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The extractive distillation was used to separate ethylbenzene and m-xylene. After the solvent screening, 1,2,4-trichlorobenzene was chosen as the extractive solvent. The vapor–liquid equilibrium (VLE) of binary mixtures of m-xylene, ethylbenzene, and 1,2,4-trichlorobenzene was measured at 101.33 kPa. The measurements were taken with a modified Rose equilibrium still. The Wisniak's test was used to assess the thermodynamic consistency of the VLE experimental results. To obtain the binary interaction parameters, the binary VLE experimental data were correlated with the NRTL, Wilson, and UNIQUAC activity coefficient models. The results showed that three models all fit the experimental values of three binary systems well, and the ternary VLE data of m-xylene + ethylbenzene + 1,2,4-trichlorobenzene were estimated using Aspen Plus V11 based on these model parameters. The experimental data agree well with the estimation values generated from three models. Finally, the effect of 1,2,4-trichlorobenzene as an extractant was analyzed, and it is proved to have a good influence on the separation of ethylbenzene from mixed xylenes by extractive distillation. [ABSTRACT FROM AUTHOR]

This work reports the selective oxidation of m-xylene by ozone in the liquid phase. It is established that the main direction of the reaction is the destruction of the aromatic system when ozone interacts with m-xylene. It is shown that the selective oxidation of m-xylene by ozone occurs at the temperature of 20°C in the system Mn(II)–CH3COOH–H2SO4 with the yield of 3-toluic acid equal to 75–78%. 3-toluyl alcohol and 3-toluyl aldehyde are formed as intermediate oxidation products. At the deeper stages of the reaction, after complete consumption of mxylene, the following oxidation products of the second methyl group appear in the system: 3-carboxybenzaldehyde, 3- carboxybenzyl alcohol, and isophthalic acid. It is found that the intermediate products are more resistant to the destructive action of O3 than the original m-xylene. The yield of oxidation products with a preserved aromatic system depends on the nature of the functional group. The kinetics of the main stages of the catalytic oxidation of m-xylene and intermediate reaction products is studied. A mechanism of catalysis is proposed, according to which the role of ozone is to generate an oxidized form of the metal, and selective oxidation occurs when the substrate interacts with Mn(III). An increase in the reaction temperature contributes to an increase in the selectivity of the process. Still, it leads to an increase in the depth of oxidation and, accordingly, the concentration of isophthalic acid. [ABSTRACT FROM AUTHOR]

The photoionization and dissociative photoionization of m-xylene (C8H10) were researched by using synchrotron radiation vacuum ultraviolet (SR-VUV) and supersonic expanding molecular beam reflectron time-of-flight mass spectrometer (RFTOF-MS) system. The photoionization efficiency spectra (PIEs) of parent ion C8H10+ and main fragment ions C8H9+ and C7H7+ were observed, and the ionization energy (IE) of m-xylene and appearance energies (AEs) of main fragment ions C8H9+ and C7H7+ were determined to be 8.60±0.03 eV, 11.76±0.04 eV and 11.85±0.05 eV, respectively. Structures of reactant, transition states (TSs), intermediates (INTs), and products involved in two dominant dissociation channels were optimized at the B3LYP/6-311++G(d,p) level, and the relative energies were calculated at the G3 level. Based on the results, two major dissociative photoionization channels, C7H7++CH3 and C8H9++H were calculated at the B3LYP/6-311++G(d,p) level. On the basis of theoretical and experimental results, the dissociative photoionization mechanisms of m-xylene were proposed. The C–H or C–C bond dissociation and hydrogen migration are the main processes in the dissociation channels of m-xylene cation. [ABSTRACT FROM AUTHOR]

Background: Biotricking filtration (BTF) based on absorption and biodegradation of waste gas by microorganisms in a biofilm can be used to degrade with difficulty hydrophobic volatile pollutants. Photocatalysis is a promising technology for the abatement of gaseous contaminants because of its nonselective oxidation of volatile organic compounds; however, photocatalysis technology has the limitations of high energy consumption and low mineralization efficiency. This study, therefore, aimed to investigate the synergistic effects of UV/TiO2 photocatalysis (PCO) pretreatment and BTF in treating gaseous m‐xylene. Results: BTF incubated with a mold, Aspergillus sp. S1, was acclimated with m‐xylene as the sole carbon source. A combined system of PCO with BTF was developed to remove gaseous m‐xylene. The results showed that the startup period was shortened by 3 days in the PCO‐BTF combined system compared to that with BTF alone. The removal efficiency reached 73% and 91% for the BTF and PCO‐BTF systems respectively when the empty bed residence time was extended to 90 s. In addition, PCO‐BTF could withstand transient shock loading of m‐xylene of 5000 mg m−3 and gradually restore its decontamination performance. Conclusions: PCO pretreatment was effective in the enhancement of the removal capacity of BTF for m‐xylene. The PCO‐BTF system proposed in this study provides an attractive alternative to abate hydrophobic volatile pollutants. The integration of PCO essentially prompted the capability of Aspergillus sp. S1 in the BTF unit, which paves the way for the treatment of gaseous waste at an industrial scale. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The monitoring of toxic vapours such as M-cymene and m-xylene from industries is a significant task using a solid-state chemical sensor. We report the structurally stable hex-star arsenene sheets (hex-star AsNS) as a base material to perceive the presence of M-cymene and m-xylene molecules. Initially, we examined the formation energy of hex-star AsNS and ensured the geometric stability. Besides, hex-star AsNS possesses an energy band gap of 1.033 eV indicating the semiconductor state. We explored the changes in the band structure and PDOS (projected density of states) spectrum of hex-star AsNS upon adsorption of M-cymene and m-xylene molecules. Also, concerning charge transfer and electron density difference studies, the electronic properties of hex-star AsNS are reconnoitered. The adsorption energy upon M-cymene and m-xylene adsorption show the physisorption of target molecules on hex-star AsNS. The outcome reveals the hex-star AsNS as an emerging material for the detection of M-cymene and m-xylene molecules. [ABSTRACT FROM AUTHOR]

