Role of Sn/ZSM-5 in direct syngas conversion

Abstract

We report here the catalytic behaviour of Sn_x/ZSM-5 as bifunctional catalysts in direct syngas conversion. Ethane selectivity as high as 84% at a CO conversion of 29% can be achieved with a Sn loading of 0.61 mmol_Sn g_cat⁻¹. Characterization of Sn_x/ZSM-5 with NH₃-TPD, pyridine adsorbed IR, XRD and UV-vis indicates that the small SnO₂ nanoparticle size as well as the close proximity between SnO₂ and Brønsted acid sites of ZSM-5 may account for the high activity in direct syngas conversion. Interestingly, activation of CO/H₂ leads to formation of ethylene first even at ambient pressure and around 400 K. However, ethylene is rather reactive and is readily converted to ethane in the presence of H₂ over Sn_x/ZSM-5. This understanding is important in the design of highly active catalysts for syngas conversion.