Kinetics of hydrogenation of dimethyl 1,4-cyclohexanedicarboxylate to 1,4-cyclohexanedimethanol

The kinetics of dimethyl 1,4-cyclohexanedicarboxylate (DMCD) hydrogenation, via the half-hydrogenated product methyl 4-(hydroxymethyl) cyclohexanecarboxylate (MHMCC), to 1,4-cyclohexanedimethanol (CHDM) in gas phase was established over CuMnAl catalyst. The intrinsic kinetic experiments were carried out on a fixed-bed reactor under a wide range of reaction conditions with temperature varied from 493 to 523 K, pressure varied from 4 to 6 MPa, and weight hourly space velocity of DMCD varied from 0.948 to 3.792 h⁻¹. Eight rival possible two-site LHHW models were proposed to simulate the experimental results. The model involving dissociative adsorption of esters and surface reaction as the rate-determining step was found to fit the experimental data best. The rather large activation energy values (138.4 and 121.4 kJ·mol⁻¹) of two reactions (DMCD to MHMCC and MHMCC to CHDM) suggest that the reactions are both temperature sensitive. The coefficients of determination (R²) for DMCD conversion and CHDM selectivity were 0.989 and 0.983 respectively. Statistical and thermodynamic test further verified the reliability of the results.