FTIR investigation of adsorption and chemical decomposition of CCl₄ by high surface-area aluminum oxide

Chlorinated hydrocarbons are among the most recalcitrant pollutants for control by sorption or catalytic destruction. High surface-area alumina holds promise as a catalytic media as well as a component of other binary catalyst systems. We have prepared an alumina catalyst using the aerogel technique that has a very high surface area of 550 m²/g. This catalyst destroys carbon tetrachloride with an efficiency >99% at 400 °C. Its reactivity toward carbon tetrachloride is remarkably higher than that of commercial alumina, which has a surface area of 155 m²/g. Carbon dioxide is the major product. Minor products include hydrogen chloride and tetrachloroethylene along with traces of phosgene. Some of the carbon tetrachloride reacts with the alumina to form aluminum chloride, which vaporizes to reveal a fresh catalytic surface. A mechanism for adsorption and destruction has been developed that involves chemisorption followed by surface to adsorbate oxygen transfer and adsorbate to surface chlorine transfer.