Mechanistic insights into methanol-to-olefin reaction on an α-Mn2O3 nanocrystal catalyst

The synthesis and utilization of an a-Mn2O3 nanocrystal catalyst for methanol-to-olefin reaction is described. A methanol conversion of 35% and a maximum selectivity of 80% toward ethylene were obtained at 250 degrees C. In particular, formaldehyde, a primary intermediate for the reaction, was used to produce ethylene via a coupling reaction. A conversion of 45% and a selectivity of 66% to ethylene were achieved at 150 degrees C in a formaldehyde stream. In situ diffuse reflectance infrared Fourier transform spectra reveal the formation of the surface CH2-containing species during reaction, which implies that the main pathway for formaldehyde coupling is probably through interactions of those intermediates. In addition, the weakly adsorbed oxygen on the alpha-Mn2O3 nanocrystal surface was found to play an important role in this reaction. (c) 2012 American Institute of Chemical Engineers AIChE J, 2012