Continuous hydrogenation of 2-butyne-1,4-diol to 2-butene- and butane-1,4-diols

Continuous catalytic hydrogenation of 2-butyne-1,4-diol (B<SUB>3</SUB>D) was carried out in a fixed-bed reactor over 1% Pt/CaCO<SUB>3 </SUB>catalyst to give 2-butene-1,4-diol (B<SUB>2</SUB>D) and butane-1,4-diol (B<SUB>1</SUB>D) without formation of any other side products. In case of continuous hydrogenation, higher selectivity (66%) to B<SUB>2</SUB>D could be obtained and the selectivity pattern was completely different from that found in case of batch slurry operation in which B<SUB>1</SUB>D selectivity was very much higher (83%) than the B<SUB>2</SUB>D selectivity (17%). Another interesting feature was that by varying the contact time, the selectivity to both B<SUB>2</SUB>D as well as B<SUB>1</SUB>D could be varied over a wide range which is an attractive option to obtain the desired products mix of B<SUB>1</SUB>D and B<SUB>2</SUB>D, depending on the fluctuation in the market demand. Further, a mathematical model for reactor performance was also developed on the basis of the kinetic data obtained previously in a batch slurry reactor. The predicted values of conversion, selectivity, and rate of hydrogenation were found to agree with the experimental data over a wide range of conditions