Deactivation And Regeneration Of Pd/C Catalysts For Catalytic Hydrogenation Of Meropenem

Meropenem,as a representative of carbapenem antibiotics,has many advantages such as broad antibacterial activity,low side effects,and rapid drug efficacy.The commonly used catalyst in the hydrogenation processi s 5%-10%palladium-carbon,which is important in synthesizing meropenem.In the process,the activity and selectivity of the Pd/C catalyst are dramatic reduced after hydroenation,resulting in the increase of the industrial costs.The production costs could be significantly reduced,by improve the reaction conditions or find ways to recycle the catalyst,only if the reasons of the decline in activity and selectivity be found out.Therefore,it is practical significance to research and improve Merapienan's industrial synthesis process.In this paper,the conditions for the liquid phase detection of the meropenem hydrogenation reaction were investigated.The liquid phase test conditions were finally established as follows:The mobile phase is phosphoric acid-0.1%trimethylamine:acetonitrile = 42:58 vol%,and the flow rate is 1 mL/min.The detection wavelength is 280 nm.The final laboratory test conditions were determined.The mass ratio of protected meropenem and 5%Pd/C is 4:1.The pressure of H₂ is 1.80 MPa in the hydrogenation progress,and the reaction temperature is 40 ?.The stirring speed is 500 rpm/min,and the reaction keep for 60 minutes.In this paper,ICP-AES,TG,SEM-EDS,H₂-O₂ Chemical adsorption,BET,XRD and other methods were used to characterize the deactivated catalyst under two different production processes.The main reasons for the deactivation of industrial catalysts are various.Firstly,the reactants and intermediates that coated on the surface of the catalyst and accumulated in the pores of the catalyst,which lead to a decrease of the active surface area.Secondly,a certain degree of palladium loss is another reason for deactivation of industrial catalysts.Thirdly,due to the different production processes,sulfur poisoning caused by sulfur compounds from raw materials is also one of the major causes of catalyst deactivation.Focused on above reasons of the deactivation,different methods were used to regenerate the catalyst.It was found that after regenerating by 40%methanol solution,the catalytic conversion rate was improved from 87.55%to 98.6%,and the selectivity was increased from 25.87%to 76.06%.The regenerated catalyst was charactered of by ICP,BET,H₂-O₂ Chemical adsorption,it was found that after washing by 40%methanol,the deactivation caused by coating and plugging pores can be effectively restored.The results show this regeneration method can effectively increase the specific surface area and active surface area of the catalyst.This method has the advantage of easy operation and low cost,and it is more suitable for manufacture.For the deactivated catalysts caused by S poisoning under different processes,a suitable and simple industrial regeneration method has not yet been found.In this study,the deactivated catalyst was regenerated by using 40%methanol aqueous solution.Tests were applied under the small-scale experimental conditions in the laboratory.It was found that the catalyst regenerated by 40%methanol aqueous solution with 5 wt%of fresh catalyst is more suitable for the hydrogenation reaction,moreover,catalyst still maintains better performance after repeated use four times.