scholarly journals Designing Active Sites for Structure-Sensitive Reactions via the Generalized Coordination Number: Application to Alcohol Dehydrogenation

2021 ◽  
Author(s):  
Kamila Kaźmierczak ◽  
Paul Clabaut ◽  
Ruben Staub ◽  
Noémie Perret ◽  
Stephan N. Steinmann ◽  
...  
Keyword(s):  
Coordination Number ◽  
Active Sites ◽  
Structure Sensitive ◽  
Alcohol Dehydrogenation ◽  
Structure Sensitive Reactions

scholarly journals Decoding Complexity in Structure-Sensitive Reactions

2021 ◽  
Author(s):  
Toyin Omojola
Keyword(s):  
Remote Control ◽  
Active Site ◽  
Active Sites ◽  
Water Adsorption ◽  
Kinetic Equations ◽  
Oxidation Catalysis ◽  
Propane Conversion ◽  
Structure Sensitive ◽  
Non Linear ◽  
Structure Sensitive Reactions

Structure-sensitive reactions involving the Mars and van Krevelen mechanism over metal and metal oxide catalysts are ubiquitous in reaction kinetics and engineering. The kinetic equations of such reactions are re-written to account for modern operando spectroscopy and microscopy observations. Emphasis is placed on reactions with nucleophilic (lattice) oxygen, oxygen reduction reversibility, an interconversion scheme, non-linear water adsorption, remote-control model, and non-uniform sites. The multiplicity of propane conversion over MoVTeNbOx catalysts is proven through a combination of non-linear competitive water adsorption, the presence of multiple active sites, a re-structuring active site, and oxygen adsorption. The modified remote-control kinetics for the Mars and van Krevelen mechanism can account for the observations of steady-state multiplicities and hysteresis. The results have implications for improving catalytic activity, reducing operating process costs, and active site engineering of selective oxidation catalysis.

scholarly journals Shifting the scaling relations of single-atom catalysts for facile methane activation by tuning the coordination number

2021 ◽  
Author(s):  
Changhyeok Choi ◽  
Sungho Yoon ◽  
Yousung Jung
Keyword(s):  
Transition State ◽  
Coordination Number ◽  
Active Sites ◽  
Methane Activation ◽  
Single Atom ◽  
Scaling Relations ◽  
Scaling Relationship ◽  
Relationship Of

The scaling relationship of methane activation via a radical-like transition state shifts toward a more reactive region with decreasing coordination number of the active sites.

scholarly journals On the behaviour of structure-sensitive reactions on single atom and dilute alloy surfaces

2020 ◽  
Vol 10 (17) ◽  
pp. 5815-5828 ◽  
Author(s):  
Konstantinos G. Papanikolaou ◽  
Michail Stamatakis
Keyword(s):  
Structure Sensitivity ◽  
Single Atom ◽  
Structure Sensitive ◽  
Dilute Alloy ◽  
Structure Sensitive Reactions ◽  
Single Atom Alloy

Typically structure sensitive dissociation reactions exhibit reduced structure-sensitivity when taking place over low-index single atom alloy surfaces.

Active sites and states in the heterogeneous catalysis of carbon–hydrogen bonds

2005 ◽  
Vol 363 (1829) ◽  
pp. 879-900 ◽  
Author(s):  
Gabor A Somorjai ◽  
Anderson L Marsh
Keyword(s):  
Surface Structure ◽  
Active Sites ◽  
High Pressures ◽  
Bond Activation ◽  
Co Adsorption ◽  
Molecular Rearrangement ◽  
Platinum Surface ◽  
Bond Dissociation ◽  
Surface Mobility ◽  
Structure Sensitive

C–H bond activation for several alkenes (ethylene, propylene, isobutene, cyclohexene and 1-hexene) and alkanes (methane, ethane, n -hexane, 2-methylpentane and 3-methylpentane) has been studied on the (111) crystal face of platinum as a function of temperature at low (<10 −6  Torr) and high (≥1 Torr) pressures in the absence and presence of hydrogen pressures (≥10 Torr). Sum frequency generation (SFG) vibrational spectroscopy has been used to characterize the adsorbate structures and high pressure scanning tunnelling microscopy (HP-STM) has been used to monitor their surface mobility under reaction conditions during hydrogenation, dehydrogenation and CO poisoning. C–H bond dissociation occurs at low temperatures, approximately 250 K, for all of these molecules, although only at high pressures for the weakly bound alkanes because of their low desorption temperatures. Bond dissociation is known to be surface structure sensitive and we find that it is also accompanied by the restructuring of the metal surface. The presence of hydrogen slows down dehydrogenation and for some of the molecules it influences the molecular rearrangement, thus altering reaction selectivity. Surface mobility of adsorbates is essential to produce catalytic activity. When surface diffusion is inhibited by CO adsorption, ordered surface structures form and the reaction is poisoned. Ethylene hydrogenation is surface structure insensitive, while cyclohexene hydrogenation and dehydrogenation are structure sensitive. n -Hexane and other C 6 alkanes form either upright or flat-lying molecules on the platinum surface which react to produce branched isomers or benzene, respectively.

scholarly journals Modifying structure-sensitive reactions by addition of Zn to Pd

2014 ◽  
Vol 318 ◽  
pp. 75-84 ◽  
Author(s):  
David J. Childers ◽  
Neil M. Schweitzer ◽  
Seyed Mehdi Kamali Shahari ◽  
Robert M. Rioux ◽  
Jeffrey T. Miller ◽  
...  
Keyword(s):  
Structure Sensitive ◽  
Structure Sensitive Reactions

Characterization of the Surface Structure of Gold Nanoparticles and Nanorods Using Structure Sensitive Reactions

2005 ◽  
Vol 109 (26) ◽  
pp. 12651-12654 ◽  
Author(s):  
Javier Hernández ◽  
José Solla-Gullón ◽  
Enrique Herrero ◽  
Antonio Aldaz ◽  
Juan M. Feliu
Keyword(s):  
Gold Nanoparticles ◽  
Surface Structure ◽  
Structure Sensitive ◽  
Structure Sensitive Reactions

Effect of nickel hexaaluminate mirror cation on structure-sensitive reactions during n-tetradecane partial oxidation

2007 ◽  
Vol 323 ◽  
pp. 1-8 ◽  
Author(s):  
Todd H. Gardner ◽  
Dushyant Shekhawat ◽  
David A. Berry ◽  
Mark W. Smith ◽  
Maria Salazar ◽  
...  
Keyword(s):  
Partial Oxidation ◽  
Structure Sensitive ◽  
Structure Sensitive Reactions
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