In this study, m-xylene nitration was scaled up in a microreactor. The effects of temperature, molar ratio, and mass fraction of sulfuric acid on the two synthesis methods were systematically analyzed. The reaction temperature and mass fraction of sulfuric acid are the main factors influencing the generation of poly-nitro impurities when the mixed acid reacts with m-xylene. When the mixed acid is used as the nitrating agent, it is difficult to control the product selectivity and the yield of poly-nitro impurities by changing the reaction conditions. A two-step nitration method was designed to solve the problems of product selectivity and yield of poly-nitro impurities. In the first step, nitric acid is used as a nitrating agent to react with m-xylene. In the second step, sulfuric acid is added to the second microreactor. It acts as a catalyst to continue activating the nitric acid in the first step to react with the unconverted m-xylene. Under the optimal experimental conditions, the yield of mono-nitro products reached 99%, and throughput of 1 kg/h. It has good advantages for industrial production compared with other methods reported in the literature. The way presented in this study can provide a reference for the design of kilogram-scale synthesis with rapid and high exothermic reactions in microreactors. [ABSTRACT FROM AUTHOR]

Synergism is an important strategy to enhance the bioavailability of pollutants and optimize biotrickling filter (BTF) performance. The synergistic biodegradation of m- xylene with the introduction of toluene was investigated in this study. The packing was diatomaceous earth pellets with a volume of 2411 cm3. The empty bed residence time (EBRT) of the BTF was kept constant at 25 s. The mixing ratios for toluene and m- xylene were 1:1, 1:2, 1:4, and 1:6, corresponding to the inlet loading rate (ILR) of m- xylene from about 36–216 g/m3/h, and the toluene ILR was maintained at about 36 g/m3/h. The biodegradation performance and biofilm characteristics were evaluated under these various mixture compositions. For mixing ratios of 1:1, 1:2, and 1:4, m- xylene was synergistically removed with toluene. The most pronounced synergism occurred when the ratio was 1:2; the average elimination capacity (EC) of m- xylene increased by 12.5%, from 64 g/m3/h to 72 g/m3/h. The presence of toluene promoted the growth of microorganisms and improved the hydrophobicity of the biofilm. In contrast, for the 1:6 toluene and m- xylene mixture, toluene inhibited the degradation of m- xylene. The microbial species composition analysis revealed that Burkholderia and Mycobacterium were correlated with synergistic removal of m- xylene, especially Burkholderia. [Display omitted] • m- xylene was synergistically removed with toluene in a biotrickling filter. • Toluene stimulated microbial growth and biomass accumulation synergistically. • Toluene synergistically improved the hydrophobicity of biofilms. • Burkholderia correlated with synergistic removal of m- xylene. [ABSTRACT FROM AUTHOR]

A series of novel graphitic carbon nitride g-C3N4-HMCM-22 composite catalysts were successfully prepared. Their structure and acid properties were well characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), N2 adsorption–desorption, Fourier transform infrared spectroscopy (TFIR), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Py-FTIR. The prepared g-C3N4-HMCM-22 composite catalysts were then used for m-xylene (MX) isomerization. The effect of introduction of g-C3N4 on catalytic performance was studied. Compared with parent HMCM-22 catalyst, g-C3N4-HMCM-22 composite catalysts exhibited an improved p-xylene (PX) selectivity in MX isomerization. Moreover, G1H1 composite catalyst showed the highest PX selectivity than other as-prepared composite samples. Correlating the catalyst performance with its physical and chemical properties uncovers that increasing amounts of Lewis acid sites and effectively inhibiting the external Brönsted acid sites of HMCM-22 would be the key to improving the selectivity of PX. [ABSTRACT FROM AUTHOR]

