Oxidation Of Formaldehyde Research Articles

Mesoporous γ-Al2 O3 Supported Mn–Ce–Co Ternary Oxides for the Efficient Plasma-Catalytic Oxidation of Formaldehyde

Coupling low-temperature plasma technology with catalysts can significantly enhance air purification efficiency and mitigate the generation of secondary pollutants. In this study, mesoporous [Formula: see text]-Al2O3 supported Mn–Ce–Co ternary oxides were introduced into a widely employed tubular dielectric barrier discharges (DBD) reactor for indoor air purification. The plasma-catalytic degradation of HCHO exhibited the following degradation efficiency order: Mn–Ce–Co/[Formula: see text]-Al2O3 [Formula: see text] Mn/[Formula: see text]-Al2O3 [Formula: see text] Mn–Ce/[Formula: see text]-Al2O3 [Formula: see text] Co/[Formula: see text]-Al2O3 [Formula: see text] [Formula: see text]-Al2O3 [Formula: see text] Ce/[Formula: see text]-Al2O3 [Formula: see text] Plasma. When compared to plasma treatment alone, the catalyst resulted in a remarkable 1.8-fold enhancement under conditions of 3.0[Formula: see text]kV, [Formula: see text]C, 60% RH. Additionally, the concentrations of the by-products O3 and NO[Formula: see text] were significantly reduced by 88.2% and 93.3%, respectively. The synergistic interaction between Mn, Ce and Co oxides facilitated the formation and transportation of surface-reactive oxygen species, thereby contributing to the thorough oxidation of HCHO and organic intermediates during the plasma-catalytic process. Moreover, the high specific surface area offered by mesoporous materials enhanced the adsorption and catalytic activity towards HCHO.

Complete genome sequence of Methylomonas sp. UP202 isolated from an urban waterway sediment.

We report the complete genome sequence of Methylomonas sp. UP202 isolated from an urban waterway sediment in Singapore. The genome contains genes involved in methane, methanol, formaldehyde, and formate oxidation. It also contains genes utilizing various nitrogen sources such as nitrogen, nitrate, nitrite, urea, and ammonium.

Novel synergistically effects of palladium-iron bimetal and manganese carbonate carrier for catalytic oxidation of formaldehyde at room temperature

The elimination of formaldehyde at room temperature holds immense potential for various applications, and the incorporation of a catalyst rich in surface hydroxyl groups and oxygen significantly enhances its catalytic activity towards formaldehyde oxidation. By employing a coprecipitation method, we successfully achieved a palladium domain confined within the manganese carbonate lattice and doped with iron. This synergistic effect between highly dispersed palladium and iron greatly amplifies the concentration of surface hydroxyl groups and oxygen on the catalyst, thereby enabling complete oxidation of formaldehyde at ambient conditions. The proposed method facilitates the formation of domain-limited palladium within the MnCO3 lattice, thereby enhancing the dispersion of palladium and facilitating its partial incorporation into the MnCO3 lattice. Consequently, this approach promotes increased exposure of active sites and enhances the catalyst's capacity for oxygen activation. The co-doping of iron effectively splits the doping sites of palladium to further enhance its dispersion, while simultaneously modifying the electronic modification of the catalyst to alter formaldehyde's adsorption strength on it. Manganese carbonate exhibits superior adsorption capability for activated surface hydroxyl groups due to the presence of carbonate. In situ infrared testing revealed that dioxymethylene and formate are primary products resulting from catalytic oxidation of formaldehyde, with catalyst surface oxygen and hydroxyl groups playing a crucial role in intermediate product decomposition and oxidation. This study provides novel insights for designing palladium-based catalysts.

Substitutional C and interstitial N in MnO2/NC catalysts enable high performance of formaldehyde oxidation at room temperature

Formaldehyde (HCHO) is a harmful gas that dangers the health of human kind. Catalytic oxidation provides a green approach converting HCHO to harmless CO2. In this work, we designed MnO2 catalysts by co-doping NC for HCHO catalytic elimination. The substitutional C and interstitial N in the MnO2 activate the surface lattice oxygen and weaken the Mn-O bond strength. The more active surface lattice oxygens and the more active adsorbed dioxygen species at the oxygen vacancies result in the greater HCHO oxidation performance over the MnO2/NC catalysts doping with NC than the MnO2 catalysts without doping. The performance enhancement is dependent on the crystal phase of MnO2, HCHO is fully converted at 30 ℃ over α-MnO2/NC catalyst, followed by 35 °C over the γ-MnO2/NC catalyst. The higher performance of the α-MnO2/NC catalyst is associated with its higher BET surface area, more active surface lattice oxygen and adsorbed dioxygen species than those of the γ-MnO2/NC catalyst. This work verifies the more effective HCHO elimination performance of MnO2-based catalysts by co-doping NC, and the strategy is applicable for other related oxidative reactions.

