Catalytic Oxidation Technology Research Articles

Research on Low Concentration Gas Catalytic Oxidation Power Generation System

In response to the difficulties in direct utilization of low concentration gas in coal mines and the slow development of industrial application of catalytic oxidation technology, a new mode of direct utilization of low concentration gas with a methane concentration of 1.0% in coal mines in catalytic oxidation gas turbine power generation is explored. And based on the development of a 30kW low concentration gas catalytic oxidation gas turbine power generation system, this paper introduces the design process of key equipment such as catalytic oxidation burners, low-temperature and low-pressure turbines, and countercurrent regenerators, providing a technical reference for the utilization of low concentration gas catalytic oxidation.

Mechanistic insights into methane total oxidation over Cu/Hydroxyapatite catalyst synthesized with β-Cyclodextrin assistance

The total oxidation of methane (CH4), a highly stable alkane volatile organic compound (VOC), using low-cost Cu-based catalysts, has garnered considerable attention. Nonetheless, challenges such as Cu particle agglomeration and the lack of consensus on mechanism of CH4 total oxidation over Cu-based catalysts remain. In this work, β-cyclodextrin (βCD) was introduced during Cu/hydroxyapatite catalyst (βCD-Cu/HAP) preparation, and its catalytic performance in CH4 total oxidation was compared with the Cu/HAP catalyst. Both materials were prepared using the wet impregnation method and thoroughly characterized. It was found that utilization of βCD, which decomposed during calcination, led to smaller Cu particle size (from 61 to 34 nm) and better Cu dispersion (from 1.9 to 3.5 %), resulting in an enhancement of the catalyst reduction properties. Additionally, the βCD-Cu/HAP catalyst possessed a higher oxygen storage capacity, demonstrating its superior ability to replenish the oxygen vacancies. The βCD-Cu/HAP catalyst activity was double that of the original Cu/HAP catalyst with a 20kJmol-1 lower activation energy, as determined by fitting the initial reaction rate to a power-law model. Further, Langmuir–Hinshelwood (LH), Eley–Rideal (ER), and Mars–van Krevelen (MVK) type rate expressions were regressed to the experimental data. After statistical and physico-chemical assessments, the MVK mechanism involving two oxidized sites and one reduced site with H2O adsorption on oxidized sites was identified as the most appropriate model for describing the experimental data. These findings offer an enhanced understanding of CH4 total oxidation, guiding the development of efficient, low-cost catalysts for this reaction. Environmental ImplicationVolatile organic compounds (VOCs) pose significant environmental and health issues due to their toxicity and widespread sources. Among VOCs, alkane contribute to a large proportion of the VOCs emitted, with light alkanes being particularly challenging to mitigate due to their high stability. Methane, the most stable light alkanes, is the focus of this study. Catalytic oxidation technology offers a promising solution for VOC mitigation. In our work, we conducted a mechanistic investigation of methane total oxidation, aiming at deepening our understanding of catalytic oxidation of light alkanes, thereby contributing to substantial environmental benefits.

Catalytic Oxidation of BTX (Benzene, Toluene, and Xylene) Using Metal Oxide Perovskites

AbstractThe high toxicity, volatility, and dispersion of the light aromatics, benzene, toluene, and xylene (BTX) pose a serious threat to the environment and human health. Compared to incineration, catalytic oxidation technologies for BTX removal offer benefits such as low energy consumption, high efficiency, and low pollution. ABO3–type perovskite catalysts (ABO3–PCs) are particularly promising materials for the catalytic oxidation of BTX due to their high activity and thermal stability, as well as their adjustable elemental composition and flexible structure allowing their properties to be improved. Nonetheless, the full potential of ABO3–PCs for the oxidation of BTX has yet to be reached. This review systematically and critically analyses progress in the catalytic oxidation of BTX by ABO3–PCs. Catalytic performance is assessed for each category of perovskite, including non–doped, doped (A–, B–, or A/B–site doped), and loading type (noble metal, metal oxide, and matrix composite), with structure–activity relationships are established. A kinetic model and proposed mechanism for the catalytic oxidation of BTX are also presented. Finally, the challenges and opportunities of ABO3–PCs applied to BTX oxidation and other reactions are highlighted.

Co3O4‐Based Catalysts for the Low‐Temperature Catalytic Oxidation of VOCs

AbstractVolatile organic compounds (VOCs) are a significant source of environmental pollution, posing threats to human safety. With growing concerns about environmental degradation, catalytic oxidation technology emerges as a paramount and widely adopted approach for VOC elimination, renowned for its operational simplicity, energy efficiency, and environmental friendliness. As a representative transition metal catalyst, cobalt‐based catalysts have garnered widespread use in VOC catalytic oxidation due to their cost‐effectiveness, versatility, and distinctive physicochemical properties. This paper provides a detailed exposition of the construction strategies and structure‐activity relationship of Co3O4‐based catalysts in VOCs oxidation reaction, encompassing both monometallic Co3O4 and multimetallic cobalt‐based catalysts. Furthermore, it offers a comprehensive summary and discussion of the latest research progress concerning Co3O4‐based catalysts in practical applications. Concluding with a meticulous analysis, the paper addresses the technical challenges inherent in developing Co3O4‐based catalysts for VOCs degradation. Additionally, it proposes research directions aimed at overcoming these challenges, contributing to the ongoing discourse on environmental sustainability.

Mechanism of the generation of benzaldehyde and benzoic acid on Pd (1 1 1) surface during the destruction of toluene: Verification of experiments and models

Catalytic oxidation technology is still the mainstream technology of VOCs treatment at present, and it is of great significance to study the main active components of catalysts and clarify the evolution and transformation process of intermediate products in the catalytic process for clarifying the reaction mechanism and guiding the catalyst design. Pd was identified as the main active component in catalytic oxidation of toluene, and the important intermediate products in the degradation of toluene, i.e., benzaldehyde and benzoic acid, were obtained through experiment and In-situ DRIFT spectra. However, the specific evolution process of intermediates is difficult to observe experimentally. The conversion of toluene on Pd (111) surface was studied by DFT calculation. Benzaldehyde was the most stable intermediate and benzoic acid was the most stable energy state of the reaction products. Then the activation energies and reaction energies of all possible reaction paths from toluene to benzaldehyde or benzoic acid were calculated, and the only transition state was obtained. Two pathways for the formation of benzaldehyde and benzoic acid were identified, in which the oxidation reaction after dehydrogenation may be the common rate-determining step of the two pathways, with a maximum energy barrier of 0.80 eV.

Photothermal dependence on catalytic activity and selectivity of HMF and benzyl alcohol oxidation over Pd/1D‐TiO2 nanotubes

AbstractBACKGROUNDPhotothermal catalytic oxidation technology for synthesis of high value‐added chemicals has become a hot topic of research at home and abroad. As a special structure, titania (TiO2) nanotubes (Ti‐NTs) possess larger specific surface area and adsorption capacity, which have shown great application prospects in photothermal catalytic oxidation.RESULTSIn this work, high‐performance palladium (Pd‐Ti‐NTs catalyst were prepared and applied to the photothermal catalytic oxidation of 5‐hydroxymethyl (HMF) and benzyl alcohol. The photothermal dependence on catalytic activity and selectivity of HMF and benzyl alcohol oxidation was studied in detail. The results revealed that compared with thermal catalytic oxidation, the catalysts showed significantly higher conversions of both benzyl alcohol and HMF under light. in particular, HMF conversion increase from 55.6% to 99.7%. Aldehyde oxidation is inhibited by alcohol and can be dramatically promoted by light radiation. This is probably because alcohol can inhibit the adsorption of aldehyde, and this inhibiting effect is weakened through light radiation, thus promoting the oxidation of aldehydes. Therefore, the selectivity of the final products 2,5‐furandicarboxylic acid (FDCA) and benzoic acid were dramatically increased in both systems under light radiation, and the selectivity for FDCA was obviously increased from 5.8% to 61.3%, and the yield reached 61.0%, which is higher than that of most of the reported Pd‐TiO2‐based catalysts for FDCA.CONCLUSIONSIn this paper, we verify that Pd‐Ti‐NTs could preferentially promote the conversion of aldehydes to acids in the presence of light, and obtained catalysts with high catalytic performance and high stability for benzyl alcohol and HMF oxidation. © 2024 Society of Chemical Industry (SCI).