The radiochemical and neutron-physical characteristics of a pelletized cryogenic moderator based on a mesitylene mixture (a mixture in the form of frozen pellets) obtained during its operation at the pulsed fast reactor IBR-2 are presented. It is shown that changes in the properties of the mixture at high absorbed-irradiation doses (~100 MGy) have no significant effect on the spectrum of cold neutrons. The gain in the number of cold neutrons from the surface of a cold moderator in comparison with a water moderator reaches 10 times. There is no deterioration in the neutron flux at the end of the reactor duty cycle. If the technology of continuous modification of the working substance in the cryogenic moderator chamber is successfully developed, the frozen mixture of mesitylene and m-xylene can be recommended for use on powerful pulsed neutron sources. [ABSTRACT FROM AUTHOR]

The properties of ZSM-12 zeolites prepared under hydrothermal conditions and microwave radiation influence were studied. The prepared zeolites are characterized by a wide range of physicochemical methods of analysis: X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, scanning electron microscopy, solid-state 27Al and 29Si NMR spectroscopy, infrared spectroscopy, temperature-programmed desorption of ammonia, infrared spectroscopy of adsorbed pyridine, and X-ray fluorescence elemental analysis. The calcined zeolites were impregnated with 0.5 wt % Pt, which performs the hydrogenation function in the reaction under study. The obtained materials were studied in the m-xylene isomerization reaction under the following conditions: Т = 300–440°С, WHSV = 1 h–1, Р(Н2) = 10 atm. It was found that, on the ZSM-12 MW catalyst, owing to its high acidity and fine particles, which promote high mass transfer, it is possible to increase the yields of m-xylene isomers, in particular p-xylene, to 36–65%. [ABSTRACT FROM AUTHOR]

Secondary organic aerosol (SOA) affects air quality, human health and climate. The multi-generation reactions of volatile organic compounds (VOCs) have become key process for explaining the SOA formation. M -xylene, as one of the most important VOCs in urban atmosphere, has got extensive study. However, the reaction mechanism of the first-generation products hydroperoxides (M-ROOH) and organonitrates (M-RONO 2) remain unknown. In this work, the hydroxyl radicals (·OH) initiated reactions of M-ROOH and M-RONO 2 were investigated by employing quantum chemical methods and kinetics modeling. The results show that new ring-retaining epoxides, a range of dialdehydes and less volatile hydroperoxides and organonitrates are formed, contributing to SOA formation. By adopting the unveiled new mechanism into the SOSAA box modeling, we found that the yield of SOA from m -xylene oxidation is up to 38%, which is comparable to the experimental value (36%). This work advances current understanding of multi-generation chemistry and elucidates the role of aromatic hydrocarbons oxidation in the formation of SOA. [Display omitted] • The formation mechanism of a novel epoxides formed from second-generation oxidation of m-xylene was revealed. • The contribution (∼33%) of m-xylene oxidation to the SOA formation was evaluated by box model. • Epoxides formed by hydroperoxides and organonitrates derived from AHs are highly structurally dependent. [ABSTRACT FROM AUTHOR]

Metal oxide-based gas sensors encounter challenges in effectively detecting hazardous benzenes due to their stability and structural similarities. Here we report an innovative in situ growth method for synthesizing Fe 2 O 3 /Si-FeWO 4 heterostructure nanotubes (NTs) using highly negatively charged multivacant lacunary TBA 4 H 6 [SiW 9 O 34 ]·2H 2 O (α -SiW 9) and Fe3+ as precursors. A two-step process involving electrospinning followed by a thermal oxidation method was employed to synthesize a series of the uniform Si-FeWO 4 decorated Fe 2 O 3 heterostructure NTs. Considering the rich Fe 2 O 3 /Si-FeWO 4 active interfaces, rapid electron transfer, and high specific surface area, the optimal Fe 2 O 3 /Si-FeWO 4 based sensors demonstrate significantly higher sensitivity (S = 27.5) towards 50 ppm m-xylene in comparison to pristine Fe 2 O 3 (S = 1.8). Furthermore, the Fe 2 O 3 /Si-FeWO 4 exhibits excellent stability, humidity resistance, and high selectivity for m-xylene. This work offers an efficient, cost-effective strategy to synthesize Fe 2 O 3 /Si-FeWO 4 heterostructure NTs, with prospects for synthesizing other advanced sensing heterostructure nanomaterials with lacunary polyoxometalates as precursors. [Display omitted] • Obtaining Fe 2 O 3 /Si-FeWO 4 nanotubes by lacunary POMs-induced in-situ growth method. • Fe 2 O 3 /Si-FeWO 4 nanotubes exhibited high m-xylene sensitivity and selectivity. • Unique heterostructure interface in nanotubes enhances nanotube sensing properties. [ABSTRACT FROM AUTHOR]

Ammoxidation of m-xylene is evaluated in the presence of a customized heteropoly acid catalyst as an imidazole/molybdovanadophosphoric acid (imidazole/PMoV). Imidazole is employed to maintain its heterogeneous phase during the ammoxidation reaction and to provide the thermal stability of PMoV with the expectation that imidazole can generate strong electronic interactions with terminal molybdenum-oxygen on PMoV. The characterizations of the prepared catalysts are performed using SEM–EDX, XRD, FT-IR, Raman, XPS, and TGA to prove the physical and chemical changes by incorporating imidazole to PMoV, respectively. Also, the thermal stability of the developed catalyst is confirmed by the means of heat treatment test at relatively high temperature. The composite catalyst, imidazole/PMoV, shows an excellent conversion rate of over 98% with high selectivity of isophthalonitrile in m-xylene ammoxidation. Moreover, while the imidazole-free PMoV catalyst is deactivated and washed out during the reaction, the catalyst durability of the imidazole/PMoV is preserved without significant activity loss after 5 reaction cycles at 380 °C. [ABSTRACT FROM AUTHOR]

