三维有序大孔复合金属氧化物脱硫剂的构建及水对脱硫作用行为研究

Ultra-fine desulfurization at ambient conditions is the key for production of hydrogen from coal based syngas. Commercial techniques for hydrogen sulfide removal cannot reach the requirements due to the contradictory of sulfur capacity and precision, as well as the low utilization. The previous study showed that the metal oxide-based sorbent had great performance advantages when three-dimensionally ordered macroporous (3DOM) structure was introduced. This proposal will focus on looking for a solution to the low precision of the 3DOM sorbent in moist gas atmosphere from two points. On the one hand, the component of the zinc/iron based sorbents will be adjusted by introducing other metals. The effect of component of the sorbent on morphology, structure as well as property will be investigated and correlated to the performance, and a perfect 3DOM mixed metal oxide sorbent will be designed. On the other hand, the behaviors of the moisture and its interaction with hydrogen sulfide will be explored by tracing the adsorbed species on sorbents. The mechanism of the desulfurization in moist atmosphere then will be illuminated. The results of this study will present scientific foundations for developing new technology of deep desulfurization at ambient conditions, and contribute to theory of non-catalytic gas-solid reaction. This work will also have great significance for promoting the application of the novel 3DOM materials.

常温温和条件下超精脱硫是煤基合成气制氢等新技术的关键。现有脱硫技术存在硫容与脱除精度的矛盾，且活性组分利用率低下。前期结果表明，将三维有序大孔的新颖结构引入金属氧化物脱硫剂，可极大提高脱硫性能，显示了其在精脱硫领域所具备的巨大优势。课题组将在此基础上，从两个关键问题入手，重点解决其在水气氛中脱硫精度不理想的问题。课题将以锌/铁为主要活性组分，通过复合其它过渡金属氧化物来调节其组成，探索脱硫剂组成与其形貌、结构、性质的关系，并关联性能评价结果，构建优异的三维大孔复合金属氧化物脱硫剂；通过追踪水及硫化氢在脱硫剂上的存在物种的变化路径，明析两者的独立吸附行为及相互作用方式，获得水参与影响脱硫反应的机理。本课题研究将为常温精脱硫技术的发展提供有力的科学依据，为气固非催化反应理论做出贡献，并对推动3DOM这一新材料的应用具有重要意义。

常温温和条件下超精脱硫是煤基合成气制氢等新技术的关键。现有脱硫技术存在硫容与脱除精度的矛盾，且活性组分利用率低下。将三维有序大孔的新颖结构引入金属氧化物脱硫剂，可极大提高脱硫性能。课题组以锌/铁为主要活性组分，通过复合其它元素来调节其组成，探索脱硫剂组成与其形貌、结构、性质的关系，并关联性能评价结果，构建了性能优良的复合金属氧化物脱硫剂。考虑到三维有序大孔脱硫剂制备工艺复杂耗时等问题，我们通过对制备工艺进行优化，研究出了一种简单且具有普适性的溶胶凝胶制备方法制备出高性能的脱硫剂。研究还发现，在溶胶前驱液中掺入AC，一方面可改善活性相的分散性并减小晶粒，另一方面还利于引入更多的缺陷位点。这些缺陷位点通过促进水的解离和S2-离子在ZnO晶格中的固体扩散，可极大地提高脱硫剂的硫容。常温钴基脱硫剂硫容很高，主要是由于催化氧化的结果。水在ZnO表面以羟基、化学吸附水和物理吸附水三种形式存在。有水参与的脱硫反应的路径不同与无水条件，反应能垒低，反应速率更高。随着反应的不断进行，化学吸附水分子可以补充消耗的羟基，从而维持脱硫活性。物理吸附水分子会抑制在吸附有羟基的氧化锌与硫化氢反应路径上S原子吸附方式的变化，导致反应活化能的增加，从而使氧化锌的活性降低。总之，项目的研究成果为常温精脱硫技术的发展提供了有力的理论依据。