Oxidation Of Volatile Organic Compounds Research Articles

Selective Recovery of Manganese from Spent Ternary Lithium-ion Batteries for Efficient Catalytic Oxidation of VOCs: Unveiling the Mechanism of Activity Enhancement in Recycled Catalysts.

With the widespread application of ternary lithium-ion batteries (TLBs) in various fields, the disposal of spent TLBs has become a globally recognized issue. This study proposes a novel method for reutilizing metal resources from TLBs. Through selective oxidation, manganese in a leaching solution of TLBs was converted into MnO2 with α, γ, and δ crystal phases (referred to as T-MnO2) for catalytic oxidation of volatile organic compounds (VOCs), while efficiently separating manganese from high-value metals such as nickel, cobalt, and lithium, achieving a manganese recovery rate of 99.99%. Compared to similar MnO2 prepared from pure materials, T-MnO2 exhibited superior degradation performance for toluene and chlorobenzene, with T90 decreasing by around 30°C. The acidic synthesis environment provided by the leaching solution and the doping of trace metals altered the physicochemical properties of T-MnO2, such as increased specific surface area, elevated surface manganese valence, and improved redox performance and oxygen vacancy properties, enhancing its catalytic oxidation capacity. Furthermore, the degradation pathway of toluene on T-γ-MnO2 was inferred using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) and in-situ DRIFT. This study provides a novel approach for recycling spent TLBs and treating VOCs catalytically.

Highly efficient Cu(II) coordination polymer catalyst for the conversion of hazardous volatile organic compounds

Three novel coordination polymers (CPs), namely [Cu(μ-1κO,2κN-L)2]n (1), [Zn (μ-1κO,2κN-L)2(H2O)2]n (2) and [Cd (μ-1κOO’,2κN-L)2]n (3) [where HL = 4-(pyrimidin-5-ylcarbamoyl)benzoic acid], were synthesized and characterized by elemental analysis, ATR-IR, TGA, XPS and single-crystal X-ray diffraction. Despite having the same organic ligand, the various metal cations had an impact in the subsequent frameworks. Hirshfeld surface analysis was performed to investigate the intermolecular interactions and to examine the stability of the crystal structures of the three polymers. Their catalytic performances were screened for the peroxidative oxidation of Volatile Organic Compounds (VOCs), with toluene and p-xylene selected as model substrates. Tert-butyl hydroperoxide (t-BuOOH or TBHP) (aq. 70 %) was employed as the oxidant. The catalytic oxidation of toluene yielded benzyl alcohol, benzaldehyde and benzoic acid. The copper CP 1 exhibited the highest total yield for toluene oxidation, reaching approximately 36% in an aqueous medium. For p-xylene oxidation, tolualdehyde, methylbenzyl alcohol, and toluic acid were produced as the primary products, accompanied by minor ones. The experiments were conducted under diverse conditions, manipulating key parameters such as the choice of solvent (water or acetonitrile), type of oxidant (t-BuOOH or H2O2), the concentration of the oxidant and reaction temperature. In the presence of catalyst 1, a maximum total yield of ca. 80% was achieved for p-xylene oxidation.

Enhancing Oxygen Activation Ability by Composite Interface Construction over a 2D Co3O4-Based Monolithic Catalyst for Toluene Oxidation.

Developing robust metal-based monolithic catalysts with efficient oxygen activation capacity is crucial for thermal catalytic treatment of volatile organic compound (VOC) pollution. Two-dimensional (2D) metal oxides are alternative thermal catalysts, but their traditional loading strategies on carriers still face challenges in practical applications. Herein, we propose a novel in situ molten salt-loading strategy that synchronously enables the construction of 2D Co3O4 and its growth on Fe foam for the first time to yield a unique monolithic catalyst named Co3O4/Fe-S. Compared to the Co3O4 nanocube-loaded Fe foam, Co3O4/Fe-S exhibits a significantly improved catalytic performance with a temperature reduction of 44 °C at 90% toluene conversion. Aberration-corrected scanning transmission electron microscopy and theoretical calculation suggest that Co3O4/Fe-S possesses abundant 2D Co3O4/Fe3O4 composite interfaces, which promote the construction of active sites (oxygen vacancy and Co3+) to boost oxygen activation and toluene chemisorption, thereby accelerating the transformation of reaction intermediates through Langmuir-Hinshelwood (L-H) and Mars-van Krevelen (MvK) mechanisms. Moreover, the growth mechanism reveals that 2D Co3O4/Fe3O4 composite interfaces are generated in situ in molten salt, inducing the growth of 2D Co3O4 onto the surface lattice of 2D Fe3O4. This study provides new insights into enhancing oxygen activation and opens an unprecedented avenue in preparing efficient monolithic catalysts for VOC oxidation.

A sprinkler- water cycle PEC-MFC system with bimetallic monatomic Co-Fe/g-C3N4/ACF cathode achieves efficient removal of gas trimethylamine

Volatile organic compounds (VOCs) air pollutants are the precursors of ozone and PM2.5, all harmful to human health. To reduce the equipment volume further and improve the treatment capacity at room temperature, a novel microbial fuel cell (MFC) system, with a sprinkler and water recycle module, was designed to integrate bio-electricity generation from biodegradation and photocatalytic oxidation of VOCs over cathodic diatomic Co-Fe/g-C3N4 doped activated carbon felt (Co-Fe/g-C3N4/ACF). The removal of trimethylamine in both the gas and liquid phase was proved (VOCs concentration in air ≈ 0.93 g m−3, the removal capacity reached ≥ 119.97 mg gcat-1h−1). Through the sprinkler-water cycle, the trimethylamine molecules in air transferred and diffused to the liquid phase, then acted as the only carbon source for the electrogenic bacteria, that supplied the electricity to drive photoelectric catalysis under light illumination. The high efficiency (>2086 mg gcat-1h−1) and low energy consumption in the new system at room temperature means broad application prospect in VOCs treatment.

Insights into the formation of secondary organic aerosols from agricultural residue burning emissions: A review of chamber-based studies.

Organic aerosols (OA) are a significant component of fine particulate matter in the ambient air and are formed through primary and secondary processes. Primary organic aerosols (POA) are directly released from sources, while secondary organic aerosols (SOA) are formed through the oligomerization and/or oxidation of volatile organic compounds (VOCs) in the atmosphere. Recently, there has an increasing attention on the SOA budgets, their formation pathways, and photochemical evolution due to their impacts on climate and human health. Biomass burning (BB) is a significant source of OA, contributing around 5-30 % to the SOA burden globally. Agricultural residue burning (ARB) is a type of BB that contributes ~10 % of total atmospheric OA mass worldwide, whereas it contributes higher in Asian regions like China and India. ARB emits a significant amount of air pollutants, including VOCs, into the atmosphere. However, there is inadequate information on the transformation of ARB emissions to SOA due to limited laboratory studies. The present review focuses on the formation mechanism of SOA from ARB emissions, summarizing the current state of the art about ARB precursors and their oxidation products from chamber-based studies, including measurement methods and analytical instrumentation. The review also discusses the role of different types of oxidants in OA mass enhancement, factors affecting the overall SOA yield, and the uncertainties involved in the process.

MAX-DOAS observations of ship emissions in the North Sea

Shipping emissions were measured in Dunkirk, France. Elevated aerosol extinction coefficients (AEC), nitrogen dioxide (NO2) and sulphur dioxide (SO2) were observed up to 500 m from surface. Formaldehyde (HCHO) did not show an increase every time, which suggests that oxidation of emitted volatile organic compounds (VOCs) took longer than the transport to the observation path and dilution of direct emissions had occurred. Background NO2, HCHO, and SO2 levels were higher when the wind came over land or the surrounding industrial area, indicating that land-based sources contribute significantly; however, clear spikes in NO2 and SO2 were observed whenever ship plumes were sampled. Observations show that the ship emission contribution to pollution is significant, but land-based sources still dominate. The SO2/NO2 ratio was low throughout the campaign, although varying according to the ship type, confirming that the new fuel content regulations are being followed by most ships in this region.

Ozone Formation Sensitivity to Precursors and Lightning in the Tropical Troposphere Based on Airborne Observations

AbstractTropospheric ozone (O3) is an important greenhouse gas that is also hazardous to human health. The formation of O3 is sensitive to the levels of its precursors NOx (≡NO + NO2) and peroxy radicals, for example, generated by the oxidation of volatile organic compounds (VOCs). A better understanding of this sensitivity will show how changes in the levels of these trace gases could affect O3 levels today and in the future, and thus air quality and climate. In this study, we investigate O3 sensitivity in the tropical troposphere based on in situ observations of NO, HO2 and O3 from four research aircraft campaigns between 2015 and 2023. These are OMO (Oxidation Mechanism Observations), ATom (Atmospheric Tomography Mission), CAFE Africa (Chemistry of the Atmosphere Field Experiment in Africa) and CAFE Brazil, in combination with simulations using the EMAC atmospheric chemistry—climate model. We use the metric α(CH3O2) together with NO to investigate the O3 formation sensitivity. We show that O3 formation is generally NOx‐sensitive in the lower and middle tropical troposphere and is in a transition regime in the upper troposphere. By distinguishing observations impacted by lightning or not we show that NO from lightning is the most important driver of O3 sensitivity in the tropics. NOx‐sensitive chemistry predominates in regions without lightning impact, with α(CH3O2) ranging between 0.56 and 0.82 and observed average O3 levels between 35 and 55 ppbv. Areas affected by lightning exhibit strongly VOC‐sensitive O3 chemistry with α(CH3O2) of about 1 and average O3 levels between 55 and 80 ppbv.

Analytical model for the mitigation of VOC vapor with horizontal permeable reactive barrier in the contaminated site considering non-uniform source

Volatile organic compounds (VOCs) contamination at the groundwater may cause vapor intrusion and pose significant threats to human health. As a novel low-carbon mitigation technology, a horizontal permeable reactive barrier (HPRB) is proposed to remove the VOC vapor in the vadose zone and mitigate the vapor intrusion risk. To estimate the performance of HPRB in the contaminated site with a non-uniform source, a transient two-dimensional analytical model is developed in this study to simulate the VOC vapor migration and oxidation processes in the layered soil. The analytical model is verified against the experimental results and numerical simulation first and the parameter study is then conducted. The HPRB has good performance for the contaminated sites involving factors including deep source and local soil with low effective diffusivity. To consider the vertical heterogeneity of the local soil, the traditional equivalent homogeneity method has limitations in considering the horizontal migration of VOC vapor and is not suitable for the two-dimensional model. On the contrary, the artificial layered method based on the proposed analytical model has better accuracy and is recommended to be adopted in practice. Leading to the exponential decrease in the VOC vapor concentration at the ground surface, increasing the thickness of HPRB is an effective measure to enhance the performance of HPRB. The fitting exponential function can be applied to determine the minimum design value of the thickness of HPRB in practice.

Kinetic Study and Catalytic Activity of Cr3+ Catalyst Supported on Calcium Silicate Hydrates for VOC Oxidation.

Volatile organic compounds (VOCs) are pollutants that pose significant health and environmental risks, necessitating effective mitigation strategies. Catalytic oxidation emerges as a viable method for converting VOCs into non-toxic end products. This study focuses on synthesizing a catalyst based on calcium silicate hydrates with chromium ions in the CaO-SiO2-Cr(NO3)3-H2O system under hydrothermal conditions and evaluating its thermal stability and catalytic performance. A catalyst with varying concentrations of chromium ions (10, 25, 50, 100 mg/g Cr3+) was synthesized in unstirred suspensions under saturated steam pressure at a temperature of 220 °C. Isothermal curing durations were 8 h, 16 h, and 48 h. Results of X-ray diffraction and atomic absorption spectroscopy showed that hydrothermal synthesis is effective for incorporating up to 100 mg/g Cr3+ into calcium silicate hydrates. The catalyst with Cr3+ ions (50 mg/g) remained stable up to 550 °C, beyond which chromatite was formed. Catalytic oxidation experiments with propanol and propyl acetate revealed that the Cr3+ catalyst supported on calcium silicate hydrates enhances oxygen exchange during the heterogeneous oxidation process. Kinetic calculations indicated that the synthesized catalyst is active, with an activation energy lower than 65 kJ/mol. This study highlights the potential of Cr3+-intercalated calcium silicate hydrates as efficient catalysts for VOC oxidation.

Surface oxygen vacancies induced by cu-doping in hexagonal ZnMn2O4 nanoplates for high efficiency photothermocatalytic oxidation of toluene

The exploitation of efficient and stable photothermal catalyst for the deep mineralization of volatile organic compounds (VOCs) is crucial and challenging. Herein, a photothermal catalyst with abundant oxygen defects was prepared for the first time via Cu-doped ZnMn2O4 hexagonal nanoplate. Experimental characterization results reveal that Cu doping enhances not only the ZnMn2O4 defect contents but also the light absorption and thermal conversion ability of ZnMn2O4. Compared to the undoped ZnMn2O4 (ZMO), the ZnMn2O4 with optimal Cu doping amount (ZMO-4Cu) exhibits excellent photothermal catalytic performance (94% toluene conversion and 87% toluene mineralization) and good resistance to low concentration SO2 under full-spectrum light irradiation. Experimental characterizations and theoretical calculations jointly demonstrated that the oxygen vacancies of ZMO-4Cu surface are more conducive to the adsorption of O2, effectively reduce the oxygen dissociation energy of ZMO-4Cu, thus generating abundant active oxygen species and improving the photothermal catalytic activity for toluene oxidation. In situ IR experiments disclosed that photothermal catalysis is more conducive to the toluene deep oxidation than thermal catalysis. This work provides new insights for the design of high efficiency photothermal catalysis for the deep oxidation of VOCs.

Refining catalytic oxidation of volatile organic compounds over Gd-Sr-Co perovskite-based oxides fabricated via viscous mixture induction: Unveiling the crucial factors influencing catalytic activity

A series of Gd-Sr-Co perovskite-based oxides have been successfully synthesized by thermally driving viscous mixture, wherein only very trace amounts of water need and the metal salts powders do not need to be thoroughly mixed. By the characterization of XRD, XPS, EPR, and Raman, the levels of oxygen vacancies, lattice oxygen, and adsorbed oxygen in the catalyst are controlled by varying the amount of Sr doping. Unlike traditional conclusions, we found that the catalytic activities of the catalysts did not enhance with the increase in the contents of adsorbed oxygen and oxygen vacancies. H2-TPR and O2-TPD confirmed that the migration of lattice oxygen in catalysts determined their activities. Comparative activity of individual catalysts was evaluated by catalytic oxidation of toluene. The best active catalyst also showed superior catalytic activity for the oxidation of acetone, ethyl acetate, and chlorobenzene. The effects of humidity and weight hourly space velocity on the stability of the catalyst were also evaluated. Catalyst’s surface structural changes in toluene oxidation were also analyzed by in-situ DRIFTS. This study provides a simple approach to tailor perovskite-based oxide structures, crucial for effective catalytic oxidation of VOCs.

Low-Temperature Catalytic Oxidation of Volatile Organic Compounds (VOCs) using Transition Metal Mixed Oxide Catalysts

This paper discusses the modification of MnOx by doping various metals, such as Cu, supported on cordierite honeycomb ceramics, which were easily synthesized by using the impregnation method. The physicochemical properties were comprehensively featured via the BET, XRD, SEM-EDX and H2-TPR techniques. Activity results suggested that the introduction of doping metals significantly enhanced the catalytic performance of Cu1Mn2Ox compared to single metal oxides. Furthermore, in the catalytic oxidation of benzene and toluene, the monolithic Cu1Mn2Ox catalyst demonstrates the best catalytic performance. It was able to completely oxidize the two compounds at 275oC with a reaction velocity (WHSV) of about 18,000 mL/(g•hr) and pollutant concentrations of 7000 ppm and 12000 ppm, respectively. The formation of a Cu-Mn solid solution with spinel Cooper-Manganese structure was thought to be the cause of the excellent catalytic performance of monolithic Cu1Mn2Ox. This resulted in an increase in the amount of adsorbed oxygen species on the surface and a high lattice oxygen mobility. This can improve catalyst reducibility and oxygen species activity, as demonstrated by significantly higher dehydrogenation temperatures of Cu-Mn composite oxides through H2-TPR. Meanwhile, the monolithic Cu1Mn2Ox catalyst showed good stability in 16 hours of testing and cycle ability test and showed great potential in practical application.

Synergistic doping and de-doping of Co3O4 catalyst for effortless formaldehyde oxidation

The pursuit of high-performance non-precious metal catalysts for Volatile Organic Compounds (VOCs) abatement is paramount in meeting stringent environmental regulations. In this study, we present a groundbreaking approach by crafting a highly defective Co3O4 catalyst through a strategic process involving Mg doping and subsequent partial de-doping. The catalyst exhibited an exceptional activity in the oxidation of formaldehyde (HCHO), achieving a remarkable conversion rate of 2.92 μmol·m−2·h−1, which is 3.1 times that of the pristine Co3O4 at 100 °C and an HCHO space velocity of 75,000 mL·g−1·h−1. Our methodology involves a dual-action process of doping and de-doping, orchestrating the introduction of significant structural and surface defects. These include surface cracks, lattice distortions, cationic vacancies, oxygen vacancies, lower metal coordination, and more. This orchestrated creation of defects serves to amplify the generation of active oxygen sites, thereby enhancing the intrinsic oxidative ability of the catalyst. The net result is a lowered activation energy barrier for HCHO, further contributing to the catalyst performance enhancement. This study not only establishes a new benchmark for Co3O4 catalysis but also provides insightful paradigms for the role of defects engineering in promoting non-noble metal-catalyzed volatile organic compounds oxidation.

Supported nano-sized precious metal catalysts for oxidation of catalytic volatile organic compounds.

Volatile organic compounds (VOCs) are common contaminants found as indoor as well as outdoor pollutants, which can induce acute or chronic health hazards to the human physiological system. The catalytic oxidation method is widely considered as one of the effective methods for removing VOCs, and the development of highly effective catalysts is highly urgent for booming this interesting field. This review focuses on the recent progress of VOC oxidation catalyzed by supported nano-sized precious metal catalysts, and discusses the effects of metal composition, supports, size, and morphology on the catalytic activity. In addition, the roles played by both nano-sized precious metals and supports in enhancing the performance of catalytic VOCs are also systematically discussed, which will guide the further development of more advanced VOC catalysts.

Performance and Reaction Mechanisms of Catalytic Combustion of Toluene and Ethyl Acetate Over Fe‐Mn Oxides

AbstractIn this paper, Fe−Mn oxide catalysts were prepared by the co‐precipitation method. (Fe2O3)‐(Mn3O4)‐3 : 1 showed the best catalytic activity in the degradation of toluene and ethyl acetate, with the removal rate reaching 90 % at 166 °C and 156 °C respectively. The XRD, SEM, TEM, and XPS characterizations revealed that the interaction between Fe and Mn and the higher surface adsorption of oxygen in the (Fe2O3)‐(Mn3O4)‐3 : 1 catalyst may be the main factors promoting the catalytic oxidation. (Fe2O3)‐(Mn3O4)‐3 : 1 exhibited a better removal rate in ethyl acetate than toluene at different space velocities, concentrations and water contents. Under the same conditions, the degradation rate of (Fe2O3)‐(Mn3O4)‐3 : 1 in ethyl acetate was also greater than that in xylene and butyl acetate, which was related to their oxidation processes. FT‐IR and GC‐MS characterizations of fresh and used (Fe2O3)‐(Mn3O4)‐3 : 1 catalysts revealed intermediates in the oxidation of volatile organic compounds, and the reaction mechanisms were analyzed: Firstly, VOCs molecules were adsorbed on the catalyst surface, then decomposed into organic intermediates and oxidized to CO2 and H2O finally.

Amorphous Ce-Ti composite as an efficient bifunctional catalyst for deep oxidation of volatile organic compounds and selective catalytic reduction of NO

In this work, a series of Ce-Ti composite oxides with different Ti/Ce molar ratios was prepared by co-precipitation method, and investigated for the catalytic degradation of toluene and selective catalytic reduction of NO. The phase transition process between Ce species and Ti species is limited by modulating the interaction between Ce4+ and Ti4+, while a completely amorphous composite is generated with an appropriate molar ratio of Ti/Ce (1.5/1). The catalyst CeTi1.5Ox exhibits the best catalytic performance, where the values of T90 and T50 for deep degradation of toluene are 297 and 330 °C respectively at high weight hours space velocity (WHSV=120000 mL/(g⋅h)). Compared with CeO2, T90 and T50 decrease by 48 and 34 °C respectively while declining by 67 and 70 °C compared to TiO2. For the SCR reaction, CeTi1.5Ox reaches 100% NO conversion at 250 °C with WHSV=60000 mL/(g⋅h), reduced by 50 °C compared to pure CeO2. The amorphous nanostructure with highly dispersed Ce and Ti species was confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) characterizations. The X-ray photoelectron spectroscopy (XPS) and Raman analyses show that a large number of active Ce-O-Ti species and surface oxygen vacancies are generated due to the strong interaction between Ti4+ and Ce4+ in CeTi1.5Ox. Additionally, H2-TPR and O2-TPD further confirm that the interaction promotes the low-temperature reducibility and mobility of surface-active oxygen species. Meanwhile, in-situ DRIFTS study reveals that CeTi1.5Ox with amorphous nanostructure can dramatically enhance the dissociative and complete oxidation capacity for toluene.

Development of a multiphase chemical mechanism to improve secondary organic aerosol formation in CAABA/MECCA (version 4.7.0)

Abstract. During the last few decades, the impact of multiphase chemistry on secondary organic aerosols (SOAs) has been demonstrated to be the key to explaining laboratory experiments and field measurements. However, global atmospheric models still show large biases when simulating atmospheric observations of organic aerosols (OAs). Major reasons for the model errors are the use of simplified chemistry schemes of the gas-phase oxidation of vapours and the parameterization of heterogeneous surface reactions. The photochemical oxidation of anthropogenic and biogenic volatile organic compounds (VOCs) leads to products that either produce new SOA or are taken up by existing aqueous media like cloud droplets and deliquescent aerosols. After partitioning, aqueous-phase processing results in polyols, organosulfates, and other products with a high molar mass and oxygen content. In this work, we introduce the formation of new low-volatility organic compounds (LVOCs) to the multiphase chemistry box model CAABA/MECCA. Most notable are the additions of the SOA precursors, limonene and n-alkanes (5 to 8 C atoms), and a semi-explicit chemical mechanism for the formation of LVOCs from isoprene oxidation in the gas and aqueous phases. Moreover, Henry's law solubility constants and their temperature dependences are estimated for the partitioning of organic molecules to the aqueous phase. Box model simulations indicate that the new chemical scheme predicts the enhanced formation of LVOCs, which are known for being precursor species to SOAs. As expected, the model predicts that LVOCs are positively correlated to temperature but negatively correlated to NOx levels. However, the aqueous-phase processing of isoprene epoxydiols (IEPOX) displays a more complex dependence on these two key variables. Semi-quantitative comparison with observations from the SOAS campaign suggests that the model may overestimate methylbutane-1,2,3,4-tetrol (MeBuTETROL) from IEPOX. Further application of the mechanism in the modelling of two chamber experiments, one in which limonene is consumed by ozone and one in which isoprene is consumed by NO3 shows a sufficient agreement with experimental results within model limitations. The extensions in CAABA/MECCA are transferred to the 3D atmospheric model MESSy for a comprehensive evaluation of the impact of aqueous- and/or aerosol-phase chemistry on SOA at a global scale in a follow-up study.

Transpacific Transport of Asian Peroxyacetyl Nitrate (PAN) Observed from Satellite: Implications for Ozone.

Peroxyacetyl nitrate (PAN) is produced in the atmosphere by photochemical oxidation of non-methane volatile organic compounds in the presence of nitrogen oxides (NOx), and it can be transported over long distances at cold temperatures before decomposing thermally to release NOx in the remote troposphere. It is both a tracer and a precursor for transpacific ozone pollution transported from East Asia to North America. Here, we directly demonstrate this transport with PAN satellite observations from the infrared atmospheric sounding interferometer (IASI). We reprocess the IASI PAN retrievals by replacing the constant prior vertical profile with vertical shape factors from the GEOS-Chem model that capture the contrasting shapes observed from aircraft over South Korea (KORUS-AQ) and the North Pacific (ATom). The reprocessed IASI PAN observations show maximum transpacific transport of East Asian pollution in spring, with events over the Northeast Pacific offshore from the Western US associated in GEOS-Chem with elevated ozone in the lower free troposphere. However, these events increase surface ozone in the US by less than 1 ppbv because the East Asian pollution mainly remains offshore as it circulates the Pacific High.

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

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.

Efficient Catalytic Elimination of Toxic Volatile Organic Compounds via Advanced Oxidation Process Wet Scrubbing with Bifunctional Cobalt Sulfide/Activated Carbon Catalysts.

Advanced oxidation process (AOP) wet scrubber is a powerful and clean technology for organic pollutant treatment but still presents great challenges in removing the highly toxic and hydrophobic volatile organic compounds (VOCs). Herein, we elaborately designed a bifunctional cobalt sulfide (CoS2)/activated carbon (AC) catalyst to activate peroxymonosulfate (PMS) for efficient toxic VOC removal in an AOP wet scrubber. By combining the excellent VOC adsorption capacity of AC with the highly efficient PMS activation activity of CoS2, CoS2/AC can rapidly capture VOCs from the gas phase to proceed with the SO4•- and HO• radical-induced oxidation reaction. More than 90% of aromatic VOCs were removed over a wide pH range (3-11) with low Co ion leaching (0.19 mg/L). The electron-rich sulfur vacancies and low-valence Co species were the main active sites for PMS activation. SO4•- was mainly responsible for the initial oxidation of VOCs, while HO• and O2 acted in the subsequent ring-opening and mineralization processes of intermediates. No gaseous intermediates from VOC oxidation were detected, and the highly toxic liquid intermediates like benzene were also greatly decreased, thus effectively reducing the health toxicity associated with byproduct emissions. This work provided a comprehensive understanding of the deep oxidation of VOCs via AOP wet scrubber, significantly accelerating its application in environmental remediation.