煤焦选择性活化与催化甲烷定向裂解的协同作用机制研究

Coal pyrolysis is a potential way for efficient utilization of coal based on the staged conversion. But coal char, as one of the main products produced by coal pyrolysis, is facing some problems and challenges caused by its excess capacity. At present, hydrogen is considered to be a rare clean energy that can bring neither greenhouse effect nor pollutants to our life. To realize high-value utilization of coal char and to obtain clean hydrogen energy, this proposal intends to design an integrated process based on the synergistic effect between selective activation of coal char and oriented decomposition of methane by catalysis. It is expected that activated carbon or porous carbon could be obtained by activating coal char while co-production of hydrogen and carbon fibers could be achieved by oriented decomposition of methane. The synergic catalytic effect can be obtained by the strategies of disassembling the integrated process and catalyst structure assembly using structure fragments and optimized knowledge. Besides, based on the inter-relations among the function, structure and preparation method of catalysts, new-type catalysts from coal char will be designed and prepared with controllable compositions and structures. Accordingly, these make it possible to achieve the process intensification and directionally regulate the products. Furthermore, the catalytic effect and mechanism will be systematically investigated and assessed on the reaction efficiency of the integrated process, product selectivity, compositions and structures, etc. And thus the quantitative structure-property relationship can be built accordingly. It is sure that the project we propose here will make a positive impact on high-value conversion and utilization of coal char, mitigating the overcapacity problem of coal char, and oriented conversion of methane into valuable chemicals. And it can also provide knowledge and methodological guidance for design and preparation of novel catalysts.

煤热解是煤炭分级分质转化利用的潜在方式，而其主产品半焦（称为煤焦）当前面临着产能过剩的问题与挑战。氢气是目前为数不多的既不产生温室效应也无污染排放的清洁能源。为实现煤焦的高值化利用联产氢能源，本项目拟构建煤焦选择性活化（转化为活性炭或多孔炭）与催化甲烷定向裂解（联产氢气和炭纤维）的协同作用机制。在技术层面，通过工艺过程“拆解”和催化剂结构组装，构筑协同催化效应；结合催化剂“功能-结构-合成”之间的关系，设计制备组分与结构可控的新型煤焦基催化剂；从而实现过程强化与产品定向调控。在理论层面，综合评价煤焦基催化剂传质强化和多中心协同催化效应对煤焦活化与甲烷裂解的反应效率、产品组成与结构的影响规律及作用机制，系统建立起定量的构效关系。本项目的开展对煤焦的高值化转化利用及化解部分过剩产能、催化甲烷定向转化成高附加值化学品都具有重要的积极意义，还可为新型催化剂的设计制备提供方法与理论指导。

中低温热解是低阶煤分级清洁高效转化的潜在方式。其中，煤焦（部分地区称为兰炭）是煤中低温热解后的固体产品（约占原料煤质量的60%），当前面临着产能过剩的困境，亟需高值化转化。甲烷裂解制氢是一种不产生温室效应也没有污染排放的清洁制氢工艺。为实现煤焦与甲烷的协同转化，本研究通过构建煤焦活化（转化为多孔炭）与催化甲烷裂解（联产氢气和炭纤维）的协同转化作用机制，实现了联产氢气和功能炭材料（包括多孔炭和炭纤维）的有益效果。通过对协同转化工艺过程的“拆解”和催化剂结构/组分的组装，构筑了协同催化效应；通过移植与构建“氧转移”催化作用体系，设计制备出了组分与结构可控的新型煤焦基催化剂；从而实现了煤焦与甲烷协同转化的过程强化与产品定向调控。本研究工作的开展对煤焦的高值化利用和催化甲烷裂解制氢技术都具有重要意义，还可为新型催化剂的设计制备提供理论指导。相关成果在国内外学术期刊上发表SCI论文9篇、EI论文1篇、中文核心期刊论文1篇，申请发明专利2件、授权发明专利4件，参加境内外学术会议交流7次，指导与培养10名研究生顺利毕业。