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Article

Understanding the Deactivation Phenomena of Small-Pore Mo/H-SSZ-13 during Methane Dehydroaromatisation

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Chemistry Department, University College of London Gordon Street, London WC1H 0AJ, UK
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Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DEU, UK
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Department of Chemistry, NGAP Centre for Research Based Innovation, University of Oslo, N-0315 Oslo, Norway
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Faculty of Physics, University of Warsaw, Pasteura 1 Street, 02-093 Warsaw, Poland
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Johnson Matthey Technology Centre, Blount’s Court, Sonning Common, Reading RG4 9NH, UK
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Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Harwell Campus, Didcot OX11 0QX, UK
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Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot OX11 0FA, UK
*
Authors to whom correspondence should be addressed.
Academic Editors: Susana Valencia and T. Jean Daou
Molecules 2020, 25(21), 5048; https://doi.org/10.3390/molecules25215048
Received: 11 August 2020 / Revised: 13 October 2020 / Accepted: 27 October 2020 / Published: 30 October 2020
(This article belongs to the Special Issue Zeolitic Microporous Materials and Their Applications)
Small pore zeolites have shown great potential in a number of catalytic reactions. While Mo-containing medium pore zeolites have been widely studied for methane dehydroaromatisation (MDA), the use of small pore supports has drawn limited attention due to the fast deactivation of the catalyst. This work investigates the structure of the small pore Mo/H-SSZ-13 during catalyst preparation and reaction by operando X-ray absorption spectroscopy (XAS), in situ synchrotron powder diffraction (SPD), and electron microscopy; then, the results are compared with the medium pore Mo/H-ZSM-5. While SPD suggests that during catalyst preparation, part of the MoOx anchors inside the pores, Mo dispersion and subsequent ion exchange was less effective in the small pore catalyst, resulting in the formation of mesopores and Al2(MOO4)3 particles. Unlike Mo/H-ZSM-5, part of the Mo species in Mo/H-SSZ-13 undergoes full reduction to Mo0 during MDA, whereas characterisation of the spent catalyst indicates that differences also exist in the nature of the formed carbon deposits. Hence, the different Mo speciation and the low performance on small pore zeolites can be attributed to mesopores formation during calcination and the ineffective ion exchange into well dispersed Mo-oxo sites. The results open the scope for the optimisation of synthetic routes to explore the potential of small pore topologies. View Full-Text
Keywords: MDA; Mo/CHA; operando XAS/XRD MDA; Mo/CHA; operando XAS/XRD
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MDPI and ACS Style

Agote-Arán, M.; Kroner, A.B.; Wragg, D.S.; Sławiński, W.A.; Briceno, M.; Islam, H.U.; Sazanovich, I.V.; Rivas, M.E.; Smith, A.W.J.; Collier, P.; Lezcano-González, I.; Beale, A.M. Understanding the Deactivation Phenomena of Small-Pore Mo/H-SSZ-13 during Methane Dehydroaromatisation. Molecules 2020, 25, 5048. https://doi.org/10.3390/molecules25215048

AMA Style

Agote-Arán M, Kroner AB, Wragg DS, Sławiński WA, Briceno M, Islam HU, Sazanovich IV, Rivas ME, Smith AWJ, Collier P, Lezcano-González I, Beale AM. Understanding the Deactivation Phenomena of Small-Pore Mo/H-SSZ-13 during Methane Dehydroaromatisation. Molecules. 2020; 25(21):5048. https://doi.org/10.3390/molecules25215048

Chicago/Turabian Style

Agote-Arán, Miren, Anna B. Kroner, David S. Wragg, Wojciech A. Sławiński, Martha Briceno, Husn U. Islam, Igor V. Sazanovich, María E. Rivas, Andrew W. J. Smith, Paul Collier, Inés Lezcano-González, and Andrew M. Beale. 2020. "Understanding the Deactivation Phenomena of Small-Pore Mo/H-SSZ-13 during Methane Dehydroaromatisation" Molecules 25, no. 21: 5048. https://doi.org/10.3390/molecules25215048

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