Chlorinated Phosphonium Catalyst And Its Catalytic Performance In Dehydrochlorination Of 1,1,2-trichloroethane Toward Vinylidene Chloride

Vinylidene chloride(VDC)is an important monomer of the synthesis of polyvinylidene chloride,which is widely used in the fields of packaging and dyes.In present,VDC is synthesized by dehydrochlorination of 1,1,2-trichloroethane(TCE)in liquid phase via the alkaline hydrolysis in industry,the method will create great quantities of brine wastewater.In this paper,the chlorinated quaternary phosphonium salts ionic liquid(IL)is introduced into the reaction system of dehydrochlorination of 1,1,2-TCE to VDC,and its catalytic performance in this reaction system are investigated.Thus,the problem of waste water can be solved,the HCl produced also can be used effectively,so as to achieve the whole process of green and cleaning.The principal achievements have been obtained in this thesis as follow.Firstly,the tetrabutylphosphonium chloride(TBPC)ionic liquid was chosen as the catalyst for this reaction in gas-liquid phase.The results showed that the catalytic activity reduced rapidly.After analyzing the used catalyst,the accumulation and polymerization of VDC may be the main reason of deactivation.The catalytic performance of the TBPC ionic liquid supported by the silicon dioxide,active carbon and silica aerosol was investigated.The results show that the activity and stability of the catalyst was improved with the silica as the carrier.The average yield of VDC can be increased from 45% to 73%.Meanwhile,the 1,1,2-TCE conversion reduced only 15% after 48 hours.The performance of the supported catalyst with different active component was investigated.It was found that high reaction stability can be achieved through tetraphenylphosphine chloride(TPPC).It was found that high reaction stability can be achieved through TPPC.By optimizing the reaction condition,we found that using silica as the support,when the loadage of TPPC was 6 wt.%,high yield of VDC of 84% could be achieved at 260?.Meanwhile,the VDC selectivity of 90% was still remained in the long stability experiment up to 2,500 hours.Combined with ESI-MS,TG and NMR,the deactivation mechanism of the catalyst is proved to be the slow decomposition of active components in the long period operation.For the first time,the catalytic performance of dehydrochlorination of 1,1,2-TCE over IL was investigated in this thesis.The lifetime of the catalyst up to 2,500 hours was achieved by optimizing the reaction condition.The catalytic and deactivation mechanism of IL catalyst was investigated.We have creatively adopted chlorine ion as Alkali Center,which had a determining role in the catalytic reaction,the result will provide theoretical and experimental foundations for exploring a more effective catalyst with potential industrial application prospect for the catalyze dehydrochlorination of Chlorinated paraffin.