MOF-derived FeOx with highly dispersed active sites as an efficient catalyst for enchaning catalytic oxidation of VOCs

Highly efficient and stable catalysts serve as the crucial factor in VOCs catalytic oxidation technology. Iron-based materials are recognized as potential VOCs catalysts due to their cost-effectiveness and non-toxic nature. However, the limited catalytic performance of traditional iron oxide catalysts hinders their further industrial applications. A series of FeOx catalysts were synthesized via pyrolysis of Fe-based MOFs with diverse morphologies for toluene catalytic oxidation. Characterization results demonstrated that the FeOx-100 catalyst performed optimal characteristics, including the abundant specific surface area and smaller crystallite size, which offered highly dispersed active sites and defects for toluene oxidation. The catalytic activity of FeOx-100 was improved by adjusting the precursors and pyrolysis conditions, achieving a 50% toluene conversion at 223 °C and 90% conversion at 249 °C. The redox abilities of FeOx catalysts were carefully evaluated to assess their impact on catalytic activity. The results confirmed that FeOx-100 exhibited superior low-temperature reducibility, remarkable presence of surface active oxygen and lattice oxygen species, jointly facilitating the toluene oxidation performance at lower temperatures. The results of in situ DRIFTS provided evidence supporting a degradation pathway for toluene, likely proceeding as follows: toluene→ benzaldehyde→ benzoate→ anhydride → …→ CO2 and H2O.

Urea catalytic oxidation for energy and environmental applications.

Urea is one of the most essential reactive nitrogen species in the nitrogen cycle and plays an indispensable role in the water-energy-food nexus. However, untreated urea or urine wastewater causes severe environmental pollution and threatens human health. Electrocatalytic and photo(electro)catalytic urea oxidation technologies under mild conditions have become promising methods for energy recovery and environmental remediation. An in-depth understanding of the reaction mechanisms of the urea oxidation reaction (UOR) is important to design efficient electrocatalysts/photo(electro)catalysts for these technologies. This review provides a critical appraisal of the recent advances in the UOR by means of both electrocatalysis and photo(electro)catalysis, aiming to comprehensively assess this emerging field from fundamentals and materials, to practical applications. The emphasis of this review is on the design and development strategies for electrocatalysts/photo(electro)catalysts based on reaction pathways. Meanwhile, the UOR in natural urine is discussed, focusing on the influence of impurity ions. A particular emphasis is placed on the application of the UOR in energy and environmental fields, such as hydrogen production by urea electrolysis, urea fuel cells, and urea/urine wastewater remediation. Finally, future directions, prospects, and remaining challenges are discussed for this emerging research field. This critical review significantly increases the understanding of current progress in urea conversion and the development of a sustainable nitrogen economy.

Catalytic Oxidation Mechanism of Toluene on the Ce0.875Zr0.125O2 (110) Surface

Aromatic volatile organic compounds (VOCs) are toxic to public health and contribute to global air pollution; thus, it is urgent to control VOC emissions. Catalytic oxidation technology has been widely investigated to eliminate aromatic VOCs; this technology exhibits high catalytic efficiency even at low temperatures. However, the reaction mechanism of aromatic VOCs’ total oxidation over metal-oxide-based catalysts, which is of great significance in the design of catalysts, is not yet clear. In this study, we systemically calculated the catalytic oxidation mechanism of toluene over the Ce0.875Zr0.125O2 catalyst using density functional theory (DFT). The results show that toluene first loses hydrogen from the methyl group via oxy-dehydrogenation and is gradually oxidized by lattice or adsorbed oxygen to benzyl alcohol, benzaldehyde, and benzoic acid following the Mars-van Krevelen (MVK) mechanism. Afterwards, there is a decarboxylation step to produce phenyl, which is further oxidized to benzoquinone. The rate-determining step then proceeds via the ring-opening reaction, leading to the formation of small molecule intermediates, which are finally oxidized to CO2 and H2O. This work may provide atomic-scale insight into the role of lattice and adsorbed oxygen in catalytic oxidation reactions.

APPLICATION OF FENTON'S HETEROGENEOUS SYSTEM FOR THE TREATMENT OF ORGANIC-CONTAINING WASTEWATER

With the growth of the Earth's population, the problem of the shortage of clean water is becoming global. And for the survival of humanity, it is necessary to significantly reduce the amount of harmful wastewater that pollutes the environment. Wastewater polluted with organic substances, usually produced by the production of dyes and the food industry, causes great damage to the environment.
 The expediency of catalytic oxidation for the treatment of organic-containing effluents has been theoretically substantiated. As a catalyst, it is proposed to use new nanostructured composites of the «core-shell» type based on transition metal oxides (CoFe2O4/SiO2/CuO) for the Fenton system. The oxidizing agent in this system is H2O2, which is used in «green technologies».
 It was investigated that the degree of destruction of the dye methylene blue (MB) depends on the composition of the catalyst, the ratio of the concentrations of the catalyst and dye, and the presence of a preliminary stage of dye adsorption.
 The investigated catalyst was tested on simulated dairy wastewater (SDW). The research was carried out in a barbotage-type apparatus (Schott filter). For the system «dairy wastewater – CoFe2O4/SiO2/CuO – О2– Н2О2», the degree of dairy wastewater treatment is 63 %, and residual COD value is 39,52 mgO2/dm3. It was established that in the process of purification by the CoFe2O4/SiO2/CuO catalyst, active oxidizing compounds are formed, which significantly intensify the process.
 Thus, there are reasons to assert that the prospect of developing a highly efficient catalytic oxidation technology in the Fenton system for the treatment of wastewater containing organic pollutants. And the results obtained and the conclusions drawn about the technological feasibility of using CoFe2O4/SiO2/CuO as a catalyst can find practical application for the implementation of technological schemes closed behind water and in other wastewater treatment technologies, in particular food production.

Research on ultrafast catalytic degradation of heterocyclic compounds by the novel high entropy catalyst

Traditional refractory wastewater treatment methods have problems of low efficiency, high cost and many by-products, so it is of great significance to develop new high-efficiency refractory wastewater treatment technology. Heterogeneous catalysts were used in the catalytic ultrafast oxidation (CUFO) process to treat textile dyeing wastewater with refractory heterocyclic compounds. Composite catalysts with varying entropies were synthesized by the ultrasonic dispersion-annealing method. The high entropy catalysts exhibited superior catalytic activity and stability compared to other catalysts. Furthermore, the impact of reaction temperature (T, 350–390 °C), residence time (t, 3–17 min), oxidation coefficient (OC, 2.1–2.9), and entropy of catalyst on the COD removal were assessed. An increase in entropy of catalyst resulted in a significant enhancement of COD removal rate. At T = 390 °C and OC = 2.90, the high entropy oxides catalyst achieved the COD removal rate of 93.95 % after the 7 min reaction. Additionally, a catalytic reaction mechanism involving the CeMnCuOx solid solution heterostructure with domino catalytic ability was proposed. Overall, the results suggest that catalytic ultrafast oxidation technology is a promising option for efficiently treating refractory organic pollutants.

Catalytic oxidation degradation of volatile organic compounds (VOCs) – a review

Abstract Volatile organic compounds (VOCs) are considered one of the significant contributors to air pollution because they are toxic, difficult to remove, come from a wide range of sources, and can easily cause damage to the environment and human health. There is an urgent need for effective means to reduce their emissions. The current treatment technologies for VOCs include catalytic oxidation, adsorption, condensation, and recovery. Catalytic oxidation technology stands out among the others thanks to its high catalytic efficiency, low energy requirement, and lack of secondary pollution. The difficulty of this technology lies in the development of efficient catalysts. The research on loaded noble metal catalysts and non-noble metal oxide catalysts in this area over the past few years is briefly described in this work. Firstly, the catalytic destruction mechanism of organic volatile compounds is introduced. Secondly, the effects of structural modulation during catalytic oxidation, such as the adjustment of noble metal particle size and morphology, metal doping, and defect engineering, on the conformational relationships are discussed. Finally, the challenges faced by thermal catalytic oxidation for the degradation of VOCs are discussed, and the prospects for its development are presented.

Periodate activation by atomically dispersed Mn on carbon nanotubes for the production of iodate radicals and rapid degradation of sulfadiazine

Sulfonamides, such as sulfadiazine (SDZ), are widely used antibiotics that pose a significant threat to the environment due to their poor biodegradability and potential to induce antibiotic resistance. In this study, a new catalyst with atomically dispersed Mn on carbon nanotubes (MnN@CNT) was applied for the first time to activate periodate (PI) for rapid degradation of SDZ. MnN@CNT/PI system achieved 100% SDZ removal in 15 min, and the kinetic rate constant (knor) reaches 406.1 min−1·g−2·L2, higher than those of the reported catalytic PI systems. Multiple reactive oxygen species (ROS), including IO3•, O2–•, 1O2, high-valent Mn-oxo complexes, and •OH, were detected, with IO3• being the most predominant. The Mn atom bridged the electron from the carbon support to IO4- via the Mn-O bond, which induced the prolonged I-O bond and thus the generation of IO3•. SDZ was degraded through S-N bond cleavage, pyrimidine destruction, SO2 extrusion, and N-N coupling. The intermediate products of the SDZ degradation process showed little antibacterial activity, indicating the greatly reduced risk of the treated water to induce antibiotic resistance in the environment. The superior performance of MnN@CNT/PI in the environmental water samples suggests its high application potential for selective degradation of SDZ in complex waters. The research presents a novel advanced catalytic oxidation technology for efficiently removing sulfonamides and similar antibiotics from water for adequate environmental and ecological protection.

Low temperature oxidation of o-xylene by Mn-based catalysts prepared by hydrothermal calcination: Influence mechanism of complicated flue gas components and intermediate product

Catalytic oxidation technology has proven to be an effective method for purifying flue gas of CFPPs. However, conventional catalysts face limitations such as limited activity and vulnerability to contamination from SO2 and H2O. This study aims to assess the efficiency of a newly synthesized Mn-based catalyst, prepared via a hydrothermal-calcination technique, in removing VOCs from simulated coal combustion flue gas. The results demonstrate that the catalyst produced through hydrothermal synthesis, followed by calcination at 400 °C, exhibits a catalytic oxidation efficiency of 96.2% for VOCs at 350 ℃. Furthermore, the catalyst demonstrates anti-poisoning properties. To gain a deeper understanding, we utilized DRIFTS to investigate the mechanism of o-xylene adsorption on the catalyst surface, reaction conversion intermediates, and the influence of complex flue gas components (NH3, NO, and SO2) on the catalytic reaction process. Our investigation provides insight in the improvement of Mn-based catalysts for the removal of VOCs from coal flue gas.

Catalytic Oxidation of Acetone on SmMn2O5: Effect of Acid Etching and Loading Treatment.

The key of catalytic oxidation technology is to develop a stable catalyst with high activity. It is still a serious challenge to achieve high conversion efficiency of acetone with an integral catalyst at low temperature. In this study, the SmMn2O5 catalyst after acid etching was used as the support, and the manganese mullite composite catalyst was prepared by loading Ag and CeO2 nanoparticles on its surface. By means of SEM, TEM, XRD, N2-BET, XPS, EPR, H2-TPR, O2-TPD, NH3-TPD, DRIFT, and other characterization methods, the related factors and mechanism analysis of acetone degradation activity of the composite catalyst were discussed. Among them, the CeO2-SmMn2O5-H catalyst has the best catalytic activity at 123 and 185 °C for T50 and T100, respectively, and shows excellent water and thermal resistance and stability. In essence, the surface and lattice defects of highly exposed Mn sites were formed by acid etching, and the dispersibility of Ag and CeO2 nanoparticles was optimized. Highly dispersed Ag and CeO2 nanoparticles have a highly synergistic effect with the support SmMn2O5, and the reactive oxygen species provided by CeO2 and the electron transfer brought by Ag further promote the decomposition of acetone on the carrier SMO-H. In the field of catalytic degradation of acetone, a new catalyst modification method of high-quality active noble metals and transition metal oxides supported by acid-etched SmMn2O5 has been developed.

