Oxidation of $NH_3$ over $YBa_2Cu_3O_7(123)$ oxide systems

Ramesh, S and Hegde, MS (1992) Oxidation of $NH_3$ over $YBa_2Cu_3O_7(123)$ oxide systems. In: Journal of Catalysis, 135 (2). pp. 335-344.

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Abstract

A temperature-programmed desorption study showed that the activation energy of oxygen desorption from $YBa_2Cu_3O_{7-x}$ (x = 0.05), $PrBa_2Cu_3O_{7-x}$ (x =0.02), and $YBa_2Cu_2CoO_{7-x}$ (x = 0.26) were 28.2, 26.4, and 22.3 kcal/mole, respectively. Anaerobic oxidation of $NH_3$ over these oxide systems shows the formation of $H_20$, $N_2$ and NO transforming the oxides to tetragonal phases. Aerobic oxidation of $NH_3$ is NO specific over all the three oxide catalysts. The Co-substituted $YBa_2Cu_2 CoO_{7+x}$ was the most reactive and stable oxide in this family; the lower oxygen desorption energy and higher reactivity are suggested to be due to the presence of holes in the form $Co^{4+}O^{2-}\rightleftharpoons Co^{3+}O^−$. The conversion of $NH_3$ to NO was nearly 100% above 400°C when the ammonia flow rates were 10 $\mu mole/cm^2/s$ over 0.3 g of the $YBa_2Cu_2CoO_{7+x}$ catalyst. Structural Chemistry Unit.

Item Type:	Journal Article
Publication:	Journal of Catalysis
Publisher:	Elsevier Science (USA).
Additional Information:	Copyright of this article belongs to Elsevier Science (USA).
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	31 Mar 2008
Last Modified:	19 Sep 2010 04:44
URI:	http://eprints.iisc.ac.in/id/eprint/13543

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