Study On Synthesis Of Pyrrolidine Derivatives

In this thesis, a series of solid acid catalyst for the amination of tetrahydrofuran to pyrrolidine were prepared by hydrothermal synthesis and impregnation. Their catalysis on the reaction was investigated on a fixed-bed reactor and the experimental results revealed that H-ZSM-5(80) showed good catalytic performances. The parameters which influence the reaction with H-ZSM-5(80) as catalyst were studied and the optimum conditions were obtained, which the reaction temperature is 350℃, the molar ratio of ammonia to tetrahydrofuran is 6:1 and the contact time is 6.9 s under atmospheric pressure. Under the optimized reaction conditions the conversion of tetrahydrofuran reached up to 82.9% with pyrrolidine selectivity of 75.2%. In addition the lifetime of catalyst was also investigated and it was found the catalyst can be effective at least for 600h under the optimized reaction conditions. During this period the conversion of tetrahydrofuran maintained higher 80% and the selectivity of pyrrolidine was above 65%. The possible reasons for the deterioration of performances of the catalyst were discussed after characterization of the catalyst by X-ray diffraction, N₂-adsorption and NH₃-TPD. Comparison of the characterization results of used sample of the catalyst with that of the fresh one revealed that the structure of the catalyst was maintained after the catalytic run. The deterioration of the catalyst is attributed to the carbon deposition on the surface of catalyst, which blocked up the smaller holes and covered the acid centers in the matrix of the catalyst. The performances of the catalyst can be recovered by oxidation on line.The catalyst was also applied to the synthesis of N-methyl-pyrrolidine from tetrahydrofuran and methylamine and excellent results were received. The optimized parameters, which are that the reaction temperature is 350℃, the molar ratio of methylamine to tetrahydrofuran is 3:1 and the contact time was 6.3 s under atmospheric pressure. Under the optimized conditions the conversion of tetrahydrofuran is 94.4% with a selectivity of 97.6% of of N-methyl-pyrrolidine.A series transition metal doped ZSM-5s were prepared for the synthesis of 2, 6-lutidine through catalytic amination of acetone and methanol on a fixed-bed reactor. One catalyst Pb_6%-Fe_0.5%-Co_0.5%-ZSM-5(200) with good performances on the reaction was obtained. The effects of reaction temperature, molar ratio of ammonia to methanol, composition of raw materials and residence time on the catalytic performances of the catalyst were studied. The conversion of acetone and the yield of 2, 6-lutidine reached 67.6% and 40.3%, respectively, when the reaction was run at 450 oC under atmospheric pressure, meanwhile, the molar ratios of ammonia to acetone and methanol were kept 2:2:1, the volume content of water was 40% and the residence time was 5.5 s at the time that the catalyst was on stream for 20h. With the time extension, the performances of the catalyst got deterioration gradually and the yield of 2, 6-lutidine dropped to 23% at the time of the catalyst being on stream for 42 h. The performances of the catalyst could be recovered largely by air oxidation on line. The possible reasons for the deterioration of performances of the catalyst were discussed after characterization of the catalyst by X-ray diffraction, N₂-adsorption and pyridine adsorption infrared spectroscopy.