Efficient formaldehyde sensor based on PtPd nanoparticles-loaded nafion-modified electrodes

The noble metal-based electrochemical sensor design for efficient and stable formaldehyde(FA) detection is important ongoing research. In this paper, PtPd/Nafion/GCE is prepared by electrochemical cyclic voltammetry deposition method based on electrodepositing nanostructured platinum (Pt)-palladium (Pd) nanoparticles in Nafion film-coated glassy carbon electrode (GCE). The influence of deposition parameters and chemical composition (atomic ratio of Pt and Pd) on the electrochemical behaviour of PtPd/Nafion/GCE has been investigated. PtPd/Nafion/GCE displays a remarked electrocatalytic activity for the oxidation of FA and exhibits a linear relationship in the range of 10–5000 μM, with a detection limit of 3.3 μM in 0.1 M H2SO4 solution. It is proved that the detection performance of PtPd/Nafion/GCE electrode is valuable for further application with low detection limit, wide linear range, favourable selectivity and high response.

Photo-induced thermal effect on Pt/CeO2 surface for promoting formaldehyde oxidation performance by photothermal catalysis

Formaldehyde is a carcinogenic chemical that seriously endangers the health of human body, the elimination of formaldehyde pollutant in enclosed spaces provides safety for breathing. This work studied Pt/CeO2 catalysts for photothermal formaldehyde oxidative elimination. In comparison with photocatalysis and thermocatalysis, the photothermal catalysis is a more promising technique to eliminate formaldehyde from the synergism between active oxygen species including mobile surface lattice oxygen, adsorbed oxygen and superoxide radical, and from the photo-induced thermal effect on catalyst surface when irradiating sunlight. The oxidative abilities of the active oxygen species were promoted by the thermal effect, which consequently leads to the improved formaldehyde conversion in photothermal catalysis. The mobile surface lattice oxygen, adsorbed oxygen and superoxide radical on the Pt/CeO2 catalysts were characterized by H2-TPR, O2-TPD and ESR, the light adsorptions of the catalysts were evaluated by UV–vis and the actual surface temperatures of the catalysts were measured by thermocouple. This work verifies the more powerful photothermal catalysis for formaldehyde oxidation, which could be extended to other reactions for performance enhancements.

Regulating the electronic structure of Ir single atoms by ZrO2 nanoparticles for enhanced catalytic oxidation of formaldehyde at room temperature

Developing low-loading single-atom catalysts with superior catalytic activity and selectivity in formaldehyde (HCHO) oxidation at room temperature remains challenging. Herein, ZrO2 nanoparticles coupled low-loading Ir single atoms in N-doped carbon (Ir1-N-C/ZrO2) was prepared. The optimal Ir1-N-C/ZrO2 with 0.25 wt% Ir loading delivers the high HCHO removal and conversion efficiency (>95%) at 20 °C, which is higher than that over Ir1-N-C with the same Ir loading. The specific rate can reach 1285.6 mmol gIr−1 h−1, surpassing the Ir based catalysts reported to date. Density functional theory calculation results and electron spin resonance spectra indicate that the introduction of ZrO2 nanoparticles modulate the electronic structure of the Ir single atoms, promoting O2 activation to •O2–. Moreover, the Ir-C-Zr channel is favorable for the dissociation of •O2– to active oxygen atom (*O), and further accelerates the transformation of HCHO and intermediates (dioxymethylene and formates) to CO2 and H2O. This work provides a facile strategy to design low-loading single-atom catalysts with high catalytic activity toward HCHO oxidation.

On the role of cationic defects over the surface reactivity of manganite-based perovskites for low temperature catalytic oxidation of formaldehyde

Defect engineering in catalytic materials is a versatile strategy to fine-tune their performance towards oxidation reactions, and break the related bottlenecks. Herein, a series of La1−xMnO3 perovskite-based materials was designedly synthesized to investigate the effect of cation defects on their physico-chemical properties. Based on extensive characterizations and density function theory (DFT) calculations, it is demonstrated that La-deficiency could orderly induce oxygen vacancies and electronic structure regulation on perovskite, which prominently promotes the catalytic activity towards formaldehyde oxidation. The leading material (La0.6MnO3) could retain high activity for 63 h, either under dry or humid air. In brief, this work unveils the feasibility of modulating the surface reactivity by modifying the electronic structure properties of lanthanum manganite perovskites following simple adjustment of the A-site cationic vacancies, and also highlights A-site deficient perovskite as a potentially efficient catalyst for environmental remediation.

