Mineralization of CCl₄ with Copper Oxide

Abstract

Experimentally, CCl4 was effectively mineralized by CuO to yield stable inorganic species of CO2 and CuCl2 (CCl4 + 2CuO --> 2CuCl2 + CO2). High CCl4 conversions (63-83%) were found in the mineralization process performed at 513-603 K for 10-30 min. Using X-ray-absorption near edge structure (XANES) and X-ray photoelectron spectroscopies, we found that most CuCl2 was encapsulated in the CCl4-mineralized product solid (mineralization at 513 K for 30 min). At higher mineralization temperatures (563-603 K), CuCl2 was found to be predominant on the surfaces of the mineralization product. Speciation of copper in the mineralization product solid was also studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. Bond distances of Cu-O and Cu-Cl in the CCl4-mineralized product solid were 1.93-1.94 and 2.10-2.12 , respectively, which were greater than those of normal CuO and CuCl2 by 0.03-0.07 A. The increase of the bond distances for Cu-O and Cu-Cl might be due to Cl insertion and concomitant structural perturbation of unreacted CuO in the mineralization process. Forthe second shell around copper atom, bond distances of Cu-(O)-Cu also increased by 0.03-0.05 A, and the coordination numbers of Cu-O and Cu-(O)-Cu decreased, as expected, in the mineralization process. In addition, stoichiometrically excess oxygen atoms were found on the solid surfaces, and they might play an important role in the mineralization of CCl4, leading to the formation of CO2 and Cl. Chloride atoms might be further captured by CuO, yielding CuCl2 in the mineralization process. This work exemplifies the utilization of X-ray spectroscopies (XANES, EXAFS, and XPS) to reveal the speciation and possible reaction pathway in a very complex mineralization process in detail.

Intermediates in the Destruction of Chlorinated C1 Hydrocarbons on La‐Based Materials: Mechanistic Implications

“…[8][9][10][11] Alkaline-earth metal oxides and lanthanide oxides convert CHCs into Ocontaining products, for example CO 2 . [12][13][14][15][16][17][18][19][20][21][22][23][24][25] This process, known as destructive adsorption, involves exchange of the Cl atoms of the CHC with the lattice O atoms of the metal oxide. As a result, the metal oxide is partially or completely converted into the corresponding metal chloride.…”

Destructive Adsorption of CCl4 over Lanthanum-Based Solids: Linking Activity to Acid−Base Properties

“…[9][10][11][12][13][14][15][16] In this reaction, the solid material is chlorinated, while the chlorinated hydrocarbons are oxidized to, e.g., CO 2 . In a continuing effort, Van der Avert et al recently combined the destructive adsorption reaction with a steam dechlorination reaction resulting in a catalytic reaction cycle, which can be envisaged as follows: [17][18][19] The main advantage of this approach is that a continuous process can be constructed, and many materials were tested for their activity in the catalytic destruction of CCl 4 in the presence of steam.…”

Photocatalytic degradation of trace CHCl3 in drinking water by nano TiO2

“…By XANES and EXAFS, it was found that copper oxide clusters were very effective in catalysis in mesopores (MCM-41), micropores (e.g., ZSM-5 and ZSM-48), and TiO2based photocatalysts [18][19][20]. These molecular-scale data turn out to be very useful in revealing nature of catalytic active species and reaction paths involved.…”