Complete Removal of Chloro-Based Volatile Organic Compounds by Thermally Activated Oxide Semiconductors

抄録

Chloro-based volatile organic compounds (VOCs) are known to exert noxious effects on the environment, and their destruction by catalytic combustion, for example, accompanies a production of hydrochloric acid (HCl) that damages the catalyst. We have been interested in complete removal of VOCs by our system based on thermally activated oxide semiconductors (i.e., catalysts) such as Cr₂O₃, TiO₂, NiO, α-Fe₂O₃. In the present investigation, we have fundamentally studied the decomposition process of dichloromethane (CH₂Cl₂: DCM) and trichloroethylene (CHCCl₃; TCE) on the basis of the mass- and Raman spectra in an attempt to identify the formation temperature of HCl. Then, we found that the decomposition of DCM and TCE starts at about 100 and 200°C, respectively; whereas HCl is abruptly formed at a critical temperature of about 350°C in both compounds. Based on this result, we have optimized the operation temperature below 300°C for Cr₂O₃-impregnated honeycomb systems and achieved the complete removal of DCM and TCE that accompanies no formation of HCl.