Metal Oxides as Catalysts for the Reaction between Methanol and Hydrogen Sulfide

Article abstract of DOI:10.1021/j100140a037

The reaction between methanol and hydrogen sulfide leading to the formation of methanethiol and dimethyl sulfide has been studied using different H2S:CH3OH molar ratios (0.5:1, 1:1, 2:1) at 623 K on various metal oxides presenting different acidity and basicity.The correlations between activity and selectivity of catalysts and their average oxygen and cation charges as well as the strength of their acidic and basic sites, determined by adsorption of probe molecules followed by IR spectroscopy, are as follows: (i) the highest strenth of basic sites and the highest negative charge on oxygen (MgO) lead to the lowest activity and the highest selectivity toward CH3SH; (ii) the lowest strength of basic sites (medium oxygen charge) and the highest cation charge (γ-Al2O3) cause the highest activity and the highest selectivity toward (CH3)2S.The dimethyl sulfide selectivity is in the reverse order of the number of basic sites.IR measurements show that the reaction occurs between chemisorbed methanol (methoxy species) and SH(1-) species or/and H2S molecules.Too strongly held methoxy species as on MgO and PO4(3-)/SiO2 do not react with H2S.The difference in activity and selectivity of both titania samples (anatase and rutile) is discussed.