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International audienceThe efficiency of organometal- (Ti, Zr, Sn, Hf, and Bi) and metal oxide- (Ge and Sb) based catalysts was investigated during the transesterification step of the synthesis of poly(butylene succinate) (PBS). PBS was prepared from succinic acid and 1,4-butanediol via a two-stage melt polycondensation process. The catalytic efficiency of the organometal catalysts was as follows: Ti≫Zr∼ Sn>Hf>Sb>Bi. The germanium and antimony metal oxides displayed desirable catalytic efficiency when were associated with hydroxy acids (lactic acid or glycolic acid), which acted as chelating agents. However, this catalytic system exhibited lower efficiency compared to the titanium system. Furthermore, at high concentrations of hydroxy acids the overall transesterification rate decreased. This effect can be explained by the substitution of PBS hydroxyl end groups by a lactic or glycolic unit, both of which are less reactive during the transesterification reaction. The role of catalytic residues during the storage and processing of PBS was also studied. The reduced viscosity of the PBS samples did not vary when processing at 190 °C from 1 to 10 minutes. However, when stored under ambient conditions, all PBS samples were prone to significant hydrolytic degradation, especially those containing a titanium catalyst. This behavior indicates that zirconium- and germanium-based catalysts could be interesting substitutes for titanium-based catalysts

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Minh, Doan Pham Besson, Michele Pinel, Catherine Fuertes, Patrick Petitjean, CaroleThe effect of addition of Re to activated carbon-supported Ru and Pd catalysts in the hydrogenation of 15 wt% succinic acid aqueous solutions to 1,4-butanediol (BDO) was examined. The yield and selectivity were in the range 62-66% at 160 A degrees C and 150 bar over the Re promoted catalysts. Bio-succinic acid from a fermentation process could be efficiently hydrogenated on 4 wt%Re-2 wt%Pd/C without significant loss of selectivity