Electrochemical removal of gaseous benzene using a flow-through reactor with efficient and ultra-stable titanium suboxide/titanium-foam anode at ambient temperature

Catalytic oxidation technology is currently considered as a feasible approach to degrade and mineralize volatile organic compounds (VOCs). However, it is still challenging to realize efficient removal of VOCs through catalytic oxidation at room temperature. In our study, a novel flow-through electrocatalytic reactor was designed, composed of porous solid-electrolyte, gas-permeable titanium sub-oxides/titanium-foam (TiSO/Ti-foam) as anode and platinum coated titanium foam (Pt/Ti-foam) as cathode. This device could oxidize nearly 100% of benzene (10 ppm) to carbon dioxide at a current density of 1.2 mA/cm2 under room temperature. More importantly, the device maintained excellent stability over 1000 h. Mechanism of benzene mineralization was discussed. Hydroxyl radicals generated on the TiSO/Ti-foam anode played a crucial role in the oxidation of benzene. This study provides a promising prototype of the electrochemical air purifier, and may find its application in domestic and industrial air pollution control.

Mutual inhibition effects on the synchronous conversion of benzene, toluene, and xylene over MnOx catalysts

Advancing the practical application of catalytic oxidation technology demands for illustrating the synchronous conversion behavior of various volatile organic compounds (VOCs) over catalysts. Here, the mutual effects of benzene, toluene and xylene (BTX) were examined for their synchronous conversion on the surface of the MnO2 nanowire. Competitive adsorption of xylene (absorption energy (Eads): −0.889 eV) facilitated its prior conversion and impeded the oxidization of toluene and benzene over the catalyst. The turnover frequencies were 0.52 min−1 (benzene), 0.90 min−1 (toluene) and 2.42 min−1 (xylene) for mixed BTX conversion over the MnO2. Doping MnO2 with K+, Na+ and Ca2+ could enhance its ability to oxidize the individual VOCs but did not alter the conversion mechanism of mixed BTX over the catalyst. When reducing the competitive effects in the adsorption of BTX, the oxidation performance of catalysts would depend on their ability to oxidize toluene and benzene. K-MnO2 showed superior properties, i.e. specific surface area, highly low-valent Mn species, high lattice oxygen content, and abundant oxygen vacancy, and then exhibited superior performance during long-term operation (90% conversion in 800 min). The present study uncovered the co-conversion mechanism of multiple VOCs and significantly leveraged the catalytic oxidization technology for VOCs removal in practical application.

Experimental study and kinetic model analysis on photothermal catalysis of formaldehyde by manganese and cerium based catalytic materials

ABSTRACT Modern people spend more and more time in cars in their daily lives, and the pollution of formaldehyde in the car may directly affect people’s health. Thermal catalytic oxidation technology by solar light is a potential way to purify formaldehyde in cars. MnOx-CeO2 was prepared by the modified co-precipitation method as the main catalyst, and the basic characteristic (SEM, N2 adsorption, H2-TPR, UV-visible absorbance) were also analyzed in detail. The experimental study was set up to simulate the solar photothermal catalysis of formaldehyde in-car environment. The results showed that the higher the temperature in the experimental box (56.7 ± 0.2°C, 62.6 ± 0.2°C, 68.2 ± 0.2°C), the better the formaldehyde degradation by catalytic effect (formaldehyde degradation percentage: 76.2, 78.3, 82.1). With increase of the initial formaldehyde concentration (200 , 500 , 1000 ), the catalytic effect first increased and then decreased (formaldehyde degradation percentage: 63, 78.3, 70.6). The catalytic effect risen gradually with the increase of load ratio (10, 20, and 40), and the formaldehyde degradation percentages were 62.8, 78.3, and 81.1, respectively. According to the expressions of the Eley-Rideal (ER) model, the Langmuir-Hinshelwood (LH) model, and the Mars-Van Krevelen (MVK) model, the experimental results were fitted and verified, and it was found that the ER model had a high degree of fit. It is more suitable to explain the catalytic mechanism of formaldehyde by MnOx-CeO2 catalyst in the experimental cabin, where formaldehyde is in the adsorption state and oxygen is in the gas phase. Implications: Judging from the current research status, vehicles have become an indispensable mode of travel for people, and the air quality in the vehicle is not optimistic. Most vehicles generally have the phenomenon of excessive formaldehyde. The characteristic of formaldehyde in the car is the continuous release, especially in the hot summer, the temperature inside the car rises sharply under the sun radiation. At this time, the formaldehyde concentration exceeds the standard by 4 to 5 times, which can cause great damage to the health of the passengers. In order to improve the air quality in the car, it is necessary to adopt the correct purification technology to degrade formaldehyde. The problem brought by this situation is how to effectively use solar radiation and high temperature in the car to degrade formaldehyde in the car. Therefore, this study uses the thermal catalytic oxidation technology to catalyze the degradation of formaldehyde in the high temperature environment of the car in summer. The selected catalyst is MnOx-CeO2, mainly because manganese oxide (MnOx) itself is the most effective catalyst for volatile organic compounds (TCO) among transition metal oxides, and CeO2 has excellent oxygen storage and release capacity and Oxidation activity, which helps to improve the activity of MnOx. Finally, the effects of temperature, initial concentration of formaldehyde and catalyst loading on the experiment were explored, and the kinetic model of thermal catalytic oxidation of formaldehyde with MnOx-CeO2 catalyst was analyzed to provide technical support for the future application of this research in practice.