Background: Isophthalic acid (IPA) is commercially produced using the Co–Mn–Br catalyst system, which suffers from the shortcomings of the discharge of CH3Br and corrosion of equipment. It is necessary to develop a technology to avoid the pollution caused by bromide. The production of IPA from the oxidation of m‐xylene (MX) by air is realized under catalysis with H3PW12O40 (HPW) loaded on carbon and cobalt. Results: Tartaric acid has been used to improve the catalytic activity of the HPW@C catalyst. Experiments indicate that the best modification condition is calcining the carbon at 450 °C for 4 h after being soaked in a 2.0 mol L−1 tartaric acid solution for 10 h. Surface characterization reveals that the tartaric acid modification leads to an increase in the acid groups and a reduction in the basic groups on the carbon surface. Conclusions: The MX conversion obtained using the HPW@C catalyst prepared from modified carbon is 6.77% over that obtained using the HPW@C catalyst prepared from the original carbon. The IPA generated using the former is 71.1% over that generated using the latter. The catalytic activity of the HPW@C catalyst relies on its surface chemical characteristics and physical properties. The surface chemistry plays a more important role than the physical properties. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Rigorous design of commercial-scale packed beds accounting multicomponent adsorptions is mathematically complex, often resulting in adopting approximate simplified methods. Hence the present work attempts to simulate adsorption of BTX (benzene, toluene, m xylene) in a packed column of 10 m height and 3 m diameter for two adsorbents namely KIT-6 and mKIT-6 (surface modified) using Aspen Adsorption. The adsorption isotherm data of pure BTX components were generated for the adsorbent using a gas phase gravimetric analyzer. A comparative adsorption capacity indicates adsorption in the following order X > T > B for both the sorbents. m-xylene and toluene performed better on mKIT-6, as a result of which breakthrough and saturation time were higher. An increase in adsorbate feed concentration reduced the breakthrough and saturation time, proportional to the magnitude of increase. A significant reduction in the breakthrough time for benzene and toluene was observed due to competitive adsorption in the case of multicomponent adsorption as compared to pure component adsorption. [ABSTRACT FROM AUTHOR]

The adsorptive behavior of clinoptilolite (Cpt) zeolite in its raw and nickel-exchanged form towards m-xylene/p-xylene/ethylbenzene unary, binary, and ternary mixtures was investigated. The motivation behind the research was to elucidate whether Cpt in its raw or ion-exchanged form could exhibit distinctive selective adsorption behavior. The natural Cpt (Si/Al atomic ratio = 4.59) was ion-exchanged twice with 0.5 M Ni(NO3)2 solution at 80°C for 6 h. Adsorption experiments were done at 40°C, using a 4 vol.% solution of the aromatic materials in iso-octane. The maximum amount of the total specific adsorption capacity for binary solute systems was ~0.8 and ~2.0 mmol g–1 for the raw and ion-exchanged Cpt, respectively. For the ternary solute systems, unexpectedly, this capacity increased to ~2.0 and ~3.0 mmol g–1, respectively. For binary mixtures, both forms of Cpt were selective for p-xylene. For ternary mixtures, both forms exhibited a clear selectivity for m-xylene but the Ni-exchanged Cpt was significantly higher over the concentration range studied. The unexpected increase in the adsorption capacity in ternary systems was attributed to the expulsion of tightly bound trace water molecules hindering the access of xylene molecules to the 10-member ring channels of the zeolite framework. Substitution of Mg2+ by Ni2+ in the 10-member ring channels enhanced the adsorption capacity by providing more space and stronger electrostatic interactions between the new cation and the polar m-xylene molecule. [ABSTRACT FROM AUTHOR]

