The Study Of Pervaporation Membrane Reactor For The Hydrolysis Reaction Of Oxime

Hydroxylamine hydrochloride (NH2OH·HC1) is an important chemical product. The current production techniques of NH2OH·HC1have some disadvantages, such as very complex process, high cost and so on. Therefore, it is necessary to improve the current techniques or develope novel techniques to satisfy the increasing technological and market demands. In this work, pervaporation membrane reactor (PVMR) for the hydrolysis reaction of oxime was developed to produce NH2OH·HC1. In the PVMR, the chemical equilibrium of the hydrolysis reaction would be broken and the conversion would increase obviously because the by-production of ketone was removed continuously by pervaporation.Based on the principles of the selection of membrane materials, PDMS was selected for the removal of ketone by pervaporation (PV). Firstly, PDMS/PTFE homo-polymer composite membrane was prepared, and the PV performance of ketone/water was investigated with cyclohexanone/water system. Effects of the content of cross-linking agent, the structure of PTFE support layer were studied. The conditions that M(TEOS/PDMS)=0.20and3#PTFE microporous membrane was used as the support layer were established. To further improve the PV behaviors of the membrane, hydrophobic zeolite filled composite membrane was prepared, however, experimental data showed that the separation factor decreased with the content of zeolite. In addition, the effects of feed temperature and concentration on PV were also studied. Finally, the homo-polymer composite membrane was selected for the study on PVMR.Prior to the study on PVMR, the pro-acid behavior of the membrane, the PV behaviors of dilute propanone, butanone and cyclohexanone solutions, and the permeation priority of the compounds in the hydrolysis reaction of oxime were investigated. Then, butanone oxime and cyclohexanone oxime was preliminarily determined as reaction agent to study the PVMR. Experimental results showed that the conversions of the hydrolysis reactions of the two agents increased obviously due to the couple of PV, but the conversion of cyclohexanone oxime was lower than butanone oxime. Therefore, the latter study on PVMR was based on the hydrolysis reactions of butanone oxime. The effects of temperature and mole ratio of HC1to oxime were investigated used as butanone oxime. The results showed that temperature was a more significant parameter than the mole ratio. At the temperature of50℃and the mole ratio of2:1, the conversion and NH2OH·HC1concentration rose to62.6%and36.86g·L-1after about11hr, respectively, which was2.7times the conversion at equilibrium state(23.2%).According to the reaction kinetics and PV separation kinetics, a PVMR kinetics model was developed. Validation of the model showed that the model value well agreed with the experimental data. Based on the model, the effects of temperature, membrane area and membrane thickness on PVMR were investigated. The simulation results showed higher temperature, larger membrane area, thinner membrane were the effective measures to improve the PVMR. At the temperature of70℃and the mole ratio of2:1, using150.72cm2and10μm PDMS composite membrane, the conversion rose to95%from26.2%, the conversion at equilibrium state after only1.2hr.