Effect of oxygen mobility in solid catalyst on transient regimes of catalytic reaction of methane partial oxidation at short contact times

Abstract

Mathematical modeling of the effect of the oxygen mobility in a solid oxide catalyst on the dynamics of transients of fast catalytic reactions has been carried out. The analysis was based upon the redox mechanistic scheme with a due regard for diffusion of oxygen from the bulk of catalyst to its surface. Parameters of kinetic and mathematical models were selected via fitting of the experimental data for methane selective oxidation into syngas on 1.4%Pt/Gd 0.2 Ce 0.4 Zr 0.4 O x catalyst. The range of the Thiele parameter (/) where the oxygen bulk diffusion affects the most strongly reaction transients corresponds to /2[0:3 Ä 7]. For highsurface-area oxide catalysts, the bulk oxygen diffusion coefficients corresponding to this range of the Thiele parameter are in the range of10 À18 Ä 10 À13 cm 2 /s.

Partial oxidation of methane into synthesis gas over a Pt-supported complex fluorite-like oxide: one-channel studies in realistic feeds

“…Hence, a lot of attention of different scientific groups has been paid to the development of monolithic catalysts with the required efficiency and stability [3][4][5][6]. Fluorite-like oxides (doped ceria or ceria-zirconia) promoted with Pt group metals were shown to be promising active components for these catalysts due to their high oxygen storage capacity, thermal stability and strong metal-support interaction stabilizing the metal dispersion and preventing the carbon build-up [3,[7][8][9][10][11][12]. In our previous publications [7-9, 11, 12], Pt-supported powdered CeO 2 -ZrO 2 mixed oxides doped with La, Pr or Gd have been studied by combining diffraction and spectroscopic techniques, and the effects of their structural and surface features on the surface/lattice oxygen mobility and reactivity that determine their activity in POM in the diluted feeds have been discussed in detail.…”

Modern Trends in Design of Catalysts for Transformation of Biofuels into Syngas and Hydrogen: From Fundamental Bases to Performance in Real Feeds

“…While testing catalysts in real concentrated feeds in POM, methane steam reforming and MDR, the temperature gradient along the length of reactor equipped with the catalyst fraction or granules caused by exothermicity or endothermicity of these reactions emerges, which complicates data analysis. To avoid this problem, catalytic layers were supported onto the inner walls of single channels cut from corundum honeycomb monoliths, which allowed to avoid any temperature gradients and estimate rate constants (Table 3) [109][110][111][112]. Among Pt/Lnx(Ce0.5Zr0.5)1-xO2-ycatalysts the highest activity was revealed for Pr-doped catalyst possessing the highest oxygen mobility, which stresses importance of this characteristic.…”

“…In reactions of oxygenates reforming a high activity and stability of catalysts based on perovskites precursors was shown as well [32,[63][64][65][66][67][108][109][110]115,116]. The same factors-exsolution of Ni-containing nanoalloys from perovskite lattice in reducing conditions, their stabilization by strong interaction with remaining matrix and oxygen transfer to metal-support interface determine their resistance to coking and activity.…”

Effect of the mobility of oxygen in perovskite catalyst on the dynamics of oxidative coupling of methane

“…We will consider in its general form the simplified mechanism of the oxidation-reduction reaction accompanied by the diffusion of oxygen from the volume of the catalyst toward its surface [6]. The mechanism includes a stage with dissociative adsorption of oxygen on the surface of the catalyst and a stage with reaction of the reagent A of the gas phase with the active center of the catalyst leading to the formation of the product P:…”