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The texture of a binary AI2O3-GeO2 gel system

Kirszensztejn P., Marciniak P., Przekop R., Szymkowiak A., Kierzkowska A.

Polish Journal of Chemical Technology

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2006

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Vol. 8, nr 2

115-117

EN

A comprehensive comparative study of binary oxide systems obtained by the sol-gel chemistry has been made. Particular attention has been paid to the texture changes. Using germanium isopropoxide and aluminium isopropoxide, binary gels with mesoporous structure have been obtained. Binary gels show a monodispersive distribution and the major contribution to the pore volume comes from the pores of diameters similar to those in the pure alumina gel.

2

Synthesis and properties of a binary Al2O3-GeO2 system obtained by sol-gel processes -TG-TA study in oxidizing atmosphere

Kirszensztejn P., Marciniak P., Przekop R., Szymkowiak A., Jurek K.

Polish Journal of Chemical Technology

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2006

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Vol. 8, nr 2

118-120

EN

The paper is a continuation of our earlier studies related to the modification of the gel aluminium oxide with the oxides of the carbon group elements and aimed at the determination of the effect of the changes in the co-gelating component on the final structure of the binary support. The transformations taking place in the bulk gel have been described on the basis of the thermogravimetric studies carried out in the oxidizing atmosphere. The thermogravimetric results have confirmed that the gelation conditions proposed in this paper lead to getting a homogeneous gel structure in which germanium oxide enhances the gel network stability.

3

Ideal continuous stirred thermobalance reactor

Nazimek D., Kuśmierz M., Kirszensztejn P.

Polish Journal of Applied Chemistry

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2006

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Vol. 50, nr 1-2

41-53

EN

This paper describes the construction of continuous stirred tank reactor (CSTR) coupled with a thermobalance. It also presents results of kinetic tests, which were carried out using Ni/γ-Al203 catalysts of various mean grain size, and involving various impeller rotational speeds. The capability for measuring the degree of catalyst reduction (verified by means of CAHN TG121 thermobalance) is presented, too.

4

Badanie możliwości zastosowania materiału katalitycznego z nośnikiem syntetyzowanym na drodze zol-żel w ogniwach paliwowych

Kirszensztejn P., Martyła A., Olejnik B., Szymkowiak A.

Przemysł Chemiczny

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2003

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T. 82, nr 8-9

562-565

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FT-IR Spectroscopic Studies of NH4ReO4 Supported on Inorganic Gels

Kirszensztejn P., Wachowski L., Zawadzki J., Skupiński W.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 11

1625-1636

EN

Results of IR study of the systems NH4ReO4/Al2O3 and NH4ReO4/Al2O3-SiO2 heated in the range 293-723 K are given. The systems contained rhenium in amounts corresponding to those in typical heterogeneous catalysts of olefin metathesis. The IR absorption spectra, recorded for the wavelengths 1700-1300 cm-1, enabled detection of adsorption at the Brönsted and Lewis type acid centres of water and ammonia, released during thermal decomposition of ammonium perrhenate. The spectra indicated a similarity between the adsorption centres present on the surface of the systems 17.8 wt.% NH4ReO4/Al2O3 and 3.3 wt.% NH4ReO4/Al2O3-SiO2 and those on the surface of the systems 3.3 and 9.9 wt.% NH4ReO4/Al2O3. The presence of adsorption centres in the former systems should be related to the phase of the surface rhenium species, while in the latter the centres occur on the surface of the support.

6

FT-IR Spectroscopic Studies of Tin-Modified Rhenium Alumina-Silica Metathesis Catalyst

Zawadzki J., Skupiński W., Kirszensztejn P., Wachowski L., Jamróz M. H., Dobrowolski J. Cz.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 12

1755-1767

EN

FT-IR spectra of the products obtained in each step of the tetramethyltin (TMT)/3-wt. % Re2O7/Al2O3-SiO2 and TMT/Al2O3-SiO2 systems preparation are presented and discussed. The obtained spectra show that TMT reacts with alumina-silica hydroxyl groups already at room temperature, yielding surface methyltin compounds; NH4ReO4 reacts with alumina–silica surface at temperatures up to 423 K, yielding rhenium surface species and ammonia, which is strongly bonded by acidic sites of the Brönsted kind. FT-IR spectrum of the system TMT/3-wt.%Re2O7/Al2O3-SiO2 indicated the absence of surface methyl tin compounds observed on the surface system TMT/Al2O3-SiO2, and the presence of physically adsorbed TMT; after 5 h of evacuation of the TMT/3-wt. % Re2O7- /Al2O3-SiO2 system, the FT-IR spectrum indicated the presence of only a single band at 2977 cm–1, which may be assigned to the C–H bond stretching of the methyl group in the surface bridged (O, O) Re(=O)2CH3 complexes formed. Analysis of FT-IR results suggests formation of a new phase containing rhenium and aluminium ions, on which olefin sites active in olefin metathesis are formed in the system studied.

7

FT-IR Spectroscopic Studies of Tin-Modified Rhenium Alumina-Silica Metathesis Catalyst

Zawadzki J., Skupiński W., Kirszensztejn P., Wachowski L., Jamróz M. H., Dobrowolski J. Cz.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 12

1755-1767

EN

FT-IR spectra of the products obtained in each step of the tetramethyltin (TMT)/3-wt. % Re2O7/Al2O3-SiO2 and TMT/Al2O3-SiO2 systems preparation are presented and discussed. The obtained spectra show that TMT reacts with alumina-silica hydroxyl groups already at room temperature, yielding surface methyltin compounds; NH4ReO4 reacts with alumina–silica surface at temperatures up to 423 K, yielding rhenium surface species and ammonia, which is strongly bonded by acidic sites of the Brönsted kind. FT-IR spectrum of the system TMT/3-wt.%Re2O7/Al2O3-SiO2 indicated the absence of surface methyl tin compounds observed on the surface system TMT/Al2O3-SiO2, and the presence of physically adsorbed TMT; after 5 h of evacuation of the TMT/3-wt. % Re2O7- /Al2O3-SiO2 system, the FT-IR spectrum indicated the presence of only a single band at 2977 cm–1, which may be assigned to the C–H bond stretching of the methyl group in the surface bridged (O, O) Re(=O)2CH3 complexes formed. Analysis of FT-IR results suggests formation of a new phase containing rhenium and aluminium ions, on which olefin sites active in olefin metathesis are formed in the system studied.