Microcalorimetry Analysis: Analysis Of The Characterizations Of Znfe2o4)

Regarding the TPR results: ZnFe2O4 did not show any sign of α-oxygen related to surface, which is looser than β or γ-oxygen related to the deeper oxygen of crystal structure. However, reducibility of lattice oxygen depends on the crystal size of the metal oxides; the smaller particles results shortening the distance for oxygen migration from the bulk to the surface. In summary, the characterizations of ZnFe2O4 reveal that the preparation protocol allowed ZnFe2O4 to have a smaller particle size and larger specific surface area leads to increasing of oxygen mobility.
3.2. Microcalorimetry analysis
3.2.1. Water adsorption
As it is known, the cation as a Lewis acid (host) contributes to the stabilization of an anion as a Lewis base (base) resulting
Afterwards, its concentration gradually decreases in the next half of the reaction. It seems, phenol is the intermediate of photocatalytic oxidation of benzene, which it consumed by active species to generate CO2 and / or H2. Furthermore, Figure 6b illustrated CO2 and H2 production on Fe2O3 versus time of irradiation, which demonstrates, consuming of benzene in the photocatalytic process; however, Fe2O3 is less active than the spinel counterpart. In addition, phenol generation over Fe2O3 was investigated diligently;Moreover, on Fe2O3, phenol production detected as the intermediate of the oxidation. It is noteworthy that carbon monoxide concentration was as equal as its concentration in the air, therefore, we assume that the CO was not produced by photooxidation reaction and the concentration was constant all over the
The bands at 1018, 1482, 1700 and 3033 cm-1 correspond to bending of the C-H aliphatic group, C=C bond of aromatic, the stretching of CO2 and the stretching of C-H bond of the aliphatic group. The stretching of hydroxyl groups due to adsorption of water on the surface appeared as a broadband at 3200-3500 cm-1, as well as, the narrow band at 3750 cm-1 attributed to stretching of OH groups that formed by dissociative chemisorption of phenol. The specific band of benzene at 1482 cm-1 is recognizable in Figure S6a, the intensity of this band is decreasing within the reaction and disappeared at the end of the reaction. In this context, a decrease in this peak is in convergence with the raising of new bands correspond to phenol and carbon dioxide. A dramatic rise in CO2 intensity detected due to oxidation of benzene and phenol for 30 minutes, and then it increased slightly. DRIFT data support the results obtained by GC; both showed production of phenol and CO2 as the intermediate and product of the benzene photooxidation, respectively. With respect to the absence of carbon monoxide peaks in both DRIFT and GC as well as the production of phenol, we introduce the mechanism of the reaction in the following