Studies On Catalytic Hydrogenation Of Dimethyl Terephthalate To Dimethyl 1,4-cyclohexanedicarboxylate

Dimethyl 1,4-cyclohexanedicarboxylate(DMCD)is an important polyester modified material and raw material for the production of 1,4-cyclohexanedimethanol(CHDM).CHDM is a commonly used material for the production of polyester.The polyester material produced with CHDM as raw materials has more excellent thermal and chemical stability,and the demand has been increasing in recent years.At present,the production process of DMCD is monopolized by foreign countries,and the domestic is in the initial stage.Therefore,it is of great significance to study the preparation process of DMCD.In this paper,dimethyl terephthalate(DMT)was used as starting materials to prepare DMCD.The effect of catalyst on DMT hydrogenation was investigated.The effects of catalyst preparation methods,carrier properties and active component loading on DMT hydrogenation were studied.The main findings are as follows:1.The group contribution method was used to estimate the ?rHm,?rGm and equilibrium constant K of the DMT hydrogenation reaction.Our results show that the reaction of DMT hydrogenation to DMCD is a strongly exothermic and reversible reaction.2.The Ru-based catalyst was prepared by precipitation-deposition method for DMT hydrogenation reaction.Our results show that the preparation conditions of the catalyst(including preparation method,support,and Ru loading)have a significant effect on the catalytic performance.When Al2O3 is used as the carrier and the specific surface area is more than 200 mn/g and the Ru loading is 3 wt%,the catalytic performance is optimal.3.The Ru/Al2O3(5 wt%loading)was used in the DMT hydrogenation reaction in a fixed-bed reactor.The effects of temperature,pressure,and the molar ratio of H2 to DMT on the reaction were investigated.The optimized reaction temperature was 150?,the reaction pressure was 5.0 MPa,the molar ratio of H2 to DMT was 50:1.In this case,the conversion rate of DMT was 94.4%,and the selectivity of DMCD was 95.7%.4.The effect of additives(Ni,W,Cu.Pt.Mg,Ba)on the performance of Ru/Al2O3 was studied.Our results show that the modification of W can significantly improve the selectivity of DMCD.Compared with Ru/Al2O3 catalyst,the optimized Ru-W/Al2O3 catalyst has higher catalytic activity and stability.