Enhanced photocatalytic degradation performance of In2O3/g-C3N4 composites by coupling with H2O2

Environmental pollution by organic pollutants poses a great threat to the ecosystem and human development. Solar-powered catalytic oxidation technology can solve the existing energy and pollution crisis. Hence, in this work, cubic nano-In2O3 modified g-C3N4 composite was synthesized by in situ calcination, then it was coupled with hydrogen peroxide for the degradation of antibiotic under visible light. The results of SEM and XPS showed that In2O3 and g-C3N4 were closely combined. The catalytic oxidation efficiency of the antibiotic doxycycline was greatly improved when the as-prepared compound was coupled with hydrogen peroxide, and 88.2% of doxycycline was degraded within 80 min. By designing the active species inhibition test, it was found that a large number of hydroxyl radicals were generated in the system after adding hydrogen peroxide, which accelerated the degradation of the target. Hydrogen peroxide not only acts as a source of hydroxyl radical, but also as an active electron acceptor, which promotes the separation of photogenerated electron-hole pairs in the composite photocatalyst. Therefore, the double oxidation system formed by In2O3/g-C3N4 coupled with hydrogen peroxide can degrade the target at a higher rate. This work provided a research basis for the synthesis of In2O3 with regular morphology and simplified synthesis of In2O3/g-C3N4, and explored the practicability of the coupling method of double advanced oxidation for pollutant degradation.

Cu-based perovskite as a novel CWPO catalyst for petroleum refining wastewater treatment: Performance, toxicity and mechanism

For the first time, Cu-based perovskite oxides were used as catalysts to treat highly toxic and refractory petroleum refining wastewater based on catalytic wet peroxide oxidation (CWPO) technology. Perovskite La2CuO4 was synthesized by sol-gel method. A series of characterizations showed that the synthesized catalyst particles are tetragonal phase perovskite structure. The experimental results showed that under the conditions of catalyst dosage of 0.75 g, temperature of 100 ℃ and reaction time of 30 min, the COD removal rate was 89.58 %, the TOC removal rate was 87.38 %. The morphology and structure of the catalyst before and after the reaction proved that the catalyst has strong stability and catalytic activity. The components of raw water, Wet Air Oxidation (WAO) effluent and CWPO effluent were compared and analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), and the possible mechanism and path of WAO and CWPO degradation of petroleum refining wastewater were further explored. The changes of Cu components in La2CuO4 before and after CWPO reaction and the transformation of lattice oxygen and adsorbed oxygen were analyzed by X-ray Photoelectron Spectroscopy (XPS). The involvement of Cu (Ⅱ) /Cu (Ⅰ) in the activation of H2O2 was speculated. Finally, the biotoxicity of raw water, WAO effluent and CWPO effluent was predicted. The results provide reference value for the application of catalyst La2CuO4 in various petrochemical wastewater.