HYDROGENATION OF UNSATURATED-HYDROCARBONS IN LIQUID-PHASE ON PALLADIUM, PLATINUM AND RHODIUM CATALYSTS .3. QUANTITATIVE SELECTIVITY RANKING OF PLATINUM, PALLADIUM AND RHODIUM IN THE HYDROGENATION OF 1-BUTENE, 1,3-BUTADIENE AND 1-BUTYNE USING A SINGLE REACTION SCHEME

The selectivity of platinum and rhodium in the hydrogenation of 1-butene, 1,3-butadiene and 1-butyne has 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 hydrogenation of b-butyne and 1,3-butadiene except for the initial formation of butane: platinum and rhodium produce a lot of 'initial' butane (S//p**B**A greater than 0), unlike palladium which is characterized by a selectivity index s// p**B**A of zero.