Slowing down the deactivation of H-ZSM-5 zeolite catalyst in the methanol-to-olefin (MTO) reaction by P or Zn modifications

Abstract
The benefits of H-ZSM-5 zeolite modification with H3PO4 or ZnCl2 have been analyzed during the methanol to olefins (MTO) reaction. The catalysts were prepared, characterized and tested using three different reactors: fixed-bed, operando FTIR and UV–vis. The spent catalysts were further characterized for analyzing the nature and location of the species trapped. The results show that the zeolite modified with H3PO4 has suffered a simultaneous dealumination, leading to a decrease of number of acid sites and activity. However, the zeolite modified with ZnCl2 shows the inclusion of Zn transforming Brønsted into Lewis acid sites, leading to reaction intermediates (hydrocarbon pool species) that decreases the rate of reaction but improves propylene selectivity (+10%), slows downs coke formation (-42%) and expands catalytic lifetime (+80%). The distinct effect of Zn modification, typically associated with the promotion of aromatics, is explained on the grounds of the severe transformation of the strong and Brønsted acid sites.

Citation
Valecillos, J., Epelde, E., Albo, J., Aguayo, A. T., Bilbao, J., & Castaño, P. (2020). Slowing down the deactivation of H-ZSM-5 zeolite catalyst in the methanol-to-olefin (MTO) reaction by P or Zn modifications. Catalysis Today, 348, 243–256. doi:10.1016/j.cattod.2019.07.059

Acknowledgements
This work was possible thanks to the financial support of the Ministry of Economy, Industry and Competitiveness of the Spanish Government (Project CTQ2016-79646-P, co-founded with ERDF funds) and the Basque Government (Project IT912-16 and IT1218-19). J.V. is thankful for his fellowship granted by the Ministry of Economy, Industry and Competitiveness of the Spanish Government (BES-2014-069980). The authors are thankful for technical and human support provided by IZO-SGI SGIker of UPV/EHU and European funding (ERDF and ESF).

Publisher
Elsevier BV

Journal
Catalysis Today

DOI
10.1016/j.cattod.2019.07.059

Additional Links
https://linkinghub.elsevier.com/retrieve/pii/S0920586119304201

Permanent link to this record
Collections