Reduction of azide in water with dihydrogen over heterogeneous Pd-Cu/Al2O3 catalysts

ENVR 288

Michael F. Fanizza, fanizza2@uiuc.edu1, Kathryn A. Guy, kaguy@uiuc.edu2, Charles J. Werth, werth@uiuc.edu3, and John R. Shapley, shapley@uiuc.edu2. (1) Department of Chemistry, University of Illinois at Urbana-Champaign, 505 S Matthews Ave., Noyes Lab 463, Urbana, IL 61801, (2) Department of Chemistry and Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, 505 S. Mathews, Urbana, IL 61801, (3) Department of Civil and Environmental Engineering and Center of Advanced Materials for Purification of Water with Systems, University of Illinois at Urbana-Champaign, 3215 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave., Urbana, IL 61801
The catalytic reduction of the anions nitrate and nitrite in water with dihydrogen over Pd-based bimetallic catalysts give dinitrogen and ammonia as primary products. Surface-bound nitrogen atoms have been proposed as intermediate species in both cases but no direct evidence exists. An alternative possible pathway to surface nitrogen species, which could provide an useful mechanistic probe, is via reduction of azide ion, N3-. The expected stiochiometry of the reaction of dihydrogen with azide in water is:

H2 + N3- + H2O → NH3 + N2 + OH-

We report that this reaction is catalyzed by a set of bimetallic Pd-Cu on alumina (Pd:Cu ratios from 90:10 to 50:50) at room temperature, with half lives on the order of 10-60 minutes. The azide ion disappearance is monitored by ion chromatography and no reaction is observed with the corresponding Pd-only catalyst. Details concerning the catalyst preparation and characterization, reaction kinetics and reaction stoichiometry will be presented and discussed.

 

Advances in Abiotic Transformation Processes for Micropollutants in Drinking Water and for Sourcewater Protection
6:00 PM-8:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Division of Environmental Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008