Portal de Periódicos da CAPES

Hydrogenation of unsaturated hydrocarbons in liquid phase on palladium, platinum and rhodium catalysts

1987; Elsevier BV; Volume: 35; Issue: 2 Linguagem: Inglês

10.1016/s0166-9834(00)82860-2

1873-3867

J.P. Boitiaux, J. Cosyns, Éric Robert,

Surface Chemistry and Catalysis

The selectivity of platinum and rhodium in the hydrogenation of 1-butene, 1,3-butadiene and 1-butyne have been determined and compared with that of palladium. The experimental results are rationalized using a single reaction scheme accounting for primary parallel formation of 1-butene, 2-butenes and butane and consecutive formation of 2-butenes and butane from the 1-butene initially produced. Platinum and rhodium behave very similarly and are not very different from palladium for hydrogenations of 1-butyne and 1,3-butadiene except for the initial formation of butane: platinum and rhodium produce a lot of "initial" butane (SBApO) unlike palladium which is characterized by a selectivity indexSBAp of zero. This particular behaviour of palladium is also apparent in thetrans/cis ratio for 2-butenes produced from butadiene hydrogenation, this ratio being 3.5 for platinum and rhodium and 12 for palladium. Results from of our laboratory and from the literature on Group VIII metals, either as heterogeneous or homogeneous catalysts, show that the initial formation of butane increases while thetrans/cis ratio decreases. It seems that this correlation is not by chance and we propose that butane is formed via a semi-hydrogenated species, originating from asyn-diadsorbed 1,3-butadiene, from whichcis-2-butenes are formed.