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Selective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
44001 45999 2007 9 PDF Available
Title
Selective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalysts
Abstract

The catalytic performance of molybdate- and tungstate-promoted zirconia catalysts for tert-butylation of phenol with tert-butanol as alkylating agent has been investigated. The reaction was carried out at 433–493 K in a fixed bed micro-reactor at normal atmospheric pressure. The promoted zirconia catalysts were synthesized by immersing the finely powdered hydrous zirconium hydroxide in aqueous ammonium heptamolybdate or ammonium metatungstate solution and subsequent oven drying and calcination at 923 K. The hydrous Zr(OH)4 was prepared from aqueous zirconium oxychloride by hydrolysis with a dilute aqueous ammonia solution. To investigate the structural and textural properties, we characterized the synthesized catalysts by X-ray powder diffraction (XRD), BET surface area, temperature programmed reduction (TPR), temperature programmed desorption (TPD) of ammonia, scanning electron microscopy (SEM), Raman spectroscopy (RS), and FT-infrared spectroscopy (FTIR) techniques. All the characterization results reveal that the incorporated promoter cations show a significant influence on the surface and bulk properties of the ZrO2. In particular, the impregnated cations stabilize the metastable tetragonal phase of zirconia at ambient conditions and enhance the total number and the strength of the acid sites. A good substrate (phenol) conversion and excellent product selectivity were obtained over the promoted zirconia catalysts.

Graphical abstractSelective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalyst.Molybdate- and tungstate-promoted zirconia catalysts exhibit a good substrate conversion and excellent para selectivity in the vapour phase tert-butylation of phenol at normal atmospheric pressure. Characterization of the catalysts by various physicochemical techniques reveals that the incorporated promoter cations show a significant influence on the surface and bulk properties of the zirconia.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Alkylation; Phenol; Solid acid; Characterization; Tetragonal zirconia
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Selective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 332, Issue 2, 20 November 2007, Pages 183–191
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
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