Partial hydrogenation of 3-hexyne over low-loaded palladium mono and bimetallic catalysts

MARÍA JULIANA MACCARRONE; CECILIA R. LEDERHOS; GERARDO C. TORRES; CAROLINA BETTI; FERNANDO COLOMA-PASCUAL; MÓNICA E. QUIROGA; JUAN C. YORI

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 441 p. 90 - 98

0926-860X

a b s t r a c tPartial hydrogenation of alkynes has industrial and academic relevance on a large scale, especially thosewith high selectivities. To increase the activity, selectivity and lifetime of low-loaded Pd monometalliccatalyst, the development of bimetallic systems has been investigated. In this work Pd mono (Pd/A) andbimetallic catalysts (PdNi/A and WPd/A) supported on _-alumina with low metal content are preparedand evaluated during the partial hydrogenation of 3-hexyne at mild conditions. XPS, XRD, TPR and hydrogenchemisorption techniques are used for the characterization, suggesting different kind of Pd specieson the mono and bimetallic catalysts. Furthermore, XPS results indicate the presence of electron richand electron-deficient palladium species (Pd d- and Pdn+, with d close to 0 and 0 < n < 2, respectively),electron-deficient species of nickel (Nin+, with n close to 2) and of W ro+ (with ro< 6) on the surface ofthe bimetallic systems. The Lindlar commercial catalyst, commonly used in these types of reactions isused for comparative purposes. Bimetallic catalysts showed higher activities and very similar selectivities(>93%) than the monometallic system and further than the Lindlar catalyst. The rank of activity order is:WPd/A > PdNi/A > Pd/A > Lindlar.