Catalytic Oxidation of Chlorobenzene over Pd-TiO2 /Pd-Ce/TiO2 Catalysts

Abstract

A series of Pd-TiO2/Pd-Ce/TiO2 catalysts were prepared by an equal volume impregnation method. The effects of different Pd loadings on the catalytic activity of chlorobenzene (CB) were investigated, and the results showed that the activity of the 0.2%-0.3% Pd/TiO2 catalyst was optimal. The effect of Ce doping enhanced the catalytic activity of the 0.2% Pd-0.5% Ce/TiO2 catalyst. The characterization of the catalysts using BET, TEM, H2-TPR, and O2-TPD showed that the oxidation capacity was enhanced, and the catalytic oxidation efficiency was improved due to the addition of Ce. Ion chromatography and Gas Chromatography-Mass Spectrometer results showed that small amounts of dichlorobenzene (DCB) and trichlorobenzene (TCB) were formed during the decomposition of CB. The results also indicated that the calcination temperature greatly influenced the catalyst activity and a calcination temperature of 550 °C was the best. The concentration of CB affected its decomposition, but gas hourly space velocity had little effect. H2-TPR indicated strong metal–support interactions and increased dispersion of PdO in the presence of Ce. HRTEM data showed PdO with a characteristic spacing of 0.26 nm in both 0.2% Pd /TiO2 and 0.2% Pd-0.5% Ce/TiO2 catalysts. The average sizes of PdO nanoparticles in the 0.2% Pd/TiO2 and 0.2% Pd-0.5% Ce/TiO2 samples were 5.8 and 4.7 nm, respectively. The PdO particles were also deposited on the support and they were separated from each other in both catalysts.

The promotion effect of Sn on Cr/KIT-6 for the catalytic combustion of chlorobenzene

“…Based on T90 (temperature for the CB conversion of 90%), the catalytic performance for CB combustion decreased in the order of Sn0.15CrK (274 °C) > Sn0.2CrK (281 °C) > Sn0.1CrK (295 °C) > Sn0.05CrK (320 °C) > CrK > SnK. Sn0.15CrK exhibited the highest activity, and its T90 temperature was considerably less than those of the other catalysts reported previously, including noble metal-based catalysts 26,27 or CuCeO 4 , 28 MnCo/MCM-41, 10 and Cr/AlZr-PILC 29 catalysts, shown as Table S1 (ESI†). Considering that the SnK catalytic activity was extremely low (only 21.0% CB conversion was obtained at a reaction temperature of up to 350 °C), the synergistic interaction between Cr and Sn in SnCr/KIT-6 catalysts was confirmed to play a key role in its high activity.…”

TiO2-based catalytic systems for the treatment of airborne aromatic hydrocarbons

“…106 Based on the H 2 -TPR analysis, the doping of Pd (as Pd 2+ ) introduces new reduction peaks (corresponding to the reduction of PdO) while increasing the oxygen mobility required to accelerate the oxidation of gaseous toluene (84% over Pd-TiO 2 catalyst). 106,107 Compared with the pristine Pd-TiO 2 catalyst, the effect of high-temperature reduction (H 2 -based) pretreatment of Pt-TiO 2 has been investigated against benzene (100 ppm) oxidation in the air stream at 25-200 1C. 108 It was noted that the thermal reduction pre-treatment for Pt-TiO 2 (before thermocatalysis) should induce surface defects (e.g., oxygen vacancies) with the efficient dispersion of Pt 0 NPs over the TiO 2 surface.…”

A new process for the recovery of palladium from a spent Pd/TiO2 catalyst through a combination of mild acidic leaching and photodeposition on ZnO nanoparticles

“…[1][2][3] Metals are the best candidates to take a similar approach, being indefinitely recyclable, without any problem related to downcycling. 2,4,5 Among the recyclable materials, PGMs, and, in particular palladium, are the most interesting, 6,7 due to the great number of applications in which they are used, [7][8][9][10][11][12][13][14] such as catalytic converters, electronic devices and chemical production (see Fig. 1 for the percentage demand in different industrial applications).…”

“…1–3 Metals are the best candidates to take a similar approach, being indefinitely recyclable, without any problem related to downcycling. 2,4,5 Among the recyclable materials, PGMs, and, in particular palladium, are the most interesting, 6,7 due to the great number of applications in which they are used, 7–14 such as catalytic converters, electronic devices and chemical production (see Fig. 1 for the percentage demand in different industrial applications).…”