Abstract

DALLAGO, Rogério M.  and  BAIBICH, Ione M.. Pd-W and Pd-Mo catalysts for NO decomposition and NO/CO reduction reactions. J. Braz. Chem. Soc. [online]. 2009, vol.20, n.5, pp. 873-879. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532009000500011.

Pd/γ-Al₂O₃ catalysts with two different metal particle sizes were prepared from [Pd(acac)₂]. Subsequently, the photochemical reaction of [M(CO)₆] (M = Mo or W) in the presence of Pd/γ-Al₂O₃ was used to prepare bimetallic Pd-M/γ-Al₂O₃ catalysts. DRIFTS FTIR spectra of the catalyst surfaces prior to thermal decomposition showed unstable subcarbonyl [M(CO)_n] species. Chemisorption and CO/NO adsorption results indicated a blockage of the Pd active sites when the second metal was incorporated. The catalytic activity and the selectivity for the NO/CO reaction were higher for Pd with higher particle size, but they were both inhibited when Mo or W were incorporated. On the other hand, when the catalysts were tested for NO decomposition, the presence of Mo or W led to an increase in the catalytic activity, with optimal results observed in the presence of Mo.

Keywords : NO decomposition; NO/CO reduction; palladium/alumina catalyst; molybdenum; tungsten.