Development of the Sulfide-Based Catalysts for the CO Hydrogenation Reaction in the Presence of H_2S

研究了在碱金属促进的MoS_2催化剂上由CO+H_2（合成气）合成高级醇的方法。然而，这些催化剂合成高醇的活性低于铜/锌基催化剂。形成的醇的链生长概率在0.2 ~ 0.25之间，说明醇的主要成分为甲醇。本文试图明确影响碱金属促进的MoS_2催化剂CO加氢反应活性和选择性的因素。在此基础上，我们开发了一种新的催化剂制备方法，对合成高醇具有较高的活性和选择性。mos_2基催化剂广泛应用于油分加氢反应。认为在还原条件下，硫化物上形成了硫空位，并参与了r…More反应。然而，在mos_2基催化剂上的CO加氢反应中，硫空位的作用尚不清楚。研究发现，K-MoS_2/Al_2O_3对C_2-C_3醇的选择性随反应时间的增加而增加，同时伴有H_2S的脱附。原位FTIR光谱结合NO探针分子的吸附结果表明，H_2S的解吸改变了催化剂的表面精细结构。结合FTIR光谱和EXAFS光谱结果表明，在反应条件下形成了配位不饱和K位点和与K种相互作用的配位不饱和Mo位点。催化剂的表面精细结构随气相H_2S浓度的变化而发生动态变化。为了像FTIR和EXAFS光谱所显示的那样增加K和Mo相互作用的种类，本工作试图将碱金属种类均匀地分布在具有高表面积的MoS_2表面上。该催化剂对C_2-C_4醇的合成具有较高的活性，比传统的低表面积催化剂具有更高的链生长概率。少

Synthesis of higher alcohol from CO+H_2 (syngas) on alkali metal-promoted MoS_2 catalysts has been studied because of their advantages of a sulfur tolerance. However, the activity for the synthesis of the higher alcohol of these catalysts is lower than those of the Cu/Zn based catalysts. Besides, the chain growth probability of the formed alcohol lies in the range from 0.2 to 0.25, which indicates that the alcohol is mainly composed of methanol. The present work tried to make clear factors in determining the activity and selectivity for the CO hydrogenation reaction of the alkali metal-promoted MoS_2 catalysts. Based on the results, we developed a novel preparation method for the catalysts which show the higher activity and selectivity for the synthesis of the higher alcohol.MoS_2-based catalysts are widely used for the hydrotreating reaction of the oil fractions. It is suggested that sulfur-vacant sites are formed on the sulfides under the reducing conditions and are involved in the r … More eaction. In the case of the CO hydrogenation reaction on the MoS_2-based catalysts, however, the role of the sulfur vacant sites has not been made clear yet. The present work found that the selectivity for C_2-C_3 alcohol of K-MoS_2/Al_2O_3 increased with increasing the time on-stream, which accompanies the desorption of H_2S.In-situ FTIR spectroscopy coupled with the adsorption of NO probe molecule showed that the surface fine structure of the catalyst changed by the desorption of H_2S.By combining the results obtained by FTIR spectroscopy with those by EXAFS spectroscopy, it was suggested that the coordinatively unsaturated K sites and the coordinatively unsaturated Mo sites interacted with K species were formed under the reaction conditions. It was also suggested that the surface fine structure of the catalyst changed dynamically depending on the concentration of the gas-phase H_2S.To increase the number of the interaction species between K and Mo species as was suggested by FTIR and EXAFS spectroscopy, the present work tried to spread the alkali metal species uniformly over the surface of MoS_2 having the high surface area. The developed catalyst showed the higher activity for the synthesis of C_2-C_4 alcohol with the higher chain growth probability than the conventional (low surface area) catalyst. Less