Biosolubilization and liquid fuel production from coal

Recently, several microorganisms have been shown to be capable of directly solubilizing low-rank coals. This bioextract has a high molecular weight and is water soluble, but is not useful as a liquid fuel. This paper presents the results of studies to biologically solubilize coal and convert the solubilized coal into more useful compounds. Preliminary experiments have been conducted to isolate cultures for the serial biological conversion of coal into liquid fuels. Coal particles have been solubilized employing an isolate from the surface of Arkansas lignite. Natural inocula, such as sheep rumen and sewage sludge, are then employed in developing cultures for converting the bioextract into fuels. This paper presents preliminary results of experiments in coal solubilization and bioextract conversion.     

褐煤亚临界—超临界水萃取研究

在半连续实验装置上，采用非等温实验技术，以水为溶剂，对大雁、昌宁两种褐煤进行了萃取。结果表明，在适宜条件下可得到高的转化率和较高的萃取物产率；萃取物中 主要馏分为预沥青烯，为原煤中的富氢组分；过程中产生的气体主要分为CO2；萃取物和气体生成速率随温度而变，在400℃左右存在极大值；萃取后褐煤（即残渣）具有比原煤低的水分、低氧含量、高的碳含量及一定的挥发分。本文对对萃取过程进行了宏观动力学处理，结果表明，萃取过程要用一级反应方程式来描述；在萃取的主要温度区间，活化能约为120kJ/mol.     

The kinetics of thermo-oxidative humic acids degradation studied by isoconversional methods

Humic acids represent a complicated mixture of miscellaneous molecules formed as a product of mostly microbial degradation of dead plant tissues and animal bodies. In this work, lignite humic acids were enriched by model compounds and the model-free method suggested by Šimon was used to evaluate their stability over the whole range of conversions during the first thermooxidative degradation step. The kinetic parameters obtained were used to predict the stability at 20 and 180°C, respectively, which served for the recognition of processes induced by heat and those naturally occurring at lower temperatures. Comparison of the conversion times brought a partial insight into the kinetics and consequently into the role of individual compounds in the thermooxidative degradation/stability of the secondary structure of humic acids. It has been demonstrated that aromatic compounds added to humic acids, except pyridine, increased stability of humic acids and intermediate chars. The same conclusion can be drawn for acetic and palmitic acids. Addition of glucose or ethanol decreased the overall humic stability; however, the char of the former showed the highest stability after 40% of degradation.     

黄县块状褐煤热解过程的研究

本文利用单一煤块热解反应装置,在升温速率为2℃/min下,对黄县块状褐煤(粒径20—60mm)进行了热解实验,测得了热解失重和煤块内外温差数据。考察了粒径对热解过程的影响,成功地建立了包括传热因素在内的热解动力学模型。结果发现,热解失重活化能约为110kJ/mol,煤块最大内外温差出现在干燥段,对于粒径为60mm的煤块,最大内外温差约为100℃。     

内在矿物对高灰褐煤CO_2气化的影响研究

利用分选结合逐级酸洗的方法制备出不同灰含量和矿物组成的褐煤煤样,使用沉降管反应器(DTR)和热重分析仪(TGA)研究内在矿物在1 000-1 200℃对褐煤CO_2气化的影响。结果表明,内在矿物对褐煤CO_2气化具有促进作用,且促进机制具有温度敏感性。低温时(1 000℃),内在矿物可通过增加初生半焦微晶结构的无序度,间接提高气化碳转化率。高温时(1 100-1 200℃),内在矿物通过催化煤焦气化,直接促进气化碳转化率的上升。碱性指数不适用于表征本研究的褐煤内在矿物的催化作用。Ca是内在矿物中影响整体催化能力的主要成分,而且羧酸盐形式的Ca是其中的活性组分。不同的催化机制是导致煤焦中钙的催化活性因其化学形式而异的根本原因。羧酸盐形式的Ca可降低煤焦气化反应的活化能,而CaO则提高反应的表观频率因子。     

不同水蒸气浓度下褐煤气化半焦的活化及机理

以胜利褐煤为原料,利用流化床/固定床石英反应器,进行褐煤气化实验,采用BET、Raman、FT-IR、微波消解ICPAES、TGA等技术表征半焦。结果表明,在800℃水蒸气气氛中,醚基裂解造成芳环间短链或无定形碳含量减少,从而削弱石墨化进程,进而提高芳香结构的缺陷程度,是半焦活化的内在原因。提高水蒸气浓度(10%-25%),半焦的反应性降低,是因为气化过程中半焦的活性位再生能力变弱,而反应(Ar,R-CO-Ar,R+2H_2O→Ar,R-O-Ar,R+2H_2+CO_2)增强,导致醚基含量增加,是半焦活性位再生能力变弱的内在原因。继续提高水蒸气浓度(25%-40%),半焦的反应性略有提高,是因为芳香小环(3-5环)缺陷结构含量增加,而反应(Ar,R-CH=CH_2+H_2O→Ar,R-CO-CH_3+H_2)和反应(Ar,R-+H-→Ar,R-H)增强是芳香小环缺陷结构含量增加的内在原因。     

CO2气氛对胜利褐煤热解过程的影响

以5-8 mm胜利褐煤为研究对象,利用固定床反应器,在400-700℃、CO₂气氛下进行热解实验,研究了CO₂气氛对煤热解气、液、固三相产物分布的影响,探讨了CO₂对煤焦结构作用的机理。研究表明,与N₂气氛相比,CO₂气氛热解提高焦油和热解水产率,降低热解气和半焦产率;400和500℃时,CO₂气氛下形成的半焦孔隙结构和总孔体积没有明显的变化,600和700℃时,CO₂气氛下所得半焦的比表面积及孔容较N₂气氛下的大,是与煤焦内部挥发分大量释放以及CO₂进入孔道与活性位反应有关;煤热解过程中CO₂的引入能促进煤焦中3-5环芳香结构的消耗,导致煤焦结构芳香度的提高;600和700℃时,CO₂气氛下热解气中H₂和CH₄产率低,同时CO₂能与煤焦发生气化反应显著提高CO含量。     

水城褐煤热解的气体产物析出特征及甲烷的生成反应类型研究

利用傅里叶红外光谱仪研究了煤中主要官能团的分布,利用热重-质谱联用（TG/MS）在10℃/min的条件下研究了水城褐煤的热解行为,获得了煤热解主要挥发分气体（H₂、CH₄、H₂O、CO、CO₂）生成的速率曲线。采用分峰拟合的方法将甲烷的生成速率曲线分解为五个峰,通过化学动力学分析,结合煤的结构特性、热解特性及其他挥发分气体的生成特征,认为甲烷的生成主要由一个脱吸附过程和四个化学反应组成。