scholarly journals Numerical analysis of mathematical model for CO oxidation on platinum

2021 ◽  
pp. 165-169
Author(s):  
Petro Kostrobij ◽  
Iryna Ryzha
Keyword(s):  
Mathematical Model ◽  
Carbon Monoxide ◽  
Structural Changes ◽  
Diffusion Processes ◽  
Catalyst Surface ◽  
Pt Catalyst ◽  
Two Dimensional ◽  
Langmuir Hinshelwood Mechanism ◽  
And Diffusion ◽  
Oxygen Atoms

In the paper a study of a two-dimensional mathematical model of carbon monoxide oxidation on the Pt catalyst surface according to the Langmuir-Hinshelwood mechanism is presented. This model takes into account the nanoinhomogeneities of Pt(110) surface and diffusion processes of CO molecules and oxygen atoms adsorbed on the catalyst surface. It is shown that the structural changes of Pt(110) surface significantly affect the character of oscillatory mode of reaction, whereas the adsorbed oxygen atoms can be considered immobile.

Stability of carbon monoxide oxidation process on gold nanoparticles

2020 ◽  
Vol 8 (1) ◽  
pp. 116-124
Author(s):  
P. P. Kostrobij ◽  
◽  
I. A. Ryzha ◽  
Keyword(s):  
Carbon Monoxide ◽  
Gold Nanoparticles ◽  
Reaction Mechanisms ◽  
Structural Changes ◽  
Oxidation Process ◽  
Lyapunov Method ◽  
Catalyst Surface ◽  
Carbon Monoxide Oxidation ◽  
One Step ◽  
The Stability

The stability conditions for mathematical models of carbon monoxide oxidation on the surface of gold nanoparticles are investigated. The cases of reaction mechanisms of one-step and step-by-step transformation of reagents are consecutively considered. Using the stability analysis by Lyapunov method, it is shown that models which take into account the possibility of structural changes of the catalyst surface can predict the occurrence of oscillatory mode in the system as a result of Hopf instability.

scholarly journals Molecule transfer mechanism in 2D heterostructured lamellar membranes: The effects of dissolution and diffusion

2021 ◽  
Author(s):  
Chongchong Chen ◽  
Xiaoli Wu ◽  
Jie Zhang ◽  
Jingjing Chen ◽  
Xulin Cui ◽  
...  
Keyword(s):  
Diffusion Processes ◽  
Cyanuric Acid ◽  
Membrane Surface ◽  
Transfer Mechanism ◽  
Two Dimensional ◽  
Polar Solvents ◽  
Nonpolar Solvents ◽  
Self Assembling ◽  
Resistance Transfer ◽  
And Diffusion

Two-dimensional (2D) lamellar membranes are promising for efficient molecule transfer, while the underlying molecule transfer mechanism is rarely elucidated. Herein, heterostructured nanosheets are prepared by self-assembling small-sized hydrophilic cyanuric acid melamine (CMN) and hydrophobic g-C3N4 nanosheets. The resultant lamellar membranes show comparable affinity to both polar and nonpolar solvents, allowing them to dissolve on membrane surface and diffuse through membrane channels. Permeance results demonstrate that the transfer of polar solvents is controlled by dissolution and diffusion processes, while that of nonpolar solvents is governed by dissolution process. And the corresponding equations are established. Importantly, polar solvents are induced to form ordered arrangement in hydrophilic nanodomains and then maintain this state in hydrophobic nanodomains, affording low-resistance transfer thus high permeance: 1025 L m-2 h-1 bar-1 for acetonitrile. In contrast, nonpolar solvents with disordered arrangement acquire lower permeance than that of polar ones, but with comparable diffusion ability in these membranes.

scholarly journals Modeling of carbon monoxide oxidation on the catalytic surface in the two-dimensional case

2017 ◽  
pp. 83-89
Author(s):  
Iryna Ryzha
Keyword(s):  
Carbon Monoxide ◽  
Co Oxidation ◽  
Stability Region ◽  
Pt Catalyst ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Catalytic Surface ◽  
One Dimensional ◽  
Co Oxidation Reaction ◽  
The Stability

