Palladium-catalyzed selective hydrogenation of nitroarenes: Influence of platinum and iron on activity, particle morphology and formation of β-palladium hydride

The influence of alloying supported palladium particles of 2 nm size with platinum and iron on the catalytic activity for the selective hydrogenation of nitrobenzene (NB) was studied. We show that the use of a carbon black support of enhanced sp(2) character has a marked 'templating' effect on the location of the palladium particles, which are preferentially deposited at the edge sites of the carbon support surface. Alloying with platinum and iron leads to disaggregation down to isolated primary particles, and this has a major effect on the catalytic activity (Pd 6.6, PdPt 36.9, PdPtFe 23.1 mmol(NB) min(-1)), as well as on the relative amounts of beta-palladium hydride formed (normalized peak integrals: Pd 127.0, PdPt 87.6, PdPtFe 27.2). The results enable a greater understanding of how better performance can be obtained in catalysts by appropriate choice of support, particle size, alloying and adjustment of hydrogen storage capability. (C) 2013 Elsevier Inc. All rights reserved.