title: An assessment of hydrocarbon species in the methanol-to-hydrocarbon reaction over a ZSM-5 catalyst.
abstract: A ZSM-5 catalyst is examined in relation to the methanol-to-hydrocarbon (MTH) reaction as a function of reaction temperature and time-on-stream. The reaction profile is characterised using in-line mass spectrometry. Furthermore, the material contained within a catch-pot downstream from the reactor is analysed using gas chromatography-mass spectrometry. For a fixed methanol feed, reaction conditions are selected to define various stages of the reaction coordinate: (i) initial methanol adsorption at a sub-optimum reaction temperature (1 h at 200 °C); (ii) initial stages of reaction at an optimised reaction temperature (1 h at 350 °C); (iii) steady-state operation at an optimised reaction temperature (3 days at 350 °C); and (iv) accelerated ageing (3 days at 400 °C). Post-reaction, the catalyst samples are analysed ex situ by a combination of temperature-programmed oxidation (TPO) and spectroscopically by electron paramagnetic resonance (EPR), diffuse-reflectance infrared and inelastic neutron scattering (INS) spectroscopies. The TPO measurements provide an indication of the degree of 'coking' experienced by each sample. The EPR measurements detect aromatic radical cations. The IR and INS measurements reveal the presence of retained hydrocarbonaceous species, the nature of which are discussed in terms of the well-developed 'hydrocarbon pool' mechanism. This combination of experimental evidence, uniquely applied to this reaction system, establishes the importance of retained hydrocarbonaceous species in effecting the product distribution of this economically relevant reaction system.
authors.affiliation: Department of Chemistry, University of Aberdeen, Aberdeen, AB24 3UE, UK.
authors.lastname: Suwardiyanto
authors.affiliation: Department of Chemistry, University of Aberdeen, Aberdeen, AB24 3UE, UK and UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK.
authors.forename: Russell F
authors.initials: RF
authors.lastname: Howe
authors.affiliation: UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK.
authors.forename: Emma K
authors.initials: EK
authors.lastname: Gibson
authors.affiliation: UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK and Department of Chemistry, University College London, 20 Gordon St., London WC1 HOAJ, UK and Cardiff Catalysis Institute, School of Chemistry, Cardiff University, CF10 3AT, UK.
authors.forename: C Richard A
authors.initials: CRA
authors.lastname: Catlow
authors.affiliation: Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
authors.forename: Ali
authors.initials: A
authors.lastname: Hameed
authors.affiliation: UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK and Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
authors.forename: James
authors.identifier: 0000-0001-6813-306X
authors.initials: J
authors.lastname: McGregor
authors.affiliation: Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading, RG4 9NH, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Collier
authors.affiliation: UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK and ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0QX, UK.
authors.forename: Stewart F
authors.identifier: 0000-0002-3228-2570
authors.initials: SF
authors.lastname: Parker
authors.affiliation: UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Chilton, Oxon, OX11 0FA, UK and School of Chemistry, University of Glasgow, Joseph Black Building, Glasgow, G12 8QQ, UK. David.Lennon@glasgow.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Lennon