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A solvent-free, acid-free, and efficient strategy was developed for the selective preparation of 4-nitro-o-xylene (4-NOX) from the catalytic nitration of o-xylene with NO2 mediated O2 over BiCl3 immobilized silicic acid catalyst (BiCl3-SA). The results indicated that the Lewis acid BiCl3-SA conjoined NO2–O2 as a composite system synergistically promotes o-xylene conversion and 4-NOX selectivity. Under optimal conditions, 52.4% of o-xylene conversion with 68.4% 4-NOX selectivity was obtained at 35 °C. The characterization demonstrated that the highly dispersed metal Bi species form stable chemical bonds with the SA surface, which can effectively inhibit the loss of metal species and generate abundant acid sites. The developed catalyst is not only inexpensive but also has excellent stability and catalytic performance. Furthermore, a plausible mechanism for the catalytic nitration of o-xylene using NO2 as a nitration agent over BiCl3-SA was proposed. This work provides an eco-friendly and practical protocol for improving desirable 4-NOX selectivity and reducing the discharge of acidic wastewater, with potential application prospects. [ABSTRACT FROM AUTHOR]

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The effects of technogenic hydrocarbons (benzo[α]pyrene, butyl acetate, and o-xylene) on the state of stress-sensitive photosystem II in leaves of seedlings of silver birch (Betula pendula Roth.), small-leaved linden (Tilia cordata Mill.), Norway maple (Acer platanoides L.), and little-leaf poplar (Populus pyramidalis Roz.) were assessed by pulse–amplitude-modulated (PAM) fluorimetry. The degree of response to intoxication was similar for toxins of different nature and depended on the previous stress in the plants, e.g., birch seedlings that had undergone natural stress reacted weaker to chemical stress. Poplar leaves showed the highest response to intoxication and rapid adaptability. The coefficient of nonphotochemical fluorescence quenching qN was the most sensitive parameter and increased after treatment with hydrocarbons by 2–5 times in seedlings of different species. Nonradiative dissipation of excitation energy was probably the main mechanism for protecting photosynthetic membranes under chemical stress. [ABSTRACT FROM AUTHOR]

It is important to develop effective strategies for enhancing the removal capacity of aromatic volatile organic compounds (VOCs) by modifying conventional porous adsorbents. In this study, a novel HZSM-5 zeolite-supported sulfonic acid (ZSM−OSO3H) was prepared through ClSO3H modification in dichloromethane and employed for the elimination of gaseous o-xylene. The ClSO3H modification enables the bonding of −OSO3H groups onto the HZSM-5 support, achieving a loading of 8.25 mmol·g−1 and leading to a degradation in both crystallinity and textural structure. Within an active temperature range of 110–145 °C, ZSM−OSO3H can efficiently remove o-xylene through a novel reactive adsorption mechanism, exhibiting a removal rate exceeding 98% and reaching a maximum breakthrough adsorption capacity of 264.7 mg. The adsorbed o-xylene derivative is identified as 3,4-dimethylbenzenesulfonic acid. ZSM−OSO3H demonstrates superior adsorption performance for o-xylene along with excellent recyclability. These findings suggest that ClSO3H sulfonation offers a promising approach for modifying various types of zeolites to enhance both the elimination and resource conversion of aromatic VOCs.

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the product due to the limitations of the process. In this study, the process underwent enhancements to attain the effective separation of styrene and accomplish deep desulfurization. A mixture of sulfolane (SUL) and N-methylpyrrolidone (NMP) was selected as the extraction solvent after calculating the UNIFAC group contributions. An orthogonal experiment was conducted to investigate the effects of the solvent/oil ratio, reflux ratio, water addition rate, and solvent ratio on the product. The correspondence between each factor and the indexes examined was determined, enabling the optimization and prediction of the styrene product quality. The final optimized conditions for the extractive distillation column are as follows: solvent/oil ratio of 7, reflux ratio of 4.5, water addition rate of 6000 kg/h, and a solvent ratio of 9:1. Under optimal conditions, the purity of the product was observed to be greater than that of the original process and the sulfur content of the product can be reduced to lower than 10 ppm at the cost of an increase of 12.31% in energy consumption. [ABSTRACT FROM AUTHOR]

Pd/Al 2 O 3 was pretreated by CO, H 2 and NaBH 4 reduction, respectively. The reduced catalysts were tested for o -xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of palladium hydride (TPDH). The characterizations indicate the pretreatments lead to distinct Pd particle sizes and amount of surface activated oxygen species, which are responsible for the catalytic performance. Compared with H 2 and NaBH 4 reduction methods, CO reduction shows a strong interaction between Pd and Al 2 O 3 with smaller Pd particle size and more surface activated oxygen. It exhibited excellent catalytic performance, complete oxidation of 50 ppmV o -xylene at 85°C with a WHSV of 60,000 mL/(g∙hr). [Display omitted] [ABSTRACT FROM AUTHOR]

• Energy-saving extractive distillation for separating dimethyl carbonate/methanol presented. • O-Xylene is selected as suitable entrainer for its relative low boiling point, price, and toxicity. • A lab-scale extractive distillation is modeled, analyzed, validated and further be scale-upped. • The optimized extractive distillation offers marked economic benefit and CO 2 emission reduction. The pressure-swing distillation traditionally used in the industry for separating dimethyl carbonate/methanol (DMC/MeOH) commonly suffers from high energy consumption and challenges in achieving high-purity separation due to the existence of pinch zone. Hence, energy-saving extractive distillation system is explored to achieve the high-purity separation of DMC/MeOH azeotrope. With the analyses of isovolatility and residue curve maps based on Wilson model calibrated by vapor–liquid equilibrium experimental data, an extractive distillation process using O-Xylene (OX) as the most suitable entrainer were modeled and experimentally validated. Furthermore, design, optimization, and comparison of an extractive distillation process and a pressure-swing distillation process for producing 10000 t DMC/a are investigated. It is demonstrated that the extractive distillation process presents significant economic and emission advantage, specifically with 34.66 % and 26.95 % reductions in operating cost (OC) and in total annual cost (TAC) respectively, as well as 42.53 % reduction in CO 2 emissions. This work should provide a feasible and promising approach to energy saving, low-carbon, and high-purity separation of DMC/MeOH azeotrope. [ABSTRACT FROM AUTHOR]

