Catalytic Oxidation of Chlorobenzene over Ruthenium-Ceria Bimetallic Catalysts

Chlorine-Tolerant Chlorobenzene Combustion over Mullite Catalysts via In Situ Constructing Ru-O-Mn Sites

The catalytic combustion of chlorine-containing volatile organic compounds (CVOCs) at low temperatures still faces chlorine poisoning challenges. Herein, chlorine-tolerant chlorobenzene combustion over manganese-based mullite (SmMn2O5) catalysts has been originally demonstrated via in situ constructing rich Ru-O-Mn sites, engineered from the in situ doping of ruthenium (Ru) and the subsequent etching of samarium (Sm). Such catalysts exhibited 90% activity for chlorobenzene combustion at 258 °C and maintained about 80% activity after the 30 h stability test. Specifically, the doping of Ru could readily replace Mn4+ of SmMn2O5 to form Ru-O-Mn sites, and the etching of Sm could expose more surface Ru-O-Mn sites, which significantly enhanced the redox capacity and oxygen activation ability, thus improving the low-temperature catalytic combustion of chlorobenzene. Besides, the Ru-O-Mn sites boosted the transformation of chlorine-containing intermediate species to low-pollution species and accelerated the removal of Cl and the formation of CO2, thus enhancing the chlorine tolerance of mullite catalysts. This study deepened the understanding of the catalytic combustion mechanism and provided a feasible strategy for the development of high-efficiency and chlorine-resistant catalysts for the catalytic combustion of CVOCs.

Comparative data on different preparation methods of Ru/CeO2 catalysts for catalytic oxidation of chlorine-containing volatile organic compounds

Under industrial conditions, efficient catalytic oxidation of Chlorinated volatile organic compounds is an important challenge, not only because of the poisonous effect of Chlorinated volatile organic compounds on catalysts, but also because of their high reaction temperature, which has an adverse impact on industrialization. In a recent article (The efficient and stable catalytic combustion of chlorobenzene utilizing a cordierite honeycomb ceramic Ru/CeO2 catalyst: Transitioning from laboratory innovation to practical application) [1], we developed a strategy for preparing a simple and efficient monolithic catalyst for the catalytic combustion of chlorobenzene. Ru/CeO2 was loaded on the industrial support cordierite by a Sol-gel method. Characterization was performed by techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunner-Emmet-Teller(BET) measurements surface area analysis. The Sol-gel method demonstrated superior performance, yielding catalysts with better dispersion, larger surface areas, and consequently, higher catalytic oxidation activity for chlorobenzene, compared to the other two methods. Catalytic tests revealed that the Ru/CeO2 catalyst prepared by the Sol-gel method maintained a 99 % conversion rate of chlorobenzene at 500 °C over 80 h, showcasing remarkable stability and resistance to deactivation. This efficacy is attributed to the enhanced dispersion of Ru and the effective interaction between Ru and CeO2, facilitated by the Sol-gel synthesis process. This method is simple and easy to prepare the catalyst and has broad industrial prospects. The data set is supplemented with XRD, XPS, SEM and SEM-EDS images of the material, providing useful supplementary data; activity evaluation data for dichloromethane, 1,2-chloroethane and chloromethane were measured.

Indoor Air Photocatalytic Decontamination by UV–Vis Activated CuS/SnO2/WO3 Heterostructure

A titania-free heterostructure based on CuS/SnO2/WO3 was obtained by a three-step sol–gel method followed by spray deposition on the glass substrate. The samples exhibit crystalline structures and homogenous composition. The WO3 single-component sample morphology consists of fibers that serve as the substrate for SnO2 development. The CuS/SnO2/WO3 heterostructure is characterized by a dense granular morphology. Photocatalytic activity was evaluated under UV–Vis radiation and indicates that the WO3 single-component sample is able to remove 41.1% of acetaldehyde (64.9 ppm) and 52.5% of formaldehyde (81.4 ppm). However, the CuS/SnO2/WO3 exhibits a superior photocatalytic activity due to a larger light spectrum absorption and lower charge carrier recombination rate, allowing the removal of 69.2% of acetaldehyde and 78.5% of formaldehyde. The reusability tests indicate that the samples have a stable photocatalytic activity after three cycle (12 h/cycle) assessments. During light irradiation, the heterostructure acted as a Z-scheme mechanism using the redox ability of the CuS conduction band electrons and the SnO2/WO3 valence band holes to generate the oxidative species required for VOC removal.

