Liquid phase hydrogenation of 2-butyne-1,4-diol and 2-butene-1,4-diol isomers over Pd catalysts: roles of solvent, support and proton on activity and products distribution

Hydrogenation of 2-butyne-1,4-diol has been investigated over palladium supported catalysts. It was found that, besides butane-1,4-diol, side products such as cis- and trans-2-butene-1,4-diol, 2-hydroxytetrahydrofuran, cis- and trans-crotyl alcohol and n-butanol were also formed. The hydrogenation of the intermediates cis- and trans-2-butene-1,4-diol has been investigated too. On the basis of the results reported, a reaction scheme for the hydrogenation of 2-butyne-1,4-diol is proposed. The influence of proton, nature of solvent and carbon support on activity and products distribution has been studied in the hydrogenation of cis-2-butene-1,4-diol. The use of water as solvent shows a better activity and selectivity to butane-1,4-diol and suppresses the hydrogenolysis reaction more than other solvents used. Addition of proton leads to a major formation of hydrogenolysis and isomerisation products. A higher activity and selectivity to isomerisation products were obtained on the palladium catalysts supported on acid modified carbon. (C) 2002 Elsevier Science B.V. All rights reserved.