THERMAL-DECOMPOSITION OF 1,1,1-TRICHLOROETHANE AND 1,1-DICHLOROETHENE OVER HIGH SURFACE-AREA ALUMINA

Mass spectrometry and X-ray photoelectron spectroscopy have been used to study the decomposition of 1,1,1-trichloroethane (CH3CCl3) over high surface area gamma-alumina (Al2O3) in the temperature range 300-1000 K under flow conditions. The dehydrochlorination of CH3CC13(g) occurs in the temperature range 400-600 K to form 1,1-dichloroethene(g) (CH2=CCl2(g)) and HCI(g). Above 700 K the CH2=CCl2(g) decomposes to form HCI(g), and carbon was deposited on the Al2O3 surface. No evidence for the production of chloroacetylene or other major gas phase products from CH2=CCl2 Was found, indicating that CH3CC13 dehydrochlorination to adsorbed C and HCI(g) involves a single gas phase intermediate, CH2=CCl2.