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Your search keyword '"Mckenna, Fiona"' showing total 3 results
Start Over Author "Mckenna, Fiona" Topic titanium dioxide
3 results on '"Mckenna, Fiona"'

1. Selective hydrogenation of actylene in ethylene streams using ligand modified palladium on titania

Author

McKenna, Fiona-Mairéad

Subjects
541.39, Palladium, Titanium dioxide
Abstract

The performance of supported palladium catalysts that had been modified with triphenyl phosphine, diphenyl sulfide and triphenyl amine was compared to unmodified Pd/TiO2 catalysts. It was found that the selectivity was superior to the unmodified catalysts with or without the use of carbon monoxide as a modifier. Ethylene selectivities in excess of 70 % at conversion levels greater than 80% were observed on the modified catalysts under conditions of excess hydrogen which compares extremely well with other catalysts found in the literature. The modifier was found to significantly reduce the number of high energy sites on the surface on the palladium, thereby significantly hindering ethylene hydrogenation but not affecting acetylene hydrogenation. The simple preparation of these catalysts together with the simplicity added by not having to use carbon monoxide or limited hydrogen promises a viable alternative strategy for commercial catalysis.

Published
2010

2. Selectivity enhancement in acetylene hydrogenation over diphenyl sulphide-modified Pd/TiO2 catalysts

Author

McKenna, Fiona-Mairead and Anderson, James A.

Subjects
*ACETYLENE, *HYDROGENATION, *SULFIDES, *PALLADIUM catalysts, *TITANIUM dioxide, *CHEMICAL reduction, *ADSORPTION (Chemistry), *ETHYLENE, *LIGANDS (Chemistry), *ALKENES, *CHEMICAL reactions
Abstract

Abstract: Pd/TiO2 catalysts have been exposed to diphenyl sulphide to assess the impact of the modifier on the selective removal of acetylene from ethylene rich feeds. The modified catalysts show a significantly reduced rate of ethylene hydrogenation without noticeably impacting on the rate of acetylene hydrogenation. Even after reduction at 393K, which led to the loss of the phenyl ligands, the sulphur retained by the Pd was still capable of maintaining this enhanced selectivity of the catalyst to ethylene as opposed to ethane. Results are interpreted in terms of a templating effect on the active Pd surface as a result of the original ligand adsorption pattern that creates appropriate ensembles which allow alkyne adsorption and reaction but severely limits adsorption and reaction of the alkene. A potential contribution to this enhanced selectivity by suppression of subsurface hydrogen formation cannot be discounted. [Copyright &y& Elsevier]

Published
2011
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3. Enhanced selectivity in acetylene hydrogenation by ligand modified Pd/TiO2catalysts.

Author

McKenna, Fiona-Mairead, Wells, Richard. P. K., and Anderson, James. A.

Subjects
*HYDROGENATION, *ACETYLENE, *LIGANDS (Chemistry), *PALLADIUM catalysts, *TITANIUM dioxide, *ADSORPTION (Chemistry), *PHOSPHINE
Abstract

Modification of Pd/TiO2catalyst by adsorption of triphenylphosphine and phenyl sulfide leads to markedly enhanced selectivity for acetylene hydrogenation in the presence of ethylene and excess hydrogen. Similar selectivities were maintained in cases where ligand decomposition took place and sulfur was retained on the catalyst surface. [ABSTRACT FROM AUTHOR]

Published
2011
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