Significance of Heterogeneous Catalysis of Certain Oxidation Reactions by Oxides in Relation to their Heats of Formation

1971 ◽  
Vol 49 (5) ◽  
pp. 809-812 ◽  
Author(s):  
Ashok K. Vijh ◽  
P. Lenfant
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalysis ◽  
Oxygen Atom ◽  
Band Gap ◽  
Electronic Conductivity ◽  
Heats Of Formation ◽  
Oxidation Reactions ◽  
Bond Energies ◽  
Oxygen Bond ◽  
Gap Values

The significance of previous correlations observed by Morooka et al. between heats of formation per oxygen atom, ΔH0, for oxides and their catalytic activity towards oxidation of some hydrocarbons has been discussed. It has been pointed out that ΔH0 values do not represent metal–oxygen bond energies, as assumed by Morooka and co-workers, but instead signify band gap values for the oxides. The catalytic activity of these oxides must therefore be interpreted in terms of their electronic conductivity and not in relation to the strength of metal–oxygen bond involved.

scholarly journals Heterogeneous catalysis with encapsulated haem and other synthetic porphyrins: Harnessing the power of porphyrins for oxidation reactions

2018 ◽  
Vol 16 (1) ◽  
pp. 763-789 ◽  
Author(s):  
Nicola A. Dare ◽  
Timothy J. Egan
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalysis ◽  
Heterogeneous Catalysts ◽  
Organic Substrates ◽  
Oxidation Reactions ◽  
Highly Efficient ◽  
Protein Environment

AbstractEncapsulated metalloporphyrins have been widely studied for their use as efficient heterogeneous catalysts, inspired by the known catalytic activity of porphyrins in haemoproteins. The oxidation of organic substrates by haemoproteins is one of the well-known roles of these proteins, in which the haem (ferriprotoporphyrin IX = FePPIX) cofactor is the centre of reactivity. While these porphyrins are highly efficient catalysts in the protein environment, once removed, they quickly lose their reactivity. It is for this reason that they have garnered much interest in the field of heterogeneous catalysis of oxidation reactions. This review details current research in the field, focusing on the application of encapsulated haem, and other synthetic metalloporphyrins, applied to oxidation reactions.

scholarly journals Some New Nickel 1,2-Dichalcogenolene Complexes as Single-component Semiconductors

2007 ◽  
Vol 62 (5) ◽  
pp. 679-684 ◽  
Author(s):  
George C. Papavassiliou ◽  
George C. Anyfantis ◽  
Barry R. Steele ◽  
Barry R. Steele ◽  
Aris Terzis ◽  
...  
Keyword(s):  
Band Gap ◽  
Single Component ◽  
Semiconducting Behavior ◽  
Gap Values

Abstract The complexes Ni(dmeds)(dmit), Ni(dmedt)(dmit), Ni(dpedt)(dsit), Ni(dpedt)(dmit), and Ni(dcdt)(dmit) (where dmeds is dimethylethylenediselenolate, dmedt is dimethylethylenedithiolate, dpedt is diphenylethylenedithiolate, dcdt is 1,2-bis-decylsulfanyl-ethene-1,2-dithiolate, dmit is 1,3-dithiol-2-thione-4,5-dithiolate, and dsit is 1,3-dithiol-2-thione-4,5-diselenolate) were prepared and characterized. The new complexes exhibit semiconducting behavior, with band gap values around 0.8 eV.

Catalytic activity of Co-åkermanite and Co-pyroxene in oxidation reactions

2011 ◽  
Vol 89 (8) ◽  
pp. 939-947 ◽  
Author(s):  
Irena Mihailova ◽  
Dimitar Mehandjiev
Keyword(s):  
Catalytic Activity ◽  
Solid Phase ◽  
Sol Gel ◽  
Cobalt Content ◽  
Octahedral Coordination ◽  
Tetrahedral Coordination ◽  
Oxidation Reactions ◽  
Oxidation Of Co ◽  
Phase Synthesis ◽  
Catalytically Active

Two calcium–cobalt silicates were synthesized in which cobalt occupies different structural positions. The crystal phases belong to two main structural silicate types. In the Co-åkermanite structure (Ca2CoSi2O7), cobalt cations take tetrahedral coordination toward oxygen atoms. In the Co-pyroxene structure of CaCoSi2O6, cobalt displays octahedral coordination. Ca2CoSi2O7 was prepared by solid-phase synthesis and CaCoSi2O6 was prepared by sol–gel method. The synthesis of the phases was confirmed by XRD, FTIR, and EPR data. On the basis of the XPS analysis, it can be concluded that Co2+ cations exist in the studied silicates. Thus, it is possible to study the catalytic activity of two silicate phases containing Co2+ cations in different coordinations: tetrahedral and octahedral. It was found that cobalt silicates with crystal structures corresponding to pyroxene and åkermanite possess catalytic activity in the reactions of complete oxidation of CO and toluene. Co-pyroxene exhibits higher catalytic activity than Co-åkermanite, but the higher cobalt content on the surface of Co-pyroxene should also be taken into account. Then, it turns out that catalytically active complexes with Со2+ ions in tetrahedral coordination are more efficient than those with such ions in octahedral coordination when equal concentrations of cobalt were used on the surface of the catalysts.

scholarly journals Importance of the oxygen bond strength for catalytic activity in soot oxidation

2016 ◽  
Vol 188 ◽  
pp. 235-244 ◽  
Author(s):  
Jakob M. Christensen ◽  
Jan-Dierk Grunwaldt ◽  
Anker D. Jensen
Keyword(s):  
Catalytic Activity ◽  
Bond Strength ◽  
Soot Oxidation ◽  
Oxygen Bond

Conglomerated system of Ag nanoparticles decorated Al2O3 supported cobalt and copper complexes with enhanced catalytic activity for oxidation reactions

2019 ◽  
Vol 462 ◽  
pp. 104-113 ◽  
Author(s):  
Tonmoy Chakraborty ◽  
Aratrika Chakraborty ◽  
Suvendu Maity ◽  
Debasis Das ◽  
Tanmay Chattopadhyay
Keyword(s):  
Catalytic Activity ◽  
Ag Nanoparticles ◽  
Copper Complexes ◽  
Oxidation Reactions
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