Selective Hydrogenation Of Maleic Anhydride To Succinic Acid And γ-butyrolactone

Maleic anhydride (MAH) is a very important organic chemical, which is mainly synthesized by oxidation of benzene or n-butane or n-butene from C4fractions. Succinic acid and y-butyrolactone as downstream products from hydrogenation of maleic anhydride have a wide application for synthesizing fine chemicals. Selective hydrogenation of maleic anhydride to succinic acid and y-butyrolactone with different catalytic systems were systematically researched in this thesis.Nano-palladium/active carbon (2%Pd/AC) catalyst prepared by colloidal method was employed for hydrogenation of maleic anhydride to succinic acid in aqueous media by one-pot method. Effects of reaction temperature, reaction pressure, the amount of maleic anhydride and the dosage of catalyst were investigated and the stability of Pd/AC catalyst was tested in the optimized reaction conditions. Moreover, the microstructures of fresh and used catalysts were characterized by using XRD and TEM, respectively. Results showed that under the optimized reaction conditions of353K,1.0MPa, m(MAH)=1.96g, V(H2O)=20mL and m(2%Pd/AC):m(MAH)=1:100, the conversion of maleic anhydride was up to100%and the selectivity of succinic acid was as high as99.8%in177minutes. Although partial aggregation of Pd nanoparticles of the used catalysts was observed, it still exhibited high catalytic activity and selectivity after it was reused for ten times.Quenched skeletal nickel catalyst (QS-Ni) was used for liquid phase hydrogenation of maleic anhydride to y-butyrolactone. Under the optimized reaction conditions of453K,3.0MPa, m(MAH)=0.98g, m(QS-Ni)=0.5g and using1,4-dioxane as solvent, the conversion of maleic anhydride was up to100%and the selectivity of y-butyrolactone was79.0%in90minutes, which could be improved to89.7%with increasing reaction time to270minutes. The catalyst still exhibited good activity and selectivity after QS-Ni was recycled for6times. In addition, after QS-Ni was modified by NH4ReO4(Re-QS-Ni), the activity of hydrogenation of succinic acid to y-butyrolactone was significantly improved. Under the reaction conditions of473K,4.0MPa and n(Re):n(Ni)=0.15:1, the yeild of y-butyrolactone was up to89.1%in90minutes.