煤热解焦油原位蒸汽催化裂化提质及反应机制

Shanxi Province has rich resources in coking coal and anthracite. She has also rich resource in steam coal with high volatile matter that accounts for 27% of the total coal reserves. It will be beneficial for clean and efficient utilization of these steam coal by means of coal staged conversion technology based on low-middle temperature pyrolysis. In view of the existing problems with high heavy component content and pyrolysis water in the tar from existing low-rank coal pyrolysis process, and the applicant previously developed technique called integrated methane-rich gas activation and coal pyrolysis with high tar yield, in this project, we propose a process to combine coal pyrolysis with in situ steam catalytic cracking of tar. In the process, the water from coal pyrolysis breaks down to form the active hydrogen and reactive oxygen species and promotes the cracking and hydrogenation of heavy component in the tar through the optimization of catalyst and reaction conditions, then improves the quality of tar. It will be expected to obtain the optimum catalyst and process parameters with high light oil yield by studying the effects of process parameters and catalyst on the product compositions in situ steam catalytic cracking of tar. Moreover, vacuum ultraviolet single-photon ionization coupled with molecular-beam mass spectrometry technique and labeled isotope tracer method will be employed to identify the changes of the product compositions and the transformation of hydrogen and oxygen in water during in situ steam catalytic cracking of tar, and then to gain an in-depth understanding of the reaction mechanism. This research will be significance for people to understand the basic rules of coal tar catalytic conversion and develop the novel coal pyrolysis technology with high yield and high quality of tar through reaction controlling.

山西省除拥有丰富的炼焦煤和无烟煤资源，以长焰煤及弱粘煤等高挥发分煤为主的动力煤储量占27%左右。以热解为基础的煤分级转化可实现其清洁高效利用。本项目针对现有煤热解工艺及申请者前期研发的具有高焦油收率的富甲烷气活化与煤热解耦合工艺存在焦油重质组分及热解水含量较高的问题，提出将煤热解水催化分解与热解焦油原位催化裂化相结合，通过催化剂和反应条件优化，实现热解水催化活化分解形成活性氢和活性氧并促使焦油中重质组分的裂化和加氢，改善焦油品质。通过研究过程参数及催化剂对焦油原位蒸汽催化裂化反应产物组成的影响规律，得到具有高轻质油收率的催化剂和工艺参数；利用分子束质谱技术和同位素示踪方法等研究体系中产物组成变化、水中氢和氧的迁移规律，揭示煤焦油原位蒸汽催化裂化反应机理及催化剂的作用机制。本项目研究对深入认识煤焦油催化转化基本规律及通过反应调控发展具有高品质和高产率焦油的煤热解工艺具有理论和现实意义。

现有煤热解工艺普遍存在焦油重质组分含量高的问题，特别是基于富甲烷气活化与煤热解耦合工艺同时存在焦油重质组分及热解水含量较高的问题。若通过煤热解水的原位催化活化产生活性组分并作用于热解焦油，促使焦油中重质组分同时发生裂化和原位加氢，可望实现改善焦油品质的目的。为此，本项目提出开展煤热解焦油的原位蒸汽催化裂化研究，通过催化剂和反应条件优化，实现热解水催化活化与焦油中重质组分的裂化和加氢，改善焦油品质。以平朔煤、煤焦油及渣油为研究对象，开展煤热解焦油蒸汽催化裂化催化剂的筛选和氧化铁催化剂的改性以及反应过程研究，获得多种具有性能优良的焦油蒸汽催化裂化催化剂（如：Ni/Al2O3、4Ni/5ZrO2-Al2O3、Ni/KD-9、FeAlCe复合金属氧化物）及优化的工艺条件；并从催化剂的共性出发，开展了铁基氧化物催化重油（煤焦油和渣油）部分氧化提质研究，得到了多种金属氧化物掺杂的Fe2O3催化剂，并发明了利用固体废弃物赤泥为载氧体的重油化学链部分氧化工艺技术。通过催化剂在煤焦油蒸汽催化裂化反应过程中物理和化学结构变化表征以及焦油和其他产物组成分析，结合同位素示踪法研究水蒸气在焦油蒸汽催化裂化过程中对焦油形成的作用，认识了煤焦油蒸汽催化裂化反应机理是蒸汽催化裂化产生的活性组分稳定焦油裂化产生的自由基，从而生成轻质焦油；而煤焦油在金属氧化物催化剂（如FeAlZr）上蒸汽催化裂化反应遵循部分氧化机理，蒸汽分解和催化剂中的氧物种参与到煤焦油的裂化，促进了煤焦油中沥青的转化，增加轻质焦油的产率；同时揭示了甲烷和水蒸气混合气氛中焦油原位催化提质是焦油催化裂解和甲烷催化重整耦合的结果。上述研究成果为深入认识焦油蒸汽催化裂化反应基本规律，发展具有高品质和高产率煤焦油的热解工艺提供重要的理论基础与方法。在项目执行期间，已在国内外本学科主流刊物发表论文12篇，国际会议邀请报告1次；国内会议特邀报告3 次；申请授权发明专利1项。培养博士研究生5名，硕士研究生3名。