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1

Minerały warstwowe jako podstawa projektowania katalizatorów do syntezy eteru dimetylowego

Grabowski R., Serwicka E., Pacuła A., Plona J., Śliwa M.

Karbo

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2009

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Nr 1

34-38

PL

Przedstawiono działania zmierzające do zaprojektowania i syntezy składowej kwasowej katalizatora hybrydowego służącego do otrzymywania DME z gazu syntezowego. W badaniach wykorzystano montmorillonit wydzielony ze skały bentonitowej z Milowic oraz handlowo dostępny montmorillonit K-10. Montmorillonit Na-mt wykorzystano także do otrzymania materiałów kompozytowych typu PILC (montmorillonit podpierany) i PCH (porowata heterostruktura). W pierwszym przypadku uzyskano wysokopowierzchniowy materiał mikroporowaty, w drugim wysokopowierzchniowy materiał mezoporowaty. Badano dwie formy kwasowe montmorillonitu: a) preparat H-mt uzyskany z formy sodowej w drodze wymiany jonowej w środowisku rozcieńczonego kwasu solnego, b) montmorillonit K-10, stanowiący produkt intensywnej aktywacji stężonym kwasem. Stwierdzono, że przeprowadzenie montmorillonitu w formę kwasową związane jest z modyfikacją jego struktury i tekstury. Stopień modyfikacji można kontrolować dobierając odpowiednio warunki obróbki kwasowej. Obie kwasowe formy montmorillonitu poddano impregnacji heteropolikwasem H3PW12O40. Właściwości strukturalne i teksturalne zależały od natury użytego nośnika (H-mt lub mt-K-10) oraz od sposobu przeprowadzenia impregnacji. Stwierdzono, że impregnacja HPW obniża wartość maksimum temperatury konwersji metanolu do DMT o ok. 90°C w porównaniu z układem niezawierającym HPW.

EN

Research part of this article deals with design and synthesis of the acidic component of hybrid catalyst for one step synthesis of DME from syngas. Montmorillonite fraction from Milowice bentonite and commercially available montmorillonite K-10 were used in the experiments. The composite materials e.g. PILC and PCH were obtained from Na-mt montmorillonite. The first is the high surface microporous material, the second is the high surface mezoporous material. Two acidic forms of montmorillonite were investigated: a) H-mt obtained from sodium form by ionic exchange in the presence of diluted hydrochloric acid, b) montmorillonite K-10, a product of intense activation with concentrated acid. It was found that the transformation of montomorillonite into acidic form is connected with the modification of its structure and texture. The degree of the modification can be controlled by selecting the appropriate conditions of acidic treatment. Both acidic forms of montmorillonite were impregnated by heteropolyacid H3PW12O40 (HPW). The structural and textural properties of montmorillonites impregnated with HPW depended on the nature of the support (H-mt or mt-K-10) and on the applied impregnation method (conventional or modified). The catalytic activity of the samples impregnated with HPW was higher than that of the starting material. It has been found that impregnation by HPW lowers the temperature of the maximum methanol conversion to DMT by about 90°C, in comparison with the system not comprising HPW.

2

The Role of Synthesis Parameters in Preparation of Cu, Cr-Layered Double Hydroxides

Michalik A., Pacuła A., Serwicka E., Bahranowski K., Gaweł A., Dziembaj R., Bielańska E.

Polish Journal of Chemistry

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2004

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Vol.78 /nr 11-12

1997-2004

EN

Aseries of Cu,Cr-layered double hydroxides of Cu/Cr ratio equal 2 has been synthesized by co-precipitation at a constant pH, using different preparative conditions. The investigated synthesis parameters included: ageing time, speed of reactants addition, temperature of co-precipitation and pH of synthesis. The dominant product of the synthesis was the nitrate form of Cu,Cr-LDH, containing ca. 10 mol% of carbonate. Modifications of experimental conditions affected chiefly the samples crystallinity. The most obvious effects were associated with changing of pH of the co-precipitation, the most acidic conditions providing a material of the best crystallinity. At the medium synthesis temperature (55°C), a slow addition of the reactants and a long ageing were favourable, but a significant shortening of the ageing time caused only minor deterioration of the sample crystallinity. The latter finding is of practical importance for an upscaling of the process.

3

Catalytic Combustion of Trichloroethylene over Pd-Doped Ti-Pillared Montmorillonites

Bahranowski K., Gaweł A., Janik R., Komorek J., Machej T., Michalik A., Serwicka E., Włodarczyk W.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 5

675-682

EN

Palladium (0.8 wt.%) was introduced onto Ti-pillared montmorillonite samples by means of incipient wetness technique either before or after calcination of the pillared matrix. Combustion of trichloroethylene (TCE) has been chosen to test the catalytic properties of clay catalysts in deep oxidation of chlorinated volatile organics. The results were referred to the performance of a commercial catalyst. Both materials based on pillared clays were more active than the reference sample. The clay sample doped after calcination was better of the two and gave complete combustion of TCE at temperature by 100 K lower than the commercial catalyst. This material showed also the highest selectivity to HCl at maximum TCE conversion. Further improvement of the clay catalyst performance in terms of the HCl yield and suppression of chlorine evolution was achieved by addition of the methanol vapour to the reaction mixture. The results are discussed in terms of textural and acidic properties of the investigated catalysts.

4

Clays as Catalysts for the Removal of Nitrogen Oxides

Serwicka E.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 3

307-328

EN

A comprehensive coverage of literature on the design and application of clay-derived catalysts for the removal of nitrogen oxides (deNOx), encompassing both the cationic and the anionic clay materials is given. Emphasis is put on the versatility of clays, which renders them excellent materials for an intelligent catalyst design. DeNOx processes discussed include SCR by ammonia and hydrocarbons, reduction of NO with CO and decomposition of N2O.

5

Oxidative dehydrogenation of isobutane on chromium oxide-titania catalysts

Grzybowska B., Słoczyński J., Grabowski R., Wcisło K., Kozłowska A., Stoch J., Serwicka E.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 9

2159-2171

EN

Oxidative dehydrogenation of isobutane has been studied at 250 degreeC for a series of chromium oxide-TiO2 (anatase) samples containing 5-50 Cr at per nm(2) of the support surface and for pure chromia. The catalysts have been characterized by XPS, Raman, ESR spectroscopies and by probe reactions for acido-basic properties and the catalyst oxygen reactivity. The maximum activity and selectivity to isobutene have been observed for a catalyst containing 1 theoretical monolayer of the chromia phase on titania. Higher selectivity to isobutene for this catalyst as compared with unsupported chromia or catalysts with higher Cr loading has been ascribed to lower acidity and lover reactivity of oxygen.