Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Carbene-like reactivity of methoxy groups in a single crystal SAPO-34 MTO catalyst

Minova, Ivalina B., Bühl, Michael, Matam, Santhosh K., Catlow, C. Richard A., Frogley, Mark D., Cinque, Gianfelice, Wright, Paul A. and Howe, Russell F. 2022. Carbene-like reactivity of methoxy groups in a single crystal SAPO-34 MTO catalyst. Catalysis Science & Technology 12 (7) , pp. 2289-2305. 10.1039/D1CY02361F
Item availability restricted.

[thumbnail of PP.pdf] PDF - Accepted Post-Print Version
Restricted to Repository staff only until 21 February 2023 due to copyright restrictions.

Download (1MB)

Abstract

Synchrotron FTIR microspectroscopy coupled with mass spectrometric analysis of desorbed products has been used to investigate the initial stages of the methanol to olefins (MTO) reaction in single crystals of SAPO-34. Surface methoxy groups (SMS) are key to initial dimethylether (DME) and subsequent carbon–carbon bond formation. Deprotonation of SMS is the critical first step in direct olefin formation at low temperatures and DME is not involved in the carbon–carbon forming step. Experiments with CD3OH confirm the deprotonation step and show an inverse kinetic isotope effect consistent with irreversible deprotonation. The subsequent formation of alkoxide species, which are the precursors of the olefinic hydrocarbon pool present in working MTO catalysts, is initiated via insertion of surface carbene-like species into adjacent SMS. The observed induction period for this process is determined by the limited mobility of SMS and/or carbene species. Olefins formed from cracking of the alkoxide species then transmit carbon–carbon bond formation through the SAPO-34 by rapid diffusion and reaction with further SMS. Acetyl species seen with methanol at higher temperatures support the insertion of CO into SMS suggested in the literature, but these species do not play a role in direct olefin formation.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Publisher: Royal Society of Chemistry
ISSN: 2044-4753
Funders: EPSRC
Date of First Compliant Deposit: 11 April 2022
Date of Acceptance: 11 February 2022
Last Modified: 13 May 2022 18:20
URI: https://orca.cardiff.ac.uk/id/eprint/149130

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics