Search Results (126)

This review examines the research progress on non-noble-metal-based catalysts for formaldehyde (HCHO) oxidation at room temperature. It begins with an introduction to the hazards of HCHO as an indoor pollutant and the urgency of its removal, comparing several HCHO removal technologies and highlighting the advantages of room-temperature catalytic oxidation. It delves into the classification, preparation methods, and regulation strategies for non-precious metal catalysts, with a focus on manganese-based, cobalt-based, and other transition metal-based catalysts. The effects of catalyst preparation methods, morphological structure, and specific surface area on catalytic performance are discussed, and the catalytic oxidation mechanisms of HCHO, including the Eley–Rideal, Langmuir–Hinshelwood, and Mars–van Krevelen mechanisms, are analyzed. Finally, the challenges faced by non-precious metal catalysts are summarized, such as issues related to the powder form of catalysts in practical applications, lower catalytic activity at room temperature, and insufficient research in the presence of multiple VOC molecules. Suggestions for future research directions are also provided. Full article

Glancing Angle Deposition (GLAD) has emerged as a versatile and powerful nanofabrication technique for developing next-generation gas sensors by enabling precise control over nanostructure geometry, porosity, and material composition. Through dynamic substrate tilting and rotation, GLAD facilitates the fabrication of highly porous, anisotropic nanostructures, such as aligned, tilted, zigzag, helical, and multilayered nanorods, with tunable surface area and diffusion pathways optimized for gas detection. This review provides a comprehensive synthesis of recent advances in GLAD-based gas sensor design, focusing on how structural engineering and material integration converge to enhance sensor performance. Key materials strategies include the construction of heterojunctions and core–shell architectures, controlled doping, and nanoparticle decoration using noble metals or metal oxides to amplify charge transfer, catalytic activity, and redox responsiveness. GLAD-fabricated nanostructures have been effectively deployed across multiple gas sensing modalities, including resistive, capacitive, piezoelectric, and optical platforms, where their high aspect ratios, tailored porosity, and defect-rich surfaces facilitate enhanced gas adsorption kinetics and efficient signal transduction. These devices exhibit high sensitivity and selectivity toward a range of analytes, including NO₂, CO, H₂S, and volatile organic compounds (VOCs), with detection limits often reaching the parts-per-billion level. Emerging innovations, such as photo-assisted sensing and integration with artificial intelligence for data analysis and pattern recognition, further extend the capabilities of GLAD-based systems for multifunctional, real-time, and adaptive sensing. Finally, current challenges and future research directions are discussed, emphasizing the promise of GLAD as a scalable platform for next-generation gas sensing technologies. Full article

Recently, research has increasingly focused on the introduction of non-precious metals and developing highly stable carriers to enhance catalyst performance. In this study, we successfully synthesized copper (Cu)-modified biochar catalysts utilizing a sequential approach involving enzymatic treatment, liquid impregnation, and activation processes, which effectively enhanced the dispersion and introduction efficiency of Cu onto the biochar, thereby reducing the requisite Cu loading while maintaining high catalytic activity. The experimental results showed that the toluene degradation of 10%Cu@BCL was three times higher than that of unmodified activated carbon (AC) at 290 °C. A more uniform distribution of Cu was obtained by the enzymatic and activation treatments, optimizing the catalyst’s structural properties and reducing the amount of Cu on the biochar. Moreover, the transformation between various oxidation states of Cu (from Cu⁰/Cu(I) to Cu(II)) facilitated the electron transfer during the degradation of toluene. To further understand the catalytic mechanisms, density functional theory (DFT) calculations were employed to elucidate the interactions between toluene molecules and the Cu-modified biochar surface. These findings reveal that the strategic modification of biochar as a carrier not only enhances the dispersion and stability of active metal species but contributes to improved catalytic performance, thereby enhancing its degradation efficiency for VOCs in high-temperature conditions. Full article

Aromatic volatile organic compounds (VOCs) pose significant environmental and public health risks due to their toxicity, carcinogenicity, and role as precursors of hazardous secondary pollutants. Zeolite-based metal catalysts, with their well-defined microporous structures, tunable acidity, and high thermal stability, have shown promise in the catalytic oxidation of aromatic VOCs. However, the influence of the zeolite microenvironment on supported metal active sites remains insufficiently understood, limiting the rational design of advanced catalysts. This review highlights how microenvironmental parameters—including pore architecture, acid site distribution, framework composition, and surface/interface engineering—can be modulated to enhance adsorption, oxygen activation, and metal–support interactions. Advances in hierarchical porosity, heteroatom substitution, and surface hydrophobicity are discussed. This review provides a framework for the development of next-generation zeolite-based catalysts and offers strategic guidance for advancing microenvironment-controlled catalysis in sustainable environmental remediation. Full article

