Conversion of methyl mercaptan and methanol to hydrocarbons over solid acid catalysts – A comparative study

• CH3SH is selectively converted into H2S and hydrocarbons over zeolites (M2TH process).
• The catalyst lifetime significantly increased in the presence of water.
• M2TH is compared with the well-known MTH (methanol to hydrocarbons) process.
• Reaction pathways are proposed for each process.

This study demonstrates that CH3SH (a harmful impurity in natural gas) can be selectively converted into H2S and hydrocarbons (M2TH process) on H-zeolite/zeotype with diverse topologies. The catalytic activity varied as follows: H-ZSM-5 > H-Y > H-FER > H-BEA > H-MOR > H-SAPO-34. In addition, H-ZSM-5 was the most stable catalyst toward deactivation by coke. The effect of the carrier gas (nitrogen or methane) and the role of water on the catalytic behavior of zeolites were explored under different conditions. Similar performances were obtained using CH3SH/N2 or CH3SH/CH4 mixtures, but the amount of coke drastically decreased and the catalyst lifetime increased when 2% of water was added into the reaction. M2TH was compared with the well-known MTH (methanol to hydrocarbons) process. Although there are similarities between the two processes, significant differences were also observed, essentially regarding the products formed and distributed. These aspects are discussed taking into account the reaction pathway involved in each process.

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