1. The influence of NH 2 groups on the adsorption and photocatalytic performance of MIL-125 for gaseous flowing o-xylene and acetaldehyde has been explored. 2. This study provides a valuable reference for understanding the effects of ligand functionalization on the photocatalytic performance of MOF materials for VOCs. [Display omitted] • Higher degradation efficiency of NH 2 -MIL-125 for o-xylene and acetaldehyde. • Higher adsorption and photocatalytic degradation of o-xylene than acetaldehyde. • High adsorption capacity of MIL-125 for o-xylene and acetaldehyde. • The incorporation of –NH 2 promoted the formation of OH and O 2 − radicals. Ligand functionalization of metal organic framework (MOF) is a great important strategy to enhance the various properties of pristine materials. In this study, MIL-125 with different extents of NH 2 -functionalization were synthesized by solvothermal method. The photocatalytic degradation efficiency of the optimal sample for o-xylene and acetaldehyde were 88 % and 49 %, respectively, which were much improved compared to pristine MIL-125 (56 % for o-xylene and 3 % for acetaldehyde). Compared to pristine MIL-125, NH 2 -functionlized MIL-125 were more easily photoexcited to form photogenerated carriers, which facilitated the formation of more OH and O 2 − radicals under visible light irradiation. In addition, NH 2 groups as the adsorption site interacted with o-xylene and acetaldehyde by the H-bonding and the Lewis acid-base effect, respectively. The above results contribute to a deep understanding of the influence of ligand functionalization of MOF on the photocatalytic degradation of VOCs. [ABSTRACT FROM AUTHOR]

In the present work, complexes formed by the rare earth elements (La, Lu) and di-(2-ethylhexyl)phosphoric acid were synthesized and identified. The densities of D2EHPA–lanthanum (lutetium) di-(2-ethylhexyl)phosphate–o-xylene solutions forming an organic phase in the lanthanide extraction processes were measured; the volumetric properties of D2EHPA–di-(2-ethylhexyl)phosphate REE–o-xylene systems were described using the Redlich-Kister polynomial model. The data on the saturated vapor pressure over D2EHPA–lanthanum (lutetium) di-(2-ethylhexyl)phosphate–o-xylene solutions are obtained at temperatures of 298.15, 303.15, and 308.15 K. The temperature-concentration dependencies of the activity coefficients of o-xylene in the investigated ternary systems were described with the UNIQUAC thermodynamic model taking into account the formation of D2EHPA dimers in solution. [ABSTRACT FROM AUTHOR]

Exploring high-efficiency and stable monolithic structured catalysts is vital for catalytic combustion of volatile organic compounds. Herein, we prepared a series of Pd/δ-MnO2 nanoflower arrays monolithic integrated catalysts (0.01–0.07 wt% theoretical Pd loading) via the hydrothermal growth of δ-MnO2 nanoflowers onto the honeycomb cordierite, which subsequently served as the carrier for loading the Pd nanoparticles (NPs) through the electroless plating route. Moreover, we characterized the resulting monolithic integrated catalysts in detail and evaluated their catalytic activities for toluene combustion, in comparison to the controlled samples including only Pd NPs loading and the δ-MnO2 nanoflower arrays. Amongst all the monolithic samples, the Pd/δ-MnO2 nanoflower arrays monolithic catalyst with 0.05 wt% theoretical Pd loading delivered the best catalytic performance, reaching 90% toluene conversion at 221°C at a gas hourly space velocity (GHSV) of 10,000 h−1. Moreover, this sample displayed superior catalytic activity for o-xylene combustion under a GHSV of 10,000 h−1. The monolithic sample with optimal catalytic activity also displayed excellent catalytic stability after 30 h constant reaction at 210 and 221°C.

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5–50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial HCPS sorbent Purolite Macronet™ MN200 was chosen due to its high sorption capacity for organic solvents. It has been found that the membranes are asymmetric when HCPS content is higher than 30 wt%; scanning electron microscopy of the cross-sections the membranes demonstrate that they have a clearly defined thin layer, consisting mainly of PTMSP, and a thick porous layer, consisting mainly of HCPS. The transport and separation characteristics of PTMSP membranes with different HCPS loading were studied during the pervaporation separation of binary and multicomponent mixtures of water with benzene, toluene and xylene. It was shown that the addition of HCPS up to 30 wt% not only increases the permeate fluxes by 4–7 times, but at the same time leads to 1.5–2 fold increase in the separation factor. It was possible to obtain separation factors exceeding 1000 for all studied mixtures at high permeate fluxes (0.5–1 kg/m2∙h) in pervaporation separation of binary solutions. [ABSTRACT FROM AUTHOR]

Efficient removal of insoluble volatile organic compounds (VOCs) from wastewater is a significant environmental challenge. In this work, we exploit the synergistic effect of photocatalysis and the high interfacial area of TiO 2 -stabilized Pickering emulsion to achieve efficient degradation of o-xylene, typically present in wastewater discharged from many industries. Interfacial photocatalysis is carried out by considering o-xylene in water Pickering emulsions stabilized by commercial titania nanoparticles in a multitube non-stirred reactor setup. Stable emulsions used for catalysis are formulated by optimizing o-xylene volume fraction, TiO 2 concentration, pH, and homogenization conditions. The influence of photocatalyst loading, emulsion droplet size, and reaction conditions are systematically examined to determine their influence on the rate of photocatalytic degradation of o-xylene. Due to enhanced photocatalytic activity compared with conventional stirred batch photocatalysis, the TiO 2 -stabilized Pickering emulsion is found to increase the degradation rate and removal efficiency of o-xylene significantly. Furthermore, the Pickering emulsion stability during the photocatalytic process is studied, demonstrating the capacity of the emulsions to maintain stability and catalytic activity over a longer time period. The distinctive characteristics of Pickering emulsions – excellent storage stability and enhanced photocatalytic activity – make them a promising option for advanced wastewater treatment. The findings lead to the development of ecologically acceptable and sustainable VOC degrading strategies, which might be used in industrial and home wastewater treatment systems. [Display omitted] • Formulation of Titania stabilized o-xylene in water pickering emulsion. • Photocatalytic degradation of o-xylene in a multitube non-stirred reactor setup. • Four times better o-xylene degradation compared to a conventional stirred tank reactor. • Key parameters like particle concentration and emulsion droplet size optimize degradation. • Promising sustainable strategy for treating VOCs in industrial and domestic wastewater. [ABSTRACT FROM AUTHOR]

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the product due to the limitations of the process. In this study, the process underwent enhancements to attain the effective separation of styrene and accomplish deep desulfurization. A mixture of sulfolane (SUL) and N-methylpyrrolidone (NMP) was selected as the extraction solvent after calculating the UNIFAC group contributions. An orthogonal experiment was conducted to investigate the effects of the solvent/oil ratio, reflux ratio, water addition rate, and solvent ratio on the product. The correspondence between each factor and the indexes examined was determined, enabling the optimization and prediction of the styrene product quality. The final optimized conditions for the extractive distillation column are as follows: solvent/oil ratio of 7, reflux ratio of 4.5, water addition rate of 6000 kg/h, and a solvent ratio of 9:1. Under optimal conditions, the purity of the product was observed to be greater than that of the original process and the sulfur content of the product can be reduced to lower than 10 ppm at the cost of an increase of 12.31% in energy consumption.

