Microstructure-performance study of cerium-doped TiO2 prepared by using pressurized fluids in photocatalytic mitigation of N2O
Abstract
Parent TiO2 and cerium-doped TiO2 photocatalysts with various Ce molar loadings (Ce0.05Ti0.95O2, Ce0.30Ti0.70O2) were prepared unconventionally using the sol-gel process controlled within the reverse micelles and the processing by pressurized hot fluids as an alternative to standard calcination. Purity, textural, micro/structural and optical properties of prepared photocatalysts were characterized by organic elementary analysis, nitrogen physisorption, powder X-ray diffraction, and DRS UV-Vis spectroscopy.
The activity of developed cerium-doped TiO2 catalysts was investigated in the photocatalytic decomposition of N2O for the first time. It was revealed that photocatalysts processed by pressurized hot fluids show significantly improved textural properties and different crystallinity compared to their calcined analogues.
Ce loading as well as the processing procedure had a key effect on the crystallization of CexTi1-xO2 materials. The maximum N2O conversion (77 % after 20 h of illumination) in inert gas was reached over the Ce0.05Ti0.95O2 photocatalyst and it can be attributed to the simultaneous N2O photocatalytic decomposition and N2O photolysis.
Reaction kinetics of N2O photocatalytic decomposition was described well by the pseudo-first-rate law. The lower photocatalytic activity of the Ce0.30Ti0.70O2 photocatalyst compared to the Ce0.05Ti0.95O2 photocatalyst can be correlated with two factors; the lower disorder within anatase crystal structure and possible presence of some cerium-containing amorphous phase (e.g., CeO2 or CeTi2O6), which can partially block the surface active sites within the anatase crystal structure.