A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse r...A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption fine structure spectroscopy. The catalytic performance for higher alcohol synthesis from syngas was measured. It was found that the Mn-doped catalysts ex- hibited a much higher activity as compared to the unpromoted catalyst, and in particular the C2＋ alcohol selectivity increased significantly. The distribution of alcohol products de- viated from the Anderson-Schulz-Flory law. The portion of methanol in total alcohol was suppressed remarkably and the ethanol became the predominant product. Characterization results indicated that the incorporation of Mn enhanced the interaction of Co and Mo and thus led to the formation of Co-Mo-O species, which was regarded as the active site for the alcohol synthesis. Secondly, the presence of Mn reduced the amount of strong acid sites significantly and meanwhile promoted the formation of weak acid sites, which had a positive effect on the synthesis of alcohol. Furthermore, it was found that the incorporation of Mn can enhance the adsorption of linear- and bridge-type CO significantly, which contributed to the formation of alcohol and growth of carbon chain and thus increased the selectivity to C2＋OH.展开更多
A series of ultrafine Mo Co K catalysts with different Co/Mo ratios but constant potassium content were characterized by TPD technique and their catalytic performance for higher alcohol synthesis was investigated The ...A series of ultrafine Mo Co K catalysts with different Co/Mo ratios but constant potassium content were characterized by TPD technique and their catalytic performance for higher alcohol synthesis was investigated The results indicated that there are two kinds of adsorption sites, ie, low temperature adsorption sites (LTAS) around 90?℃ and high temperature adsorption sites (HTAS) above 400?℃ for H 2 and CO on the surface of the catalysts The desorption temperature of HTAS for H 2 and CO as well as the desorption amount of HTAS for H 2 were strongly influenced by the Co/Mo ratio of the catalysts It was found that the addition of Co into the ultrafine Mo K catalyst resulted in a decrease of the HTAS desorption temperature and an increase of the HTAS desorption amount for H 2 As the Co/Mo ratio increased further, the HTAS desorption amount for H 2 increased accordingly while the HTAS desorption temperature remained constant However, the HTAS desorption temperature for CO was found to be mainly influenced by the Co/Mo ratio, and the HTAS desorption temperature got its minimum at the Co/Mo ratio of 1∶7 It was found that a weaker adsorption of H 2 and CO on the HTAS and an appropriate H 2 adsorption amount were favourable for the formation of higher展开更多
采用BET、XPS和TPD表征手段对超细Mo Co K催化剂的织构、表面结构和吸附行为进行了研究,结合催化剂的合成低碳醇性能,论证了Co在超细Mo Co K催化剂合成低碳醇中的作用。Co的加入提高了催化剂合成低碳醇的活性和选择性,同时也提高了催化...采用BET、XPS和TPD表征手段对超细Mo Co K催化剂的织构、表面结构和吸附行为进行了研究,结合催化剂的合成低碳醇性能,论证了Co在超细Mo Co K催化剂合成低碳醇中的作用。Co的加入提高了催化剂合成低碳醇的活性和选择性,同时也提高了催化剂的比表面并促进了微孔的形成,催化剂的催化性能与其织构之间呈现出很好的顺变关系。Co对催化剂中可能作为合成低碳醇活性中心的低价Mo物种的电子结合能值影响较小。Co的加入降低了H2和CO在催化剂表面的强吸附中心的吸附强度,从而有利于合成低碳醇反应的发生。研究结果表明,Co仅仅是作为结构助剂,通过调变催化剂的织构和催化剂表面的H2及CO的强吸附中心而影响其合成低碳醇性能的。展开更多
文摘A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption fine structure spectroscopy. The catalytic performance for higher alcohol synthesis from syngas was measured. It was found that the Mn-doped catalysts ex- hibited a much higher activity as compared to the unpromoted catalyst, and in particular the C2＋ alcohol selectivity increased significantly. The distribution of alcohol products de- viated from the Anderson-Schulz-Flory law. The portion of methanol in total alcohol was suppressed remarkably and the ethanol became the predominant product. Characterization results indicated that the incorporation of Mn enhanced the interaction of Co and Mo and thus led to the formation of Co-Mo-O species, which was regarded as the active site for the alcohol synthesis. Secondly, the presence of Mn reduced the amount of strong acid sites significantly and meanwhile promoted the formation of weak acid sites, which had a positive effect on the synthesis of alcohol. Furthermore, it was found that the incorporation of Mn can enhance the adsorption of linear- and bridge-type CO significantly, which contributed to the formation of alcohol and growth of carbon chain and thus increased the selectivity to C2＋OH.
文摘A series of ultrafine Mo Co K catalysts with different Co/Mo ratios but constant potassium content were characterized by TPD technique and their catalytic performance for higher alcohol synthesis was investigated The results indicated that there are two kinds of adsorption sites, ie, low temperature adsorption sites (LTAS) around 90?℃ and high temperature adsorption sites (HTAS) above 400?℃ for H 2 and CO on the surface of the catalysts The desorption temperature of HTAS for H 2 and CO as well as the desorption amount of HTAS for H 2 were strongly influenced by the Co/Mo ratio of the catalysts It was found that the addition of Co into the ultrafine Mo K catalyst resulted in a decrease of the HTAS desorption temperature and an increase of the HTAS desorption amount for H 2 As the Co/Mo ratio increased further, the HTAS desorption amount for H 2 increased accordingly while the HTAS desorption temperature remained constant However, the HTAS desorption temperature for CO was found to be mainly influenced by the Co/Mo ratio, and the HTAS desorption temperature got its minimum at the Co/Mo ratio of 1∶7 It was found that a weaker adsorption of H 2 and CO on the HTAS and an appropriate H 2 adsorption amount were favourable for the formation of higher
文摘采用BET、XPS和TPD表征手段对超细Mo Co K催化剂的织构、表面结构和吸附行为进行了研究,结合催化剂的合成低碳醇性能,论证了Co在超细Mo Co K催化剂合成低碳醇中的作用。Co的加入提高了催化剂合成低碳醇的活性和选择性,同时也提高了催化剂的比表面并促进了微孔的形成,催化剂的催化性能与其织构之间呈现出很好的顺变关系。Co对催化剂中可能作为合成低碳醇活性中心的低价Mo物种的电子结合能值影响较小。Co的加入降低了H2和CO在催化剂表面的强吸附中心的吸附强度,从而有利于合成低碳醇反应的发生。研究结果表明,Co仅仅是作为结构助剂,通过调变催化剂的织构和催化剂表面的H2及CO的强吸附中心而影响其合成低碳醇性能的。
