煤液化残渣基介孔碳负载型中高温煤气脱硫剂微波脱硫机理

Coal gasification is one of the most important techniques involved in efficient clean coal technologies. However, the sulfur in coal is transferred to coal gas during gasification process. Therefore, sulfur removal is necessary before utilization of coal gas. Mid- and high-temperature coal gas desulfurization is the most promising technology of dry desulfurization for coal gas purification. However, there are several problems such as large diffusion resistance and significant influence of atmosphere effect on desulfurization, which greatly influence industrial applications of mid- and high-temperature coal gas desulfurization. Microwave can promote the diffusion of solid-state ion. It also exhibits thermal and nonthermal effects when applied in chemical reactions. Based on the description mentioned above, microwave heating will be used in the process of removing H2S by desulfurizer in this study, which may facilitate desulfurization and suppress side reactions. Coal liquefaction residual-based mesoporous carbon with low cost and good ability of adsorbing microwave, will be used as the support of desulfurizers. This project aims to study structure characteristics of sorbents and the influence of coal gas components on desulfurization during sulfidation process by conventional and microwave methods. Desulfurization kinetics will also be studied. Based on the study stated above, the ion diffusion mechanism, microwave effects during sulfidation process and the influence of atmosphere effect on desulfurization, will be clarified. The desulfurization mechanism of sorbents under simulative coal gas atmosphere will be proposed. This work will provide theoretical basis for the industrial development of desulfurization by mid- and high-temperature coal gas desulfurizer under microwave irradiation and enrich theory of microwave-assisted gas-solid reaction.

煤气化技术是煤炭洁净高效利用的关键技术之一，而煤中硫会在气化过程中转移到气相中，因此煤气在利用前必须脱硫。中高温煤气脱硫净化被认为是最具潜力的干法煤气脱硫技术，但至今仍存在脱硫剂硫化后期产物层离子扩散阻力大、气氛效应对脱硫反应影响明显等问题，直接制约该技术的工业应用。基于微波促进固态离子扩散的特性、微波化学反应中存在的热效应与非热效应，本课题提出将微波用于脱硫剂的脱硫过程，期望促进硫化反应、抑制气氛效应。以低成本且吸波性能优良的煤液化残渣基介孔碳为脱硫剂载体，通过对比研究常规和微波两种脱硫方式下脱硫剂硫化过程中的结构特征、不同煤气组分对脱硫反应的影响、硫化动力学，阐明脱硫剂微波脱硫过程中的离子扩散机理与微波效应，揭示微波对气氛效应的影响机制，进而推断脱硫剂在模拟煤气气氛下的微波硫化机理。项目的实施可为中高温煤气脱硫剂微波脱硫的工业应用提供理论依据，同时将丰富微波气固反应理论。

针对气化煤气中高温脱硫存在的脱硫剂硫化后期扩散阻力大、气氛效应对脱硫剂脱硫性能影响明显等问题，本课题提出采用微波脱硫来解决上述问题。通过研究焙烧温度、焙烧时间等参数对脱硫剂脱硫性能的影响，明确了脱硫剂的可控制备规律；搭建了微波脱硫固定床微反应评价装置；通过脱硫剂硫化前后的结构表征分析，发现除金属硫化物外，脱硫过程的还生成了一部分单质硫；对比研究了脱硫剂在常规和微波两种脱硫方式下脱硫剂硫化前后的织构差异，揭示了脱硫剂微波硫化性能较优的内在原因；脱硫剂硫化反应动力学研究结果表明，微波主要是通过强化脱硫剂脱硫过程的传质（包括离子扩散）来改善脱硫剂脱硫性能；煤气组分在微波脱硫方式下并未对脱硫剂的脱硫过程表现出明显的抑制作用。上述研究为碳基多孔材料负载型脱硫剂的进一步应用提供了相关的基础数据，也可为其它微波气固反应的研究提供参考，同时也丰富了微波气固反应理论。