National Institute Of Materials Physics - Romania

Publications

161 articles found

141. Paramagnetic defect centres in crystalline Alq(3)

Authors: Grecu, MN; Mirea, A; Ghica, C; Colle, M; Schwoerer, M

Published: OCT 5 2005, JOURNAL OF PHYSICS-CONDENSED MATTER, 17, 6283, DOI: 10.1088/0953-8984/17/39/012

X- and Q-band electron paramagnetic resonance (EPR) investigation of different crystalline Alq(3) (tris(8-hydroxyquinoline)aluminium (III)) fractions formed by a train sublimation method are reported. Several paramagnetic defect centres corresponding to 1/2, 1, and 3/2 spin are observed at room temperature. Their intensity is dependent on the temperature, nature of the crystalline phase, and preparation conditions. Spectra simulation and analysis based on the spin Hamiltonian appropriate to a high spin system (S >=, 1) suggest the existence of randomly oriented triplets and quartets in annealed Alq(3) fractions. The crystalline Alq(3) phases responsible for the EPR powder spectra have been identified by transmission electron microscopy measurements performed on these sample fractions.

142. Supported perovskites for total oxidation of toluene

Authors: Alifanti, M; Florea, M; Somacescu, S; Parvulescu, VI

Published: SEP 1 2005, , DOI: 10.1016/j.apcatb.2005.02.018

143. Vanadium aluminium oxynitride catalysts for propane ammoxidation reaction - Effect of the V/Al ratio on the structure and catalytic behviour

Authors: Florea, M; Silvy, RP; Grange, P

Published: MAY 26 2005, , DOI: 10.1016/j.apcata.2005.02.032

144. Evidence for the participation of lattice nitrogen from vanadium aluminum oxynitrides in propane ammoxidation

Authors: Olea, M; Florea, M; Sack, I; Silvy, RP; Gaigneaux, EM; Marin, GB; Grange, P

Published: MAY 15 2005, , DOI: 10.1016/j.jcat.2005.02.020

145. Supported Co-based perovskites as catalysts for total oxidation of methane

Authors: Alifanti, M; Blangenois, N; Florea, M; Delmon, B

Published: MAR 8 2005, , DOI: 10.1016/j.apcata.2004.11.005

146. Influence of the co-precipitation pH on the physico-chemical and catalytic properties of vanadium aluminum oxide catalyst

Authors: Blangenois, N; Florea, M; Grange, P; Silvy, RP; Chenakin, SP; Bastin, JM; Kruse, N; Barbero, BP; Cadus, L

Published: JUN 10 2004, , DOI: 10.1016/j.apcata.2003.12.008

147. Epoxidation of cyclohexene on silicalite embedded BiOx clusters

Authors: Parvulescu, VI; Florea, M; Gelbard, G; Centeno, MA; Macovei, D; Lemay, G; Kaliaguine, S

Published: 2004, RECENT ADVANCES IN THE SCIENCE AND TECHNOLOGY OF ZEOLITES AND RELATED MATERIALS, PTS A - C, 154, 2654, DOI:

Silicalite embedded BiOx Clusters were prepared both with and without Na using sodium silicate and tetraethylorthosilicate as silicium precursors. Catalysts with 3 and 5 wt% Bi were obtained. The MFl structure was established from XRD, TEM, and N-2 adsorption measurements. No deterioration of the silicalite framework by bismuth was observed. Bi exists as BiOx clusters as evidenced from XPS and EXAFS characterization. These clusters are localized inside the silicalite channels. Py-FTIR measurements indicated that 5wt% Bi led to the formation of strong Lewis acid sites. Epoxidation of cyclohexene was found to depend oil both Bi and Na content. On 3%Bi-ZSM-5 it occurred with rather good conversion and selectivity to epoxide. No visible leaching was evidenced. The catalysts were reused for several runs.

148. Vanadium aluminium oxynitride catalyst for propane ammoxidation

Authors: Florea, M; Silvy, RP; Grange, P

Published: MAY-JUN 2004, , DOI:

149. Influence of the nitrogen content on butan-1-ol and butan-2-ol dehydration properties of nitrided phosphates

Authors: Delsarte, S; Florea, M; Grange, P

Published: MAY-JUN 2004, , DOI:

150. Influence of the preparation conditions on the physico-chemical and catalytic properties of a vanadium-aluminum oxynitride propane ammoxidation catalyst

Authors: Silvy, RP; Blangenois, N; Florea, M; Grange, P; Cadus, L; Barbero, B

Published: MAY-JUN 2004, , DOI: