Selective hydrogenation of 3,4‐dimethoxybenzophenone in liquid phase over Pd/C catalyst in a slurry reactor

Selective hydrogenation of benzophenone to benzhydrol is industrially relevant. In the current work, selective hydrogenation of 3,4‐dimethoxybenzophenone (3,4‐DMBP) to 3,4‐dimethoxybenzhydrol (3,4‐DMBH) was investigated over 5 % w/w Pd/C and 5 % w/w Pt/C as catalysts in a slurry reactor. The effects of hydrogen partial pressure (0.2–1 MPa), catalyst loading (2.0 × 10−4to 8.0 × 10−4 g/cm3), initial concentration of 3,4‐dimethoxybenzophenone (5.0 × 10−6to 1.5 × 10−4 mol/cm3) and temperature (40–70 °C) on rate of reaction and selectivity were studied. Effect of solvent such as methanol, ethanol, 2‐propanol and tetrahydrofuran (THF) was also investigated. 5 % w/w Pd/C was the better catalyst with THF as the best solvent, which gave 100 % conversion and 80 % selectivity in 1 h for 0.5 MPa hydrogen pressure at 60 °C. The Langmuir‐Hinshelwood‐Hougen‐Watson model was fitted. The intrinsic kinetics and mechanism of hydrogenation were established.