Sulfation Mechanism and Catalytic Behavior of Manganese Oxide in the Oxidation of Methanethiol

Abstract

This work studies the behavior of a manganese dioxide catalyst during the total oxidation of methanethiol. Modifications of the working γ-MnO2 catalyst were characterized by XPS, XRD, DRIFTS, and potentiometric measurements after reactions at different durations and at different temperatures. At temperatures below 200 °C, sulfur adsorbs on γ-MnO2 in the form of sulfate species and poisons CH3SH adsorption sites. Accordingly, the methanethiol conversion is strongly inhibited. At higher temperatures (260−280 °C), γ-MnO2 is strongly reduced and is converted to a moderately active manganese sulfate phase while the reaction proceeds. This contribution also shows that the activity and selectivity of the manganese sulfate phase formed in situ at high temperature are comparable to those of a commercial manganese sulfate. The variation of the reaction temperature between 280 and 150 °C controls the reversible hydration/dehydration of the manganese sulfate phase and its associated activation/deactivation. This important change in activity is accompanied by a change in the main byproduct formation. At 280 °C, the dehydrated manganese sulfate phase is fairly active and favors the production of dimethyl disulfide. On the contrary, the hydrated phase that exists only in the lower-temperature region is much more reactive and promotes the production of methanol.

Manganese Dioxide Nanostructures as a Novel Electrochemical Mediator for Thiol Sensors

“…While other metal oxide catalysts are easily poisoned by sulfur, manganese dioxide exhibits good stability [17]. Moreover, due to the frequent involvement of thiols and corresponding disulfides in a variety of important biochemical reactions, as well as employment of artificial sulfur-containing substrates such as acetyl (butyryl) thiocholine in bioanalytical applications, development of sensitive, selective, and simple methods for their analysis using electrochemical sensors on the basis of electron transfer mediators is of interest.…”

Adsorption/oxidation of sulfur-containing gases on nitrogen-doped activated carbon

“…The first peak centered at about 80 o C which means desorption of water. According to the results reported by many researchers, the second peak which centered beween 80°C and 300°C may represent desorption of dimethyl disulfide [6]. An interseting behavior was found for the sample treated at 950°C.…”

Methyl mercaptan removal from gas streams using metal-modified activated carbon

“…6 presents the S 2p3/2 binding energies measured on the CueAC after reaction with methanethiol and on a fresh sample taken as a reference. Sulfate species were detected on the surface of the exhausted catalyst (Mullins and McDonald, 2008;Cellier et al, 2004). In addition, the amount of sulfate deposited on the surface increases with the reaction time.…”