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Regenerative thermal oxidizers (RTO) serve as pivotal equipment for the treatment of volatile organic compounds (VOCs). However, a diversity of faults of the RTO system may threaten personnel safety and lead to unscheduled downtime. In this work, we develop a traceability inference method based on dynamic uncertain causality graph (DUCG) to identify root fault cause of RTO at early anomaly alarm. A general expert knowledge base for the fault diagnosis of RTO system is constructed. And the anomaly alarm thresholds are modified according to historical data with n-sigma rules to improve the diagnostic accuracy. Results on different cases show advantages in both triggering early anomaly alarms and avoiding invalid alarms, which is crucial to improve the fault inference accuracy. By applying our method to 35 fault cases of a real RTO for pharmaceutical VOCs treatment, the fault detection rate reaches 94.29%, and the fault inference accuracy is 82.86%. The two scores are 3% and 21% higher than those with the conventional DUCG (with fixed alarms), respectively. This remarkable improvement underlines the significance of our proposed method for RTO maintenance, and it is expected to assure the system's operational stability and reliability. [Display omitted] [ABSTRACT FROM AUTHOR]

• Sn was used to regulate the catalytic activity of TiO 2 for dichloromethane oxidation. • The crystal phase transition effect of Sn doping on TiO 2 was systemically investigated. • Adsorption/dissociation behaviors of dichloromethane on dominant crystal surfaces were revealed. Efficient removal of chlorinated volatile organic compounds (CVOCs) has received great attention because of the considerable harm that they cause to the environment and to human health. Developing novel catalysts and exploring the catalytic activation and deconstruction mechanism of CVOCs molecule are always the focus in this field. Here, a set of Sn doped TiO 2 catalysts were investigated for the decomposition of dichloromethane (DCM). Rietveld refinement of the XRD patterns showed that Sn ions can uniformly disperse into TiO 2 and induce the crystal transition of anatase. Meanwhile, such decorating can induce an increase in specific surface area and affect the surface oxygen vacancy concentration of these samples, which have been demonstrated by N 2 adsorption and XPS, respectively. Catalytic performance tests indicated that the Sn 0.2 Ti 0.8 O 2 has the best activity for DCM decomposition, and a lower CH 3 Cl selectivity than that of pure TiO 2. Computational results suggested the dominant surface (110) of rutile Sn 0.2 Ti 0.8 O 2 is more beneficial for the adsorption/dissociation of DCM molecule than that of anatase TiO 2 (101). That's because the anchoring of DCM to Sn sites and electron enrichment on the surface bridge oxygen atoms of rutile Sn 0.2 Ti 0.8 O 2 (110) can promote the nucleophilic substitution process for breaking of C Cl bonds. [ABSTRACT FROM AUTHOR]

Abstract In recent years, significant effort has been made in the development of novel catalysts for the total oxidation of chlorinated volatile organic compounds. In this work the catalytic activity of Cu doped cerium-titanium binary oxides for the oxidation of dichloromethane (DCM) have been studied for the first time. Combining catalysts characterization and activity data, it was found that Cu ions can uniformly disperse into titanium dioxide to form solid solution and induce the creation of additional surface oxygen species on the catalysts surface, while moderate amount of Ce ions are still needed for the activation of C Cl. Detailed analysis of the in-situ FTIR experiment results revealed that the surface oxygen species, especially the hydroxyl groups associated with Cu ions, can promote the deep oxidation of the intermediate species formed in the nucleophilic substitution process occurred on the active sites of catalysts surface. The sample with the Cu/Ce molar ratio of 1:3 obtained a better CO 2 selectivity than that reached with cerium-titanium binary oxides. Meanwhile, according to element balance analysis, removal of chlorine from the catalyst surface was also promoted by Cu doping. Graphical abstract Image 1 Highlights • Catalytic oxidation of dichloromethane over Ce, Cu, Ti ternary oxides has been studied. • Cu doping can promote the products selectivity to CO2 and enhance Cl balance. • Correlation between catalyst structure and catalytic behavior is revealed. • Promotion Mechanism of Cu doping for dichloromethane deep oxidation was explored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel catalysts for CVOCs removal present excellent low-temperature activity and high chlorine resistance. • WO x loading affects the surface species morphology while polymer structure at 10% loading shows the best performance. • The RuO 2 -WO x /Sn 0.2 Ti 0.8 O 2 catalysts exhibit highly stable activity in both dry and wet conditions. • Experimental and computational results prove WO 2 Cl 2 to be the main species for tungsten loss on chlorine poisoned catalysts. • The removal performance of CB, TCE and DCM by the cordierite catalyst is validated. The development of catalysts with high activity, selectivity, and durability is crucial for the catalytic oxidation of chlorinated volatile organic compounds (CVOCs). Although acid-modified supports are widely used in catalysis to improve the catalytic activity at low temperature, the acid sites are easily deactivated by Cl poisoning, and the poisoning mechanism remains unclear. Here, a series of RuO 2 -WO x /Sn 0.2 Ti 0.8 O 2 catalysts were synthesized for dichloromethane (DCM) catalytic oxidation. Spectroscopic characterizations revealed that the loading amount of tungsten oxide highly affects the structure of the surface species and, consequently, the low-temperature catalytic activity. SEM, XRD and DFT calculations elucidated that the loss of tungsten species in the form of WO 2 Cl 2 is the main reason for the catalyst deactivation. By loading RuO 2 , the loss of tungsten species could be effectively avoided via the Deacon reaction. The cordierite catalyst exhibits excellent catalytic activity for the oxidation of different types of CVOCs. [ABSTRACT FROM AUTHOR]

A novel hierarchical MnO x /TiO 2 composite nanofiber was fabricated by combining the electrospinning technique and hydrothermal growth method. The synthesized nanomaterial, which comprised primary TiO 2 nanofibers and secondary MnO x nanoneedles, was further investigated for complete catalytic oxidation of volatile organic compounds for the first time, and this presented high-oxidation performance on low-concentration acetone. The morphological, structural, physicochemical characterization, and catalytic performance analyses demonstrated that the highest catalytic activity was achieved from the obtained MnO x /TiO 2 nanofiber catalyst with 30 wt.% manganese loading. This finding can be ascribed to the synergistic effect of the specific hierarchical nanofibrous morphology, the abundant surface-adsorbed oxygen, the superior redox property, and the sufficient specific surface. [ABSTRACT FROM AUTHOR]

This paper investigated the enhancement of plasma on dimethyl sulfide (DMS) removal over commercial V-W/Ti catalysts. The effects of catalyst composition, discharge power, and gas temperature on DMS removal in the plasma-based system were analyzed. The results showed that the V0.9–W/Ti catalyst exhibited the best performance toward DMS removal due to its highest reducibility among the employed samples. The introduction of plasma exhibited a synergistic effect on catalysts and significantly enhanced the removal of DMS over the studied temperature range, especially in high discharge power cases. The activation energy Ea of DMS removal in the presence of plasma was dramatically reduced to less than 10% of the catalysis only case, indicating different DMS removal pathways in plasma-activated catalysis system. The reaction mechanisms of DMS were also discussed based on the reaction products. [ABSTRACT FROM PUBLISHER]

TiO 2 –carbon and vanadium–TiO 2 –carbon composite nanofibrous membranes were synthesized through electrospinning and investigated for the complete oxidation of low-concentration acetone. The novel nanofibrous membranes were characterized through various techniques, including TG/DSC, SEM-EDX, HRTEM, XRD, N 2 sorption, XPS, NH 3 -TPD, and H 2 -TPR analyses. Introduction of vanadium at an appropriate amount enhances the catalytic performance in complete acetone oxidation. The best result was obtained with 10V–TiC nanofibers that contain 10 wt.% vanadium. Furthermore, the 10V–TiC nanofibers displayed higher activity than that of the V 2 O 5 /TiO 2 reference catalyst prepared by impregnation method. Characterization results indicate that these fibers exhibit a typical nanofibrous morphology. Vanadium incorporation accelerates the decomposition of the gel precursor nanofibers and causes variations in textural properties, surface chemistry, acidity, and reducibility. The high porosity of the nanofibrous structure, abundant adsorbed oxygen species on the surface, strong acidity, and reducibility enhance the catalytic performance. [ABSTRACT FROM AUTHOR]

