Intermediaries fine chemicals in the selective hydrogenation reaction of alkynes with WPd catalyst

MARÍA JULIANA MACCARRONE; CECILIA R. LEDERHOS; CAROLINA P. BETTI; FERNANDO COLOMA-PASCUAL; CARLOS R. VERA; MÓNICA E. QUIROGA

Congreso; 16th International Congress on Catalysis (ICC 16); 2016

The selective hydrogenation reaction aim to transform molecules with triple bond in molecules with double bond and is a critical step in the synthesis of a wide range of fine chemicals including vitamins, fragrances, drugs and many other products with a worldwide production more than 1000 tons per year [1]. In this paper the effect of substrate concentration, temperature and hydrogen pressure in the 3-hexyne selective hydrogenation over a low cost WPd/Al2O3 catalyst was evaluated. Orders of reaction and the apparent activation energy were calculated.The optimum operating temperature was 323K because obtains a high conversion of 3-hexyne (100%, 150 min. Reaction) to (Z) -3-hexene with high selectivity (95%). This selctividad values are justified by the absence of the β-PdH phase prevents the formation of n-hexane. The higher activity of the catalyst is due to the presence of electron rich species Pd- (92% at/at) that prevent overhydrogenation the alkane (undesired product). This is associated with factors of electronic type, but can not rule out the influence of geometric factors and / or mixed sites on the catalyst activity. The order of reaction for 3-hexyne (-0.45), the reaction order with respect to hydrogen partial pressure (-1.04) and the apparent activation energy (calculated 14.6 KJ mol-1) were calculated.