Criegee Intermediate-Mediated Oxidation of Dimethyl Disulfide: Effect of Formic Acid and Its Atmospheric Relevance.

The oxidation-reduction reactions of disulfides are important in both chemistry and biology. Dimethyl disulfide (DMDS), the smallest reduced sulfur species with a disulfide bond, is emitted in significant quantities from natural sources and contributes to the formation of aerosols and hazardous haze. Although atmospheric removal of DMDS via the reactions with OH or NO3 radicals and photolysis is known, the reactions of DMDS with other atmospheric oxidants are yet to be explored. Herein, using quantum chemical calculations, we explored the reactions of DMDS with CH2OO (formaldehyde oxide) and other methyl-substituted Criegee intermediates. The various reaction pathways evaluated were found to have positive energy barriers. However, in the presence of formic acid, a direct oxygen-transfer pathway leading to the corresponding sulfoxide (CH3SS(O)CH3) was found to proceed through a submerged transition state below the separated reactants. Calculations for the methyl-substituted Criegee intermediates, particularly for anti-CH3CHOO, show a significant increase in the rate of the direct oxygen-transfer reaction when catalyzed by formic acid. The presence of formic acid also alters the mechanism and reduces the enthalpic barrier of a second pathway, forming thioformaldehyde and hydroperoxide without any rate enhancement. Our data indicated that, although Criegee intermediates are unlikely to be an important atmospheric sink of DMDS under normal conditions, in regions rich in DMDS and formic acid, the formic acid-catalyzed Criegee intermediate-mediated oxidation of DMDS via the direct oxygen-transfer pathway could lead to organic sulfur compounds contributing to atmospheric aerosol.

Oxidation of Formaldehyde on PdNi Nanowires Synthetized in Superfluid Helium

Oxidation of Formaldehyde on PdNi Nanowires Synthetized in Superfluid Helium

Oxidation of Formaldehyde on PdNi Nanowires Synthesized in Superfluid Helium

The possibility of using a boron-doped diamond electrode with a net structure of PdNi alloy nanowires deposited on its surface by laser ablation in superfluid helium as a formaldehyde sensor is considered. High sensitivity of such an electrode to trace amounts of formaldehyde was shown.

Enhanced formaldehyde oxidation over MnO2 and doped manganese-based catalysts: Experimental and theoretical Insights into mechanism and performance

Thermal catalytic degradation of formaldehyde (HCHO) over manganese-based catalysts is garnering significant attention. In this study, both theoretical simulations and experimental methods were employed to elucidate the primary reaction pathways of HCHO on the MnO2(110) surface. Specifically, the effects of doping MnO2 with elements such as Fe, Ce, Ni, Co, and Cu on the HCHO oxidation properties were evaluated. Advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS), were employed to discern the physical properties and chemical states of the active components on the catalyst surface. The comprehensive oxidation pathway of HCHO on the MnO2(110) surface includes O2 adsorption and dissociation, HCHO adsorption and dehydrogenation, CO2 desorption, H2O formation and desorption, oxygen vacancy supplementation, and other elementary reactions. The pivotal rate-determining step was identified as the hydrogen migration process, characterized by an energy barrier of 234.19 kJ mol−1. Notably, HCHOO and *CHOO emerged as crucial intermediates during the reaction. Among the doped catalysts, Fe-doped MnO2 outperformed its counterparts doped with Ce, Ni, Co, and Cu. The optimal degradation rate and selectivity were achieved at a molar ratio of Fe: Mn = 0.1. The superior performance of the Fe-doped MnO2 can be ascribed to its large specific surface area, conducive pore structure for HCHO molecular transport, rich surface-adsorbed oxygen species, and a significant presence of oxygen vacancies.

Formaldehyde oxidation boosts ultra-low cell voltage industrial current density water electrolysis for dual hydrogen production

The high cost is a major issue that has contributed to the slow industrialization of electrolytic water. To reduce the cell voltage to below 0.5 V, we constructed a hybrid electrolytic water system with coupled hydrogen evolution reaction (HER) and formaldehyde oxidation reaction (FOR). For FOR, the abundant Cu0 and Cu+ in nitrogen-doped Cu/Cu2+1O on Cu foam (N-Cu/Cu2+1O/CF) can effectively promote the adsorption and activation of H2O and HCHO molecules, and facilitate the cleavage of O-H and C-H, while nitrogen doping can promote the exposure of Cu active sites. For HER//FOR, a cell voltage of only 0.42 V is required to achieve 500 mA cm−2. The system can not only produce H2 routinely at the cathode through HER but also release H2 by HCHO oxidation. The construction of a dual hydrogen production system with industrial current density at ultra-low voltage provides a new idea to reduce the cost of hydrogen production.

Hydrogen co-production via nickel-gold electrocatalysis of water and formaldehyde

Hydrogen is one of the most promising future energy sources due to its highly efficient energy storage and carbon-free features. However, the energy input required for a hydrogen production protocol is an essential factor affecting its widespread adoption. Water electrolysis for hydrogen production currently serves a vital role in the industrial field, but the high overpotential of the oxygen evolution reaction (OER) dramatically impedes its practical application. The formaldehyde oxidation reaction (FOR) has emerged as a more thermodynamically favorable alternative, and the innovation of compatible electrodes may steer the direction of technological evolution. We have designed Au-Vo-NiO/CC as a catalyst that triggers the electrocatalytic oxidation of formaldehyde, efficiently producing H2 at the ultra-low potential of 0.47V (vs. RHE) and maintaining long-term stability. Integrated with the cathodic hydrogen evolution reaction (HER), this bipolar H2 production protocol achieves a nearly 100% Faraday efficiency (FE).

Principle on Selecting the Coordination Ligands of Palladium Precursors Encapsulated by Zeolite for an Efficient Purification of Formaldehyde at Ambient Temperature.

High-performance zeolite-supported noble metal catalysts with low loading and high dispersion of active components are the most promising materials for achieving the complete oxidation of formaldehyde (HCHO) at room temperature. In this work, palladium nanoparticles (Pd NPs) with different sizes were successfully encapsulated inside the silicalite-1 (S-1) zeolite framework by using diverse stabling ligands via the one-pot method. Thereafter, the rule on selecting the coordinative ligands for palladium was clarified: more N atoms, a short carbon chain, a smaller branch chain, and bidentate coordination are characteristics of an ideal ligand. Accordingly, the best-performing 0.2Pd@S-1(Ethylenediamine) catalyst exhibited outstanding performance for HCHO oxidation, achieving 100% conversion even at room temperature. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HR HAADF-STEM) and density functional theory (DFT) calculations indicate that the chelate is formed by complexation of Pd2+ ions with ethylenediamine, displaying the smallest spatial site resistance simultaneously with the zeolite synthesis, resulting in Pd located mostly within the 5-membered ring (5-MR) channels of S-1 after calcination, thus limiting the growth of Pd clusters and promoting their dispersion.

A platinum ensemble catalyst for room-temperature removal of formaldehyde in the air

Minimal use of noble metals is ideal in developing catalytic systems against carcinogenic formaldehyde (FA) in air. Although single-atom catalysts (SACs) have been proposed to maximize atomic utilization, metals dispersed to the single-atom limit are less durable in redox environments. A highly dispersed platinum (Pt) ensemble (Ptn) on titanium dioxide (TiO2) was synthesized and validated to achieve 100% conversion of 100 ppm FA in dry air at room temperature (RT) at a gas hourly space velocity of 47,771 h−1. In contrast, Pt SAC (Pt1/TiO2) and a reference Pt nanoparticle catalyst (PtNP/TiO2) exhibited much lower performances. The turnover frequencies (TOFs) of Ptn/TiO2, Pt1/TiO2, and PtNP/TiO2 for the RT FA oxidation reaction were 0.03, 0.01, and 0.005 s−1, respectively. The critical role of the surface lattice oxygen (Olatt) in the overall reaction was supported by the prominence of the Mars van Krevelen kinetics in FA oxidation by the Ptn catalyst. The performance of the PtNP catalyst matched with Ptn only when the Pt loading in the former was raised to 2 wt%. Hence, the Pt dose can be reduced by one-fourth through the ensemble form dispersed at the sub-nanometer scale. The density functional theory simulation also distinguished the roles of different Pt catalysts. The Ptn sites could serve as an oxygen reservoir (effective dissociation of molecular oxygen) to promote proximate reactions (between the adsorbed –CHO and surface Olatt species). Conversely, Pt1 is a single site that restricts proximate reactions with vulnerability to surface poisoning.

