Methanol‐to‐olefin (MTO) catalysis is a very active field of research because there is a wide variety of sometimes conflicting mechanistic proposals. An example is the ongoing discussion on the initial C−C bond formation from methanol during the induction period of the MTO process. By employing a combination of solid‐state NMR spectroscopy with UV/Vis diffuse reflectance spectroscopy and mass spectrometry on an active H‐SAPO‐34 catalyst, we provide spectroscopic evidence for the formation of surface acetate and methyl acetate, as well as dimethoxymethane during the MTO process. As a consequence, new insights in the formation of the first C−C bond are provided, suggesting a direct mechanism may be operative, at least in the early stages of the MTO reaction.
After a prolonged effort over many years, the route for the formation of a direct carbon-carbon (C-C) bond during the methanol-to-hydrocarbon (MTH) process has very recently been unveiled. However, the relevance of the "direct mechanism"-derived molecules (that is, methyl acetate) during MTH, and subsequent transformation routes to the conventional hydrocarbon pool (HCP) species, are yet to be established. This important piece of the MTH chemistry puzzle is not only essential from a fundamental perspective, but is also important to maximize catalytic performance. The MTH process was probed over a commercially relevant H-SAPO-34 catalyst, using a combination of advanced solid-state NMR spectroscopy and operando UV/Vis diffuse reflectance spectroscopy coupled to an on-line mass spectrometer. Spectroscopic evidence is provided for the formation of (olefinic and aromatic) HCP species, which are indeed derived exclusively from the direct C-C bond-containing acetyl group of methyl acetate. New mechanistic insights have been obtained from the MTH process, including the identification of hydrocarbon-based co-catalytic organic reaction centers.
Methanol-to-olefin (MTO) catalysis is av ery active field of researchb ecause there is aw ide variety of sometimes conflicting mechanistic proposals.A ne xample is the ongoing discussion on the initial C À Cb ond formation from methanol during the induction period of the MTOprocess.Byemploying ac ombination of solid-state NMR spectroscopyw ith UV/Vis diffuse reflectance spectroscopya nd mass spectrometry on an active H-SAPO-34 catalyst, we provide spectroscopic evidence for the formation of surface acetate and methyl acetate,aswell as dimethoxymethane during the MTOp rocess.A saconsequence,new insights in the formation of the first C À Cbond are provided, suggesting ad irect mechanism may be operative,a t least in the early stages of the MTOr eaction.
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