Malondialdehyde (MDA) content is a widely used parameter as a measure of lipid peroxidation in plant tissue that increases under oxidative stress. In model experiments, the effect of various doses of volatile organic compounds (o-xylene, benzopyrene, butyl acetate) on the MDA content in the leaves of small-leaved linden Tilia cordata Mill. and Norway maple Acer platanoides L. was studied. It was found that one day after the treatment butyl acetate has the strongest stimulating effect on the MDA content in the leaves of small-leaved linden and o-xylene and benzopyrene – in the leaves of Norway maple. Three days after processing, o-xylene and benzopyrene are highly active substances for small-leaved linden, and benzopyrene for Norway maple. The complex effect on the leaves of small-leaved linden and Norway maple seedlings with a mixture of butyl acetate and o-xylene leads to an increase in the toxicity of butyl acetate in the presence of o-xylene compared with its single effect. Under natural conditions, the MDA content in the leaves of small-leaved linden and Norway maple near industrial factories was 1.5-2.0 times higher than in the plants growing in protected areas. Ontogenetic and species differences in the MDA content in the leaves of small-leaved linden and Norway maple caused by their growth in different industrial zones were established. [ABSTRACT FROM AUTHOR]

This work focuses on the optimization of the acid treatment and calcination process factors affecting the catalytic performance of the SmMnO3/cordierite monolithic catalyst for o-xylene oxidation, using response surface methodology (RSM) analysis. A central composite rotatable design (CCRD) was used to statistically visualize the complex interactions of acid treatment time, acid concentration, calcination temperature, and calcination time for T50 and T90 values. And the validity of the models developed was verified by experiments. Statistics showed the most significant process factor which affects catalytic combustion activity is acid treatment time. It is also shown that the catalytic activity increases with increasing acid treatment time or acid concentration and that a moderate calcination temperature or time is required to increase the catalytic activity. Furthermore, it was found through SEM analysis that the acid treatment process significantly impacts the morphology of the SmMnO3/cordierite monolithic catalysts. Thus, RSM is an effective technique for estimating the catalytic activity of monolithic catalysts. In this work, the effects of acid treatment and calcination process on the catalytic performance of SmMnO3/cordierite monolithic catalyst for o-xylene oxidation were based on response surface methodology (RSM) through presenting a mathematical modeling and factorial analysis. [ABSTRACT FROM AUTHOR]

The detailed experimental studies of the autothermal and steam reforming of model mixtures simulating the composition of commercial diesel fuel were carried out over Rh/Ce 0.75 Zr 0.25 O 2-δ -ƞ-Al 2 O 3 /FeCrAl wire mesh honeycomb catalytic modules. The components of the diesel surrogates were n -hexadecane, o-xylene, and naphthalene as model compounds of aliphatics, mono-aromatics and diaromatics, respectively. It was shown that low reaction rate of diaromatics steam reforming facilitated increasing concentration of C 1 –C 5 hydrocarbon by-products (primarily ethylene) in the gas phase, as well as formation of polyaromatic compounds by concurrent condensation reaction. These undesirable processes were responsible for increasing catalyst coking. Monoaromatic constituents hadn't any significant effect on the progress of undesirable side-reactions during autothermal and steam reforming of diesel surrogates. [Display omitted] • Rh/Ce 0.75 Zr 0.25 O 2-δ -ƞ-Al 2 O 3 /FeCrAl wire mesh honeycomb catalytic module. • Hexadecane autothermal and steam reforming. • High conversion of hexadecane and o-xylene blend in autothermal and steam reforming. • By-products formation due to undesirable side-processes of naphthalene reforming. [ABSTRACT FROM AUTHOR]

[Display omitted] • The decreased adsorption energy of TiO 2 decorated with rare-earth single atoms enhanced the adsorption capability to O-xylene. • Improved charge separation was ascribed to charge transfer channel between rare-earth atom and O atom. • TiO 2 decorated with rare-earth single-atom exhibited an enhanced photocatalytic performance. • The influence of rare-earth single atoms on intermediates produced of O-xylene during photocatalytic process was proposed. In this work, rare-earth single atoms (La, Er) were decorated on the surface of 2D-TiO 2 nanosheets by an impregnation-calcination strategy. The formation of rare-earth single atoms was certified by AC HAADF-STEM and XAS. TiO 2 decorated with rare-earth single atoms (La 1 -TiO 2 and Er 1 -TiO 2) exhibited outstanding photocatalytic activity than pure 2D-TiO 2 nanosheets (2D-TiO 2) towards gas-phase degradation of O-xylene. Compared with 2D-TiO 2 , the rare-earth single atoms greatly improved the adsorption capacity of O-xylene without increasing their specific surface area. This is because rare-earth single atoms provide additional adsorption sites and reduce the adsorption energy of O-xylene. In addition, the hybrid orbital formed by the combination of rare-earth single atom and oxygen atom is beneficial to the rapid transmission and separation of photo-induced electrons, thereby improving the performance of photocatalytic degradation. In addition, in-situ DRIFTS and GC–MS were used to reveal the photocatalytic oxidation mechanism. Interestingly, the results showed that the La 1 -TiO 2 and Er 1 -TiO 2 samples can reduce the types of intermediates and simplify the reaction route, implying that the single atoms play an important role in the modulation and thorough mineralization of intermediate products. This work shows that the rare-earth single atom decorated 2D-TiO 2 nanosheets have great potential in photocatalytic air pollution control. [ABSTRACT FROM AUTHOR]

It is important to develop effective strategies for enhancing the removal capacity of aromatic volatile organic compounds (VOCs) by modifying conventional porous adsorbents. In this study, a novel HZSM-5 zeolite-supported sulfonic acid (ZSM-OSO 3 H) was prepared through ClSO 3 H modification in dichloromethane and employed for the elimination of gaseous o -xylene. The ClSO 3 H modification enables the bonding of -OSO 3 H groups onto the HZSM-5 support, achieving a loading of 8.25 mmol·g -1 and leading to a degradation in both crystallinity and textural structure. Within an active temperature range of 110-145 °C, ZSM-OSO 3 H can efficiently remove o -xylene through a novel reactive adsorption mechanism, exhibiting a removal rate exceeding 98% and reaching a maximum breakthrough adsorption capacity of 264.7 mg. The adsorbed o -xylene derivative is identified as 3,4-dimethylbenzenesulfonic acid. ZSM-OSO 3 H demonstrates superior adsorption performance for o -xylene along with excellent recyclability. These findings suggest that ClSO 3 H sulfonation offers a promising approach for modifying various types of zeolites to enhance both the elimination and resource conversion of aromatic VOCs.

For organic photovoltaic cells, the development of new green solvents and nontoxic and halogen‐free additives is an urgent issue. Here, a simple combination of o‐xylene (O‐XY) and ethyl 2‐hydroxybenzoate (EHB) is introduced in inverted devices based on poly[4,8‐bis(5‐(2‐ethylhexyl)‐thiophene‐2‐yl) benzo[1,2‐b;4,5‐b′] dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b] thiophene)‐2‐carboxylate‐2‐6‐diyl]:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PTB7‐Th:PC71BM) as blend layers, the device performance reaches optimal values (9.29%) when O‐XY and 3% EHB are introduced as additives, accompanied by the maximum fill factor (67.5%) and JSC (17.20 mA cm−2). From the results of characterization analysis, it is clear that EHB additive improves the crystallinity of the donor by regulating the kinetic process of active layer formation, selectively solubilizes the more aggregated fullerene acceptors, which allows PTB7‐Th to enter the conformational domain of PC71BM, and accelerates the molecular rearrangement. Besides, the EHB additive not only reduces the recombination, increases the carrier migration rate but also promotes the crystallinity of the donor, resulting in a tighter stacking. This work provides a green combination of solvents and additives that is important for the mass production of solar cells. [ABSTRACT FROM AUTHOR]

Plastic waste is one of the major contributing factors to the growth of municipal solid wastes globally. It is a threat to public health and negatively impact the aquatic and terrestrial animals due to its persistence in the environment. Bacterial and fungal isolates were tested for their ability to degrade polystyrene. The cultures were grown on mineral salts medium supplemented with polystyrene as the sole carbon source in 250 mL conical flasks. The polystyrene reduced from 1 g (week 0) to 0.7g (week 7). Statistical analysis of variance (one-way ANOVA) shows a significant difference between the reduction in weight of polystyrene in the experimental flask compared to the control (P<0.05). Gas chromatography mass spectrometry analysis of biodegradation products shows that some toxic polystyrene constituents such as O-xylene, cis-9-hexadecenal and 3-phenol pentadecyl were removed. [ABSTRACT FROM AUTHOR]

SmMnO3/cordierite monolithic catalysts were synthesized by a modified citric acid method and treated with dilute HNO3, which was used to explore the effect of acid treatment on the catalytic performance and mechanical stability of the monolithic catalysts. Firstly, acid treatment can significantly improve catalytic activity of catalyst in o‐xylene oxidation, which is attributed to the increase of the specific surface area of the catalyst and the change of surface oxygen species. A series of single factor experiments show that the SmMnO3/cordierite monolithic catalyst treated by 1.0 mol/L HNO3 for 6 h and calcined at 450 °C for 1 h has the best performance. Furthermore, the mechanical stability of the catalysts treated by dilute HNO3 was tested, which show that too long acid treatment time and too high acid concentration will reduce the mechanical stability of the catalyst and 1.0 mol/L HNO3 treatment for 1 h is the best. Different calcination temperature and calcination time will also affect the mechanical stability of the catalyst. Finally, the catalyst has good stability of catalytic performance and mechanical stability. [ABSTRACT FROM AUTHOR]

• Low temperature oxidation of o-xylene was enhanced by adding dimethyl ether in an atmospheric jet stirred reactor. • The negative temperature coefficient phenomenon of o-xylene and featured low temperature intermediates were detected by using SVUV-PIMS. • Featured phenyl hydroperoxides and ketohydroperoxides were identified by combining experimental and theoretical analyses. • A kinetic model was proposed for revealing the low temperature oxidation of oxylene, as well as its crucial interactions with dimethyl ether. The branched aromatic hydrocarbon with short side chains, such as o -xylene, has weak low temperature oxidation reactivity, while it could proceed low temperature chain recycling reactions by blending a fuel component with higher oxidation reactivity. However, the study of low temperature oxidation kinetics of o -xylene is very scarce. Therefore, this work investigated the low temperature oxidation process of o -xylene in an atmospheric jet stirred reactor by adding a biofuel with higher low temperature oxidation reactivity, i.e. dimethyl ether (DME). A series of characteristic low temperature intermediates, such as phenyl hydroperoxides and ketohydroperoxide from the oxidation of o -xylene, were detected by using the synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The chemical structures of representative low temperature intermediates were determined by comparing the ionization thresholds from measured photoionization efficiency curves with calculated ionization energies. A kinetic model for o -xylene and DME mixture was developed and verified by literature and present experimental data. Rate of production (ROP) and sensitivity analyses were performed, which indicate that the low temperature oxidation chemistry of o -xylene, such as the negative temperature coefficient behavior, is enhanced by the reaction pool of DME. According to the classical low temperature oxidation mechanism of n -alkanes, the low temperature reactions of o -xylene were proposed. In particular, phenyl hydroperoxides and ketohydroperoxides were revealed to be key indicators for the occurrence of first and second O 2 addition reactions during the oxidation of o -xylene, respectively. In addition, the sensitivity analysis uncovers the interaction kinetics between the reaction pools of o -xylene and DME, as well as their effects on fuel consumption and products formation. In summary, present evidence elucidates the low temperature chemistry of a representative branched aromatic, which could contribute to the development of future engines and control of combustion pollutants. [ABSTRACT FROM AUTHOR]

Utilizing cost-effective solid waste, fly ash, the present study has successfully synthesized fly ash-based zeolite (FAZ) and systematically engineered fly ash-based zeolite template carbon (FA-ZTC) with regular pore structure. FA-ZTC exhibits an average pore diameter ranging from 4.95 nm to 6.74 nm, inheriting the hierarchical porosity characteristic of FAZ. This hierarchical porosity effectively alleviates the substantial diffusion limitations commonly encountered in volatile organic compounds adsorption processes associated with purely microporous substrates. FAZ and FA-ZTC achieved maximum o-xylene adsorption capacities of 94.1 mg/g and 338.6 mg/g, respectively. Significantly, the functional groups on the surface of the FA-ZTC within an air atmosphere facilitated its adsorption of o-xylene, while SO 2 exhibited inhibitory effects. The Langmuir adsorption isotherm and Bangham kinetic models yielded excellent adsorption fitting results, revealing a primarily exothermic adsorption process driven by physical interactions, with pore diffusion as the key rate-determining factor. Adsorption heat (∆H ads =−13.78 kJ/mol) and Weber-Morris intraparticle diffusion model further confirmed the weaker adsorption affinity of FA-ZTC, highlighting the significant advantage of its hierarchical mesoporous structure in mass transport. Desorption and regeneration demonstrate that FA-ZTC exhibits low desorption temperatures and achieves effective thermal regeneration. These findings significantly underscore the potential commercial utility and cost-effectiveness of FA-ZTC as a promising adsorbent for gaseous o-xylene. [Display omitted] • Zeolite and zeolite-templated carbon materials were successively prepared using fly ash as the raw material. • The fly ash-based zeolite-templated carbon possesses a large specific surface area, abundant hierarchical pore structure, and high adsorption capacity. • The adsorption performance is closely related to the synthesis conditions. • The hierarchical pore structure is beneficial to the pore diffusion of o-xylene adsorption and desorption process. • The adsorption behavior is exothermic physical adsorption. [ABSTRACT FROM AUTHOR]

An efficient continuous-flow nitration process of o-xylene at pilot scale was demonstrated. The effects of parameters such as temperature, ratio of H2SO4 to HNO3, H2SO4 concentration, flow rate, and residence time on the reaction were studied. Under the optimal conditions, the yield of products reached 94.1%, with a product throughput of 800 g/h. The main impurities of this continuous-flow nitration process were also studied in detail. Compared with batch process, phenolic impurity decreased from 2% to 0.1%, which enabled the omission of the alkaline solution washing step and thus reduced the wastewater emission. The method was also successfully applied to the nitrification of p-xylene, toluene, and chlorobenzene with good yields.

