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

Abstract

K-promoted Mo-based catalysts showed great promise for the hydrogenation of CS2 to methyl mercaptan (CH3SH). However, the research on the synergistic effect of K and Mo, and the active site of CS2 hydrogenation to CH3SH were unexplored widely. To solve this problem, the synergistic effect of K and Mo in the K-promoted Mo-based catalysts for CS2 hydrogenation to prepare CH3SH was investigated. The mesoporous alumina was the support and loaded the active components potassium and molybdenum to prepare the catalyst. The results suggested that the active components K and Mo can not only cooperatively regulate the acid-base sites on the catalyst surface, but also stabilize the molybdate species at +5 valence during the reduction process and increase the Mo unsaturated coordination sites. Combined with the results of the catalytic activity evaluation, indicating that the main active site of the catalysts is the weak Lewis acid-base site, and the strong acidic site and strong alkaline site are not conducive to the formation of CH3SH. Moreover, the possible catalytic mechanism of CS2 hydrogenation to CH3SH on the weak Lewis acid-base sites of the catalysts was proposed. The research results of this paper can provide an experimental basis and theoretical guidance for the design of high-performance CH3SH synthesis catalyst and further mechanism research.

Methyl mercaptan production – catalysts and processes

“…Methyl mercaptan from CS 2 and COS. As shown above, CS 2 and COS are key intermediates in the CH 3 SH synthesis from syngas and H 2 S. Therefore, some research groups used CS 2 and COS as raw materials to produce CH 3 SH, according to eqn (3) and (4). [68][69][70][98][99][100][101][102][103][104] Both reactions are fast and thermodynamically allowed under industrial conditions. 68 CS 2 + 3H 2 → CH 3 SH + H 2 S…”

“…As shown above, CS 2 and COS are key intermediates in the CH 3 SH synthesis from syngas and H 2 S. Therefore, some research groups used CS 2 and COS as raw materials to produce CH 3 SH, according to eqn (3) and (4). 68–70,98–104 Both reactions are fast and thermodynamically allowed under industrial conditions. 68 CS 2 + 3H 2 → CH 3 SH + H 2 SCOS + 3H 2 ↔ CH 3 SH + H 2 O Δ H = 124 kJ mol −1 In one of the earlier studies, Kubicek 98 showed that CH 3 SH can be obtained from CS 2 over the Co–Mo/Al 2 O 3 catalyst, at 200–300 °C and 3.9 MPa.…”

“…More recently, Peng et al 103 studied the synergistic effect of K and Mo in the K-promoted Mo-based catalysts for CS 2 hydrogenation. The experimental results suggested that K and Mo regulate the acid–base sites on the catalyst surface and stabilize the molybdate species at +5.…”