Acetone Efficient Degradation under Simulated Humid Conditions by Mn–O–Pt Interaction Taming-Triggered Water Dissociation Intensification

Achieving no or low polychlorinated byproduct selectivity is essential for the chlorinated volatile organic compounds (CVOCs) degradation, and the positive roles of water vapor may contribute to this goal. Herein, the oxidation behaviors of chlorobenzene over typical Mn-based catalysts (MnO 2 and acid-modified MnO 2 ) under dry and humid conditions were fully explored. The results showed that the presence of water vapor significantly facilitates the deep mineralization of chlorobenzene and restrains the formation of Cl 2 and dichlorobenzene. This remarkable water vapor-promoting effect was conferred by the MnO 2 substrate, which could suitably synergize with the postconstructed acidic sites, leading to good activity, stability, and desirable product distribution of acid-modified MnO 2 catalysts under humid conditions. A series of experiments including isotope-traced (D 2 O and H 2 18 O) CB-TPO provided complete insights into the direct involvement of water molecules in chlorobenzene oxidation reaction and attributed the root cause of the water vaporpromoting effect to the proton-rich environment and highly reactive water-source oxygen species rather than to the commonly assumed cleaning effect or hydrogen proton transfer processes (generation of active OOH). This work demonstrates the application potential of Mn-based catalysts in CVOCs elimination under practical application conditions (containing water vapor) and provides the guidance for the development of superior industrial catalysts.

Section: Resultsmentioning

confidence: 99%

Efficient Catalytic Elimination of Chlorobenzene Based on the Water Vapor-Promoting Effect within Mn-Based Catalysts: Activity Enhancement and Polychlorinated Byproduct Inhibition

Lv,

Wu,

Shao

et al. 2024

“…Typically, some simple aromatic VOCs (benzene, toluene, and xylene) and oxygenated VOCs (esters and ketones) have been treated widely by researchers as model air pollutants because they are common byproducts of many chemical processes using petroleum and organic solvents. − Significant efforts have been made to design efficient catalysts for VOC oxidation, mainly including supported noble metal catalysts and transition metal oxides. Precious metal catalysts are widely applied commercially owing to their excellent activity in spite of their high cost. , In contrast, among the noble-metal-free catalysts, Mn-based catalysts show the advantages of low cost, environmental friendliness, and comparatively high activity; thus, the performance and structure–activity relationship of Mn-based catalysts for the oxidation of various VOCs have been extensively investigated. − It is widely confirmed that the Mn oxide-based catalysts outperform common noble metal catalysts in completely degrading oxygen-containing VOCs such as ethyl acetate and acetone − (50–100 °C lower T 100 for Mn-based catalysts than those for Pt- and Pd-based catalysts), while for aromatic VOCs, the oxidation activity of precious metal catalysts is significantly superior to that of Mn-based catalysts . Therefore, a distinct difference in suitability exists for Mn-based catalysts and noble metal catalysts between aromatic VOCs and oxygen-containing VOCs.…”

Section: Introductionmentioning

confidence: 99%

In-Depth Understanding of the Oxidative Compatibility of Volatile Organic Compounds with Mn₂O₃ and Pt-Loaded Catalysts

Pan,

Bai,

Zhang

et al. 2024

Designing suitable catalysts for efficiently degrading volatile organic compounds (VOCs) is a great challenge due to the distinct variety and nature of VOCs. Herein, the suitability of different typical VOCs (toluene and acetone) over Pt-based catalysts and Mn2O3 was investigated carefully. The activity of Mn2O3 was inferior to Pt-loaded catalysts in toluene oxidation but showed superior ability for destroying acetone, while Pt loading could boost the catalytic activity of Mn2O3 for both acetone and toluene. This suitability could be determined by the physicochemical properties of the catalysts and the structure of the VOC since toluene destruction activity is highly reliant on Pt0 in the metallic state and linearly correlated with the amount of surface reactive oxygen species (Oads), while the crucial factor that affects acetone oxidation is the mobility of lattice oxygen (Olat). The Pt/Mn2O3 catalyst shows highly active Pt-O-Mn interfacial sites, favoring the generation of Oads and promoting Mn–Olat mobility, leading to its excellent performance. Therefore, the design of abundant active sites is an effective means of developing highly adaptive catalysts for the oxidation of different VOCs.

“…Pt-based materials were active in total catalytic oxidation of CO and HCs. − Generally, the microchemical state, the coordinated environment and particle size of active surface species, the support properties, and the strength of metal–support interaction affected greatly the catalytic activity and/or selectivity of catalysts. − Among these critical parameters, the surface hydroxyl species were crucial for achieving high performance toward the oxidation reaction, especially in CO oxidation, because those groups can impact dramatically the electronic structure and dispersion of precious metals and also act as adsorption sites or the key active intermediates. − Hence, the careful fabrication of highly active hydroxy-related species over Pt-based catalysts was critical for obtaining a high oxidation reactivity. The methods to regulate types and amounts of surface OH groups mainly involved cofeedwater, (hydro)thermal treatment, adding alkaline metal, acidic treatment, H 2 O 2 treatment, etc .…”

Section: Introductionmentioning

confidence: 99%

Facilely Fabricated Single-Site Pt^δ+–O(OH)_x– Species Associated with Alkali on Zirconia Exhibiting Superior Catalytic Oxidation Reactivity

Chen,

Li,

Tan

et al. 2024

Fabrication of robust isolated atom catalysts has been a research hotspot in the environment catalysis field for the removal of various contaminants, but there are still challenges in improving the reactivity and stability. Herein, through facile doping alkali metals in Pt catalyst on zirconia (Pt−Na/ZrO 2 ), the atomically dispersed Pt δ+ − O(OH) x − associated with alkali metal via oxygen bridge was successfully fabricated. This novel catalyst presented remarkably higher CO and hydrocarbon (HCs: C 3 H 8 , C 7 H 8 , C 3 H 6 , and CH 4 ) oxidation activity than its counterpart (Pt/ZrO 2 ). Systematically direct and solid evidence from experiments and density functional theory calculations demonstrated that the fabricated electron-rich Pt δ+ −O(OH) x − related to Na species rather than the original Pt δ+ −O(OH) x −, serving as the catalytically active species, can readily react with CO adsorbed on Pt δ+ to produce CO 2 with significantly decreasing energy barrier in the rate-determining step from 1.97 to 0.93 eV. Additionally, owing to the strongly adsorbed and activated water by Na species, those fabricated single-site Pt δ+ −O(OH) x − linked by Na species could be easily regenerated during the oxidation reaction, thus considerably boosting its oxidation reactivity and durability. Such facile construction of the alkali ion-linked active hydroxyl group was also realized by Li and K modification which could guide to the design of efficient catalysts for the removal of CO and HCs from industrial exhaust.