Mössbauer analysis of the state of iridium and platinum in supported catalysts

193Ir Mössbauer spectroscopy of Pt–IrO2 nanoparticle catalysts developed for detection and removal of carbon monoxide from air

“…The observed strong preference of iridium towards oxidation and of platinum towards metallic is remarkable, because an opposite trend was found by us earlier, in the case of Pt-Ir catalysts supported on amorphous silica [8]. Also, it should be noted that in the case of bimetallic Pt-Ir alumina-supported catalysts for hydrocarbon conversion studied by Sinfelt [2], EXAFS showed -contrary to our CO oxidation catalysts studied here -that both metallic components behave quite similarly, without a tendency to segregate and without different oxidation/reduction tendencies.…”

“…We have previously studied Pt-Ir catalysts supported on amorphous silica (Cabosil) which have been prepared either by ion exchange from aqueous solutions of Pt(NH 3 ) 4 Cl 2 and [Ir(NH 3 ) 5 Cl]Cl 2 [7], or by impregnation with solutions of hexachloroplatinic, H 2 PtCl 6 , and hexachloroiridic, H 2 IrCl 6 , acids [8,9], followed by calcination and reduction in hydrogen. The Pt-Ir catalysts prepared by these methods indicated as a rule a strong tendency towards segregation of the two metals, which could be the cause of the relatively poor efficiency and stability of those catalysts against deactivation in air.…”

“…The early progress in micro structural studies of the Pt-Ir catalysts supported on amorphous silica (Cabosil -a low density fumed silica powder) has been reported in Refs. [8,9]. In this paper, we describe an examination of a hydrophobic Pt-Ir polymer-supported granular catalyst, which proved to be particularly effective for oxidizing CO in moist air even at temperatures below 0°C.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13]. The work was initiated in the early 1970s by Sinfelt [1,2] who clearly showed that bimetallic catalysts could be tailored to effectively reduce undesirable competing reactions, and thus control the kinetic specificity of surface reactions.…”

“…The work at Atomic Energy of Canada Limited has over the years focused on the development and examination of Pt-Ir catalysts for detection and removal of carbon monoxide from air at ambient conditions and with avoidance of their thermal reactivation [7][8][9]. The early progress in micro structural studies of the Pt-Ir catalysts supported on amorphous silica (Cabosil -a low density fumed silica powder) has been reported in Refs.…”