CF4 decomposition over solid ternary mixture NaF-Si-MO (MO = La2O3, CeO2, Pr6O11, Nd2O3, Y2O3)

Abstract

A solid ternary mixture consisting of NaF, silicon and one metal oxide such as La2O3, CeO2, Pr₆O₁₁, Nd2O3, and Y2O3 was prepared and used as de-fluorinated reagent for CF4 decomposition. The results show that 90% conversion of CF4 can be reached initially over NaF-Si-La2O3, NaF-Si-CeO2, NaF-Si-Nd2O3, and NaF-Si-Y2O3 at 850 °C. The fresh and used reagents were characterized using XRD and XPS techniques. It was found that the active components of NaF and metal oxides in NaF-Si-CeO2, NaF-Si-Pr₆O₁₁, NaF-Si-Nd2O3, and NaF-Si-Y2O3 were transformed into inert phases of mixed metal fluorides and silicates, respectively, resulting in an ineffective utilization of these de-fluorinated reagents, whereas no inert phases from NaF and La2O3 can be observed in the used NaF-Si-La2O3, indicating the NaF-Si-La2O3 reagent could be utilized more efficiently than the other reagents in CF4 decomposition.