Chinese lacquer, a historically significant bio-based coating, has garnered increasing attention in sustainable materials research due to its outstanding corrosion resistance, thermal stability, and environmental friendliness. Its curing process relies on the laccase-catalyzed oxidation and polymerization of urushiol to form a dense lacquer film. However, the stringent temperature and humidity requirements (20–30 °C, 70–80% humidity) and a curing period that can extend over several weeks severely constrain its industrial application. Recent studies have significantly enhanced the curing efficiency through strategies such as pre-polymerization control, metal ion catalysis (e.g., Cu²⁺ reducing drying time to just one day), and nanomaterial modification (e.g., nano-Al₂O₃ increasing film hardness to 6H). Nevertheless, challenges remain, including the sensitivity of laccase activity to environmental fluctuations, the trade-off between accelerated curing and film performance, and issues related to toxic pigments and VOC emissions. Future developments should integrate enzyme engineering (e.g., directed evolution to broaden laccase tolerance), intelligent catalytic systems (e.g., photo-enzyme synergy), and green technologies (e.g., UV curing), complemented by multiscale modeling and circular design strategies, to drive the innovative applications of Chinese lacquer in high-end fields such as aerospace sealing and cultural heritage preservation. Full article

This study explored how pore size engineering in Nb-Mn/MCM-41 catalysts affects plasma-catalytic toluene oxidation. Adjusting the pore diameter (2.49–3.98 nm) modulated metal-support interactions and oxygen dynamics, with pore expansion to 3.73 nm (M3) optimizing the Mn⁴⁺/(Mn²⁺ + Mn³⁺) ratio (XPS: 36.8%), the amount of lattice oxygen species (O₂-TPD: 0.222 mmol/g), and crystallite size control (1.5 ± 0.2 nm, TEM). Smaller pores (M1: 2.49 nm) enhanced toluene adsorption but limited active site accessibility, while oversized pores (M4: 3.98 nm) reduced oxygen storage capacity (0.600→0.412 mmol/g). The Nb-Mn/M3 catalyst achieved superior performance with 96.8% toluene conversion, 55.0% CO₂ selectivity, and 85.4% carbon balance, while minimizing organic byproducts (GC-MS). Mechanistic studies revealed pore-mediated oxygen storage-transport cycles as critical for decoupling adsorption and oxidation steps. This study reveals fundamental mechanisms linking pore architecture to plasma-catalytic synergy in toluene oxidation, offering critical insights for the systematic design of energy-efficient, plasma-catalytic systems targeting industrial VOCs remediation. Full article

The construction of multicomponent transition metal oxide catalysts can effectively increase the surface defects of catalysts, and bring a synergistic effect from different components, thus enhancing the generation of reactive oxygen species and improving the catalytic activity of catalysts for volatile organic compounds (VOCs) oxidation. In this article, CuO/Co₃O₄ catalysts with abundant oxygen vacancies for the degradation of ethyl acetate was prepared by a simple impregnation method. The effect of the ratio of Co/Cu on the redox capacity, oxygen vacancy, active oxygen species and catalytic oxidation activity of ethyl acetate were studied. The 90% conversion and mineralization temperatures of ethyl acetate for the optimal catalyst Co₃O₄-20Cu are 211 and 214 °C (WHSV = 60,000 mL/(g·h), 1000 ppm ethyl acetate), which also shows good stability and excellent water vapor resistance. Compared with pure Co₃O₄, the CuO/Co₃O₄ catalysts have more oxygen vacancies, provide more reactive oxygen species, allowing the catalyst better low-temperature reduction. Through in situ DRIFTS study, the intermediates of ethyl acetate decomposition were analyzed, then a possible catalytic oxidation mechanism of ethyl acetate on the Co₃O₄-20Cu catalyst was proposed. In addition, we prepared a Co₃O₄-20Cu/cordierite monolithic catalyst on the basis of Co₃O₄-20Cu, exhibiting a good catalytic activity in degradation of ethyl acetate. Full article

Volatile organic compound (VOC) emissions have become a critical environmental concern due to their contributions to photochemical smog formation, secondary organic aerosol generation, and adverse human health impacts in the context of accelerated industrialization and urbanization. Catalytic oxidation over perovskite-type catalysts is an attractive technological approach for efficient VOC abatement. This review systematically evaluates the advancements in perovskite-based catalysts for VOC oxidation, focusing on their crystal structure–activity relationships, electronic properties, synthetic methodologies, and nanostructure engineering. Emphasis is placed on metal ion doping strategies and supported catalyst configurations, which have been demonstrated to optimize catalytic performance through synergistic effects. The applications of perovskite catalysts in diverse oxidation systems, including photocatalysis, thermal catalysis, electrocatalysis, and plasma-assisted catalysis, are comprehensively discussed with critical analysis of their respective advantages and limitations. It summarizes the existing challenges, such as catalyst deactivation caused by carbon deposition, sulfur/chlorine poisoning, and thermal sintering, as well as issues like low energy utilization efficiency and the generation of secondary pollutants. By consolidating current knowledge and highlighting future research directions, this review provides a solid foundation for the rational design of next-generation perovskite catalysts for sustainable VOC management. Full article

Diesel particulate matter (DPM) represents a deleterious environmental contaminant that necessitates the development of effective catalytic oxidation methodologies. This research delineates a comparative analysis of silver-supported metal oxide catalysts (Ag/Al₂O₃, Ag/TiO₂, Ag/ZnO, and Ag/CeO₂), with an emphasis on the effects of silver distribution and the metal-support interaction on the oxidation of DPM. An array of characterization techniques including XRD, HRTEM, XPS, H₂-TPR, TEM, GC-MS, TGA, and in situ DRIFTS was employed. The novelty of this study resides in elucidating the oxidation mechanism through a tripartite pathway and recognizing Ag⁰ as the predominant active species involved in soot oxidation. The Ag/Al₂O₃ catalyst demonstrated superior catalytic performance, achieving a reduction in the ignition temperature by more than 50 °C, attributable to the optimal dispersion of Ag nanoparticles and a balanced metal-support interaction. Conversely, an excessive interaction observed in Ag/ZnO resulted in diminished catalytic activity. The oxidation of DPM transpires through the volatilization of VOCs (<300 °C), the oxidation by reactive oxygen species, and the combustion of soot (>300 °C). This investigation offers significant contributions to the formulation of highly efficient silver-based catalysts for emissions control, with a particular focus on optimizing Ag dispersion and support interactions to enhance catalytic efficacy. Full article

With the increasing demand for air pollution control, the development of efficient and stable catalysts to degrade hazardous VOCs such as toluene has become particularly important. Herein, various copper-doped attapulgite-supported cobalt oxide spinel composites (Cu_xCo_3−xO₄/ATP) were synthesized using an ultrasonic-assisted precipitation method. The results showed that the abundant Si-OH groups on the surface of ATP played a crucial role in anchoring Co, and the instantaneous high-energy input of ultrasonication facilitated the formation of Si-O-Co bonds in Co₃O₄/ATP. The doping of Cu ions induced the expansion of the Co₃O₄ lattice, resulting in a significant number of oxygen vacancies. The ultrasound-induced synthesized Cu_0.1Co_2.9O₄/ATP catalyst exhibited the best catalytic oxidation performance, achieving a 99% toluene degradation rate at 300 °C under a weight hourly space velocity (WHSV) of 10,000 mL·g⁻¹ h⁻¹ and initial toluene concentration of 1000 ppm, along with high stability during 12 h of continuous running. This work presents a new strategy for the cost-effective catalytic elimination of VOCs. Full article

Catalytic combustion is an efficient and economic technology for eliminating volatile organic compounds (VOCs) in industrial environments. This study evaluated the synergistic catalytic properties of bimetallic oxides, viz., CoM/γ-Al₂O₃ (M = Cu, Fe, or Ni), for improving the combustion efficiency of toluene. The CoM/γ-Al₂O₃ catalysts were prepared by an impregnation method and characterized by using advanced techniques. Among the bimetallic catalysts, CoCu/γ-Al₂O₃ exhibited the best performance. The findings revealed that owing to the strong synergistic interaction between Cu, Co, and the γ-Al₂O₃ support, the active species in the CoCu/γ-Al₂O₃ catalyst were effectively stabilized, and they significantly enhanced the redox performance and acidity of the catalyst, demonstrating superior catalytic activity and sulfur resistance. Conversely, the CoFe/γ-Al₂O₃ catalyst performed poorly, exhibiting a significant decline in its activity owing to sulfur poisoning. The insights from this study provide theoretical support for designing efficient, sulfur-resistant catalysts that are crucial to reducing industrial VOC emissions. Full article

