Response to comments on the paper: “Effect of organic impurities on the hydrocarbon formation via the decomposition of surface methoxy groups on acidic zeolite catalysts” by Y. Jiang, W. Wang, V.R.R. Marthala, J. Huang, B. Sulikowski, M. Hunger

Abstract

The conversion of methanol over ZSM-5 catalysts was studied using step response and temperature-programmed desorption and surface reaction analyses in a temporal analysis of products reactor, as well as quasi-elastic neutron scattering and Fourier transform infrared investigations, buttressed by archived 13C magic angle spinning nuclear magnetic resonance studies. The results were combined with micro-kinetic models that simulated the formation of the first C–C bond and primary olefin(s) from methanol. Dimethyl ether was the major surface oxygenate and a source of surface methoxy species. Propylene, the major olefin produced from dimethyl ether, was formed with a reaction barrier of ∼ 200 kJ mol−1, in agreement with archived density functional theory calculations. Propylene could form from dimethyl ether via a methoxymethyl mechanism under intrinsic kinetic conditions. Site-specific scaling relations between the barriers to methyl propenyl ether and methoxy methyl species formation and dimethyl ether desorption were observed. The active sites of the ZSM-5 catalysts can be locally optimised and selectively tuned to improve their activity during the conversion of methanol to olefin(s).