On The New Production Process Of Chlorosulfonated Polyethene

At present, all chlorosulfonated polyethene (CSM) is commercially produced using carbon tetrachloride (CTC) as process agent, leading to a large amount of CTC emission to the air. As an ozone depleting substance (ODS), such application of CTC should be well controlled under the Montreal protocol. According to the national sector plan for ODS process agent application, CTC consumption as process agent will be completely phased out by 2010. However, CSM product possesses important developing foreground and favorable market. Thus study and development on the substitute solvent for CSM production is of great importance for China to fulfill the requirement of the Montreal Protocol and keep production of CSM product in the future.This dissertation focuses on the study of non-ODS solvent substitute for CSM production and process technology. Regarding solvent substitute development, the feasibility of using such solvents as water, cyclohexane, chloroform, chlorobutane, n-hexane, dichloroethane, benzene, liquid paraffin, and chlorobenzene for the production of CSM is studied experimentally. The results show that liquid paraffin, chlorobenzene or chloroform/water mixture can be used as a solvent substitute of CTC. If the mass ratio of polymer to solvent can be enhanced, leading to a lower output of byproduced chlorinated paraffin, liquid paraffin as a solvent substitute is quite promising. The production process of CSM using chlorobenzene as a solvent is advantageous for its ease operation, fast and uniform chlorination, and the quality CSM thus obtained is comparable with that using CTC solvent except the residue of somewhat unpleasant odor. If the product odor can be removed, chlorobenzene may be used as a substitute solvent of CTC.In order to remove the chloroform from its hydrochloric acid solution via adsorption process, it is of vital importance to choose an appropriate adsorbent. Toward this end, the adsorptive ability of some novel adsorbents, namely fine powders of chlorinated rubber (CR), polypropylene (PP), chlorinated polypropylene (CPP) and polyvinylchloride (PVC) for chloroform from water and 20% of hydrochloric acid at 298.15K was evaluated experimentally, and compared with that of active carbon and paraffin. The results showed that the adsorption followed the Langmuir pattern and the adsorption ability of these adsorbents followed the order active carbon>PVC> CR>PP >CPP > solid paraffin. This order is basically in line with the decrease of chlor-content of the adsorbents from PVC to paraffin, as a higher chlor-content means a higher polarity and thus a stronger interaction between chloroform and the polymer. The adsorptivity of PVC and CR is nearly equivalent to that of active carbon as indicated by their saturated adsorption being ca. 1.4g-CHC13/g-absorbent. For all adsorbents studied, their adsorption capacity decreases with the concentration increase of hydrochloric acid due to the strong interaction between chloroform and HCl in the solution. In conclusion, the commercial fine powder of PVC or CR can be used as an efficient absorbent for the removal of chloroform from its aqueous solution for its low cost and good adsorption ability.