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IR study of chlorination of alumina employing mixtures of gaseous chlorine and carbon monoxide


  • Dedicated to Professor Dr.-Ing. Hanns Hofmann on the occasion of his 65th birthday


The chlorination of an alumina with BET surface area of 100 m2/g has been studied in situ by transmission IR measurements at about 670 K. The chlorinating gases consisting of Cl2 and CO were employed individually and in equimolar proportion. The IR results do not reveal the presence of a phosgene surface species which could support the only mechanism proposed so far to explain the chlorination. A detailed alternative reaction mechanism is suggested for the high temperature chlorination reaction, taking into account the IR results, together with the known electron donor-acceptor properties of the activated alumina and the reaction gases: Cl2 molecules accept electrons from oxide ions with a lower coordination number on the alumina surface, leading to the formation of Cland Oad. While Cl yields AlCl3, Oad reacts further with CO producing CO2.

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