基于微型流化床在线反应分析的原位半焦对煤焦油催化裂解动力学及反应机理

The utilization of char as a catalytic for tar removal has been considered to be promising and attractive because of its property of high catalytic activity, wide source, low cost, and strong resistance in deposited carbon. The existing researches mainly focus on the examination of catalytic performance, selection of char with good catalytic activity, and influencing parameters for tar removal. However, it always ignores the deactivation mechanism of char in tar removal and also lacks of reaction kinetics involved char deactivation and fuel gas production. In this study, a new micro fluidizied bed reaction analysis platform will be adopted, which has the functions of on-line feeding coal, online charging char, and real-time analysis for fuel gas components. Firstly, for displaying the necessity and meaning for adopting in-situ char, a systematical comparison between in-situ and ex-situ char will be conducted. At the same time, the effect of char property on tar catalytic reforming, such as carbon crystallite structure, surface functional group distribution, specific surface and pore distribution, alkaline and alkaline earth metal, will be fully examined, to illustrate structure-function relationship. Then, based on the evolution of structure and active site of char during tar catalytic reforming, the catalytic and deactivation mechanism will be probed and analyzed. Finally, reaction kinetics models about tar catalytic reforming and fuel gas production will be proposed, which can be used to predict the char deactivation during this period. From this study, we hope to deepen the understanding in tar catalytic reforming by in-situ char, fill the gaps in char deactivation mechanism and reaction kinetics, and also guide the development of novel and gasification technology.

热解/气化过程中的原位半焦对焦油催化效果显著，且来源广、成本低、抗积碳能力强。现有研究在原位半焦催化和失活机理方面比较薄弱，且在动力学研究中常忽视半焦失活和气体生成信息的表达。基于此，本研究利用具有在线加料、在线取样和气体实时分析功能的微型流化床反应平台，构建原位半焦催化焦油的在线分析方法，比较原位/非原位半焦在碳微晶结构、表面官能团、孔道结构、碱(土)金属等方面的差异，阐述采用原位半焦的必要性和意义；同时系统考察原位半焦结构和活性位点等对焦油催化的贡献，揭示其构效关系；其次，在H2O/CO2气氛下考察反应过程中半焦结构和活性位点的演变规律，探讨半焦催化焦油及其失活机理；最后，构建原位半焦对焦油催化的动力学模型，预测焦油催化过程中半焦的失活行为，并提出预防机制。本研究将深化对半焦催化脱除焦油机理的认识，填补焦油脱除过程在半焦失活和反应动力学方面薄弱的局面，为新型气化工艺的开发提供理论。

焦油是中、低温气化过程中不可避免的粘稠性液体副产物。低温下，焦油凝结，易堵塞管路、腐蚀设备、引起催化剂中毒，并产生大量含酚废水。这不仅影响设备的正常运行，还降低气化效率。因此，研究焦油热转化行为对脱除技术的选择和工艺设计具有重要意义。热解/气化过程中生成的半焦对焦油具有良好的催化效果，然而半焦催化重整焦油过程中其自身结构和活性也会发生变化，降低其催化效果，进而影响半焦气化特性和气化炉的操作，这也是气化工艺中利用半焦催化脱除焦油亟待解决的难题和关键。. 基于此，本项目利用微型流化床反应分析仪和两段流化床反应装置，主要开展了下列研究：① 原位半焦制备方法及焦油高温转化数据处理方法的构建；② 原位半焦对焦油的催化脱除行为及动力学分析，并与焦油热裂解特性进行对比；③ 微型流化床反应分析仪中H2O气氛下焦油反应特性分析，并与惰性气氛下热解特性进行对比；④ 半焦结构参数和金属氧化物对焦油裂解的贡献分析；⑤ 焦油催化重整过程中半焦失活及活性恢复特性研究；⑥ 原位半焦催化焦油对分段气化工艺设计和创新的指导和启发。上述研究内容验证了原位半焦对焦油的催化脱除效果，并求算了反应动力学；揭示了原位半焦中重要参数(孔结构、金属氧化物)在不同温度、气氛等情况下对焦油催化重整的贡献，明晰了在此过程中焦油组分和含量的演变规律；揭示了原位半焦对真实焦油的催化脱除机理，总结了半焦催化活性的演变机制，提出了实际气化炉中半焦失活的预防机制；为低焦油气化技术提供理论依据和数据支撑，促进分段解耦气化工艺创新。. 项目执行期间，取得的成果如下：发表文章8篇，申请专利2项，参与申请国家标准1项，有2名参与人员晋升为副研究员，培养研究生7名，支撑了2项省部级科学技术奖励的成功申报。