Dispersion of alkali on the surface of Co-MoS2/clay catalyst: a comparison of K and Cs as a promoter for synthesis of alcohol
Dispersion of alkali on the surface of Co-MoS2/clay catalyst: a comparison of K and Cs as a promoter for synthesis of alcohol
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DOI：
10.1016/s0926-860x(03)00092-9
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发表时间：
2003-07
影响因子：
5.5
通讯作者：
J. Iranmahboob;H. Toghiani;D. Hill
中科院分区：
文献类型：
--
作者：
J. Iranmahboob;H. Toghiani;D. Hill
采用X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和能谱（EDS）对碱（K，Cs）促进的Co-MoS 2/粘土催化剂表面进行了表征。催化剂表面K和Cs的富集程度随合成气暴露量的增加而增加。XPS表明，合成气处理使K促进的催化剂的K 2 p线略有偏移（K 2 p3/2=292.9和2 p1/2=295.7eV）到更高的结合能（BE）（K2p ~（3/2）=293.2，2p ~（1/2）=296eV）; Cs 3d ~（5/2）（724.6eV）和Cs 3d ~（3/2）（738.7eV）向较高的结合能（0.2eV）轻微移动。Cs促进的催化剂在合成气暴露过程中形成Co_9S_8，而K促进的催化剂在合成气暴露过程中没有形成Co_9S_8。XPS，SEM和EDS分析表明，当使用研钵和研杵混合活性化学品时，钾和铯在新鲜催化剂上的分布是不均匀的。Cs促进的Co-MoS_2/粘土催化剂表面生成Co_9S_8，可能导致Co-Mo-S比表面积降低，催化剂的产醇活性降低。K促进的Co-MoS 2/粘土催化剂在300°C和2000 psig气时空速（GHSV= 2000 h-1）下实现了最高的乙醇生产率（129 g/kgcath-1）。随着反应温度的升高，总醇合成（AS）产率增加，但总醇选择性降低。
The surface of alkali (K, Cs) promoted Co-MoS2/clay catalysts were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The surface enrichment of K and Cs on the surface of catalysts increased with syngas exposure. XPS suggests that syngas treatment slightly shifted the K 2p lines of K-promoted catalyst (K 2p3/2=292.9 and 2p1/2=295.7eV) to a higher binding energy (BE) (K 2p3/2=293.2 and 2p1/2=296eV), and for Cs-promoted catalyst, the Cs 3d5/2(724.6eV) and Cs 3d3/2(738.7eV) were shifted slightly to a higher binding energy (0.2eV). Co9S8was formed during syngas exposure of Cs-promoted catalyst, but it was not formed during syngas exposure of the K-promoted catalyst. XPS, SEM and EDS analysis indicated that potassium and cesium distributions on the fresh catalysts were not uniform when a mortar and pestle was used to mix the active chemicals. The formation of Co9S8on the surface of Cs-promoted Co-MoS2/clay catalyst may result in a reduction of Co-Mo-S surface area and its activity toward alcohol production. The highest ethanol production rate (129g/kgcath−1) was achieved for K-promoted Co-MoS2/clay catalyst at 300°C and 2000psig for gas hour space velocity (GHSV=2000h−1). The total alcohol synthesis (AS) production rate increased upon increasing the reaction temperature, however, the total alcohol selectivity was decreased.