HALOGENATED HYDROCARBONS. PART 2. DECOMPOSITION OF SELECTED CHLORINATED HYDROCARBONS OVER HOPCALITE CATALYST
Abstract : A study was made of the decomposition of several chlorocarbons in air when exposed to Hopcalite catalyst in a laboratory reactor from 50 to 350 C. The chlorocarbons studied were methyl chloroform, vinylidene chloride, trichloroethylene and tetrachloroethylene. At 300 C the percentage decomposition ranged from 70% for tetrachloroethylene to 100% for methyl chloroform. All yielded substantial amounts of hydrochloric acid as they decomposed. Yields of organic compounds during the decomposition of the chlorocarbons were quite small, except in the case of methyl chloroform, which yielded as much as 50% of vinylidene chloride.
In this paper the state of hollow cathode life time modelling at the University of Southampton will be reported. Two models have been developed: one for BaO depletion from the hollow cathode insert and another for low work function compounds deposition and desorption. The model developed to predict BaO depletion from hollow cathode insert will be presented together with some comparison between experimental and numerical data to prove its validity. A model for low work function compounds deposition and desorption will also be presented. This model will be used to simulate the NSTAR cathode showing a very conservative estimate of the cathode life due to conservative character of the hypotheses made in the model development and due to the chosen criteria for the end of life.