基质隔离红外光谱研究H2S脱氢-CO加氢耦合反应机理

Extensive research has been conducted on hydrogen production from decomposition of hydrogen sulfide. However, there are few reports on the utilization of the hydrogen regenerated here to react with CO further. This is mainly due to the formation of COS intermediate which, instead of CO, participates in subsequent hydrogenation reaction. In view of this, Group IVA atom (Si, Ge, Sn, Pb) is introduced to induce dehydrogenation of H2S while passivating sulfur atom so as to increase the possibility of CO hydrogenation. With the aid of matrix isolation infrared spectroscopy, isotopic labeling, as well as density functional theory calculation, the reaction mechanism, especially the structure and interconversion of some important reactive intermediates in the reaction of Group IVA atom (Si, Ge, Sn, Pb) with H2S and CO will be explored in detail. Through this project, it is expected to find a new way of S-H bond activation and transformation, offering new ideas for the design of similar reactions.

硫化氢分解制氢已有大量研究，但是利用硫化氢分子中潜在的“氢资源”与一氧化碳进行氢气加成反应的研究鲜有报道。究其原因，主要是因为相关反应过程中易于生成COS活性中间体，并且该活性中间体取代一氧化碳参与后续加氢反应。有基于此，本项目拟通过硅及其同族原子的竞争性引入，在诱导硫化氢活化脱氢的同时钝化反应体系中的硫原子，为一氧化碳的选择性加氢创造条件。拟开展项目将结合低温基质隔离红外光谱技术, 同位素取代实验与密度泛函理论计算，围绕S-H键活化及高效转化这一基本科学问题，重点研究Group IVA原子M (M = Si, Ge, Sn, Pb)与硫化氢及一氧化碳反应相关活性中间体的结构及其相互转化规律。通过本项目的实施，可望发现S-H键活化转化的新途径，为同类反应的设计提供新思路。

本项目结合低温基质隔离红外光谱技术, 同位素取代实验与密度泛函理论计算，重点研究了Group IVA原子(Si, Ge, Sn, Pb)与硫化氢及两类碳源（一氧化碳和二氧化碳）反应相关活性中间体的结构及其相互转化规律，发现了S-H键活化及高效转化所涉及的一类重要活性中间体HSiSH。较之H2S，HSiSH分子中存在三类重要的化学键：Si-Hδ−键，S-Hδ+键以及潜在的Si=S多重键，其中Si-Hδ−键可以诱发CO2的硅氢加成反应；而S-Hδ+化学键的断裂则非常有利于Hδ+进攻HCOO基团；Si与S之间形成较强多重键的倾向进一步促进了HCOOH的形成。该反应途径的发现为同类反应的设计提供了新思路。