The large-pore zeolite omega (SiAl = 3.1) has been treated with solutions of the surfactant hexadecyltrimethylammonium (CTA) in aqueous ammonia in order to generate intracrystalline mesoporosity. For this purpose, the as-made sample was calcined, transformed in the acid form by ion exchange with ammonium chloride solution followed by calcination, and the resulting acid form subsequently treated with steam at 620 ºC to partially dealuminate the framework. The samples were characterized by XRD, N 2 adsorption, TGA, SEM, 29Si and 27Al MAS NMR, pyridine adsorption for acidity determination, and tested in the isomerization/disproportionation of m -xylene. It has been found that partial dealumination of the framework (Si/Al ∼ 7.3) followed by mild acid leaching (HCl = 0.3 M) to remove only the extraframework aluminium species is required for CTA to generate intracrystalline mesopores with a narrow pore diameter of 4 nm. The CTA treatment is ineffective when applied to the acid form (Si/Al ∼ 5.7) or the steamed sample before acid leaching. The concentration of strong acid sites and the average acid strength of the CTA samples are lower than those of the steamed/acid leached sample, which suggests the presence of weak acid sites located at the mesopores. The mesopores greatly enhanced the catalytic activity in the m -xylene conversion by decreasing diffusional constraints. However, the selectivity to the bulky trimethylbenzenes is not improved by the CTA treatment, which suggests that the reaction mainly takes place at the strong acid sites located at the micropores. [Display omitted] • Extraframework Al can be removed from steamed zeolite omega by mild acid leaching. • Basic treatment with the surfactant CTA generates mesoporosity in acid-leached omega. • CTA-treated samples had lower acid strength than parent dealuminated omega. • Mesoporosity strongly enhanced the activity in m -xylene transformation. • m -xylene transformation mostly takes place at the micropores. [ABSTRACT FROM AUTHOR]

meta‐Xylene (m‐xylene) is one of three isomers of xylene, which is widely used as a solvent and detergent in various industries and medical technology. Exposure to volatile organic compounds, such as m‐xylene, causes pulmonary inflammation and airway inflammation, thereby contributing to the onset of asthma. Exposure to m‐xylene increases acute wheezing and intensity of asthma symptom. However, the mechanism of the onset of asthma by m‐xylene has not been studied yet. C57BL/6 mice were sensitized and challenged by m‐xylene at 100 or 300 mg/kg. The mice were then sacrificed after the last challenge. Exposure to m‐xylene increased the total number of inflammatory cells and the production of interleukin (IL)‐4, IL‐5, IL‐13, and immunoglobulin E related to the Th2 immune response. In contrast, the production of interferon‐γ related to the Th1 immune response was decreased. In addition, the airway resistance increased according to the airway hyper‐responsiveness measurements. Finally, a histological analysis revealed infiltration of inflammatory cells, mucus production, and lung fibrosis. These results suggest that m‐xylene is a potential risk factor for asthma and the onset of asthma is caused by TH2 cytokines. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the stability of Cu-doped manganese oxide catalyst in the oxidation of m-xylene. The catalyst was prepared by hydrothermal method and characterized by TGA, XRD and TEM methods. The TGA results indicated high thermal stability of the prepared material. The XRD, TEM and catalytic results proved that Cu-doped manganese oxide exhibited high recyclability and stability with time on stream. The catalytic studies also indicated the probability of adsorption of m-xylene and its oxidation products on the surface of the catalyst, leading to the minimal deactivation of the catalyst at low temperatures. The reversible effect of water vapor on the oxidation of on Cu-doped manganese oxide was considered to be the result of the competitive adsorption of water vapor and m-xylene. [ABSTRACT FROM AUTHOR]

Beta zeolite (nominal Si/Al = 19) has been treated with HF/NH 4 F solutions under different HF concentration, temperature and reaction time. It has been found that the crystallinity of the resulting materials is >80% for HF concentration up to 0.5 M, but it drops below this value for the most severe condition (HF = 1 M and 40 °C). The treatment dissolves selectively aluminum, in such a way that the Si/Al increases to 34 for the most attacked material. As a consequence of these treatments, the mesopore volume increases by up to 80% respect to the parent Beta for samples retaining high crystallinity, corresponding to newly created mesopores in the range of 5–20 nm. Detailed STEM-HAADF studies reveal that the chemical attack of the Beta crystals by the acidic fluoride solution progresses slowly along the crystals, leaving behind highly corroded and porous "sponge-like" crystals where the structure of the zeolite is nevertheless retained. Pyridine adsorption/desorption experiments show that a fraction of the extraframework Al present in the starting Beta is reinserted in framework sites, a process that would be mediated by aluminum-fluoride soluble species. As a consequence of this process, the Bronsted/Lewis ratio of the strong acid sites increases from 1 in the starting Beta to close to 3. The concentration of total and strong Bronsted acid sites associated to framework Al increases with the treatment. However, the activity of the samples in the isomerization/disproportionation of m-xylene is lower than that of the parent Beta zeolite, a result that could be due to the higher B/L ratio. Image 1 • Zeolite Beta (Si/Al = 19) can be etched with HF/NH 4 F solutions at mild conditions. • The crystallinity is retained while the pore volume increases. • Crystals of sponge-like morphology are formed. • A fraction of the extraframework aluminum is reinserted in framework positions. • Activity in m-xylene reaction depends on acid strength and Bronsted/Lewis ratio. [ABSTRACT FROM AUTHOR]