A two-dimensional model of carbon monoxide (CO) catalytic oxidation on a platinum (Pt) surface for the Langmuir-Hinshelwood mechanism is investigated. The adsorbate-driven (1×1)-(1×2) structural phase transition of Pt(110) and the formation of new crystal planes on the catalytic surface (faceting) as well as the effect of the substrate temperature are taken into account. It is shown that the stability region for CO oxidation reaction changes when two dimensions are taken into account. Similarly to the one-dimensional case, the reaction of CO oxidation on Pt-catalyst surface is periodic in the stability region. Mixed-mode oscillations (MMO) for CO and oxygen (O) surface coverages as well as the fraction of the surface in the non-reconstructed (1×1)-state were found. Such behavior cannot be predicted by one-dimensional models when the equation for the change of degree of faceting is not taken into account.

scholarly journals Modeling of Pt-catalyst surface influence on characteristics of oxygen and carbon monoxide molecules

2016 ◽  
Vol 3 (1) ◽  
pp. 43-50 ◽  
Author(s):  
P. Kostrobij ◽  
◽  
A. Beznosiuk ◽  
V. Dmytruk ◽  
V. Polovyi ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Catalyst Surface ◽  
Pt Catalyst

scholarly journals Sudėtinės geometrinės struktūros biojutiklių kompiuterinis modeliavimas

2011 ◽  
Vol 56 ◽  
pp. 156-162
Author(s):  
Romas Baronas ◽  
Karolis Petrauskas
Keyword(s):  
Numerical Approximation ◽  
Diffusion Processes ◽  
Dimensional Space ◽  
Computer Software ◽  
Two Dimensional ◽  
Geometrical Properties ◽  
Domain Specific ◽  
Physical Experiments ◽  
Modeling Software ◽  
And Diffusion

Biojutikliai yra analitiniai įrenginiai, skirti medžiagų koncentracijoms matuoti. Kuriant naujus biojutiklius reikia atlikti daug eksperimentų. Siekiant sumažinti atliekamų fizinių eksperimentų skaičių taikomas kompiuterinis biojutiklių veiksmo odeliavimas, kai įprastai kiekvienam struktūriškai naujam biojutikliui yra sudaromas matematinis modelis, tuomet jis keičiamas skirtuminiu, o jo lygčių sistemos sprendimas įgyvendinamas sudarant kompiuterinį modelį. Kiekvienas žingsnis reikalauja atidos ir turėtų būti automatizuotas. Straipsnyje yra pateikiamas biojutiklio metamodelis, leidžiantis formuluoti biojutiklių modelius dalykinės srities sąvokomis. Pasiūlytasis metamodelis aprašo biojutiklių modelius, formuluojamus dvimatėje erdvėje, apimančius biojutiklio struktūros, jo geometrinių savybių, biojutikliuose vykstančių reakcijų ir difuzijos procesų aprašus. Sudarius metamodelį, buvo sukurta programinė įranga, automatiškai sukonstruojanti kompiuterinį biojutiklio modelį pagal metamodeliosąvokomis išreikšto biojutiklio aprašą. Metamodelis ir programinė įranga buvo taikoma realiam biojutiklio modeliui sudaryti ir jo veiksmui modeliuoti kompiuteriniu būdu.", t. y. ištrinti žodžius "biojutiklių veiksmo.Computer-Aided Modeling of Biosensors with a Complex Geometrical StructureRomas Baronas, Karolis Petrauskas SummaryBiosensors are analytical devices used to measure the concentration of substances. When developing new biosensors, a lot of experiments are needed to be performed. Mathematical modeling of biosensors is used to decrease the number of physical experiments. Models of biosensors are usually created for each structurally unique biosensor by defining its mathematical model and the corresponding numerical approximation. Equations of the numerical model are then solved using computer programs, usually created for a particular model of the biosensor. Each of these steps requires a great attention and should be automated. The article presents a metamodel for a biosensor, enabling one to define models of biosensors in domain-specific terms. The proposed metamodel describes biosensor models, defined in the two-dimensional space and including definitions of the structure of a biosensor, its geometrical properties, reactions and diffusion processes taking place in it. Upon defining the metamodel, we compiled the computer software able to create computer models for biosensors from the models formulated according to the proposed metamodel. The metamodel was practically used to define a model for a real biosensor, and the biosensor modeling software was used to simulate its operation.

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