Catalytic denitration by HCO2H of HNO3 concentrated media in the presence Of Pt/SiO2 catalysts:: mechanism and influence of Pt particle size

被引：12

作者：

Coq, B

Guenais, S

Bouyer, C

Broudic, JC

机构：

[1] CNRS, UMR 5618, ENSCM, Lab Mat Catalyt & Catalyse Chim Organ, F-34296 Montpellier 5, France

[2] Commissariat Energie Atom, DRCP, SEAT, F-30207 Bagnols Sur Ceze, France

来源：

APPLIED CATALYSIS B-ENVIRONMENTAL | 2003年 / 45卷 / 03期

关键词：

formic acid; nitric acid; platinum; chemical denitration; nuclear fuel reprocessing;

D O I：

10.1016/S0926-3373(03)00164-4

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The denitration by HCO2H of highly concentrated HNO3 media (3-5 M) was studied on PtSiO2 catalysts with Pt particle size varying from 1 to 10 nm. The reaction was carried out in batch mode at 343 K. The actual active intermediate is HNO2, which is formed very slowly in the absence of Pt/SiO2. The chief function of Pt/SiO2 is the initial fast generation of HNO2 in order to reach a threshold concentration of 5 x 10(-3) mol l(-1). Above this threshold, the homogeneous process between HNO3 and HCO2H, with HNO2 as an autocatalytic species, prevails. The initial generation of HNO3 on Pt/SiO2 is regulated by a catalytic cycle involving "Pt-H" and Pt-0 species. This was demonstrated by redox cycle experiments in which Pt-H was reacted with HNO3 to yield Pt-0, which was back reactivated to Pt-H by HCO2H. Large Pt clusters were the most active, possibly due to a faster reaction rate between Pt-H and HNO3. (C) 2003 Elsevier B.V. All rights reserved.

引用

页码：205 / 211

页数：7