caa a22 4500 378941313 CHVBK 20180305123653.0 cr unu---uuuuu 161128e20040201xx s 000 0 eng 10.1524/ract.92.2.81.27463 doi (NATIONALLICENCE)gruyter-10.1524/ract.92.2.81.27463 Heterogeneous catalytic redox reactions of neptunium ions in the aqueous system HNO3-HCOOH [Elektronische Daten] [A. V. Ananiev, V. P. Shilov, Ph. Moisy, Charles Madic] The redox behaviours of neptunium(VI,V) ions in aqueous solutions containing nitric and formic acids in the presence of Pt/SiO2 catalyst have been studied. It was shown that neptunium(VI), being quite stable in 0.1-2.0M HNO3and 0.1-1.5M HCOOH, is reduced effectively to neptunium(V) inthe presence of ∼1 wt. % Pt/SiO2. In the presence of 0.05-0.5M urea (anti-nitrous agent) the reduction of neptunium(VI) proceeds to neptunium(IV) through the stage of the neptunium(V) formation. The effects of the solid-to-liquid mass to volume ratio, the concentration of urea, the concentration of nitricacid, the concentration of formic acid and the temperature on the rates of the Np(VI) and Np(V) reductions in the presence of ∼1 wt. % Pt/SiO2 were investigated. It was proposed that both reactions proceed through the stage of the HCOOH activated adsorption on Pt catalyst. Mechanisms of the Np(VI) and Np(V) catalytic reductions by formic acid were postulated. © 2004 Oldenbourg Wissenschaftsverlag GmbH Laboratory techniques, experiments nationallicence Analytical chemistry nationallicence Inorganic chemistry nationallicence Ananiev A. V. aut Shilov V. P. aut Moisy Ph aut Madic Charles aut Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 92/2/2004(2004-02-01), 81-88 0033-8230 92:2/2004<81 2004 92 ract https://doi.org/10.1524/ract.92.2.81.27463 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/ract.92.2.81.27463 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ananiev A. V. aut NATIONALLICENCE 700 1- Shilov V. P. aut NATIONALLICENCE 700 1- Moisy Ph aut NATIONALLICENCE 700 1- Madic Charles aut NATIONALLICENCE 773 0- Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 92/2/2004(2004-02-01), 81-88 0033-8230 92:2/2004<81 2004 92 ract CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter