In situ FTIR study of the adsorption and reaction of ortho-dichlorobenzene on Pd–Co sulfated zirconia catalysts

Low temperature catalytic combustion of 1,2-dichlorobenzene over CeO2–TiO2 mixed oxide catalysts

“…But most of them focused on three types of catalysts based on noble metals [3,6,7], transition metals [5,8,9] and zeolites [10][11][12]. The activity of noble metal catalysts was often very high, but they were susceptible to the deactivation by adsorption of HCl and Cl2 and were also sensitive to higher temperatures.…”

“…Hence, stringent environmental regulations are in place in several countries limiting PCDD/PCDF emissions [2,3]. Therefore, various control methods were designed and used [2,4], of which, catalytic oxidation is the preferred approach [3,5,6]. Its major advantage is that oxidation can be effectively performed at temperatures between 250 and 550 o C and very dilute pollutants which cannot be thermally combusted without additional fuel can be treated effectively by this way [7].…”

“…It can be seen that the fcc fluorite structure of ceria, with the diffraction peaks at 2θ values of 8. 6, 33.0, 47.5, 56.3, 59.2,, is retained nearly down to Ti/Ce+Ti ratio of 0.5, while the anatase structure of TiO2 is formed nearly at Ti/Ce+Ti ratio of 0.9. However, the intermediate compositions with Ti/Ce+Ti ratio between 0.7 and 0.5 form mixed phases [24].…”

“…Therefore, Ce1-xTixO2 catalysts with a suitable ratio of Ti/Ce+Ti, which can provide enough surface oxygen available for the oxidation, present high activity for the oxidation of B, CB and DCB and high selectivity for CO or CO2. In order to obtain deep insights into this reaction at a molecular level, a mechanism over effective Ce1-xTixO2 catalysts consisting of six elementary steps is schematized: (1) the formation of π-complex of o-DCB adsorption during the interaction of o-DCB with common Lewis acid sites (Ce 3+ /Ce 4+ and Ti 4+ ) and with Ce-OH and Ti-OH, (2) chlorine abstraction by nucleophilic oxygen (basic lattice oxide ions or hydroxyl groups) to form phenolate intermediate, (3) adsorption of the gas-phase oxygen on the surface to replenish the consumed oxygen, (4) the attack of active surface oxygen species (such as O2 -and O -adsorbed in vacancies) to aromatic ring, (5) the formation of oxygenate species, such as carbonate bidentate and partially oxidized surfacespecies such as formates, acetates, maleates, carboxylates of the acetate type;(6) further effective reaction of oxygenate species to form gas-phase reaction products (CO2, CO, H2O, HCl and Cl2)(Fig. S7).…”

Hydrocarbon adsorption and NOx-SCR on (Cs,Co)mordenite

“…Aristizabal et al [35] suggested that the weak band at 1388 cm -1 is associated with the interaction between the methyl group and Lewis acid sites. Figure 7 (B and C) shows the spectra corresponding to the adsorption of toluene on Cs 2 CoM, and a subsequent reaction with NO/He flow at different temperatures.…”