Construction of Supported MnOx/MgAl Hydrotalcite Catalysts and Their Highly Efficient Catalytic Performance for Low-Temperature Formaldehyde Removal

A series of supported MnOx/MgAl-layered double hydroxide (LDH) catalysts were prepared by hydrothermal co-precipitation to investigate their catalytic performances for low-temperature formaldehyde oxidation reactions. Activity tests show that the 10Mn/Mg3Al1-LDH catalyst exhibits higher efficiency for low-temperature formaldehyde oxidation with a high CO2 yield. It also shows remarkable long-term operational stability as well as good adaptability to different velocities and humidities. Various characterizations were carried out to establish the possible structure–activity correlations. The results show that there were a large number of hydroxyl groups in the 10Mn/MgAl-LDH catalysts, and the hydroxyl groups were positively correlated with Mg2+ content. The outstanding catalytic performance of 10Mn/Mg3Al1-LDH can be attributed to abundant surface hydroxyl groups, surface adsorbed oxygen and higher Mn4+/Mn3+ ratios. Through in situ Fourier-transform infrared spectroscopy (in situ FTIR), it was revealed that formaldehyde was gradually converted into CO2 and water with dioxymethylene (DOM), formate and carbonate as the major intermediates under the action of both active oxygen and active hydroxyl groups. The active oxygen and active hydroxyl groups consumed in the process are continuously replenished by the effective reaction between the oxygen molecules in the air and the active site of the catalyst. The low-temperature asynchronous conversion of formaldehyde results in the accumulation of some intermediates on the catalyst surface covering the active center, which induces catalyst deactivation.

Plant‐mediated fabrication of cobalt oxide nanoparticles and evaluation of their catalytic effects on electro‐oxidation of formaldehyde

AbstractCobalt oxide nanoparticles (Co3O4‐NPs) were synthesized by aqueous extract of Artemisia vulgaris plant at 50°C. The biosynthesized extract mediated Co3O4‐NPs were characterized through different methods containing FT‐IR (Fourier transform infrared spectroscopy), FESEM (Field emission scanning electron microscopy), EDS (Energy‐dispersive x‐ray spectroscopy), and XRD (x‐ray diffraction). Co3O4‐NPs as an efficient and practical catalyst was employed for the electrochemical oxidation of formaldehyde; which was an irreversible charge transfer controlled by mass transfer. The coefficients of electron transfer and diffusion were 0.87 and 0.122 cm2/s for formaldehyde oxidation on Co3O4 electrode, respectively. The formation of the CoOOH species during potential sweeping appears to be involved in the catalytic activity of the Co3O4 toward formaldehyde oxidation.

Optimization of Photothermal Catalysis for Formaldehyde Oxidation Through Modulating Crystal Phase of MnO2

Optimization of Photothermal Catalysis for Formaldehyde Oxidation Through Modulating Crystal Phase of MnO2

Electrospinning synthesis of Co3O4 porous nanofiber monolithic catalysts for the room-temperature indoor catalytic oxidation of formaldehyde at low concentrations

Room-temperature catalytic oxidation is a highly promising method for controlling formaldehyde (HCHO) concentrations indoors because it does not require any additional energy input, while completely converting HCHO into harmless H2O and CO2. This study focuses on the synthesis of Co3O4 porous nanofiber monolithic catalysts through electrospinning and investigates the mechanism behind the formation of its porous structure by analyzing the morphological changes that occur during the calcination of its fibers. In this research, we utilized heat-resistant polyacrylonitrile (PAN) as template to synthesize Co3O4 porous nanofiber monolithic catalysts. The synthesis process involved the utilization of the oxidation characteristics of PAN in the presence of cobalt acetate tetrahydrate (CH3COO)2Co·4H2O at 270–330 °C. Co3O4 porous nanofiber monolithic catalyst demonstrated exceptional performance, exhibiting over 99% catalytic activity toward HCHO at room-temperature in indoors (10–12 ppm, 25 °C) at a gas hourly space velocity of 60,000 mL·g−1h−1. This catalyst demonstrates its suitability for practical applications and its potential for energy savings. These results highlight the superiority of Co3O4 porous nanofiber monolithic catalyst over catalysts produced via the direct calcination method. The outstanding activity and stability of Co3O4 porous nanofiber monolithic catalyst make it a promising candidate for applications requiring efficient formaldehyde removal, particularly in indoors.