This perspective discusses three alternative techniques which complement conventional infrared spectroscopy for obtaining vibrational information about zeolite catalysts and adsorbed molecules: inelastic neutron scattering, infrared micro-spectroscopy, and two-dimensional infrared spectroscopy. The techniques are illustrated briefly and future prospects for their use discussed.
. [J]. Frontiers of Chemical Science and Engineering, 2024, 18(11): 123.
Russell F Howe. New approaches to vibrational spectroscopy of zeolite catalysts: a perspective. Front. Chem. Sci. Eng., 2024, 18(11): 123.
Advantages: No selection rules. Highest sensitivity to hydrogen containing vibrations. Access to full frequency range. High penetration (bulk analysis).
Minimal sample size.Probe uniformity of zeolite catalysts.Map distribution of acid sites and adsorbed species.In-situ operando studies.Rapid kinetic response of adsorbed species to changed reaction conditions.
Resolve overlapping bands.Identify coupling of modes.Quantification without extinction coefficients.Information about anharmonicity.Operando possible.Vibrational dynamics.
Limitations: Large sample size required. Cryogenic measurement temperatures. Operando measurements not possible. Limited access to neutron sources.
Require crystals > 10 microns in size.Limited transmission frequency range through zeolite crystals.Limited access to synchrotron sources.
Frequency range restricted by laser sources.Limited access to expensive laser facilities.Complex experimental set-up and data analysis.
Tab.1
1
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A Zachariou, A P Hawkins, R F Howe, J M S Skakle, N Barrow, P Collier, D W Nye, R I Smith, G B G Stenning, S F Parker. et al.. Counting the acid sites in a commercial ZSM-5 zeolite catalyst. ACS Physical Chemistry Au, 2023, 3(1): 74–83 https://doi.org/10.1021/acsphyschemau.2c00040
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A P Hawkins, A Zachariou, P Collier, R A Ewings, R F Howe, S F Parker, D Lennon. Low-temperature studies of propene oligomerization in ZSM-5 by inelastic neutron scattering spectroscopy. RSC Advances, 2019, 9(33): 18785–18790 https://doi.org/10.1039/C9RA03568K
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A P Hawkins, A Zachariou, S F Parker, P Collier, N S Barrow, I P Silverwood, R F Howe, D Lennon. Effect of steam de-alumination on the interactions of propene with H-ZSM-5 zeolites. RSC Advances, 2020, 10(39): 23136–23147 https://doi.org/10.1039/D0RA03871G
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A P Hawkins, A Zachariou, S F Parker, P Collier, I P Silverwood, R F Howe, D Lennon. Onset of propene oligomerization reactivity in ZSM-5 studied by inelastic neutron scattering spectroscopy. ACS Omega, 2020, 5(14): 7762–7770 https://doi.org/10.1021/acsomega.9b03503
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A P Hawkins, A J O’Malley, A Zachariou, P Collier, R A Ewings, I P Silverwood, R F Howe, S F Parker, D Lennon. Investigation of the dynamics of 1-octene adsorption at 293 K in a ZSM-5 catalyst by inelastic and quasielastic neutron scattering. Journal of Physical Chemistry C, 2019, 123(1): 417–425 https://doi.org/10.1021/acs.jpcc.8b08420
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A P Hawkins, A Zachariou, S F Parker, P Collier, N S Barrow, R F Howe, D Lennon. On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts. Applied Catalysis A, General, 2023, 667: 119442 https://doi.org/10.1016/j.apcata.2023.119442
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A P Hawkins, A Zachariou, S F Parker, P Collier, R F Howe, D Lennon. Studies of propene conversion over H-ZSM-5 demonstrate the importance of propene as an intermediate in methanol-to-hydrocarbons chemistry. Catalysis Science & Technology, 2021, 11(8): 2924–2938 https://doi.org/10.1039/D1CY00048A
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S Suwardiyanto, R F Howe, E K Gibson, C R A Catlow, A Hameed, J McGregor, P Collier, S F Parker, D Lennon. An assessment of hydrocarbon species in the methanol-to-hydrocarbon reaction over a ZSM-5 catalyst. Faraday Discussions, 2017, 197: 447–471 https://doi.org/10.1039/C6FD00195E