Volatile organic compounds (VOCs) from petrochemical, pharmaceutical, and other industries have serious damage to human health and the environment. Catalytic oxidation is a promising method to eliminate air pollution due to its high efficiency, wide application range, and environmental friendliness. However, in the actual industrial environment, the composition of industrial exhaust gases is complex, including VOCs, water vapour, chloride, sulfide and so on. The impurities would have competitive adsorption with reactants or react with the active sites, leading to the decline of catalytic activity, even the deactivation of catalysts. Therefore, this review summarises the recent research on the anti-poisoning ability of catalysts in the catalytic oxidation of VOCs, primarily focusing on the effect of water vapour, chloride, and sulfide. The catalytic oxidation mechanism manifested that the adsorption and activation of reactants are significant in VOCs degradation. On this basis, the mechanism of catalyst poisoning was analysed, and the inhibitory effect of impurities on the oxidation reaction was elucidated. According to the research status, three anti-poisoning strategies are proposed, including building a bimetallic system, modifying supports, and establishing the protected coating. This work provides a theoretical foundation and reference point for the rational construction of anti-poisoning catalysts in VOCs elimination. Full article

Developing efficient strategies for VOC emission abatement is an urgent task for protection of the environment and human health. Complete catalytic oxidation exhibits advantages, making it an effective, environmentally friendly, and economically profitable approach for VOC elimination. Pd-based catalysts are known as highly active for hydrocarbon catalytic oxidation. The nature of carrier materials is of particular importance because it may affect activity by changing physicochemical properties of the palladium species. In this work, Al₂O₃, CeO₂, CeO₂-Al₂O₃, and Y-doped CeO₂-Al₂O₃ were used as carriers of palladium catalysts. Methane and benzene were selected as representatives of two types of hydrocarbons. A decisive step in complete methane oxidation is the first C–H bond breaking, while the extraordinary stability of the six-membered ring structure is a challenge in benzene oxidation. The support effect was explored by textural measurements using XRF, XRD, XPS, EPR, and TPR techniques. Three ceria-containing samples showed superior CH₄ oxidation performance, achieving 90% methane conversion at about 300 °C and complete oxidation at 320 °C. Evidence for presence of Pd²⁺ species in all samples regarded as most active was provided by XP-derived analysis. Pd/Y-Ce/Al catalysts exhibited very high activity in benzene oxidation by reaching 100% conversion at 180 °C. The contributions of higher Pd and Ce³⁺ surface concentrations, the presence of O₂⁻-adsorbed superoxo species, and Pd⁰ ↔ PdO redox transfer were considered. The potential of a simple, environmentally friendly, and less energy demanding mechanochemical preparation procedure of mixed oxides was demonstrated. Full article

The catalytic oxidation of volatile organic compounds (VOCs) is the subject of considerable interest due to its applications in environmental protection. Noble metal-based catalysts are widely employed to remove toxic compounds from gas mixtures. The objective of the present study was the synthesis of a palladium-containing catalyst deposited on a support modified with La₂O₃ zinc oxide. The composite support was initially obtained by a simple method, and then palladium was deposited on it by impregnation. Various methods, including N₂-physisorption, XRD, HRTEM, XPS, TPD, TPR, and FTIR, were used to characterize the material. The obtained catalyst was studied in the reaction of the complete oxidation of butane, propane, and methane. It was found that the addition of La₂O₃ to ZnO led to an improved pore texture. The catalytic tests showed that the reaction of the complete oxidation of butane on Pd/La₂O₃/ZnO proceeded at the lowest temperatures. Full article

This article presents a comprehensive examination of the combined catalytic conversion technology for nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are the primary factors contributing to the formation of photochemical smog, ozone, and PM2.5. These pollutants present a significant threat to air quality and human health. The article examines the reaction mechanism and interaction between photocatalytic technology and NH₃-SCR catalytic oxidation technology, highlighting the limitations of the existing techniques, including catalyst deactivation, selectivity issues, regeneration methods, and the environmental impacts of catalysts. Furthermore, the article anticipates prospective avenues for research, underscoring the necessity for the development of bifunctional catalysts capable of concurrently transforming NOx and VOCs across a broad temperature spectrum. The review encompasses a multitude of integrated catalytic techniques, including selective catalytic reduction (SCR), photocatalytic oxidation, low-temperature plasma catalytic technology, and biological purification technology. The article highlights the necessity for further research into catalyst design principles, structure–activity relationships, and performance evaluations in real industrial environments. This research is required to develop more efficient, economical, and environmentally friendly waste gas treatment technologies. The article concludes by outlining the importance of collaborative management strategies for VOC and NOx emissions and the potential of combined catalytic conversion technology in achieving these goals. Full article