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Hafnium salts of dodeca-tungstophosphoric acid catalysts for liquid phase benzylation of anisole with dibenzylether

Paper ID Volume ID Publish Year Pages File Format Full-Text
39893 45839 2014 11 PDF Available
Title
Hafnium salts of dodeca-tungstophosphoric acid catalysts for liquid phase benzylation of anisole with dibenzylether
Abstract

•Hafnium salts of heteropoly tungstate (HfxTPA) catalysts were prepared.•Catalytic activity was investigated for benzylation of anisole with dibenzylether.•The catalytic activity of HfxTPA depended on the exchangeable hafnium ion.•Exchange of TPA protons with Hf4+ generated Lewis acidic sites.

A series of hafnium salts of heteropoly tungstate (HfxTPA) catalysts were prepared by exchanging the counter cations (hydrogen) of heteropoly tungstate with hafnium ions. The prepared catalysts were characterized by FT-IR, Laser Raman, temperature programmed desorption of ammonia, scanning electron microscopy, and X-ray photo electron spectroscopy. FT-IR and Raman characterization results suggested retention of the Keggin ion structure of heteropoly acid. Pyridine adsorbed FT-IR spectra of the catalysts showed that generation of Lewis acidic sites was due to the presence of hafnium ions in the catalyst. Activity of these catalysts was investigated for liquid phase benzylation of anisole with dibenzylether. In the partial exchanged catalyst (Hf0.5TPA), higher conversion was due to high mobility of residual protons. The catalytic activity of HfxTPA depended on the exchangeable hafnium ions in the secondary structure of heteropoly tungstate that, in turn, relates to variation in acidity of the catalyst. Thermal stability and structural properties of the Hf0.5TPA catalyst were studied by treating it at different temperatures. Dibenzylether conversion and selectivity towards benzylated products were found to depend on the anisole to dibenzylether ratio, reaction temperature, and catalyst loading.

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Keywords
Anisole; Benzylation; Dibenzylether; Hafnium; Heteropoly tungstate; Keggin ion
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Hafnium salts of dodeca-tungstophosphoric acid catalysts for liquid phase benzylation of anisole with dibenzylether
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 471, 10 February 2014, Pages 1–11
Authors
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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