Mechanistic insights into the dominant reaction route and catalyst deactivation in biogas reforming using ab initio microkinetic modeling

2021 ◽  
Author(s):  
Fatima Jalid ◽  
M. Ali Haider ◽  
Md. Imteyaz Alam ◽  
Tuhin S. Khan
Keyword(s):  
Ab Initio ◽  
Catalyst Deactivation ◽  
Microkinetic Modeling ◽  
Reaction Route

Co and Ru are proposed as two possible catalyst candidates for the biogas reforming process as these convert most of the CH4 to CO and yield less coke.

scholarly journals Prediction of morphological changes of catalyst materials under reaction conditions by combined ab initio thermodynamics and microkinetic modelling

2018 ◽  
Vol 8 (14) ◽  
pp. 3493-3503 ◽  
Author(s):  
Raffaele Cheula ◽  
Aloysius Soon ◽  
Matteo Maestri
Keyword(s):  
Ab Initio ◽  
Structural Changes ◽  
Morphological Changes ◽  
Microkinetic Modeling ◽  
Reaction Conditions

Microkinetic modeling, ab initio thermodynamics and Wulff–Kaishew construction are used to predict catalyst structural changes under reaction conditions.

Reaction path analysis for 1-butanol dehydration in H-ZSM-5 zeolite: Ab initio and microkinetic modeling

2015 ◽  
Vol 330 ◽  
pp. 28-45 ◽  
Author(s):  
Mathew John ◽  
Konstantinos Alexopoulos ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin
Keyword(s):  
Path Analysis ◽  
Ab Initio ◽  
Reaction Path ◽  
Microkinetic Modeling

Ab initio coverage-dependent microkinetic modeling of benzene hydrogenation on Pd(111)

2017 ◽  
Vol 7 (22) ◽  
pp. 5267-5283 ◽  
Author(s):  
Maarten K. Sabbe ◽  
Gonzalo Canduela-Rodriguez ◽  
Jean-François Joly ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin
Keyword(s):  
Ab Initio ◽  
Catalytic Hydrogenation ◽  
Benzene Hydrogenation ◽  
Microkinetic Modeling ◽  
Mechanistic Understanding

Coverage-dependent calculations are required for an accurate DFT-based prediction of the activity and a correct mechanistic understanding of catalytic hydrogenation.

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

1989 ◽  
Vol 47 ◽  
pp. 272-273
Author(s):  
Sooho Kim ◽  
M. J. D’Aniello
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Noble Metal ◽  
Catalyst Deactivation ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Metal Particles ◽  
Automotive Exhaust ◽  
Exhaust Catalysts ◽  
Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

An analytical microscopic study of metals in fluidized catalytic cracking catalyst

1986 ◽  
Vol 44 ◽  
pp. 854-855
Author(s):  
Clifford S. Rainey
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Catalytic Cracking ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Acid Sites ◽  
Y Zeolite ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
High Regeneration

The spatial distribution of V and Ni deposited within fluidized catalytic cracking (FCC) catalyst is studied because these metals contribute to catalyst deactivation. Y zeolite in FCC microspheres are high SiO2 aluminosilicates with molecular-sized channels that contain a mixture of lanthanoids. They must withstand high regeneration temperatures and retain acid sites needed for cracking of hydrocarbons, a process essential for efficient gasoline production. Zeolite in combination with V to form vanadates, or less diffusion in the channels due to coke formation, may deactivate catalyst. Other factors such as metal "skins", microsphere sintering, and attrition may also be involved. SEM of FCC fracture surfaces, AEM of Y zeolite, and electron microscopy of this work are developed to better understand and minimize catalyst deactivation.

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