高硫化氢合成气制甲硫醇新型钼基催化剂研究

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”相关联的反应机

Novel Mo-based catalysts for methanethiol synthesis from high H2S-containing syngas

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

少模光纤中模式选择性激励技术

基于少模光纤的模分复用系统能继续提高光纤通信系统的传输容量,目前已成为全球的研究热点。在介绍了少模光纤设计后,文章对3种模式选择性激励技术（偏移注入、长周期光纤光栅和空间光调制）的激励机制、特点及实现进行了研究,并重点介绍了基于空间光调制的模式选择性激励技术

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies