摘要
研究了一系列负载型钼基催化剂催化含高硫化氢合成气制甲硫醇的性能 ,用XPS和ESR对其进行表征 .活性测试显示 ,钾促进的钼基催化剂催化的反应产物中甲硫醇成为主导产物 .几种钼基催化剂合成甲硫醇的活性大小顺序 :K2 MoO4/CoO/SiO2 >K2 MoO4/SiO2 >MoO3 /K2 CO3 /SiO2 >K2 MoS4/SiO2 >MoS2 /K2 CO3 /SiO2 .ESR表征显示 ,反应后的催化剂可以检测到“oxo Mo(V)”和“thio Mo(V)”物种 .XPS表征显示反应后催化剂中的Mo包含着Mo4+ ,Mo5+ 和Mo6+ ,S包含着S2 -,(S—S) 2 -和S6+ 三种价态 .添加CoO后 ,“oxo Mo(V)”含量减少 ,而“thio Mo(V)”含量增加 ,(S—S) 2 -物种的生成得到抑制 ,S2 -物种的量增多 .(Mo4+ +Mo5+ ) /Mo6+ 峰强度比为 0 75以及S2 -/(S—S) 2 -接近 1有利于甲硫醇的生成 .本文提出甲硫醇的合成与“Mo S K”
A series of supported Mo-based catalysts for methanethiol synthesis from high H2S-containing syngas were investigated by kinetics and XPS, ESR characterization. The activity evaluating results show that upon the potassium-promoted Mo-based catalysts, the methanethiol will become dominant product of the reaction, and the activity sequence of several Mo-based catalysts for the reaction is as follows: K2MoO4/CoO/SiO2 > K2MoO4/SiO2 > MoO3/K2CO3/SiO2 > K2MoS4/SiO2 > MoS2/K2CO3/SiO2. In the ESR characterization of the catalysts used the resonant signals of 'oxo-Mo(V)' and 'thio-Mo(V)' can be detected. The XPS characterization indicates that mixed valence Mo species Mo4+, Mo5+ and Mo6+ and three kinds of S species S2-, (S-S)(2-) and S6+ exist in the catalysts. As a promoter CoO was introduced into Mo-based catalysts. It was observed that the addition of CoO leads to decrease of the amount of 'oxo-Mo(V) ' in the catalysts, but increase of the amount of 'thio-Mo(V)', which may be connected with 'Mo-S-K' phase or 'Co-Mo-S-K' phase, meanwhile CoO in die catalyst was found to enhance the formation of S2-, but inhibit the formation of (S-S)(2-). It was found also that the methanethiol synthesis is favored if the peak intensity ratios of (Mo4+ + Mo5+)/Mo6+ and S2-/(S-S)(2-) are kept at about 0.75 and 1 level respectively. A possible mechanism about the relationship of CH3SH formation with 'Mo-S-K' phase was proposed.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2004年第23期2297-2302,共6页
Acta Chimica Sinica
基金
国家自然科学基金 (No.2 0 1 730 4 3)资助项目
