Study of Catalysts Comprising Heteropoly Acid H3PW12O40 Supported on MCM-41 Molecular Sieve and Amorphous Silica Full article
Journal |
Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169 |
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Output data | Year: 1996, Volume: 114, Number: 1-3, Pages: 287-298 Pages count : 12 DOI: 10.1016/S1381-1169(96)00328-7 | ||||||
Tags | 31P NMR, Heteropoly acid H3PW12O40, MCM-41 molecular sieve, Silica, TEM, Trans-de-t-butylation of 2,6-di-t-butyl-4-methylphenol, XRD | ||||||
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Abstract:
With the aim of obtaining pure Keggin-type heteropoly acid (HPA) species on siliceous surfaces, the preparation of HPA catalysts, comprising of 10 to 50 wt.% H3PW12O40 (PW) supported on an amorphous silica or a mesoporous all-silica molecular sieve MCM-41, was studied. The state of HPA on the siliceous surface was characterized by 31P NMR, XRD and TEM. Impregnating MCM-41 or amorphous SiO2 with an aqueous solution of PW gave catalysts with, in general, two HPA species: one with intact Keggin structure (A) and the other with a different structure (B), supposedly, H6P2W18O62 (P2W18) and/or H6P2W21O71 (P2W21). The relative amount of species A and B depends on HPA loading, with A dominating. At higher loadings, 30–50 wt.%, A is practically the only one present on the surface; at lower loadings, both species exist, the amount of B increasing as the HPA loading decreases. In contrast, catalysts prepared by impregnation with a methanol solution of HPA contained exclusively Keggin-type A over the whole range of PW loading. In the PWMCM-41 catalysts, as shown by TEM, the PW species are mainly located inside the MCM-41 pores. The B species was about 8 times as active as A in the liquid-phase trans-de-t-butylation of 2,6-di-t-butyl-4-methylphenol.
Cite:
Kozhevnikov I.V.
, Kloetstra K.R.
, Sinnema A.
, Zandbergen H.W.
, van Bekkum H.
Study of Catalysts Comprising Heteropoly Acid H3PW12O40 Supported on MCM-41 Molecular Sieve and Amorphous Silica
Journal of Molecular Catalysis A: Chemical. 1996. V.114. N1-3. P.287-298. DOI: 10.1016/S1381-1169(96)00328-7 WOS Scopus РИНЦ
Study of Catalysts Comprising Heteropoly Acid H3PW12O40 Supported on MCM-41 Molecular Sieve and Amorphous Silica
Journal of Molecular Catalysis A: Chemical. 1996. V.114. N1-3. P.287-298. DOI: 10.1016/S1381-1169(96)00328-7 WOS Scopus РИНЦ
Dates:
Published print: | Dec 23, 1996 |
Published online: | Dec 16, 1999 |
Identifiers:
Web of science | WOS:A1996WC26500030 |
Scopus | 2-s2.0-0030599612 |
Elibrary | 13234148 |
Chemical Abstracts | 1996:737406 |
Chemical Abstracts (print) | 126:91737 |
OpenAlex | W2029605038 |