This work reports an experimental and kinetic modelling investigation on flow reactor pyrolysis and jet-stirred reactor oxidation of o -xylene. The flow reactor pyrolysis experiments were conducted over 1050–1600 K at 0.04 and 1.0 atm. Key products related to fuel decomposition such as o -xylyl radical, o -xylylene, benzocyclobutene and styrene, as well as polycyclic aromatic hydrocarbons (PAHs), were detected by using synchrotron vacuum ultraviolet photoionization mass spectrometry. The jet-stirred reactor oxidation experiments were performed at 10 atm, 800–1200 K, a residence time of 0.5 s and equivalence ratios of 0.5, 1.0 and 2.0. Speciation were conducted by using gas chromatography and Fourier transform infrared spectrometry. A kinetic model of o -xylene was developed from our previous models of aromatic fuels and validated against both present data and experimental data in literature. Styrene is observed as the dominant product in the pyrolysis of o -xylene and it is mainly produced from the isomerization of o -xylylene directly or via benzocyclobutene as an intermediate species. C 9 PAHs (indenyl, indene and indane), phenanthrene and its methyl derivatives were observed as the abundantly produced bicyclic and tricyclic PAHs. The main formation pathways of bicyclic and tricyclic PAHs are found to be different at low and atmospheric pressures, depending on the major precursors produced. Particularly, the self-combination reactions of o -xylyl and the addition reaction of o -xylyl with benzyl and subsequent stepwise H-loss/cyclization reactions are found to be the main sources of methylphenanthrene and dimethylphenanthrene. In the JSR oxidation of o -xylene, toluene and benzene were observed as the abundantly produced aromatic products, while o -methylbenzaldehyde was among the most abundantly produced oxygenated aromatics. modelling analysis reveals that o -xylyl radical is also the dominant fuel consumption product. Its consumption mainly proceeds through the oxidation by HO 2 and finally produces o -methylbenzaldehyde. Further decomposition reactions of o -methylbenzaldehyde contribute to the formation of other major oxygenated aromatics such as cresol and benzofuran. Indene and naphthalene were also observed in the oxidation of o -xylene, which are mainly produced from the stepwise H-loss/cyclization reaction sequence of o -methylethylbenzene and decomposition of dibenzofuran, respectively. [ABSTRACT FROM AUTHOR]

Oxidation of o-xylene was performed using alkaline battery-based catalyst doped with platinum to investigate the properties and activities. O-xylene was selected as the model of volatile organic compound (VOC) in this work. Physicochemical properties of the selected catalysts were characterized by FE/TEM (field emission transmission electron microscopy), BET (Brunauer-Emmett-Teller) analysis, XRD (X-ray powder diffraction), SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy), and H2-TPR (hydrogen temperature programmed reduction). Major elements of the spent alkaline battery-based catalyst treated with sulfuric acid solution [SAB (400) catalyst] were manganese, zinc, iron, oxygen, carbon, chlorine, aluminum, sodium, silicon, and potassium. Increasing the doping amount of platinum on SAB (400) catalyst from 0.1 to 1 wt% increased particle size of platinum and lowered the temperature of TPR (TTP) for SAB (400) catalyst. Better redox properties were achieved with an increase in the o-xylene conversion according to the doping amount of platinum. When GHSV (gas hourly space velocity) was 40,000 h−1, o-xylene was oxidized completely over SAB (400) catalyst and 1.0 wt% Pt/SAB(400) catalyst at temperatures of 400 °C and 280 °C, respectively. [ABSTRACT FROM AUTHOR]

o -Xylene oxidation displays an autoignition behavior similar to alkanes at low temperatures. This paper presents a detailed investigation of the chemical kinetics of oxygen additions with the o -xylyl radical that control the ignition reactivity of o -xylene at low temperatures. High-level electronic structure calculations, transition state theory, and master equation simulations are combined to predict the rate coefficients of main elementary reactions. For the initially formed o -methylbenzylperoxy (ROO) in the first oxygen addition o -xylyl + O 2 , its isomerization to o -hydroperoxymethyl-benzyl (QOOH) proceeds with a much smaller branching ratio compared to the counterpart ROO → QOOH in alkanes. Despite the slow formation of QOOH, the absence of fast dissociation pathways enable QOOH concentration to build up. QOOH that has the unpaired electron located on a side-chain carbon can readily react with a second molecular oxygen. The QOOH + O 2 reaction then efficiently leads to the growth of the radical pool through a highly chain-branching reaction sequence QOOH + O2 → 2-hydroperoxymethyl-benzaldehyde + OH → 1,2-diformylbenzene + 2OH + H. The predicted oxygen addition kinetics offers a good explanation for the alkane-like autoignition behavior of o -xylene. Meanwhile, as the key intermediate to chain branching, the lower yield of QOOH results in its lower ignition reactivity. The present study shows that classical low temperature scheme is also valid for benzylic-type hydrogens and radicals of o -xylene where the transferred hydrogen from the ortho -methyl chain facilitates the isomerization ROO ↔ QOOH. It is also easy to deduce that for m - and p -xylenes, where no such isomerization step is available, little reactivity should be expected at the low temperature. [ABSTRACT FROM AUTHOR]

Xylenes are considered one of the most common hazardous sources of environmental contamination. The biodegradation of these compounds has been often reported, rarer the ability to oxidize the ortho-isomer. Among few o-xylene-degrading bacteria, Rhodococcus opacus R7 is well known for its capability to degrade diverse aromatic hydrocarbons and toxic compounds, including o-xylene as only carbon and energy source. This work shows for the first time the RNA-seq approach to elucidate the genetic determinants involved in the o-xylene degradation pathway in R. opacus R7. Transcriptomic data showed 542 differentially expressed genes that are associated with the oxidation of aromatic hydrocarbons and stress response, osmotic regulation and central metabolism. Gene ontology (GO) enrichment and KEGG pathway analysis confirmed significant changes in aromatic compound catabolic processes, fatty acid metabolism, beta-oxidation, TCA cycle enzymes, and biosynthesis of metabolites when cells are cultured in the presence of o-xylene. Interestingly, the most up-regulated genes belong to the akb gene cluster encoding for the ethylbenzene (Akb) dioxygenase system. Moreover, the transcriptomic approach allowed identifying candidate enzymes involved in R7 o-xylene degradation for their likely participation in the formation of the metabolites that have been previously identified. Overall, this approach supports the identification of several oxidative systems likely involved in o-xylene metabolism confirming that R. opacus R7 possesses a redundancy of sequences that converge in o-xylene degradation through R7 peculiar degradation pathway. This work advances our understanding of o-xylene metabolism in bacteria belonging to Rhodococcus genus and provides a framework of useful enzymes (molecular tools) that can be fruitfully targeted for optimized o-xylene consumption.