• High pressure density data of n -decane and m -xylene mixtures were reported. • The sPC-SAFT and CPA EoSs were applied to predict the densities of n-decane and m-xylene and their mixtures. • The effects of pressure and temperature on the excess molar volume were discussed. In this work, the experimental measurements for liquid densities of n -decane and m -xylene binary mixtures were performed over the entire composition range with a high-pressure vibrating-tube densimeter. The range of temperatures for the present measurements was from 293.15 K to 363.15 K and the pressures were up to 60 MPa. The combined expanded uncertainty of the density measurements is estimated to be 0.001 ρ with 0.95 confidence. Experimental density values were correlated by the modified Tammann-Tait equation. The simplified Perturbed Associating Fluid Theory (sPC-SAFT) and Cubic Plus Associated (CPA) equations of state (EoS) were applied to predict the densities of n -decane and m -xylene and their mixtures. Reasonably results were observed between the experimental data and calculated results for the two equations, and the deviation is less than 0.48% and 0.89% with sPC-SAFT and CPA EoS, respectively. In addition, excess molar volumes were determined from the experimental density data as well as from sPC-SAFT and CPA models. The effects of pressure and temperature on the excess molar volume were also discussed. [ABSTRACT FROM AUTHOR]

The production of isophthalic acid (IPA) from the oxidation of m‐xylene (MX) with air can be sped up by Co(II) and phosphotungstic acid (HPW) loaded on activated carbon. In this paper, activated carbon is modified with a ZnCl2 solution to improve the catalytic performance of the HPW@C catalyst. The experiments indicate that the optimum modification condition is the carbon immersed in a 0.10 mol L−1 ZnCl2 solution for 6 h at the temperature of 40 °C followed by being carbonized at 600 °C for 4 h. The characterization proves that the ZnCl2 modification leads to the increase of surface area and acidic groups on the activated carbon. The MX conversion catalyzed by the HPW@C prepared from the carbon modified is 7.0 % over that by the HPW@C from the original carbon and the IPA produced by the modified sample is 78.9 % over that produced by the original one. [ABSTRACT FROM AUTHOR]

Abstract This paper presents performance analysis of a high temperature cascade organic Rankine cycle coupled with water heating system capable of providing maximum power output of 542 kW and hot water at 35 °C for household purposes. The analysis makes use of monthly ambient air and water temperature data of the city of Busan, South Korea as input parameters of the system. The working fluid at the exit of turbine 1 is split into two mass fractions, one providing heat to the bottom cycle (ORC II) and the other used to heat water in the water heating system. These mass fractions are adjusted according to the expected seasonal demand of hot water. Among three high critical temperature working fluids, m-xylene has been selected for the top cycle whereas R245fa has been selected for the bottom cycle among five low critical temperature working fluids. A comprehensive thermal and exergy efficiency analysis shows the performance of the system during the different months of the year. The analysis show the comparison of the winter season (when demand for hot water is high) with the summer season (when demand for hot water is low). Highlights • High temperature cascade ORC coupled with water heating system is investigated. • Ambient air and water temperature data are used as input parameters of the system. • The water heating system shows greatest variation in exergy destruction values. • m-xylene and R245fa are selected as best fluids for top and bottom ORCs. • Winter months show greater η t h and summer months show greater η e x . [ABSTRACT FROM AUTHOR]

Alkylbenzenes, such as toluene and m-xylene, are an important class of contaminant hydrocarbons that are widespread and tend to accumulate in subsurface anoxic environments. The peripheral pathway for the anaerobic oxidation of toluene in bacteria consists of an initial activation catalyzed by a benzylsuccinate synthase (encoded by bss genes), and a subsequent modified β-oxidation of benzylsuccinate to benzoyl-CoA and succinyl-CoA (encoded by bbs genes). We have shown here that the bss and bbs genes, which are located within an integrative and conjugative element, are essential for anaerobic degradation of toluene but also for m-xylene oxidation in the denitrifying beta-proteobacterium Azoarcus sp. CIB. New insights into the transcriptional organization and regulation of a complete gene cluster for anaerobic catabolism of toluene/m-xylene in a single bacterial strain are presented. The bss and bbs genes are transcriptionally coupled into two large convergent catabolic operons driven by the PbssD and PbbsA promoters, respectively, whose expression is inducible when cells grow anaerobically in toluene or m-xylene. An adjacent tdiSR operon driven by the PtdiS promoter encodes a putative two-component regulatory system. TdiR behaves as a transcriptional activator of the PbssD, PbbsA, and PtdiS promoters, being benzylsuccinate/(3-methyl)benzylsuccinate, rather than toluene/m-xylene, the inducers that may trigger the TdiS-mediated activation of TdiR. In addition to the TdiSR-based specific control, the expression of the bss and bbs genes in Azoarcus sp. CIB is under an overimposed regulation that depends on certain environmental factors, such as the presence/absence of oxygen or the availability of preferred carbon sources (catabolite repression). This work paves the way for future strategies toward the reliable assessment of microbial activity in toluene/m-xylene contaminated environments.

