Microcalorimetric Heats of Adsorption for CO, NO, and Oxygen on Pt{110}

Abstract

The reactions of CO, NO, and oxygen on platinum surfaces have received a great deal of research attention, because of both their industrial importance in the three-way automobile catalytic converter and the academic interest surrounding the kinetic oscillations observed under some conditions. Crucial parameters in many of the kinetic models of these systems are the coverage-dependent heats of adsorption of the reacting species, which, with the exception of isosteric data for CO, have not previously been determined experimentally.Here the results of microcalorimetric measurements of the heats of adsorption of CO, NO, and O 2 as a function of coverage on Pt{110} are presented. The initial adsorption heats are 183, 160, and 335 kJ mol -1 , respectively.

Importance of the oxygen bond strength for catalytic activity in soot oxidation

“…For platinum a heat of adsorption of 140 kJ/mol has been selected. This value corresponds to a moderately high coverage on Pt(111) [59,60] and is reasonably representative for a high coverage on Pt(110) [61]. In the case of gold the dependence of the catalytic properties on the particle size is well established [62][63][64].…”

NO Oxidation Catalysis on Pt Clusters: Elementary Steps, Structural Requirements, and Synergistic Effects of NO2Adsorption Sites

“…Metal-oxygen bonds on metal cluster surfaces weaken as oxygen coverages increase 25,26 because of Coulombic repulsion between adsorbates. 5 Such effects persist and become stronger as oxygen atoms start to bind with Pt atoms within clusters at higher oxygen chemical potentials.…”

Time Resolved Operando X-ray Techniques in Catalysis, a Case Study: CO Oxidation by O2 over Pt Surfaces and Alumina Supported Pt Catalysts

“…In the limit of saturation CO coverage, heats of desorption for CO adsorbed at high coverages, and over a wide range of Pt dispersions, fall in the 54-63 kJ·mol −1 range [170]; the same is true for Pt single crystal surfaces at saturation coverage of CO ((111) 60 kJ·mol −1 [171] and (110) 70 kJ·mol −1 ) [172] obtained at low CO pressures.…”

“…In the limit of saturation CO coverage, heats of desorption for CO adsorbed at high coverages, and over a wide range of Pt dispersions, fall in the 54-63 kJ·mol −1 range; [170] the same is true for Pt single crystal surfaces at saturation coverage of CO ((111) 60 kJ·mol −1 [171] and (110) From these central observations, made from perspectives of the net CO2 production (MS), the infrared visible surface speciation, and the redox events occurring in the Pt component of the catalyst (Pt L3-edge XAFS), a novel mechanism, that involves the participation of both atomic Pt species (that provide the sites for carbonate formation and turnover) and Pt nanoparticles (that supply the All of the applied techniques can be used to derive estimates of the apparent activation energies for the two branches of the CO 2 production, and the results derived from the Pt L 3 -edge XANES are shown in Figure 20c. This shows that under CO the reduction of a portion of the Pt, corresponding to the formation and turnover of the carbonate is subject to a very low apparent activation energy (E app ); a fact confirmed by analyses of the MS and DRIFTS that all sample the catalyst bed in different manners.…”