性、碱性和中性,如羧基、酚基、酸酐基、内酯基等酸性含氧基团,氧杂萘满基和吡喃酮基等碱性含氧基团,羰基、醌基和环状过氧基等中性含氧基团。这些官能团决定了炭黑的表面活性,是其进行化学改性的反应点,如自由基对化学吸附影响很大;表面氢比较活泼,容易发生取代反应等,利用炭黑表面性质对其进行改性研究已经成为炭黑应用中的热点课题。     

煤燃烧过程中碳、氧官能团演化行为

采用X射线光电子能谱（XPS）系统研究燃烧过程中准格尔褐煤及其煤焦颗粒表面中碳、氧的存在形态及演化过程.研究结果表明，准格尔褐煤颗粒表面含碳官能团中石墨化碳含量非常低，但同时具有一定含量的双键碳;含氧官能团中无机氧含量较低，有机氧含量相对较高.随着燃烧的进行，颗粒表面碳、氧官能团呈现不同的变化趋势.     

褐煤物化结构对水分复吸的影响

阐述了褐煤中水分的赋存形态及其在受热过程中的转化行为。分析了不同提质干燥过程中褐煤物化结构的变化,探讨了褐煤物化结构与水分脱除及复吸的关系。结果表明:褐煤表面丰富的孔结构和大量亲水性含氧官能团是其水分较高的主要原因。干燥提质过程中,孔结构坍塌和交联反应的剧烈程度对于抑制复吸非常重要。加热过程中褐煤表面活性含氧官能团的数量、形成和分解行为直接影响褐煤的持水和吸氧能力,含氧官能团的分解会使煤的疏水性增加,自燃倾向性降低。最后说明褐煤提质的关键是水分的高效安全脱除,脱水煤表面氧化和水分复吸的抑制,并提出了抑制提质褐煤复吸水分的可能途径是依据不同组成、结构褐煤的水分赋存和脱除行为,针对性地改善干燥操作条件,调节样品孔径分布、比表面积和表面含氧官能团的存在形态及数量。     

褐煤热转化过程氢键分布特征及调控手段研究进展

褐煤氧含量高且具备良好热反应性,是制备酚类、腐植酸等高附加值含氧化学品的重要原料。褐煤中的杂原子尤其是丰富的含氧官能团(酚羟基、羧基等)导致了大量氢键的存在,褐煤热转化过程(热解、干燥和直接液化等)中常见氢键包括煤中氢键和褐煤-溶剂间氢键等。煤中氢键和褐煤-溶剂间氢键在构型和强度上存在明显区别,目前可通过体积溶胀度、红外光谱等观测手段以及量子化学计算进行探究。煤中氢键和褐煤-溶剂间氢键广泛存在且明显作用于褐煤热解和直接液化等热转化过程。煤中氢键是维持褐煤大分子网络结构稳定的重要因素,能在热解过程中诱导酚羟基和羧基脱水,进而促进褐煤热转化过程中的低温交联反应,不利于焦油等轻质产物的生成。褐煤-溶剂间氢键是褐煤与溶剂相互作用的重要形式,其强度显著影响褐煤在热转化过程中的物理化学反应如萃取、溶胀以及脱氧等。充分认识褐煤相关氢键的存在形态和影响因素,并以此为基础进行氢键调控,对于褐煤清洁高效转化具有重要意义。现有的氢键调控主要目的在于破坏煤中氢键,从而在一定程度上抑制热转化过程中的交联反应。氢键调控方法主要包括低温预热以及使用吡啶、离子液体等强氢键受体进行溶剂预处理等。当前针对褐煤-溶剂间氢键的研究主要停留在定性层面,缺乏褐煤热转化过程中的原位观测以及定量分析。     

锡林郭勒褐煤在超临界水和不同气氛下的液化性能

研究了锡林郭勒褐煤在超临界水和N₂气氛下,以及K₂CO₃,FeS+S和KOH三种催化剂分别作用下的液化性能,并与其在供氢溶剂四氢萘和H₂气氛下的液化性能进行比较。结果表明:锡林郭勒褐煤在供氢溶剂四氢萘和H₂气氛下具有较高的液化活性,在420℃、无催化剂条件下褐煤的液化转化率和油水气收率分别为76.8%和51.0%;而在相同温度、添加5%甲酸的超临界水和N₂气氛下,褐煤的液化转化率和油水气收率分别降为32.0%和29.2%,且褐煤液化主要转化为附加值高的油气部分。K₂CO₃,FeS+S和KOH三种催化剂对锡林郭勒褐煤在超临界水中液化都具有较好的催化活性,按催化活性由高到低排序为K₂CO₃,FeS+S,KOH;420℃时K₂CO₃对锡林郭勒褐煤具有最好的催化效果,褐煤的液化转化率和油水气收率最高,分别为46.5%和42.2%。气氛对锡林郭勒褐煤在超临界水中的液化性能具有较大的影响,在CO气氛下锡林郭勒褐煤的液化活性最高,420℃时褐煤的液化转化率和油水气收率最高,分别为52.2%和44.4%。这是由于在CO气氛下能够发生水煤气变换反应,可以为液化过程提供原位活性H,从而促进了油气收率和液化转化率的提高。     