To establish a novel approach for VOCs resource utilization, coupled o-xylene oxidation and hematite reduction was investigated in this study in a high-temperature gas-solid reactor in the temperature range 300–700 °C. As the o-xylene-containing inert gas (N2) stream traveled through the hematite particle bed, its reaction behavior was determined in programmed heating and constant temperature modes. Consequently, the effect of bed temperature, flow rate and o-xylene inlet concentration on both o-xylene removal performance and degree of hematite reduction was studied. The raw hematite and solid products were analyzed by TGA, XRF, XRD and SEM-EDS. The results showed that a temperature above 300 °C was required to completely eliminate o-xylene by hematite, and both o-xylene removal capacity and degree of hematite reduction at 5% breakthrough points enhanced on increasing the temperature and decreasing the flow rate. The increment in temperature from 300 °C to 700 °C led to a gradual reduction of Fe2O3 to Fe3O4, FeO and metallic iron. Thus, this study provides a novel, economic and promising technology for treating the VOC pollutants.

Different band bending situations would be formed when o-xylene and acetaldehyde adsorbed on TiO 2 surface, and this could result in different generation situations of active radicals. • O-xylene and acetaldehyde adsorption could influence the band structure of TiO 2. • O-xylene was acceptor molecule while acetaldehyde was donor molecule. • Acetaldehyde and o-xylene adsorption would change the band structure of TiO 2. • The photocatalysis of o-xylene was dominant by OH, while the photocatalysis of acetaldehyde was dominant by O 2 −. Most studies on the photodegradation of volatile organic compounds (VOCs) have focused on the synthesis of efficient photocatalysts. However, little attention has been paid to the band bending change of semiconductive photocatalysts after the adsorption of VOCs. Herein, we first disclose how the adsorption of two typical VOCs influences the band bending of P-type rutile TiO 2 and consequently changes the amount of reactive radicals. This provides a new way to understand the experimental phenomenon of heterogeneous reactions. Theoretical computations of the adsorption model and zeta potential tests both verified that o-xylene is an acceptor molecule when it adsorbs on the TiO 2 surface, and it tends to attract electrons from TiO 2. In contrast, acetaldehyde is a donor molecule. A distinct electron transfer direction between TiO 2 and adsorbed molecules (o-xylene and acetaldehyde) induces a different band bending degree. O-xylene adsorption alleviates the downward band bending of TiO 2 itself, whereas acetaldehyde adsorption strengthens the downward band bending. The probability of electrons and holes reaching the TiO 2 surface is influenced by this change, which has a considerable influence on the generation of active radicals. Consequently, o-xylene adsorption leads to more hydroxyl radical generation, and acetaldehyde adsorption results in less hydroxyl radical generation. As a result, hydroxyl radicals play the predominant role in the degradation of o-xylene, whereas the photocatalysis of acetaldehyde is dominant for superoxide radicals. In addition, the band bending of a semiconductor induced by gaseous molecule adsorption has the potential for application in gas sensors to improve sensitivity. [ABSTRACT FROM AUTHOR]

In this work, the liquid densities of n -decane/ o -xylene mixtures were measured at four different component proportions, the mole fractions of n -decane are 0.2001, 0.4065, 0.5835, and 0.8041, respectively. The measurements were performed based on the high-pressure vibrating-tube densimeter, and the measured temperatures were from 283.15 K to 363.15 K and the pressures were from 0.1 MPa to 60 MPa. The Tammann-Tait equation was used to correlate the experimental densities, and the simplified Perturbed Associating Fluid Theory (sPC-SAFT) and Cubic Plus Associating (CPA) equation were used to predict the high-pressure densities of the mixtures with the binary interaction parameters. Derived properties, including isothermal compressibilities and isobaric thermal expansivities, were calculated from Tait equation, sPC-SAFT equation, and CPA equation, respectively. In addition, excess molar volumes of the considered mixtures were obtained and the effects of pressure and temperature on the excess molar volume were discussed. [ABSTRACT FROM AUTHOR]

• The factors affecting VSA performance of micropore and mesopore in SG were analyzed. • A piecewise loading method with microporous SG and mesoporous SG was proposed. • The breakthrough time of the piecewise loading bed increases by 55.8%. • Piecewise loading bed gets 28.8% decrease in energy consumption than mesoporous SG. The vacuum swing adsorption (VSA) with silica gel (SG) is proved to be a promising method for the recovery of volatile organic compounds (VOCs). The adsorption mechanisms of o -xylene on silica gels with different pore size have been revealed through the mathematic modeling of adsorption isotherms. The analysis of adsorption kinetics indicates that SG with micropore shows a steep concentration front and a long breakthrough time due to the strong adsorption force field, negligible transfer resistance and compressive effect of favorable isotherm. However, the reversible capillary condensation and mass transfer resistance cause a dispersed front and a short breakthrough time for mesoporous SG. The fast desorption rate makes mesoporous SG more energy-efficient compared with SG with micropore. Accordingly, to further improve the front slope and utilization of mesoporous SG in the adsorption process, a small amount of SG with micropore was loaded in the end of the fixed bed. The breakthrough time of the piecewise loading bed increased by 55.8% at the same loading volume with single mesoporous SG. The energy consumption was observed to exhibit an obviously decrease from 1.819 kWh/m3 to 1.295 kWh/m3, which proved that the piecewise loading method could recover VOCs in a more energy-saving way. [ABSTRACT FROM AUTHOR]

The extraction of sulfur-containing and aromatic compounds from light hydrocarbons using water-soluble polymers has been studied experimentally and theoretically. During experimental studies, the extraction of thiophene, toluene, and o-xylene from n-hexane using extraction systems based on polyethylene glycols with different molecular weights, polypropylene glycol 425, and polyvinylpyrrolidone 3500 has been investigated. Based on mathematical modeling, the dependences of distribution coefficients for toluene and o-xylene on the concentration of the polymer using an extraction system based on polyethylene glycol 400 have been derived. The results of this study can be used in the development of new extraction processes for purifying light hydrocarbon fractions from sulfur-containing and aromatic compounds. [ABSTRACT FROM AUTHOR]

Highlights • Ag/NiOx-MnO 2 shows superior performance for o -xylene oxidation at low temperatures. • This is ascribed to its high reducibility and ability for oxygen activation. • The doped Ag and Ni increase the mobility and content of surface lattice oxygen. • Possible pathway for o -xylene oxidation with and without oxygen was discussed. Abstract Ag/NiOx-MnO 2 was synthesized by redox and deposition-precipitation methods and its catalytic performance for o -xylene oxidation was investigated. It exhibited higher activity than NiOx-MnO 2 and OMS-2. The T 20 , T 50 and T 100 values were 72, 145 and 190 °C, respectively (500 ppm o -xylene/humid air, GHSV = 6000 h−1). Moreover, it showed excellent water-resistance and stability, demonstrating its potential for practical application. Characterization results revealed that the introduction of Ni and Ag increased the catalyst reducibility, the amount of electrophilic oxygen species, and the ability for oxygen molecules activation, resulting in the superior performance at low temperatures. In situ DRIFT study indicated that aromatic ring could be directly oxidized into maleate by the electrophilic lattice oxygen of Ag/NiOx-MnO 2 in the absence of oxygen molecules, and the formed maleate could be oxidized into formate and/or carbonate in the presence of oxygen molecules. Finally, the possible degradation pathway of o -xylene in the presence or absence gaseous oxygen was discussed. [ABSTRACT FROM AUTHOR]