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities. [ABSTRACT FROM AUTHOR]

• Developed a new RuO 2 -WO 3 /Sn 0.2 Ti 0.8 O 2 catalyst formula for CVOCs catalytic removal. • Studied the effect of RuO 2 loading on catalyst's acidity and catalytic performance. • Studied the synergistic catalysis of CVOCs and multiple pollutant components. Chlorine-containing volatile organic compounds emitted from combustion boilers and chemical industries will cause great harm to the ecological environment and human health. Catalytic combustion technology is one of the commonly used technologies for the treatment of CVOCs. Poor low-temperature activity, high levels of toxic by-products, and poor resistance to chlorine poisoning are common problems faced by its catalyst development. In order to effectively remove CVOCs, we constructed a RuO 2 -WO 3 / Sn 0.2 Ti 0.8 O 2 catalyst formula in which RuO 2 and WO 3 were supported on Sn 0.2 Ti 0.8 O 2 , and tested with DCM as a model molecule. By detecting the catalytic performance of RuO 2 -WO 3 /Sn 0.2 Ti 0.8 O 2 series catalysts with different RuO 2 loadings on DCM and corresponding characterization methods, we found that 3 wt%RuO 2 -5 wt%WO 3 /Sn 0.2 Ti 0.8 O 2 catalyst had the best catalytic performance (T 90% value was 291 °C, CO 2 selectivity was close to 100% at 325 °C). The actual industrial environment often contains multiple gas pollutants at the same time, so it is important to study the ability of the catalyst to co-process multiple pollutants. The effects of other pollutants (propane, acetone, SO 2 and NO 2) in the reaction atmosphere on the catalytic oxidation performance of DCM were further studied. It was found that the RuO 2 -WO 3 /Sn 0.2 Ti 0.8 O 2 catalyst could achieve the coordinated removal of acetone, propane and dichloromethane, and the effects of SO 2 and NO 2 on catalytic oxidation performance of DCM was revealed. It is hoped that it can serve as a reference and guidance for the subsequent industrial application of the catalyst in this system. [ABSTRACT FROM AUTHOR]

• Porous carbons were obtained by KOH activation of hydrothermal carbonized sucrose. • Highest specific area of 2604 m2/g could be reached when KOH/hydrochar ratio was 3. • Adsorption capacities of PCs were closely related to the vapor pressure of VOCs. • Pores with size of 1–3 times of VOC diameter in PCs played key roles in adsorption. • 90 % of initial adsorption capacity could be reached after four regeneration cycles. The pore structure of materials plays a key role in adsorption, and it is of great significance to regulate the porosity of adsorbent for specific adsorbate. Herein, porous carbons (PCs) with engineered porosity were synthesized as adsorbents for volatile organic compounds (VOCs), which employed sucrose-based hydrochar via KOH activation. Surface area of 2604 m2/g together with pore volume of 1.685 cm3/g could be reached when KOH/hydrochar ratio was 3. The adsorption capacities of three typical VOCs were in the order of toluene > acetic ether > acetone, with the vapor pressure had greatest effect on adsorption among the properties of adsorbates. Influence of carbon porosity was further investigated, showing that micropores in the range of 1–3 times of the VOC diameter were crucial to the adsorption process. In addition, more than 90 % of the initial adsorption capacity could be reached after four regeneration cycles. Considering economic and environmental aspects, we demonstrated porous carbons derived from hydrothermal carbonized sucrose could be promising materials in adsorption. This work could also provide guidance for the porosity regulation of adsorbents for different VOCs. [ABSTRACT FROM AUTHOR]