几种低阶煤的过氧化氢氧化解聚性能研究

在40℃利用5％H2 O2水溶液分别对神府次烟煤（ SF）、准东次烟煤（ ZD）、胜利褐煤（ SL）和先锋褐煤（ XF）四种低阶煤进行了氧解,计算其氧解转化率和CO2生成率,结合元素分析、红外光谱以及酸性官能团测定结果比较了四种低阶煤的氧解性能以及其结构特征对氧化解聚性能的影响。结果表明,煤的氧化解聚与变质程度密切相关,变质程度越高,氧化反应性降低。另外煤的氧含量越高,特别是羧基以及酚羟基含量较高时,氧化解聚程度增大。     

Construction of a macromolecular structural model of Chinese lignite and analysis of its low-temperature oxidation behavior

The aim of this paper is to analyze the change in the active structure of lignite during the process of low-temperature oxidation by constructing a molecular structure model for lignite.Using quantum computation combined with experimental results of proximate analysis,ultimate analysis,Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS),a structural model for the large molecular structure was constructed.By analyzing the bond lengths in the model molecule,the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation.In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite,though ether may also react.These active functional groups react with oxygen to release heat,thereby speeding up the reaction between coal and oxygen.Finally,the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis,and the accuracy of the model was verified.     

Comparison of drying methods on physical and chemical properties of Shengli lignite

The physicochemical properties of Shengli lignite dewatered by three methods in hot air, microwave, and vacuum conditions were investigated. The effects of drying method on the coal pore structure, surface morphology, surface carbon-containing groups, and moisture readsorption performance of dewatered lignite were studied by the Brunauer-Emmett-Teller (BET) method, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and dynamic water vapor sorption analysis (DVS). The results indicate that a large quantity of semi-open micropores and open-ended mesopores with a slit-like or cylinder shape exist in lignite. The specific surface area and total pore volume value of dewatered lignite decrease as follows: microwave-dried lignite (MD) > vacuum-dried lignite (VD) > hot air–dried lignite (HAD), which is consistent with MIP results. SEM images show that lignite dried by different methods is characterized by varied surface morphology. The XPS results reveal that VD has the highest content of C–C/C–H and the lowest content of C–O, and HAD has a higher content of C–O and a higher surface oxidation degree (α) than MD. In addition, the moisture readsorption capability of the dewatered lignite follows the sequence MD > VD > HAD.     

胜利褐煤水蒸气气化制富氢合成气及其固有矿物质的催化作用

利用微型固定床反应装置,研究了内蒙古胜利褐煤水蒸气气化过程中H₂、CO₂、CO和CH₄生成规律及其固有矿物质的催化效应。原煤(SL-raw)、盐酸洗脱(SL-HCl)、氢氟酸洗脱(SL-HF)及盐酸洗脱液回添煤样(SL-HCl-Re)在水蒸气气化反应过程中,H₂、CO₂和CO生成速率存在明显差异,充分说明胜利褐煤中某些固有的矿物质对其水蒸气气化反应具有显著的催化作用,可大幅度提高其气化反应速率,并使其起始气化温度降低96℃,气化反应主体温度降低150℃以上,同时促进了合成气中H₂生成,抑制了CO的生成,使胜利褐煤水蒸气气化反应过程中一直维持着较高的H₂/CO摩尔比,SL-raw、SL-HCl-Re水蒸气气化所得合成气中H₂/CO摩尔比分别为17.3和4.3,而SL-HCl和SL-HF水蒸气气化所得合成气中H₂/CO摩尔比均只有1.22。SL-HCl和SL-HF水蒸气气化生成H₂、CO₂和CO的规律基本相同,说明起催化作用的物质是可溶解在盐酸洗脱液中的矿物质。经过分析,发现矿物质对胜利褐煤水蒸气气化反应的催化作用主要是通过提高水煤气变换反应(WGSR)速度实现的。最后结合文献报道提出了胜利褐煤水蒸气气化反应过程中矿物质的原位催化机理。     

