fulltext.study @t Gmail

Active intermediates formed on phosphorous-modified MTW zeolites in methanol to olefin conversion: An ESR study

Paper ID Volume ID Publish Year Pages File Format Full-Text
39198 45812 2015 9 PDF Available
Title
Active intermediates formed on phosphorous-modified MTW zeolites in methanol to olefin conversion: An ESR study
Abstract

•Phosphorous modification on MTW zeolites reduces the strong acid sites.•P(1.5)-MTW resulted in the yields of C3C6 above 90% at 450 °C in MTO.•P-modification facilitates the observation of ESR signals with hyperfine splittings.•ESR signals confirm the formation of hexamethylbenzene as an active intermediate.

The active intermediates formed on phosphorous-modified MTW zeolites in methanol-to-olefin (MTO) were investigated using electron spin resonance (ESR) spectroscopy. The porous and acidic properties of the modified catalysts were characterized by XRD, SEM, N2 adsorption, o-xylene uptake, and temperature-programmed desorption of ammonia. In addition to the repeated potential restrictions to adsorbed aromatic compounds in its 12 membered-ring, the phosphorous modification on MTW zeolites reduces the number of strong acid sites and limits the close distribution of polymethylbenzenes formed during MTO conversion, facilitating the observation of ESR signals with hyperfine splittings of hexamethylbenzenium radical cations, while the poor resolution of the hyperfine splittings supposed the co-presence of other radical cations. The positive relationship between the conversion of methanol and the spin number of radical cations over the MTW catalysts at the early stage confirms the role of these radical cations as actual active intermediates. The high methyl group substitution of the active intermediate formed on MTW catalysts is responsible for the high yields to C3C6 (above 90%) at 450 °C in MTO conversion.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (83 K)Download as PowerPoint slide

Keywords
MTO conversion; MTW zeolite; Phosphorous modification; Active intermediate; Hexamethylbenzene
First Page Preview
Active intermediates formed on phosphorous-modified MTW zeolites in methanol to olefin conversion: An ESR study
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 499, 25 June 2015, Pages 168–176
Authors
, , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us