高硫合成气制甲硫醇K_2MoO_4/SiO_2催化剂的研究 Ⅰ.镍的促进作用

Study on the K_2MoO_4/SiO_2 Catalysts Promoted by Nickel for Methanethiol Synthesis from High H_2S-Containing Syngas

采用共同浸渍法制备了K_2MoO_4-NiO/SiO_2催化剂,考察了NiO添加量对高硫合成气制甲硫醇K_2MoO_4/SiO_2催化剂性能的影响。活性评价结果表明,添加了NiO的催化剂活性有很大的提高,当Ni/Mo物质的量比为2/9时,CO转化率为72.6%,较未添加NiO的催化剂提高了一倍多。程序升温还原(TPR)表征显示,添加的NiO与Mo有强相互作用,促进了Mo物种的还原。电子自旋共振(ESR)表征显示,反应后的催化剂中可检测到"oxo-Mo(V)"物种和"thio-Mo(V)"物种,K_2MoO_4-NiO/SiO_2催化剂表面主要为"thio-Mo(V)"物种,而K_2MoO_4/SiO_2催化剂表面主要为"oxo-Mo(V)"物种,NiO的添加促进了Mo物种的还原、硫化,可能是造成催化剂活性极大提高的原因。

The catalysts of NiO loadings on K2MoO4/SiO2 were prepared by co-impregnated method for methanethiol synthesis. The effect of NiO loading dose on K2 MoO4/SiO2 catalystic activity was investigated. The activity evaluating results showed that the activity of K2MoO4/SiO2 catalyst was promoted by NiO obviously, the CO conversion could reach 72.6% over K2MoO4-NiO/SiO2 with 2/9 molar ratio of Ni to Mo, which was more than twice of that over the catalyst without NiO. TPR characterization indicated that there was strong interaction with NiO and Mo, which leaded to the reduction of Mo species more easily. The ＂oxo-Mo（V）＂ and ＂thio-Mo（V）＂ species in functioning catalysts could be detected by ESR characterization. ＂Thio-Mo （V）＂ species were dominant on the surface of K2MoO4-NiO/SiO2 catalysts, but the ＂thio-Mo （V）＂ species were dominant for K2 MoO4/SiO2 catalyst, which indicated that the adding of NiO could promote the reduction and sulfurization of Mo species. And This maybe the reason of the good activity of K2MoO4-NiO/SiO2 catalyst.