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Dehydration of glycerol in gas phase using heteropolyacid catalysts as active compounds

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Abstract.
Different silica-, alumina-, and aluminosilicate-supported heteropolyacid catalysts were prepared using
phosphomolybdic acid H3PMo12O40·xH2O, phosphotungstic acid H3PW12O40·xH2O, silicotungstic acid
H4SiW12O40·xH2O, and ammonium phosphomolybdate (NH4)3PMo12O40·xH2O as precursor compounds.
The as-synthesised solids were characterised by nitrogen adsorption, XRD, TG/DTA, Raman spectroscopy,
and TPD of ammonia. Silica-supported heteropolyacids are rather well crystallised, whereas aluminasupported
samples are X-ray amorphous. Investigations using Raman spectroscopy of calcined samples
and TG/DTA revealed that molybdenum-containing heteropolyacids tend to decompose partly close to
400 ◦C into molybdates and MoO3 whereas tungsten-containing samples are stable. This makes in
particular tungsten-based materials interesting acid catalysts for the dehydration of glycerol in the gas
phase. In particular, the influence of selected support materials, catalyst loading, and temperature on
acrolein formation was studied at standardised reaction conditions (10% by weight of glycerol in water,
225–300 ◦C, modified contact time 0.15 kg hmol−1). Surprisingly, alumina is found to be superior to
silica as support material with regard to catalyst activity and selectivity. Nevertheless, tungsten based
heteropolyacids showed outstanding performance and stability. Acrolein was always the predominant
product with maximum selectivity of 75% at complete conversion over silicotungstic acid supported over
alumina and aluminosilicate.

Keywords:
Glycerol
Dehydration
Acrolein
Heteropolyacids
Catalysis
Gas phase

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Informasi Detail

Judul Seri

Journal of Catalysis

No. Panggil

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Penerbit

London : Elsevier Inc.., 2008

Deskripsi Fisik

Journal of Catalysis 258 (2008) 71–82

Bahasa

English

ISBN/ISSN

00219517

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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