High catalytic performances of CeO2–CrOx catalysts for chlorinated VOCs elimination

Abstract

A series of porous CeO2–CrOx mixed oxides are synthesized using different precipitants (NaOH, NH4OH, (NH4)2CO3 and urea) and evaluated for deep oxidation of various chlorinated VOCs (CH2Cl2, C2HCl3, C2H4Cl2 and C6H5Cl). The results show that all these materials represent porous structures and small particle sizes (2–8nm). Part of Cr element can go into the lattice of CeO2, resulting in the formation of Ce–Cr–O mixed oxide. Compared with pure CeO2 and Cr2O3, the amount of Cr6+ species and oxygen vacancies in CeO2–CrOx mixed oxides are significantly increased, due to the strong interaction between CeO2 and CrOx. Thus, all the CeO2–CrOx mixed oxides exhibit high catalytic activity and good durability for deep oxidation of chlorinated VOCs, especially the CeO2–CrOx prepared using (NH4)2CO3 as precipitant. Moreover, only slight chlorinated byproducts are detected in the process of chlorinated VOCs oxidation, and the surface accumulation of coke and Cl species as well as the loss of Cr element is slight during the long-term reaction at 265°C, indicating that these CeO2–CrOx materials possess interesting fundamental result, deserving more research before conclusion on practical value.