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Your search keyword '"Ratnasamy, P."' showing total 13 results
Start Over Author "Ratnasamy, P." Journal applied catalysis a: general
13 results on '"Ratnasamy, P."'

11. Direct conversion of methane to methanol

Author

Raja, Robert and Ratnasamy, Paul

Abstract

Methane has been converted to a mixture of methanol and formaldehyde at ambient conditions with high activity (TON above 100) and selectivity (CO2 less than 5%) using phthalocyanine complexes of Fe and Cu encapsulated in zeolites as catalysts and O2/tert-butyl hydroperoxide as oxidants.

Published
1997
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12. Selective oxidation of phenols using copper complexes encapsulated in zeolites

Author

Raja, Robert and Ratnasamy, Paul

Abstract

The oxidation and hydroxylation of phenols to dihydroxy aromatic compounds have been investigated using phthalocyanines and substituted (chloro- and nitro-) phthalocyanines of copper encapsulated in zeolites (X and Y). H2O2 has been used as oxidant. At ambient conditions, the encapsulated copper chloro- and nitro phthalocyanine complexes, unlike their unsubstituted analogs, are able to oxidise, selectively, phenol to catechol and hydroquinone. The catalytic efficiency (turnover number) of the copper atoms are higher in the encapsulated state compared to that in the “neat” complex. The solid catalysts have been characterised by IR, UV, ESR and ESCA spectroscopy. The influence of various process parameters (like temperature, reaction time, substrate/oxidant ratio, catalyst weight etc.) on the conversion and product distribution is also illustrated and discussed.

Published
1996
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13. Structural studies on NiO-CeO2-ZrO2 catalysts for steam reforming of ethanol

Author

Srinivas, D., Satyanarayana, C.V.V., Potdar, H.S., and Ratnasamy, P.

Subjects
*CATALYSTS, *BENZENE, *HYDROGENATION, *NICKEL, *CESIUM
Abstract

The influence of Ce/Zr ratio on the redox behavior of Ni in a series of NiO-CeO2-ZrO2 catalysts was investigated using in situ electron paramagnetic resonance (EPR), diffuse reflectance UV-visible (DRUV-visible) and X-ray photoelectron spectroscopy (XPS). At all concentrations, a small amount of Ni (species I) substitutes in the fluorite lattice. Superparamagnetic, nanosize Ni crystallites (species II) were found in samples with 1–5 wt.% NiO and ferromagnetic, larger Ni crystallites (species III) were detected in samples with 20 wt.% or more NiO when contacted with hydrogen. Ce promoted the reduction of Ni. The reducibility of Ni decreased in the order: I>III>II. At steam reforming conditions (in the presence of H2+H2O+hydrocarbon/alcohol at 773 K), the extent of Ni reduction varies in the order: H2+alkane>H2+alcohol>H2 alone. Catalytic activity and especially stability in the steam reforming of bio-ethanol (containing 5 ppm S) correlates with the type III Ni species and is influenced by both the Ni-content and the Ce/Zr ratio in the support. A catalyst of composition NiO (40 wt.%)-CeO2 (30 wt.%)-ZrO2 (30 wt.%) maintained its activity for more than 500 h without deactivation. [Copyright &y& Elsevier]

Published
2003
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