Investigation of the Active Phase in K-Promoted MoS₂ Catalysts for Methanethiol Synthesis

Abstract

K-promoted MoS 2 is an active catalyst for the synthesis of CH 3 SH, a valuable chemical intermediate, from synthesis gas (CO/H 2 ) and H 2 S. The promotion of MoS 2 by K increases the CO conversion rate and the CH 3 SH selectivity and is usually linked to the stabilization of the 1T-MoS 2 polymorph as compared to the 2H-MoS 2 in K-free samples. Sulfided catalysts were characterized using TEM, XPS, and EXAFS. TEM showed that MoS 2 particles became larger and more stacked when the K/Mo ratio increased above unity. XPS and EXAFS evidenced the formation of the 1T-MoS 2 phase at higher K/Mo ratio in addition to 2H-MoS 2 . The addition of K to MoS 2 led to increased CH 3 SH productivity due to both increased CO conversion and CH 3 SH selectivity (T = 300−400 °C, P = 10 bar). The performance of the most active catalyst with a K/Mo ratio of 2 was found to be stable, despite the observation that the initially present 1T-MoS 2 phase slowly converted to the 2H-MoS 2 phase during the reaction at high pressure. There is no correlation between the CH 3 SH productivity and the amount of 1T-MoS 2 in K-promoted MoS 2 catalysts.

Synthesis of Methyl Mercaptan on Mesoporous Alumina Prepared with Hydroxysafflor Yellow A as Template: The Synergistic Effect of Potassium and Molybdenum

“…To sum up, as far as the synthesis of CH3SH by CS2 hydrogenation is concerned, we have concluded that the main active site of the catalysts is the weak Lewis acid-base site, and the strong acidic site and strong basic site are not conducive to the formation of CH3SH. In addition, it is generally believed that the active phase for the synthesis of CH3SH over K-promoted MoS2-based catalysts is the K-Mo-S phase [8,10,11,16], but in this paper, we did not pre-sulfurization the catalyst before the reaction, so it can be considered that apart from the K-Mo-S phase, the K-Mo-O phase may also be the main active phase.…”

“…More and more researchers are mainly focused on finding a more economical and environmentally friendly synthesis routes in recent years. Among them, the catalytic synthesis of CH 3 SH from sulfur-containing synthesis gas has aroused great interest among researchers [7][8][9][10][11][12][13][14], but the conversion and yield of CH 3 SH are relatively low, which does not meet the requirements of large-scale industrialization. CS 2 is relatively surplus and the price is low at present, and the one-step synthesis of CH 3 SH by CS 2 hydrogenation has the advantages of low reaction temperature (260~280 • C) and fewer three wastes.…”

“…In the field of catalytic synthesis of methanethiol, transition metal sulfides are generally considered to be the main active phase [10,11,14,[17][18][19][20]. Among them, MoS 2 -based catalysts promoted by alkali metals have potential application prospects because of their unique properties, such as sulfur resistance, not ease to coking and avoiding expensive deep desulfurization in industry, which have been also widely used in water-gas shift [21][22][23][24], syngas to higher alcohols [25][26][27][28][29][30], hydrodesulfurization [31][32][33][34] and hydrogenation [35][36][37][38].…”

Periodical 2D Photonic–Plasmonic Au/TiOx Nanocavity Resonators for Photoelectrochemical Applications

“…Both sam ples showed strong and sharp Raman active modes from TiO x species. [39,40] In addition, a large luminescence background at 1000-2000 cm −1 was detected, which was generated from the excitation in the intrabands in TiO x , and implied the existence of structural disorder defects in TiO x . [41] Furthermore, after Au NPs deposition, the luminescence background has been remarkably quenched, which revealed effective charge transfer between Au NPs and TiO x , and thus the optical energy can be efficiently converted into electricity, thus quenched the lumi nescence.…”

Vertically-Oriented WS2 Nanosheets with a Few Layers and Its Raman Enhancements

“…Considerable attention has been devoted to two-dimensional (2D) materials as promising functional materials, in particular to transition metal dichalcogenides (TMDCs) [ 1 , 2 , 3 , 4 ], due to rapid advances in synthesis, transfer, spectroscopic detection, and manipulation. Since 2D TMDCs have unique physicochemical properties such as high mobility, large surface area, and significant catalytic activities, they can be effectively used for efficient light harvesting, sensitive photo-detection, and catalytic conversion systems [ 5 , 6 , 7 , 8 ]. Among 2D TMDCs, particularly, tungsten disulfide (WS 2 ), with direct optical band gaps of 1.35 and 2.05 eV for bulk and monolayer structure, is of great interest due to its particular semiconducting behavior, intrinsic electrical conductivity, and electrocatalytic property when the number of layers is lower [ 9 , 10 , 11 ].…”