Nitrate hydrogenation on Pt,In/Al2O3. EXAFS and XANES characterization

MARCHESINI, F.A.; MIRÓ, E.E.; FÉLIX GREGORIO REQUEJO; JOSE MARTIN RAMALLO LOPEZ

Campinas

Workshop; 20a Reunion Annual de Usuarios del LNLS; 2010

Laboratorio Nacional de Luz Sincrotron

In this work, bimetallic Pt,In supported on Al2O3 catalysts active for the reduction of nitrate to N2 in water using H2 as reducing agent were characterized by EXAFS and XANES. Among the catalysts studied, the one that contained 1 wt. % of Pt and 0.25 wt. % of In had a remarkable high initial activity which decreased with reaction time. For this catalyst, EXAFS characterization showed that the fresh solid consisted of a mixture of bimetallic Pt-In nanoparticles and monometallic Pt ones. Both EXAFS and XANES results show that after the nitrate hydrogenation reaction in aqueous media at room temperature was carried out, the amount of bimetallic nanoparticles decreased and that of unalloyed Pt considerably increased. This phase segregation could explain the partial deactivation of the catalyst.