Effect of acid-base properties of catalysts on their activity in methylmercaptane synthesis

Zeolite and Metal Oxide Catalysts for the Production of Dimethyl Sulfide and Methanethiol

“…The sulfidation activity is highest for catalysts with Lewis centers of modest strength (Q CO of 30-40 kJ/mol) [2]. Alumina falls in this range and the activity sharply decreases when the Al cation is replaced with a neighboring element from the periodic table (either Mg or Si).…”

“…Other studies found that HZSM-5 was the most active of the common zeolites for this reaction [7,8]. Additionally, it was concluded that reaction (4) is faster on zeolites than either (1) or (2).…”

“…Additionally, the more basic metal oxides tend to be more selective for MT, while the more acidic metal oxides are more selective for DMS [1,2,11]. Several X and Y zeolites containing different cations from the alkali series have been characterized for these reactions [9].…”

“…The primary molecules involved in the condensation reactions are MeOH, DME, MT, DMS, H 2 S, and H 2 O, all of which can be activated by associative adsorption onto Lewis acid centers, protic (Bronsted) centers, and basic centers on the catalyst surface [2,3]. Further activation can occur by dissociative adsorption (especially for MeOH, MT, H 2 S) on pairs of Lewis acid and base sites [3][4][5][6].…”

“…Mashkina et al [2] proposed a serial mechanism by which surface methoxy and bisulfide species on Lewis centers interact to form MT, which then desorbs. MT also adsorbs on Lewis centers, reacting with a methoxy group to form DMS.…”