In situ X-ray absorption spectroscopic studies of CCl4 mineralization with CuO

Mineralization of CCl4 with CuO has been studied by in situ X-ray absorption spectroscopy (XAS) in the present work. The least-square fitted X-ray absorption near-edge structural (XANES) spectra showed that 18.9-20.1% of CuCl2 was yielded in the mineralization of CCl4 with CuO at 513-603 K for 20 min. By in situ extended X-ray absorption fine structural (EXAFS) spectroscopy, the structural perturbation of CuO during mineralization was observed. The perturbation may be due to an insertion of Cl species into the matrix of CuO and formation of CuCl2. Bond distances of CuO (first shell) and Cu(O)Cu (2nd shell) were increased by 0.01-0.04 Å with slight decreases of their coordination numbers (CNs) in the mineralization process. CuCl2 in the CCl4-mineralized product solids possessed CuCl bond distances of 2.10-2.12 Å, which were greater than that of the CuCl2 model compound (2.05 Å). The in situ XAS technique exemplifies a direct observation of perturbation of CuO by Cl species during the mineralization at elevated temperatures.