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A Zachariou, A P Hawkins, D Lennon, S F Parker, S Suwardiyanto, S K Matam, C R A Catlow, P Collier, A Hameed, J McGregor. et al.. Investigation of ZSM-5 catalysts for dimethylether conversion using inelastic neutron scattering. Applied Catalysis A, General, 2019, 569: 1–7 https://doi.org/10.1016/j.apcata.2018.10.010
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A Zachariou, A P Hawkins, P Collier, R F Howe, S F Parker, D Lennon. The effect of co-feeding methyl acetate on the H-ZSM5 catalysed methanol-to-hydrocarbons reaction. Topics in Catalysis, 2020, 63(3–4): 370–377 https://doi.org/10.1007/s11244-020-01258-3
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A Zachariou, A P Hawkins, S F Parker, D Lennon, R F Howe. Neutron spectroscopy studies of methanol to hydrocarbons catalysis over ZSM-5. Catalysis Today, 2021, 368: 20–27 https://doi.org/10.1016/j.cattod.2020.05.030
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A Zachariou, A P Hawkins, S Suwardiyanto, P Collier, N Barrow, R F Howe, S F Parker, D Lennon. New spectroscopic insight into the deactivation of a ZSM-5 methanol-to-hydrocarbons catalyst. ChemCatChem, 2021, 13(11): 2625–2633 https://doi.org/10.1002/cctc.202100286
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A Zachariou, A P Hawkins, R F Howe, N Barrow, J Bradley, P Collier, D Lennon, S F Parker. A spectroscopic paradox: the interaction of methanol with ZSM-5 at room temperature. Topics in Catalysis, 2021, 64(9–12): 672–684 https://doi.org/10.1007/s11244-021-01462-9
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A Zachariou, A P Hawkins, P Collier, R F Howe, S F Parker, D Lennon. Neutron scattering studies of the methanol-to-hydrocarbons reaction. Catalysis Science & Technology, 2023, 13(7): 1976–1990 https://doi.org/10.1039/D2CY02154D
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R F Howe, S Suwardiyanto, D J Price, M Castro, P A Wright, A Greenaway, M D Frogley, G Cinque. Reactions of dimethylether in single crystals of the silicoaluminophosphate STA-7 studied via operando synchrotron infrared microspectroscopy. Topics in Catalysis, 2018, 61(3–4): 199–212 https://doi.org/10.1007/s11244-018-0890-9
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I B Minova, S K Matam, A Greenaway, C R A Catlow, M D Frogley, G Cinque, P A Wright, R F Howe. Elementary steps in the formation of hydrocarbons from surface methoxy groups in HZSM-5 seen by synchrotron infrared micro-spectroscopy. ACS Catalysis, 2019, 9(7): 6564–6570 https://doi.org/10.1021/acscatal.9b01820
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I B Minova, S K Matam, A Greenaway, C R A Catlow, M D Frogley, G Cinque, P A Wright, R F Howe. Effects of crystal size on methanol to hydrocarbon conversion over single crystals of ZSM-5 studied by synchrotron infrared microspectroscopy. Physical Chemistry Chemical Physics, 2020, 22(34): 18849–18859 https://doi.org/10.1039/D0CP00704H
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I B Minova, M Bühl, S K Matam, C R A Catlow, M D Frogley, G Cinque, P A Wright, R F Howe. Carbene-like reactivity of methoxy groups in a single crystal SAPO-34 MTO catalyst. Catalysis Science & Technology, 2022, 12(7): 2289–2305 https://doi.org/10.1039/D1CY02361F
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P M Donaldson, R F Howe, A P Hawkins, M Towrie, G M Greetham. Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts. Journal of Chemical Physics, 2023, 158(11): 114201 https://doi.org/10.1063/5.0139103
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P M Donaldson. Spectrophotometric concentration analysis without molar absorption coefficients by two-dimensional-infrared and Fourier transform infrared spectroscopy. Analytical Chemistry, 2022, 94(51): 17988–17999 https://doi.org/10.1021/acs.analchem.2c04287
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A P Hawkins, A E Edmeades, C D M Hutchison, M Towrie, R F Howe, G M Greetham, P M Donaldson. Laser induced temperature-jump time resolved IR spectroscopy of zeolites. Chemical Science, 2024, 15(10): 3453–3465 https://doi.org/10.1039/D3SC06128K