The production of isophthalic acid (IPA) from the oxidation of m-xylene (MX) by air is catalyzed by H3PW12O40 (HPW) loaded on carbon and cobalt. We used H2O2 solution to oxidize the carbon to improve the catalytic activity of HPW@C catalyst. Experiments reveal that the best carbon sample is obtained by calcining the carbon at 700 °C for 4 h after being impregnated in the 3.75% H2O2 solution at 40 °C for 7 h. The surface characterization displays that the H2O2 modification leads to an increase in the acidic groups and a reduction in the basic groups on the carbon surface. The catalytic capability of the HPW@C catalyst depends on its surface chemical characteristics and physical property. The acidic groups play a more important part than the physical property. The MX conversion after 180 min reaction acquired by the HPW@C catalysts prepared from the activated carbon modified in the best condition is 3.81% over that obtained by the HPW@C catalysts prepared from the original carbon. The IPA produced by the former is 46.2% over that produced by the latter. [ABSTRACT FROM AUTHOR]

Aromatics that are present in the feed of the Claus sulfur recovery process are well known to poison the catalyst and hence continued efforts are being made within the scientific community to remove them. In this context, the present work attempts to develop superior adsorbents in comparison with contemporary adsorbents for removal of toluene and m-xylene. In a bid to improve adsorption properties, nitrogen-containing surface functional groups were successfully introduced onto porous carbon by minimizing pore damage while maximizing nitrogen content. The surface modified adsorbents were subjected to gas phase adsorption of toluene and m-xylene at 45°C to generate the adsorption isotherms. Toluene adsorption capacity for the modified adsorbent was observed to have increased by approximately 30% at pressure of about 20 mbar and m-xylene by about 10% at about 22 mbar. Several orders of magnitude increase in adsorption capacity was observed for both aromatics at pressures less than 10 mbar. Such high adsorption capacity have not been reported in literature and could potentially favorably alter the economics of aromatics removal in gas processing. Regenerability of nitrogen doped adsorbent was ensured through cyclic adsorption/desorption tests. The adsorption isotherms as well as the kinetics of adsorption were modelled. [ABSTRACT FROM AUTHOR]

Alkylbenzenes, such as toluene and m-xylene, are an important class of contaminant hydrocarbons that are widespread and tend to accumulate in subsurface anoxic environments. The peripheral pathway for the anaerobic oxidation of toluene in bacteria consists of an initial activation catalyzed by a benzylsuccinate synthase (encoded by bss genes), and a subsequent modified β-oxidation of benzylsuccinate to benzoyl-CoA and succinyl-CoA (encoded by bbs genes). We have shown here that the bss and bbs genes, which are located within an integrative and conjugative element, are essential for anaerobic degradation of toluene but also for m-xylene oxidation in the denitrifying beta-proteobacterium Azoarcus sp. CIB. New insights into the transcriptional organization and regulation of a complete gene cluster for anaerobic catabolism of toluene/m-xylene in a single bacterial strain are presented. The bss and bbs genes are transcriptionally coupled into two large convergent catabolic operons driven by the PbssD and PbbsA promoters, respectively, whose expression is inducible when cells grow anaerobically in toluene or m-xylene. An adjacent tdiSR operon driven by the PtdiS promoter encodes a putative two-component regulatory system. TdiR behaves as a transcriptional activator of the PbssD, PbbsA, and PtdiS promoters, being benzylsuccinate/(3-methyl)benzylsuccinate, rather than toluene/m-xylene, the inducers that may trigger the TdiS-mediated activation of TdiR. In addition to the TdiSR-based specific control, the expression of the bss and bbs genes in Azoarcus sp. CIB is under an overimposed regulation that depends on certain environmental factors, such as the presence/absence of oxygen or the availability of preferred carbon sources (catabolite repression). This work paves the way for future strategies toward the reliable assessment of microbial activity in toluene/m-xylene contaminated environments. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials have been identified as potential carbon–neutral sources of sustainable power production. Catalytic conversion of lignocellulosic biomass results in liquid fuels with a variety of aromatic molecules. This paper investigates the combustion characteristics and exhaust emissions of a series of alkylbenzenes, of varying number of methyl branches on the monocyclic aromatic ring, when combusted in a direct injection, single cylinder, compression-ignition engine. In addition, benzaldehyde (an aldehyde (-CHO) branch on the monocyclic ring) was also tested. All the molecules were blended with heptane in different proportions, up to 60% wt/wt. The tests were conducted at a constant engine speed of 1200 rpm, a fixed engine load 4 bar IMEP, and at two injection modes: constant start of fuel injection at 10 CAD BTDC, and varying fuel injection timing to maintain constant start of fuel combustion at TDC. The results showed that the ignition delay period increased with increasing number of methyl branches on the ring, due to the rapid consumption of OH radicals by the alkylbenzenes for oxidation to stable benzyl radicals. Peak heat release rates, and concurrently NOx emissions, initially increased with increasing methyl branches, but subsequently both decreased as the bulk of heat release occurred further into the expansion stroke with significant thermal energy losses. With the exception of toluene, the number of particles in the engine exhaust increased as the number of methyl branches on the aromatic ring increased, attributable to the formation of thermally stable benzyl radicals. [ABSTRACT FROM AUTHOR]

