Chlorine removal from polyvinyl chloride (PVC) with the addition of catalysts, such as solid acid catalysts, and adsorbents, such as alkali and metal oxide, including a multiple one, was described using superheated steam and nitrogen as pyrolysis media in this research. The effect of the dechlorination temperature indicated that the treatment temperature was an important factor to control the carbonization and dechlorination ratio of PVC. The addition of a single metal oxide, such as TiO 2 , MgO, and CoO, showed better dechlorination ability compared to β-zeolite and NaOH. CoO had a higher dechlorination ability than TiO 2 and MgO. The metal-oxide-supported adsorbent of ZnO/CoO, MgO/CoO, and NiO/CoO systems was prepared by the impregnation method to increase decomposition and chlorine capture ability of the adsorbent during dechlorination. The ZnO/CoO adsorbent achieved the highest dechlorination ratio and especially increased the dechlorination ratio of PVC at ZnO ≥ 25 wt % under a superheated steam atmosphere compared to CoO alone. CoCl 2 •2H 2 O was observed in the X-ray diffraction pattern of 25ZnO/CoO and 50ZnO/CoO adsorbents after PVC dechlorination. The PVC dechlorination in a nitrogen atmosphere had the same results as superheated steam with no additive and CoO adsorbent at 473 K. However, the addition of 25ZnO/CoO adsorbent at 473 K had a lower dechlorination ability than superheated steam. It is supposed to result from the formation of CoCl 2 •2H 2 O in a superheated steam atmosphere. To obtain a similar dechlorination ratio and solid production yield to no additive, 25ZnO/CoO and 50ZnO/CoO adsorbents were able to decrease the pyrolysis temperature from 523 to 473 K.

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Sugarcane bagasse is one of the biomass wastes which have a high thermal value (HHV) when dried and can be converted into energy by physical, biological or thermochemical process. Carbonization behavior of sugarcane bagasse and heat transfer properties were studied with superheated steam and nitrogen gas. In the carbonization experiment, char yield, HHV and carbon losing rate of superheated steam showed the same trend as that of nitrogen heating at the treatment temperature between 491 and 702 K. It means that no special oxidation occurs in superheated steam carbonization and the pyrolysis by superheated steam was the same as nitrogen gas. In the heat transfer properties, temporal change in the sample temperature attained a good agreement between calculation and experiment for superheated steam and nitrogen gas. The sample temperature in superheated steam atmosphere reached the set carbonization temperature faster than that in the nitrogen atmosphere due to the superior heat transfer property of radiation in addition to heat convection. As described above, superheated steam carbonizes the sugarcane bagasse with no additional oxidation as well as nitrogen pyrolysis and has better heat transfer property than nitrogen heating, which leads to conclusion that superheated steam is one of the useful carbonization tools of biomass.