Study on methanethiol synthesis from H2S and dimethyl sulfide over Al2O3 catalysts promoted with phosphorus

Abstract A series of P-promoted alumina catalysts with phosphorous contents varying in the range of 1–5% for the reaction of hydrogen sulfide (H 2 S) and dimethyl sulfide (DMS) to produce methanethiol (MT) were prepared and characterized by using XRD, SEM, BET, FT-IR and NMR techniques. The activity assay results showed that at the reaction temperature of 593 K, the P-promoted alumina catalyst exhibits as high as 100% selectivity toward MT; the DMS conversion ranges from 44.7% to 51.4% depending on the loading of phosphorus. The characterization results showed that introducing a small amount of phosphorus into γ-Al 2 O 3 increases the specific surface area, pore volume and the amount of Lewis acid sites. The increase of the Lewis acid sites enhances the capacity of the catalyst to break the C S bond of dimethyl sulfide to methylthiolate (CH 3 S − ) and CH 3 + , and H 2 S adsorbed on alumina to SH − and H + , both of CH 3 + and H + then interact further with lattice oxygen O 2− of the catalyst to form methoxyl (CH 3 O − ) and OH − , respectively, subsequent combination of CH 3 S − with OH − or CH 3 O − with SH − leads to the formation of methanethiol.