The Adsorption and Reactions of Halogenated Volatile Organic Compounds (VOCs) on Metal Oxides - Final Report

Lunsford, J. H.

Texas A and M Univ., College Station, TX (United States)

关键词: Destructive Adsorption;    Chlorides;    Removal Carbon Tetrachloride;    Carbon Tetrachloride;    Carbon Dioxide;   

DOI  :  10.2172/775042
RP-ID  :  DOE/ER/14724
RP-ID  :  FG07-96ER14724
RP-ID  :  775042

美国|英语

来源: UNT Digital Library

【 摘 要 】

The purpose of this research was to provide a fundamental understanding of the adsorption and catalytic reactions of CCl{sub 4} on metal oxide surfaces with a view to developing strategies for its remediation. The scientific knowledge generated by this project should enable environmental engineers to evaluate the potential of destructive adsorption of CCl{sub 4} and the catalytic reaction of CCl{sub 4} with H{sub 2}O as an alternative for the remediation of carbon tetrachloride. Emphasis was placed on the alkaline earth metal oxides, i.e., MgO, CaO, SrO and BaO because it had previously been demonstrated that MgO and CaO reacted with CCl{sub 4} to form the corresponding metal chloride and carbon dioxide. This process was named destructive adsorption. It was found that the activity toward CCl{sub 4} parallels the basicity of the alkaline earth metal oxide, i.e., the activity decreased in the order BaO>SrO>CaO>MgO. It was found that MgO is active as a catalyst for the reaction of CCl{sub 4} with H{sub 2}O to form CO{sub 2} and HCl. The HCl could be neutralized in aqueous NaOH, and the resulting dilute salt solution could be easily disposed of. Among the alkaline earth oxides, MgO is the only active catalyst at moderate temperatures. Thus, nearly complete removal of CCl{sub 4} can be achieved over a long period. The favorable catalytic activity of MgO relative to the other alkaline earth oxides is attributed to two factors; first, MgO is not as readily converted to MgCl{sub 2}, and, second, the decomposition temperature of MgCO{sub 3} ({approximately}430 C) is substantially less than that of the other carbonates. As a consequence, chloride and carbonate phases do not substantially inhibit the catalytic activity.