Platinum catalyzed hydrogenation of 2-butyne-1,4-diol

Hydrogenation of 2-butyne-1,4-diol (B3D) using 1% Pt/CaCO3 catalyst was carried out to give 2-butene-1,4-diol (B2D) or butane-1,4-diol (B1D) selectively or a mixture of two diols eliminating the formation of acetal, aldehyde, and alcohols as side products. In presence of ammonia, nearly complete selectivity to B2D was obtained in a batch reactor while, in a fixed bed reactor total selectivity to B1D was obtained. Effect of concentration of ammonia, metal loading and catalyst pre-treatment on catalyst activity and selectivity has been investigated in a batch reactor. The formation of B1D and B2D is explained on the basis of associative or dissociative adsorption of B3D via carbene and carbyne type intermediates which react with adsorbed hydrogen to give the corresponding products. A kinetic model based on Langmuir-Hinshelwood (L-H) type mechanism has been proposed which shows a good agreement with experimental data