不同干燥程度胜利褐煤燃烧与自燃特性

为了探究高水分褐煤干燥后的燃烧与自燃特性变化,采用一维火焰炉、煤粉着火炉以及自燃试验台对不同干燥程度的胜利褐煤进行了试验研究。试验结果表明,试验样品的着火温度随着干燥程度的增加而降低,随着风煤比的增加而增加,煤粉细度同样会对着火温度产生影响。在燃用干燥褐煤过程中宜采用较高一次风率以提高制粉系统的安全性。胜利褐煤及其干燥褐煤均属于极易燃尽煤种,燃尽率均在99.4%以上,水分的变化对燃尽率影响不大。建议胜利褐煤与20%水分干燥褐煤的运行氧含量控制在3.5%左右。随着干燥程度的加深和粒径的减小,褐煤越容易自燃。胜利褐煤干燥到20%以下可能有自燃的风险。     

Application of TG–FTIR to the determination of organic oxygen and its speciation in the Argonne premium coal samples

During rapid pyrolysis of coal, TG–FTIR (thermogravimetry – Fourier transform infrared) technique can be effectively used to simultaneously detect and measure the three main O-containing gases, namely H₂O, CO and CO₂. Their sum corresponds to the quantitative amount of oxygen in the coal and is, in general, inherently more accurate than the ‘by-difference’ values.In this paper, we first attempt to relate the ‘by-difference’ values for %O reported for the Argonne premium coal samples (lignite to bituminous rank) (Argonne Users Handbook) to those determined from a TG–FTIR examination of the pyrolysis gases evolved. Another objective of the work is to relate the pyrolysis gases (H₂O, CO and CO₂) evolved to oxygen-containing functional groups found in coals as well as the evolution of these functional groups as a function of rank. Correlations are also developed between the TG–FTIR oxygen values and other parameters determined for the Argonne Premium Coals. In particular, comparisons of our results using TG–FTIR with analyses carried out by other workers on functional group analysis of acidic groups are considered.     

Evolution of microstructure and combustion reactivity of lignite during high-temperature drying process

The evolutions of the microstructure characteristics and the combustion reactivity of lignite during high temperature drying process at 600–800°C were addressed in the paper. The information about the oxygen functional groups, carbon skeleton, pore structure, and combustion reactivity of the lignite before and after the drying treatment was obtained by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller technique, Raman spectroscopy and thermogravimetric analyzer, respectively. The results show that a different evolutionary trend of the chemical structure of the lignite appears at the high drying temperature of 700°C at which the carbonyl, carboxyl, and carboxylate significantly decomposed and the treatment gave a slight elimination of structural imperfections and the formation of new cross-linking structures. Then, at the drying temperature of 800°C, a slight increase of the oxygen functional groups was found. The break of the aromatic ring or heterocycle contributed to the rapid increase of amorphous carbon to some extent. During the drying process, the surface area of the resulted lignite gradually increased until 700°C and then decreased. The evolution may be attributed to the decomposition of organic compounds, shrinkage forces, and thermal relaxation effect. The investigation indicates that the change in chemical nature of the coal had a greater impact on the combustion reactivity than the internal pore structure did. In addition, the combustion intensity and performance of the treated lignite was enhanced by the drying process.     

Efficient drying and oxygen-containing functional groups characteristics of lignite during microwave irradiation process

To remove the high moisture of ZhaoTong lignite, the efficient drying characteristics and oxygen-containing functional groups changes in lignite during microwave irradiation process were highlighted in this study. As the microwave absorbers, lignite char and NaNO₃ were added to microwave drying of ZhaoTong lignite. The minimum chemical oxygen demand of waste water generated from microwave drying process of lignite was 99.89?mg?O₂?L^?1. The effects of microwave power, lignite mass, the weight ratio of lignite char to lignite and NaNO₃ content on the drying rate, and moisture diffusion coefficient of lignite were investigated during lignite microwave irradiation process. It was found that the drying rate and moisture diffusion coefficient of lignite increased with increasing microwave power, the weight ratio of lignite char to lignite and NaNO₃ content, but decreased with increasing lignite mass. Lignite char and NaNO₃ were mixed with lignite that can enhance the instantaneous surface temperature of lignite sample under microwave irradiation. Compared with addition of lignite char to lignite, the addition of NaNO₃ to lignite can decrease the unit electric power consumption of moisture evaporating. And the minimum unit electric power consumption of moisture evaporating was 9.44?Wh?g^?1. The FTIR technology was used to investigate the oxygen-containing functional groups changes in lignite during microwave drying process. The oxygen-containing functional groups of lignite were effectively removed with increasing microwave power.