Study On Catalytic System In Catalyzing Carbonylation Of Ethylene Oxide

Compared to the Polyethylene Terephthalate(PET), Polytrimethylene Terephthalate(PTT) has many advantages, such as light resistance, water absorption, high stability. It has been widely used in fibers and plastics because of it has resilienceand stress/recovery properties and easy degradation which can reduce environmental pollution.1,3-PDO has attracted considerable industrial interest as a component for polyester(PPT). However,1,3-PDO limiting their development in the field of application due to the difficulty synthesis progress. The synthesis of1,3-propanediol by the ethylene oxide is generally recognized as a promising route due to the abundant source of ethylene oxide (EO). Ethylene oxide has a broad application in the markets and high value in the next production, ethylene oxide project continue to be launched in the domestic. At the same time can be expected for the project, launched in the domestic ethylene oxide, it can be expected that the prices of ethylene oxide will be a large gap compared to now. The use of ethylene oxide to prepared high-value downstream products such as1,3-propanediol has a strong practical significance.In this work, the synthesis of methyl3-hydroxypropanoate (MHP) which can be further hydrogenation to get1,3-propanediol by hydroesterification of EO over carbonyl cobalt catalyst system was investigated. Using a relatively simple process successfully prepared carbonyl cobalt catalyst. Based on the product which were analysised by the GC-MS, combination of the catalytic mechanism in the carbonylation reactions of the olefin, and to propose the possible reaction mechanism in the carbonylation of the EO, The shared ion pairs is based on the Lewis-acid complexes and carbonyl cobalt is importanted in the reaction mechanism. Accorded to the reaction mechanism, the effects of different ligands such as phosphine ligands, phosphite, phase transfer catalyst, Nitrogen-donor ligands were investigated. The results revealed that imidazole was a good ligand could provide the highest ethylene oxide conversion rate and the MHP selectivity is also high, the most important point compared to other ligands it can reduce the consumption of ligands, which is economical for the industry.Choosed the best catalytic system to optimize the reaction condition, the optimal reaction conditions were catalyst/ligand molar ratiol:1.5, reaction temperature75℃, CO pressure6.0MPa, methanol/(ethylene oxide) volume ratio5:1, n(catalyst):n(EO)=1:100, n(catalyst)/n(ligand)=1:1.5, reaction time4hours. The conversion of ethylene oxide was92.24%, the selectivity and yield for methyl3-hydroxypropanoate were91.45%and84.35%, respectively.