Transitions between strongly correlated and random steady-states for catalytic CO-oxidation on surfaces at high-pressure

Abstract

We explore simple lattice-gas reaction models for CO-oxidation on 1D and 2D periodic arrays of surface adsorption sites with CO adsorption and desorption, dissociative O2 adsorption and recombinative desorption (at low rate), and CO + O reaction to form CO2. Adspecies interactions are neglected, and adspecies diffusion is effectively absent. The models are motivated by studies of CO-oxidation on RuO2(110) at high-pressures. Despite the lack of adspecies interactions, negligible adspecies diffusion results in kinetically induced spatial correlations. A transition occurs from a random primarily CO-populated steady-state at high CO-partial pressure, pCO, to a strongly correlated near-O-covered steady-state for low pCO as noted by Matera et al. [ J. Chem. Phys. 134, 064713 (2011)]. In addition, we identify a second transition to a random near-O-covered steady-state at very low pCO. Furthermore, we identify and analyze the slow "diffusive dynamics" for very low pCO and provide a detailed characterization of the crossover to the strongly correlated O-covered steady-state as well as of the spatial correlations in that state. PHYSICS 142, 134703 (2015) Transitions between strongly correlated and random steady-states for catalytic CO-oxidation on surfaces at high-pressure We explore simple lattice-gas reaction models for CO-oxidation on 1D and 2D periodic arrays of surface adsorption sites with CO adsorption and desorption, dissociative O 2 adsorption and recombinative desorption (at low rate), and CO + O reaction to form CO 2 . Adspecies interactions are neglected, and adspecies diffusion is effectively absent. The models are motivated by studies of CO-oxidation on RuO 2 (110) at high-pressures. Despite the lack of adspecies interactions, negligible adspecies diffusion results in kinetically induced spatial correlations. A transition occurs from a random primarily CO-populated steady-state at high CO-partial pressure, p CO , to a strongly correlated near-O-covered steady-state for low p CO as noted by Matera et al. [J. Chem. Phys. 134, 064713 (2011)]. In addition, we identify a second transition to a random near-O-covered steady-state at very low p CO . Furthermore, we identify and analyze the slow "diffusive dynamics" for very low p CO and provide a detailed characterization of the crossover to the strongly correlated O-covered steady-state as well as of the spatial correlations in that state. C 2015 AIP Publishing LLC. [http://dx

Beyond mean-field approximations for accurate and computationally efficient models of on-lattice chemical kinetics

“…The main advantage of this approximation lies in the fact that, to evaluate Eqs. (15) and (16), we only need to take into account the 2 7 possible states of the cluster (of course symmetry arguments can be used to reduce this number of states and improve computational efficiency). From Eq.…”

“…Such correlations can arise from slow diffusion in tandem with reaction or from adsorbate-adsorbate lateral interactions. [13][14][15] An example of the former case is CO oxidation on RuO 2 (110). 13 In this situation, a microkinetic model incorporating the correct expressions of the pair probabilities of finding vacancies or adatoms in neighboring sites is enough to yield results in quantitative agreement with KMC.…”

“…13 In this situation, a microkinetic model incorporating the correct expressions of the pair probabilities of finding vacancies or adatoms in neighboring sites is enough to yield results in quantitative agreement with KMC. 14,15 A different route is to numerically approximate the solution of the highdimensional MME directly. The tensor train approximation recently reported by Gelβ et al, 16 for solving a MME for the aforementioned CO oxidation process, is an interesting example of this approach.…”

Discontinuous non-equilibrium phase transition in a threshold Schloegl model for autocatalysis: Generic two-phase coexistence and metastability

“…Stochastic systems where such behavior might be revealed are those exhibiting bistability in a mean-field (MF) description, but where there is an underlying discrete spatial lattice structure to break rotational isotropy, as well as strong fluctuations. Such systems might include catalytic CO-oxidation on crystalline surfaces with limited surface mobility at high pressure [13][14][15] or spatially discrete population dynamics or epidemic models. 16,17 Perhaps, the most simple and natural models in which to explore non-equilibrium phase transitions are threshold versions of single-component Schloegl models for autocatalysis 18 or the equivalent threshold contact processes.…”

Extended families of critical and stationary droplets for nonequilibrium phase transitions in spatially discrete bistable systems

“…(Introduction of significant diffusion leads to large characteristic length scales and the disappearance of such features as propagation failure, behavior being effectively described by continuum formalisms.) Examples of such reaction models are the generic monomer-dimer model [6,32,44,45], and also realistic models for catalytic CO oxidation on crystalline oxide surfaces at high pressure [8,[46][47][48]. Mean-field treatments based on homogeneous and heterogeneous master equations can be developed for these models as for the QCP [8].…”