ChemInform Abstract: CATALYSIS BY HETEROPOLY COMPOUNDS. VIII. REDUCTION-OXIDATION AND CATALYTIC PROPERTIES OF 12-MOLYBDOPHOSPHORIC ACID AND ITS ALKALI SALTS. THE ROLE OF REDOX CARRIERS IN THE BULK

1985 ◽  
Vol 16 (16) ◽  
Author(s):  
N. MIZUNO ◽  
T. WATANABE ◽  
M. MISONO
Keyword(s):  
Catalytic Properties ◽  
Heteropoly Compounds ◽  
Molybdophosphoric Acid ◽  
Alkali Salts

Dehydrogenation, Deamination and Disproportionation of Diethylamine over Heteropoly Compounds

1995 ◽  
Vol 60 (12) ◽  
pp. 2047-2056 ◽  
Author(s):  
Abdel-Ghaffar A. Ali ◽  
Laila I. Ali
Keyword(s):  
Reaction Mechanism ◽  
Continuous Flow ◽  
Flow System ◽  
Tungstophosphoric Acid ◽  
Lewis Acidity ◽  
Heteropoly Compounds ◽  
Molybdophosphoric Acid ◽  
System Transformation ◽  
Continuous Flow System

In a continuous flow system, transformation of diethylamine over heteropoly compounds was studied at 250 to 350 °C. It was found that ammonium molybdophosphate and tungstophosphate are the most active catalysts while copper molybdophosphate is the most stable one. 12-Molybdophosphoric acid and its salts were highly selective catalysts for dehydrogenation of diethylamine to ethyliden- ethylamine whereas 12-tungstophosphoric acid and its salts directed the reaction selectively to deamination. The role of Lewis acidity of metal cations, Bronsted acidity and basic sites in the reaction mechanism is discussed.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Physicochemical and catalytic properties of hybrid catalysts derived from 12-molybdophosphoric acid and montmorillonites

2015 ◽  
Vol 498 ◽  
pp. 192-204 ◽  
Author(s):  
Aleksandra Pacuła ◽  
Katarzyna Pamin ◽  
Joanna Kryściak-Czerwenka ◽  
Zbigniew Olejniczak ◽  
Barbara Gil ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Molybdophosphoric Acid ◽  
Hybrid Catalysts

scholarly journals Enhancement of aromatase activity by D-aspartic acid in the ovary of the lizard Podarcis s. sicula

Reproduction ◽  
2001 ◽  
pp. 803-808 ◽  
Author(s):  
L Assisi ◽  
V Botte ◽  
A D'Aniello ◽  
MM Di Fiore
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Reproductive Cycle ◽  
Catalytic Properties ◽  
Ovarian Tissue ◽  
Experimental Treatment ◽  
Tissue Homogenate ◽  
Aromatase Activity

The present study investigated the role of D-aspartic acid (D-Asp) in ovarian steroidogenesis and its effect on aromatase activity in the lizard, Podarcis s. sicula. It was determined that D-Asp concentrations vary significantly during phases of the reproductive cycle: they vary inversely with testosterone concentrations and directly with oestradiol concentrations in the ovary and plasma. Experimental treatment showed that administration of D-Asp induces a decrease in testosterone and an increase in oestradiol, and that treatment with other amino acids (L-Asp, D-Glu and D-Ala) instead of D-Asp has no effects. Experiments in vitro confirmed these results. Furthermore, these experiments showed an increase in aromatase activity, as the addition of D-Asp either to fresh ovarian tissue homogenate or to acetonic powder of ovarian follicles induced a significant increase in the conversion of testosterone to oestradiol. Aromatase activity is four times greater in the presence of D-Asp than in its absence. However, almost equivalent values of the two K(m) values (both approximately 25 nmol l(-1)) indicate that aromatase has the same catalytic properties in both cases.

scholarly journals Role of Dimerization in the Catalytic Properties of the Escherichia coli Disulfide Isomerase DsbC

2009 ◽  
Vol 284 (36) ◽  
pp. 23972-23979 ◽  
Author(s):  
Silvia A. Arredondo ◽  
Tiffany F. Chen ◽  
Austen F. Riggs ◽  
Hiram F. Gilbert ◽  
George Georgiou
Keyword(s):  
Escherichia Coli ◽  
Catalytic Properties ◽  
Disulfide Isomerase
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