Influence of alkali metal doping on selectivity behaviour of platinum catalysts for hydrogenation of 2-butyne-1,4-diol

Hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol (B2D) and butane-1,4-diol (B1D) using Pt catalysts doped with alkali metals was studied. These catalysts showed higher selectivity to the olefinic diol (B2D) compared to that with monometallic platinum catalyst. Among various alkali metals, Cs-doped catalyst showed highest selectivity (>99%) to B2D. The selectivity to B2D increased (up to 99.9%) with increase in the concentration of Cs from 0.25% to 1%. The increase in the basic strength of alkali doped catalysts measured by CO2-TPD, would be responsible for the increase in electron density of Pt hence, faster desorption and higher selectivity to the intermediate olefinic diol (B2D). The reaction parameters, such as temperature, H2 pressure and substrate concentration have strong influence on the catalyst activity but almost no effect on the selectivity to B2D.