Issue 16, 2016

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Abstract

Gas phase Prins condensation of isobutene with formaldehyde has been studied over different Keggin-type heteropolyacids supported on amorphous silica. The catalysts were characterized by elemental analysis, X-ray diffraction, low temperature nitrogen adsorption, TPD of ammonia, FTIR of adsorbed pyridine and NMR spectroscopy. The activity of the supported heteropoly compounds was found to increase in the following order: H4SiMo12O40 < H3PMo12O40 < H4SiW12O40 ≈ H3PW12O40. The lower activity of the supported molybdenum heteropolyacids was attributed to their low thermal stability and partial decomposition during catalyst activation, which resulted in lower acidity. The variation of HPA content from 5 to 33 wt% was also shown to increase catalyst activity. Based on the relationship between the content of weak Brønsted sites, the amount and type of carbonaceous deposits and the catalytic activity, it was concluded that the generation of “working” active sites over HPA catalysts involves the formation of unsaturated branched surface species over weak Brønsted sites. These active carbonaceous species are responsible for selective isoprene synthesis. The best catalyst performance is observed over the catalyst with 20 wt% of H3PW12O40, which shows an isoprene yield of 48% with a selectivity of 63%.

Graphical abstract: Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Supplementary files

Article information

Article type
Paper
Submitted
06 Apr 2016
Accepted
06 Jun 2016
First published
07 Jun 2016

Catal. Sci. Technol., 2016,6, 6354-6364

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

V. L. Sushkevich, V. V. Ordomsky and I. I. Ivanova, Catal. Sci. Technol., 2016, 6, 6354 DOI: 10.1039/C6CY00761A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements