煤焦油重质组分气相催化裂解轻质化的过程解析与机理探讨

It is essential for us to produce petroleum substitutes from coal to guarantee the energy security for that up to 56% of the petroleum consumption is dependent on import now. While coking is the main part of the coal chemical industry, the amount of coal tar as by-product in 2011 is up to 16.8 million tons, which has drawn extensive attention. Considering that heavy tar accounts for about 50% of coal tar is not utilized in a high value-added way at present, a novel energy-conservation way to convert the heavy tar to light oils is proposed, namely catalytic hydrocracking of uncondensed tar with H2 and CH4 in the accompanied gas. In this study, PY-GC-MS, which has the distinguishing feature by the multi-step temperature programming with up to 8 GC-MS runs per one sample is used to elaborately reveal the thermochemical formation reaction of light oils such as BTX、naphthalene, which are get from the catalytic hydrocracking reaction of H2, CH4 in the accompanied gas with several typical heavy tar with more than three aromatic rings; Selecting high efficiency catalysts and catalytic conditions to improve the splitting rate of heavy tar and increase the yield of BTX、naphthalene according to coal rank; Discussing the reaction mechanism of heavy tar catalytic hydrocracking to BTX、naphthalene; Obtaining the inherent correlations between coal rank parameter (volatile matter and aromatic-carbon ratio) and the catalytic splitting rate of uncondensed heavy tar as well as the conversion extent of heavy tar to light oils to laid theoretical foundation for commercial application.

我国高达56%的对外石油依存度， 使煤制替代石油产品成为保证能源安全的发展需求。而作为煤化工主体的焦化行业，年副产1680万吨煤焦油（2011年）已引起广泛关注。本项目针对目前约占焦油50%以上的重质焦油未能高附加值利用的现状，提出在焦油气未冷凝前进行催化裂解并与伴生煤气中H2和CH4耦合，实现重质组分轻质化的节能创新方法。本研究在PY-GC-MS上进行，利用每个样品可连续得到8个热解催化温度段组分分析数据的独特功能，详细解析不同变质程度煤、不同催化条件下数个3环以上典型重质组分催化裂解并与热解气中H2和CH4耦合生成BTX、萘等轻质组分的热化学反应过程；筛选依煤质不同而能提高重质组分裂解率和增加BTX、萘收率的高效催化剂和催化条件；探讨典型重质组分催化裂解为BTX、萘的反应机理；获得煤阶参数（挥发分与芳碳率）与焦油重质组分气态催化裂解率及轻质化程度之间内在关联，为该技术工业应用提供理论。

我国高达56%的对外石油依存度，使煤制替代石油产品成为保证能源安全的发展需求。而作为煤化工主体的焦化行业，年副产1767万吨煤焦油（2015年）已引起广泛关注。本项目针对目前约占焦油50%以上的重质焦油未能高附加值利用的现状，提出在焦油气未冷凝前进行催化裂解并与伴生煤气中H2和CH4耦合，实现重质组分轻质化的节能创新方法。利用Py-GC/MS在线考察了具有不同孔结构性质和酸强度的催化剂对不同变质程度煤样热解气相焦油的催化性能，分析了催化前后产物中苯、甲苯、乙基苯、二甲苯和萘（BTEXN）的变化规律，进而探讨了煤结构与催化剂之间适配关系。研究了煤热解过程中，矿物质、低分子化合物对BTEXN形成的影响特征，并在此基础上探析了富氢组分（低分子化合物、热解伴生H2和CH4）对焦油催化改质效果的作用。结合模型化合物催化裂解形成BTEXN的途径，探析了煤热解重质焦油裂解碎片耦合伴生富氢组分形成BTEXN的过程机制。研究结果表明，在所选煤样中，USY催化剂对中等变质程度烟煤（气肥煤、肥煤）热解焦油催化提质效果较佳，BTEXN产量可达催化前的5.3和4.1倍。酸位丰富的HY、ReUSY和USY催化剂更能促进BTEXN的形成。吡啶抽提残煤的催化产物中BTEXN产量明显低于原煤，重质芳烃的裂解率也较低。可见催化过程中低分子化合物可作为富氢组分及时稳定稠环芳烃等重质焦油的裂解碎片，进而逐步形成BTEXN。低分子化合物对低阶煤的低温焦油（600°C）催化改质效果影响更大。煤结构中含较多的环烷基和亚甲基桥键时，更利于热解焦油的催化改质。代表煤结构的模型化合物中，苄基苯基醚、联苄、正丁基苯和邻乙基甲苯可形成较高产量的BTEXN，而USY催化剂对邻苯二酚、荧蒽和芘的催化裂解能力较弱，催化产物总量较联苄减少了90%。本研究项目的结果将为该技术的工业应用提供理论。通过本研究项目，发表SCI收录论文7篇，EI收录论文1篇。培养博士研究生1名，硕士研究生4名。