Biotechnology and nanotechnology for remediation of chlorinated volatile organic compounds: current perspectives

Chlorinated volatile organic compounds (CVOCs) are persistent organic pollutants which are harmful to public health and the environment. Many CVOCs occur in substantial quantities in groundwater and soil, even though their use has been more carefully managed and restricted in recent years. This review summarizes recent data on several innovative treatment solutions for CVOC-affected media including bioremediation, phytoremediation, nanoscale zero-valent iron (nZVI)-based reductive dehalogenation, and photooxidation. There is no optimally developed single technology; therefore, the possibility of using combined technologies for CVOC remediation, for example bioremediation integrated with reduction by nZVI, is presented. Some methods are still in the development stage. Advantages and disadvantages of each treatment strategy are provided. It is hoped that this paper can provide a basic framework for selection of successful CVOC remediation strategies.

The performance of chlorobenzene degradation in groundwater: comparison of hydrogen peroxide, nanoscale calcium peroxide and sodium percarbonate activated with ferrous iron

The chlorobenzene (CB) degradation performances by various oxidants, including hydrogen peroxide (H₂O₂), nanoscale calcium peroxide (nCaO₂) and sodium percarbonate (SPC), activated with ferrous iron (Fe(II)) were investigated and thoroughly compared. The results showed that all tested systems had strong abilities to degrade CB. The CB removal rate increased with increasing dosages of oxidants or Fe(II) because the generation of reactive oxygen species could be promoted with the chemical dosages' increase. Response surface and contour plots showed that CB could achieve a better removal performance at the same H₂O₂ and Fe(II) molar content, but the Fe(II) dosage was higher than that of oxidants in the nCaO₂ and SPC systems. The optimal molar ratios of H₂O₂/Fe(II)/CB, nCaO₂/Fe(II)/CB and SPC /Fe(II)/CB were 5.2/7.6/1, 8/8/1, and 4.5/8/1, respectively, in which 98.1%, 98%, and 96.4% CB removals could be obtained in 30 min reaction. The optimal pH condition was around 3, while CB removal rates were less than 20% in all three systems when the initial pH was adjusted to 9. The oxidative hydroxyl radicals (HO•) and singlet oxygen (¹O₂) had been detected by the electron paramagnetic resonance test. Based upon the results of liquid chromatograph-mass spectrometer analysis, the pathways of CB degradation were proposed, in which ¹O₂ roles were elaborated innovatively in the CB degradation mechanism. The CB degradation performance was significantly affected in actual groundwater, while increasing the molar ratio of oxidant/Fe(II)/CB was an effective way to overcome the adverse effects caused by the complex of actual groundwater matrix.

Bimetallic Catalysts for Volatile Organic Compound Oxidation

In recent years, the impending necessity to improve the quality of outdoor and indoor air has produced a constant increase of investigations in the methodologies to remove and/or to decrease the emission of volatile organic compounds (VOCs). Among the various strategies for VOC elimination, catalytic oxidation and recently photocatalytic oxidation are regarded as some of the most promising technologies for VOC total oxidation from urban and industrial waste streams. This work is focused on bimetallic supported catalysts, investigating systematically the progress and developments in the design of these materials. In particular, we highlight their advantages compared to those of their monometallic counterparts in terms of catalytic performance and physicochemical properties (catalytic stability and reusability). The formation of a synergistic effect between the two metals is the key feature of these particular catalysts. This review examines the state-of-the-art of a peculiar sector (the bimetallic systems) belonging to a wide area (i.e., the several catalysts used for VOC removal) with the aim to contribute to further increase the knowledge of the catalytic materials for VOC removal, stressing the promising potential applications of the bimetallic catalysts in the air purification.

Efficient and stable degradation of chlorobenzene over a porous iron–manganese oxide supported ruthenium catalyst

Oxalate pyrolysis and subsequent wet impregnation are facile and effective for loading Ru nanoparticles in the mesopores of Fe–Mn oxides, which leads to a dramatic enhancement in their catalytic reactivity for chlorobenzene combustion.