Oxygen vacancy (VO) engineering can efficiently improve the catalytic activity of metal oxides. This work developed a solvent-free mechanochemical method to tailor VO levels on the surface of commercial MnO2 under ambient conditions. After a typical ball milling treatment at 350 rpm for 20 min, the obtained VO-rich MnO2 activated peroxymonosulfate (PMS) to completely degrade tetrabromobisphenol (TBBPA) with a pseudo-first-order rate constant of 0.21 min−1, being 22 times larger than that for non-milled MnO2. 18O-labeling tests confirmed that singlet oxygen was generated from both PMS and lattice oxygen of MnO2 as dominant active species for the TBBPA degradation. It was clarified that the catalytic activity of MnO2 depends on not only VO levels, but also the local environment of VO, i.e., VO-associated cations. The Mn4+/Mn3+ redox couple is more important than Mn3+/Mn2+, and VO improves the oxygen mobility in/on MnO2 and Mn4+/Mn3+ redox reactions for the activation of PMS. 

Mechanochemically Tailoring Oxygen Vacancies of MnO2 for Efficient Degradation of Tetrabromobisphenol A With Peroxymonosulfate

https://hal.archives-ouvertes.fr/hal-02923398/document

Biofuel purification: Coupling experimental and theoretical investigations for efficient separation of phenol from aromatics by zeolites

Adsorption and desorption characteristics of hydrophobic hierarchical zeolites for the removal of volatile organic compounds

Light-driven thermocatalysis has emerged as an attractive approach for catalytic oxidation of volatile organic compounds (VOCs). Herein, we have synthesized Pt-mTiO2/USY nanocomposites for the catalytic degradation of toluene under full solar spectrum. The mTiO2/USY with increasing Pt content show increased activity, among which 0.9Pt-mTiO2 exhibits toluene conversion of 86.6% and CO2 yield of 74.5% at 243 °C with a light intensity of 490 mW/cm2 under 5 vol.% water vapor. The high catalytic performance of Pt-mTiO2/USY can be attributed to the large surface area, strong light absorption, highly efficient conversion of light-to-heat, abundant oxygen vacancies, uniform Pt distribution, and Ti3+ species on the catalyst surface. The introduction of Pt nanoparticles (NPs) in mTiO2/USY enhances light absorption and improves the mobility of surface lattice oxygen. The combination of EPR, O2-TPD, and in situ DRIFTS analysis reveals that light irradiation further stimulates more active lattice oxygen to participate in the toluene oxidation. 

Construction of Pt-mTiO2/USY multifunctional catalyst enriched with oxygen vacancies for the enhanced light-driven photothermocatalytic degradation of toluene

To overcome the main challenge of low photocatalytic efficiency and high energy consumption of thermocatalysis in the oxidation of volatile organic compounds (VOCs), MOF-derived mesoporous disk-like y Pd/ x N-TiO 2 ( x = 3.2, 5.5, 7.7 wt%, and y = 0.26 wt%) were prepared by ball milling-calcination method for photothermal catalytic oxidation of ethyl acetate. Morphological and pore structure characterization indicated that Pd/N-TiO 2 had abundant pore structure and large specific surface area, which facilitated the adsorption of pollutants on the active sites. Among the catalysts, 0.26 Pd/3.2N-TiO 2 exhibited optimal photothermal catalytic performance. The corresponding temperature required for 50 and 90% conversion of ethyl acetate was 192 and 212 o C, with the specific reaction rate of 0.95 µmol/(g Pd s) at 150 o C. Doping of N and loading of Pd nanoparticles enhanced the light absorption capacity, promoted the charge separation, and the adsorption capacity of ethyl acetate, resulting in a high photothermal catalytic oxidation activity. The detection of free radicals indicated that the photothermal synergy was associated with the generation of reactive oxygen species over 0.26 Pd/3.2N-TiO 2 under light irradiation condition, which directly participated in the catalytic removal of ethyl acetate. A proper increase in temperature could also promote the migration of carriers. The photothermal catalytic oxidation of VOCs over MOF-derivatives had great potential application for environmental protection. • MOF-derived mesoporous disk-like Pd/N-TiO 2 is prepared by a simple ball milling-calcination method. • The Pd/N-TiO 2 catalyst shows better photo-thermo catalytic performance for ethyl acetate oxidation. • The Pd/N-TiO 2 catalyst exhibits the excellent adsorption capacity of ethyl acetate and optical property. • OOH species due to the introduction of water improves the photo-thermal performance. • Photo-thermal synergy is due to more reactive oxygen species generation under light conditions. 

Photothermal synergistic catalytic oxidation of ethyl acetate over MOFs-derived mesoporous N-TiO2 supported Pd catalysts

Adsorptive removal of toluene and dichloromethane from humid exhaust on MFI, BEA and FAU zeolites: An experimental and theoretical study

Facile homogeneous precipitation method to prepare MnO2 with high performance in catalytic oxidation of ethyl acetate

Interaction between Noble Metals (Pt, Pd, Rh, IR, Ag) and Defect-Enriched Tio2 and its Application in Toluene and Propene Catalytic Oxidation

A simple strategy to tune α-MnO2 and enhance VOC oxidation via precipitation rate control

The control of ethyl acetate emissions from fermentation and extraction processes in the pharmaceutical industry is of great importance to the environment. We have developed three Mn2O3 catalysts by using different Mn precursors (MnCl2, Mn(CH3COO)2, MnSO4), named as Mn2O3-Cl, -Ac, -SO4. The tested catalytic activity results showed a sequence with Mn precursors as: Mn2O3-Cl > Mn2O3-Ac > Mn2O3-SO4. The Mn2O3-Cl catalyst reached a complete ethyl acetate conversion at 212℃ (75℃ lower than that of Mn2O3-SO4), and this high activity 100% could be maintained high at 212℃ for at least 100 hr. The characterization data about the physical properties of catalysts did not show an obvious correlation between the structure and morphology of Mn2O3 catalysts and catalytic performance, neither was the surface area the determining factor for catalytic activity in the ethyl acetate oxidation. Here we firstly found there is a close linear relationship between the catalytic activity and the amount of lattice oxygen species in the ethyl acetate oxidation, indicating that lattice oxygen species were essential for excellent catalytic activity. Through H2 temperature-programmed reduction (H2-TPR) results, we found that the lowest initial reduction temperature over the Mn2O3-Cl had stronger oxygen mobility, thus more oxygen species participated in the oxidation reaction, resulting in the highest catalytic performance. With convenient preparation, high efficiency, and stability, Mn2O3 prepared with MnCl2 will be a promising catalyst for removing ethyl acetate in practical application.

Tingting Pan

Papers

Adsorptive removal of toluene and dichloromethane from humid exhaust on MFI, BEA and FAU zeolites: An experimental and theoretical study

Facile homogeneous precipitation method to prepare MnO2 with high performance in catalytic oxidation of ethyl acetate

Interaction between Noble Metals (Pt, Pd, Rh, IR, Ag) and Defect-Enriched Tio2 and its Application in Toluene and Propene Catalytic Oxidation

A simple strategy to tune α-MnO2 and enhance VOC oxidation via precipitation rate control

Investigation of suitable precursors for manganese oxide catalysts in ethyl acetate oxidation