Synthesis And Mechanism Of Methanethiol Active Center By CO/H₂S/H₂ One-Step Method

At present,several kinds of air pollution problems exposed in China,such as haze and acid rain,have seriously threatened the healthy development of human body and mind and the normal operation of work and life,and sulfur pollutants produced in the industrial application of coal and oil are the"main culprit"causing such air pollution problems.Synergistic catalytic conversion of coal gasification process of carbon-sulfur pollutants（CO/H₂S/CS₂）for chemical intermediates with high additional value-methyl mercaptan（CH₃SH）is to realize clean utilization of coal,oil,a new way of thinking,to achieve efficient use of synthetic gas catalytic synthesis of methyl mercaptan,preparation has rich active site high catalytic activity of the catalyst is the key.MoS₂ material has become the focus of research in this reaction system because of its excellent sulfur resistance and high catalytic activity.However,due to the complex reaction path and many intermediate products in this reaction,the active phase and active center of this reaction cannot form a structure-activity relationship with the structure of the catalyst,which further restricts the further research in this system.To solve the above problems,this paper prepared a series of K-Mobased catalysts and Mobased catalysts,explored the influence of metal-support interaction on the catalyst,and determined the position of the active site and active phase in the reaction system by designing related activity experiments and combining with related characterization techniques.The main research contents and conclusions are as follows:（1）Research on k-Mocatalyst supported on support with different properties:By preparing three kinds of catalysts supported on different properties of support（mesoporous SBA-15,γ-Al₂O₃ and TiO₂）,X-ray photoelectron spectroscopy（XRD）,X-ray diffraction（XRD）and high Angle ring dark field transmission electron microscopy（HAADF-TEM）were used to prove the existence and content difference of k-doped MoS₂ active phase brought by three different force carriers,resulting in the activity difference.（2）Exploration of the reaction active center site on Mo-based catalysts:Several catalysts with pure Mo-based supports were prepared,and the active site of the reaction was guessed by the difference of their catalytic activity in the mixed gas system.X-ray photoelectron spectroscopy（XRD）,X-ray diffraction（XRD）and high Angle ring dark field transmission electron microscopy（HAADF-TEM）were used to verify the conjecture.The results showed that MoS₂ supported on Al₂O₃ with acid point and TiO₂with REDOX site showed a good activity of methanethiol synthesis,while MoS₂supported on SBA-15 and SiO₂ did not have corresponding acid site or REDOX site,so it could not synthesize methanethiol.（3）Study on reaction path and mechanism on MoS₂ and Al₂O₃:By preparing a series of MoS₂-Al₂O₃ catalysts with different physical mixtures,combining the reaction activity and product selectivity,it is found that CH₃SH is difficult to be synthesized in single MoS₂ and single Al₂O₃,or even not synthesized,but the interface contact degree and reaction activity of the two substances can show a certain linear law.The reaction is inferred to be a series reaction based on vacancy and acid site coordination.