Supported MoS 2 based materials are widely used as heterogeneous catalysts. In this work, we propose a rapid and facile method (ultrasound-induced impregnation assisted by microwave thermal treatment) to synthesize mesoporous silica (SBA-15)-supported, few-layer, ordered and K-promoted MoS 2 nanosheets with different K/Mo ratios. The prepared catalysts are characterized by various physical and chemical techniques. Their catalytic performance is evaluated by methyl mercaptan (CH 3 SH) synthesis from CO/H 2 /H 2 S. The results show that our catalysts exhibit a much higher CO conversion and selectivity to CH 3 SH than the catalysts prepared using the conventional impregnation and reported in the literature. The good performance arises because of two main factors: MoS 2 nanosheets of only 2–4 layers and K promotion. Experimental characterizations and (density functional theory) calculations show that the former is the typical nano-size effect, and the latter stabilizes C S bonds when activating COS molecules.
Yang Zhi,Luo Mingsheng,Liu Qinglong,Li Chenmeng,Wang Yatao,Li Hongjuan,Yao Lifei
Abstract The direct production of higher alcohols from syngas in a single step remains a great challenge. In this work, a series of K and Ni promoted Mo 2 C/Al 2 O 3 catalysts were prepared by impregnation method to enhance the selectivity of Mo 2 C-based catalysts for the one-step conversion of syngas to higher alcohols. The catalysts were continuously tested under the following conditions: 300°C, 3.0 MPa, velocity—11.50 \({\text{Lg}}_{{{\text{Mo}}}}^{{ - 1}}\) h –1 , H 2 /CO ratio of 2. The catalysts promoted with K and Ni demonstrated the highest total alcohol selectivity of 67.7%. Moreover, the selectivity for total C 2+ alcohols reached as high as 56%, with 37% being ethanol. X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H 2 -TPR) and X-ray photoelectron spectroscopy (XPS) characterization data reveal that K can promote the crystallinity of β-Mo 2 C, lower the catalyst reduction temperature and increase the proportion of high-valent Mo on the catalyst surface. In addition, adding Ni as a promoter to the KMo 2 C/Al 2 O 3 catalyst can generate a synergistic effect to further enhance the catalytic activity and the selectivity of higher alcohols.
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