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Unit cell expansion upon coke formation in a SAPO-34 catalyst: A combined experimental and computational study

Abstract

We have investigated the mechanism of anisotropic changes in the unit cell dimensions of SAPO-34 during the methanol-to-olefin (MTO) process. Retained hydrocarbon analysis was employed to quantify the amount of coke in the cages of thermally quenched SAPO-34 samples which had been used as the catalyst in the MTO reaction. Molecular mechanics structural optimizations were carried out on structural models with different coke molecules in the pores, and the results were compared to experimentally determined cell dimension changes and coke composition. Our results indicate no correlation between small hydrocarbon intermediates and cell expansion, with all changes in the unit cell parameters being due to bulky coke molecules like phenanthrene and pyrene. Further, only a small fraction of the cavities in the material need to be filled with such large molecules in order to bring about changes of the magnitude observed experimentally.

Category

Academic article

Client

  • Notur/NorStore / NN2147K

Language

English

Author(s)

Affiliation

  • University of Oslo
  • Diverse norske bedrifter og organisasjoner
  • SINTEF Industry / Process Technology
  • SINTEF Industry / Materials and Nanotechnology

Year

2013

Published in

Microporous and Mesoporous Materials

ISSN

1387-1811

Publisher

Elsevier

Volume

165

Page(s)

1 - 5

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