Predicting Selectivity for Ethane Dehydrogenation and Coke Formation Pathways over Model Pt–M Surface Alloys with ab Initio and Scaling Methods

2017 ◽  
Vol 121 (33) ◽  
pp. 17882-17892 ◽  
Author(s):  
Alec Hook ◽  
Fuat E. Celik
Keyword(s):  
Ab Initio ◽  
Coke Formation ◽  
Surface Alloys ◽  
Ethane Dehydrogenation ◽  
Scaling Methods

Ab initio study on elementary radical reactions in coke formation

2002 ◽  
Vol 91 (3) ◽  
pp. 384-388 ◽  
Author(s):  
V. Van Speybroeck ◽  
D. Van Neck ◽  
M. Waroquier ◽  
S. Wauters ◽  
M. Saeys ◽  
...  
Keyword(s):  
Ab Initio ◽  
Coke Formation ◽  
Radical Reactions ◽  
Ab Initio Study

scholarly journals Ethane dehydrogenation on pristine and AlOx decorated Pt stepped surfaces

2018 ◽  
Vol 8 (8) ◽  
pp. 2159-2174 ◽  
Author(s):  
Guowen Peng ◽  
Duygu Gerceker ◽  
Mrunmayi Kumbhalkar ◽  
James A. Dumesic ◽  
Manos Mavrikakis
Keyword(s):  
Atomic Layer Deposition ◽  
Ethylene Production ◽  
Coke Formation ◽  
Atomic Layer ◽  
Stepped Surfaces ◽  
Ethane Dehydrogenation ◽  
Layer Deposition

Atomic layer deposition (ALD) alumina overcoating over Pt enhances ethylene production and decreases coke formation in ethane dehydrogenation.

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.

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.

Elemental Distribution in Pt-Re:Al2O3 Naphtha Reforming Catalysts

1980 ◽  
Vol 38 ◽  
pp. 200-201
Author(s):  
R. L. Freed ◽  
M. J. Kelley
Keyword(s):  
Bimetallic Catalyst ◽  
Supported Catalysts ◽  
Coke Formation ◽  
Materials Characterization ◽  
Metal Catalyst ◽  
Elemental Distribution ◽  
Exact Nature ◽  
Naphtha Reforming ◽  
Reforming Catalysts ◽  
Commercial Introduction

The commercial introduction of Pt-Re supported catalysts to replace Pt alone on Al2O3 has brought improvements to naphtha reforming. The bimetallic catalyst can be operated continuously under conditions which lead to deactivation of the single metal catalyst by coke formation. Much disagreement still exists as to the exact nature of the bimetallic catalyst at a microscopic level and how it functions in the process so successfully. The overall purpose of this study was to develop the materials characterization tools necessary to study supported catalysts. Specifically with the Pt-Re:Al2O3 catalyst, we sought to elucidate the elemental distribution on the catalyst.

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