Perovskite/perovskite‐like (LaBO3, B=Mn, Co or Ni)/Co3O4 with different morphologies were successfully integrated onto the surface of three‐dimensional (3‐D) cordierite honeycomb ceramics by two‐step combination method of hydrothermal synthesis and impregnation for the catalytic combustion of o‐xylene. The La2NiO4/Co3O4 composite exhibits a 3D hierarchical hollow microsphere construction assembled by numerous nanowires, which is different from the nanowire structure of LaMnO3.15/Co3O4 and LaCoO3/Co3O4. Compared to LaMnO3.15/cordierite, Co3O4/cordierite, LaMnO3.15/Co3O4/cordierite and LaCoO3/Co3O4/cordierite, the La2NiO4/Co3O4/cordierite catalyst possesses lower light‐off temperature and better catalytic performance. The higher catalytic activity of La2NiO4/Co3O4/cordierite catalyst may be correlated with higher specific surface area, larger oxygen storage and the synergistic effect of the La2NiO4 and Co3O4. In addition, when the perovskite‐like loading was 11.39 wt% and calcined at 600 °C for 4 hours, it exhibited the best catalytic performance for o‐xylene oxidation with 90% conversion at 299 °C. In addition, the catalyst also has good conversion stability. [ABSTRACT FROM AUTHOR]

Quantifying functional biomarker genes and their transcripts provides critical lines of evidence for contaminant biodegradation; however, accurate quantification depends on qPCR primers that contain no, or minimal, mismatches with the target gene. Developing accurate assays has been particularly challenging for genes encoding fumarate-adding enzymes (FAE) due to the high level of genetic diversity in this gene family. In this study, metagenomics applied to a field-derived, o-xylene-degrading methanogenic consortium revealed genes encoding FAE that would not be accurately quantifiable by any previously available PCR assays. Sequencing indicated that a gene similar to the napthylmethylsuccinate synthase gene (nmsA) was most abundant, although benzylsuccinate synthase genes (bssA) also were present along with genes encoding alkylsuccinate synthase (assA). Upregulation of the nmsA-like gene was observed during o-xylene degradation. Protein homology modeling indicated that mutations in the active site, relative to a BssA that acts on toluene, increase binding site volume and accessibility, potentially to accommodate the relatively larger o-xylene. The new nmsA-like gene was also detected at substantial concentrations at field sites with a history of xylene contamination. [ABSTRACT FROM AUTHOR]

The effects of different concentrations of water-soluble fraction of crude oil (WSFO) from the Zhanazhol oil field (Aktobe region, Kazakhstan) and compared to o-xylene, prevalent in this oil, on growth and development of marsh frog (Rana ridibunda) were assessed. In subchronic experiments (7 d), a dose-related increase in mortality and incidence of deformities in embryos were observed. In chronic experiments (60 d; starting from the Gosner stage 26), a dose-dependent decrease in body weight, size and developmental delay by 3-4 stages were also detected. In addition, the content of lipid hyperoxide (LHO) and malondialdehyde (MDA), as well as activities of superoxide dismutase (SOD) and catalase (CAT) enzymes in liver of the tadpoles were determined at the end of chronic experiment. Exposure to 0.5 mg/L or 1.5 mg/L WSFO elevated the content of LHO by 76% and 86%, and MDA by 47% and 58% but decreased SOD activity by 26% and 49%, and CAT by 35% and 46%, respectively. A less pronounced adverse effect was found after chronic exposure to the same concentrations of o-xylene. In tadpole liver exposed to o-xylene levels of LHO was increased by 40% and 51%, MDA by 11% and 29%, while the activity of SOD was lowered by 18% and 41%, and CAT - by 13% and 37% in the 0.5 mg/L and 1.5 mg/L treatment groups, respectively. Data demonstrated the embryotoxic and teratogenic effects attributed to WSFO and o-xylene exposure which may involve oxidative stress mechanisms. [ABSTRACT FROM AUTHOR]

The performance of metal-organic xerogels (MOXs) in the photocatalytic oxidative degradation (PCO) of volatile organic compounds (VOCs) relies on their Lewis acid-base interaction and the generation of oxidative radicals. Herein, by engineering the local charge imbalance of carboxyl ligands through synthesizing NaFe bimetal MOXs, the Lewis acidity of MIL-100(Fe) MOX was well tuned for the adsorption-degradation of electron-rich (aromatic hydrocarbons) and electron-deficient (aldehydes) VOCs. Benefiting from the implanted Lewis basic sites, NaFe-MOXs showed increased adsorption-PCO capacity for single acetaldehyde, while Fe-MOX with abundant Lewis acid sites could capture and degrade more o-xylene. The Lewis basic sites promoted the mineralization of single o-xylene and acetaldehyde by altering their interactions with the photocatalysts and improving the generation of oxidative radicals, which extended the lifetime of photocatalysts. By regulating the Lewis acid/basic sites within MOXs, this work provides an effective way for optimizing photocatalysts to enable the photocatalytic degradation of both electron-rich/deficient VOCs. [Display omitted] • NaFe bimetal MOXs with adjustable Lewis acid/basic sites were prepared. • Controllable adsorption-PCO of single o-xylene and acetaldehyde were achieved. • Lewis basic sites were created by engineering local charge imbalance of carboxyl ligands. • Mineralization of VOCs was promoted with the introduction of Lewis basic sites. • Impacts of Lewis acid/basic sites on the adsorption-PCO mechanisms were explored. [ABSTRACT FROM AUTHOR]

Alkoxy side chain engineering on the β-position of the thienothiophene units of Y6 derivatives plays a vital role in improving photovoltaic performances with simultaneously increasing open-circuit voltage ( V oc ) and fill factor (FF). In this work, we prepared a series of asymmetric non-fullerene acceptors (NFAs) by introducing alkoxy side chains and phenoxy groups on the state-of-the-art Y6-derivative BTP-BO-4F. For the comparison, 2O-BO-4F with a symmetric alkoxy side chain on the outer thiophene units and BTP-PBO-4F with an asymmetric N -attached phenoxy alkyl chain on the pyrrole ring are synthesized from BTP-BO-4F. Thereafter, we construct four asymmetric NFAs by introducing different lengths of linear/branched alkoxy chains on the β-position of the thienothiophene units of BTP-PBO-4F. The resulting NFAs, named L10-PBO, L12-PBO, B12-PBO, and B16-PBO (L = linear and B = branched alkoxy side chains), are collectively called OR-PBO-series. Unexpectedly, all OR-PBO NFAs exhibit strong edge-on molecular packing and weaker π-π interactions in the film state, which diminish the charge transfer in organic solar cell (OSC) devices. As a consequence, the optimal devices of OR-PBO-based binary blends show poor photovoltaic performances [power conversion efficiency (PCE) = 6.52-9.62%] in comparison with 2O-BO-4F (PCE = 12.42%) and BTP-PBO-4F (PCE = 15.30%) reference blends. Nevertheless, the OR-PBO-based binary devices show a higher V oc and smaller V loss . Especially, B12-PBO- and B16-PBO-based devices achieve V oc over 1.00 V, which is the highest value of Y-series OSC devices to the best of our knowledge. Therefore, by utilizing higher V oc of OR-PBO binary blends, B12-PBO and B16-PBO are incorporated into the PM6:BTP-PBO-4F-based binary blend and fabricated ternary devices. As a result, the PM6:BTP-PBO-4F:B12-PBO ternary device delivers the best PCE of 15.60% with an increasing V oc and FF concurrently.

