*3.1.4. Hydrogenation of benzoic acid with 5%Pd-2%Re/C bimetallic catalyst*

The activity of bimetallic 5%Pd-2%Re/C catalyst was higher than that for monometallic 5% Pd/C and 5% Re/C catalysts in terms of benzoic acid conversion (98.5%). But the selectivity to benzyl alcohol, cyclohexane carboxylic acid, or cyclohexyl methanol was low as compared to the other catalysts such as 5% Re/C and 5% Pd/C. This is because hydrogenation of benzoic acid with 5%Pd-2%Re/C catalyst gives benzyl alcohol which undergoes hydrogenolysis. The reaction is thus both consecutive and parallel, which gives a series of products such as CCA, cyclohexyl methanol (CHM), toluene (TOL), and methyl cyclohexane (MCH).

**Scheme 2.** Reaction scheme for hydrogenation of benzoic acid using 5%Ru/C catalyst.

**Scheme 3.** Reaction scheme for hydrogenation of benzoic acid with 5% Re/C catalyst.

The selectivity for hydrogenation of BZA with 5%Pd-2%Re/C to CCA, CHM, TOL, and MCH is 19, 47, 3.3, and 30.6%, respectively (at 6 h). Such a difference in activity and selectivity for monometallic and bimetallic catalyst only confirms that Pd and Re form a synergistic combination [11].