Two types of volatile organic chemicals (VOCs), acetaldehyde and o-xylene, were selected to probe the different adsorption and photodegradation mechanism of gaseous photocatalysis. Reduced graphene oxide (rGO)-TiO 2 nanocomposites were prepared by facile solvothermal process to perform the photocatalytic reactions. In the experiments, the removal efficiencies of the acetaldehyde and o-xylene at 80 mL·min −1 flow rate were only 15% and 12% when P25 was applied, while the efficiencies were sharply increased to 42% and 54% by using 0.5 wt% rGO-TiO 2 as the photocatalyst, respectively. Interestingly, it is notable that the removal efficiency of o-xylene was higher than that of acetaldehyde with identical rGO-TiO 2 photocatalyst. Experiments suggested that there were possibly two reasons. Firstly, the adsorbance of o-xylene was more than that of acetaldehyde owing to the π-π conjugation between rGO and aromatic compounds, which was proved by adsorption equilibrium and TPD tests. ESR tests proved that rGO can promote the generation of surface OH radicals and depress the O 2 − radicals formation. Compared with the dominant role played by O 2 − radicals in the degradation of acetaldehyde, an almost equal position of O 2 − and OH radicals was observed in the degradation of o-xylene according to the subsequent radical scavenger experiments. Moreover, the optimized rGO-TiO 2 exhibited sustainable photocatalytic activity at 40–120 mL·min −1 flow rate through 160 min tests, while P25 was deactivate only after 25 min. This work demonstrated the different adsorption and degradation characteristics of two types of VOCs, which could propel the target orientation design of photocatalyst in VOCs removal applications. [ABSTRACT FROM AUTHOR]

The oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H3PW12O40@TiO2 was investigated. The experimental results demonstrated that the prepared catalyst effectively catalyzed the oxidation of o‐xylene to phthalic anhydride. Also, the synergistic effect between three metals plays vital roles in this reaction. From a green chemistry point of view, this method is environmentally friendly due to carrying out the oxidation in a fixed‐bed reactor under solvent‐free condition and using molecular oxygen as a green and cheap oxidizing agent. The resulting solid catalysts were characterized by FT‐IR, XRD, XPS, ICP‐OES, FESEM, TEM, EDX, DR‐UV spectroscopy, BET and thermogravimetric analysis. The oxidation of o‐xylene yields four products: o‐tolualdehyde, phthaldialdehyde, phthalide and finally phthalic anhydride as the main product. The reaction conditions for oxidation of o‐xylene were optimized by varying the temperature, weight hourly space velocity and oxygen flow rate (contact time). The optimum weight percentage of phosphotungstic acid (HPW) and Co/Mn for phthalic anhydride production were 15 wt % and 2 wt%, respectively. The best Co/Mn ratio was found to be 10/1. Oxygen flow rate was very important on the phthalic anhydride formation. The optimum conditions for oxidation of o‐xylene were T = 370 °C, WHSV = 0.5 h−1 and oxygen flow rate = 10 mL min−1. Under optimized conditions, a maximum of 88.2% conversion and 75.5% selectivity to phthalic anhydride was achieved with the fresh catalyst. Moreover, reusability of the catalyst was studied and catalytic activity remained unchanged after at least five cycles. [ABSTRACT FROM AUTHOR]

Abstract Organic-inorganic hybrid halide perovskite solar cells (PVSCs) are promising low-cost photovoltaic technologies with their impressive power conversion efficiency (PCE) and low temperature solution processability. A large amount of toxic solvents has been used in the fabrication of PVSCs, especially the halogenated solvent chlorobenzene (CB) which is heavily applied as the anti-solvent of the perovskite layer and the solvent of electron transport layer (ETL) in p-i-n type PVSCs. Herein, we replace CB with non-halogenated solvents, o-xylene (OXY) and 1,2,4-trimethylbenzene (TMB), and introduce perovskite-fullerene graded heterojunction (GHJ) to engineer efficient perovskite layer and ETL. By merging two deposition processes of perovskite layer and ETL, high efficiencies of 16.82% and 16.88% are obtained for PVSCs with OXY and TMB, respectively. The PVSCs prepared from non-halogenated solvents engineering demonstrate superior performance over their CB counterparts of which the PCE is 14.45%, mainly due to much larger grains, improved electron collection and reduced recombination loss in the former PVSCs. These results indicate both OXY and TMB are potential alternative non-halogenated solvents for PVSCs manufacturing. Moreover, since two separate deposition processes are merged, the process becomes easier and simpler, leading to reduction of fabrication costs. Graphical abstract Image 1 Highlights • Less toxic and non-halogenated solvents were successfully applied to replace chlorobenzene as anti-solvent. • Perovskite film with large grains was fabricated by merging separated deposition processes of perovskite layer and ETL. • PVSCs fabricated by modified method exhibit much higher photovoltaic performance. • The enhanced performance was attributed to improved electron collection and reduced recombination loss. [ABSTRACT FROM AUTHOR]

Undoped NiO, W-doped NiO and Pd-doped NiO nanoflowers were prepared by hydrothermal, or precipitation method using NiSO 4 , WCl 6 and PdCl 2 as precursor compounds. The characterizations and microstructural analyses were performed by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDAX). Thin films of these materials were prepared and the gas adsorption properties of the prepared thin films were investigated towards o-xylene vapor. The influence of doping on o-xylene adsorption was studied. To this intent, thin films were deposited by dip-coating on quartz substrates and fixed onto the end of an optical fiber. This device worked in reflection mode, and transduction took place in the light that traveled through the core of the fiber. W-doped NiO exhibited superior performance to o-xylene compared to the other two samples. The response time, sensitivity and recovery time for undoped NiO, W-doped NiO and Pd-doped NiO thin films towards o-xylene were found as (∼50 s, 0.08 and ∼5 min), (∼35 s, 0.19 and ∼1 min), and (∼20 s, 0.10 and ∼3 min), respectively. Other volatile organic compounds such as benzene, toluene, ethanol, methanol and acetone vapors were also tested by W-doped NiO and the sensitivity order was o-xylene > toluene > benzene > acetone > ethanol > methanol. [ABSTRACT FROM AUTHOR]