Aromatic volatile organic compounds (VOCs) are an important precursor of secondary organic aerosol (SOA) in the urban environment. SOA formed from the oxidation of anthropogenic VOCs can be substantially more abundant than biogenic SOA and has been shown to account for a significant fraction of fine particulate matter in urban areas. A potential aerosol mass (PAM) chamber was used to investigate the oxidised products from the photo-oxidation of m -xylene and toluene. The experiments were carried out with OH radical as oxidant in both high- and low-NO x conditions and the resultant aerosol samples were collected using quartz filters and analysed by GC × GC-TOFMS. Results show the oxidation products derived from both precursors included ring-retaining and -opening compounds (unsaturated aldehydes, unsaturated ketones and organic acids) with a high number of ring-opening compounds observed from toluene oxidation. Glyoxal and methyl glyoxal were the major ring-cleavage products from both oxidation systems, indicating that a bicyclic route plays an important role in their formation. SOA yields were higher for both precursors under high-NO x (toluene: 0.111; m -xylene: 0.124) than at low-NO x (toluene: 0.089; m -xylene: 0.052), likely linked to higher OH concentrations during low-NO x experiments which may lead to higher degree of fragmentation. DHOPA (2,3-dihydroxy-4-oxo-pentanoic acid), a known tracer of toluene oxidation, was observed in both oxidation systems. The mass fraction of DHOPA in SOA from toluene oxidation was about double the value reported previously, but it should not be regarded as a tracer solely for oxidation of toluene as m -xylene oxidation gave a similar relative yield. [Display omitted] • PAM chamber was used to investigate the oxidised products from m -xylene and toluene. • Filter samples were analysed using GC × GC-TOFMS. • High number of ring-opening compounds were observed from toluene oxidation. • SOA yields were higher for both precursors under high-NO x than at low-NO x. • DHOPA (2,3-dihydroxy-4-oxo-pentanoic acid), was observed in both oxidation systems. [ABSTRACT FROM AUTHOR]

The effects of different ligand exchange solvents and heat treatment conditions on the densification and microstructure development of CuIn 0.7 Ga 0.3 Se 2 (CIGS) crystallites synthesized using the heating-up method were studied in this work. The heat treatment effects on the organic molecules and crystalline structure were investigated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was observed that oleylamine (OLA) adsorbed onto the CIGS surface was difficult to remove during sintering. Ligand-exchange with m-xylene or 1-hexanethiol can promote the removal of oleylamine adsorbed onto the CIGS surface and prevent the residual carbon from forming during sintering, which leads to grain growth and densification. A dense CuIn 0.7 Ga 0.3 Se 2 can be obtained using the precursor powders after ligand-exchange with 1-hexanethiol and m-xylene to remove organic molecules and sintering at 600 °C for 2 h under Se atmosphere. [ABSTRACT FROM AUTHOR]

Different wt% of vanadium-substituted molybdophosphoric acid H4PMo11VO40 loaded on titania (TiO2) are prepared by wet impregnation method. The catalytic activity of PMoV-supported titania catalyst for the vapor-phase ammoxidation of m-xylene at different temperatures is reported here. The synthesized catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, N2 adsorption-desorption, thermogravimetric/differential thermal analysis, temperature programmed desorption (TPD), temperature programmed reduction (TPR) scanning electron microscopy, energydispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). FTIR studies confirmed that the Keggin structure of PMoV does not change even up to 460°C when loaded on TiO2 surface. Among all the PMoV-supported TiO2 catalysts, 1.7% PMoV/TiO2 showed excellent activity for vapor-phase ammoxidation of m-xylene with 85.4% yield of isophthalonitrile. [ABSTRACT FROM AUTHOR]

• The LLE data for EG + EGDA + xylene/ethylbenzene were obtained at 303.2 and 323.2 K. • Ethylbenzene exhibits the highest extraction capability. • The interaction parameters were obtained by NRTL and UNIQUAC models. • The reliability of data regression were confirmed by the GUI-MATLAB method. Ethylene glycol diacetate (EGDA) is a kind of environment-friendly organic solvent with high boiling point, which has broad application prospect in chemical production. For the optimization of ethylene glycol (EG) – EGDA mixture solvent extraction separation, o-xylene, m-xylene and ethylbenzene were used as extractants to measure the liquid–liquid equilibrium data of EG + EGDA + extractants ternary system at 303.2 K and 323.2 K under 101.3 kPa, respectively. The extraction and separation performance of extractant was evaluated by separation factor. The results show that the separation factor of the solvent is greater than 1, o-xylene, m-xylene and ethylbenzene can effectively separate EGDA. NRTL and UNIQUAC thermodynamic models are used to correlate experimental data and obtain corresponding binary interaction parameters. The calculated relative root mean square deviations (RMSD) are all less than 0.01, indicating that NRTL and UNIQUAC can correlate experimental data well. In order to verify the reliability of the binary interaction parameters, the graphical user interface developed by MATLAB is used for topology analysis. [ABSTRACT FROM AUTHOR]

The substituted and unsubstituted aromatic hydrocarbons, present in transportation fuels such as gasoline and diesel, are thought to be responsible for most of the soot particles produced during their combustion. However, the effects of the substituted alkyl groups on the aromatic hydrocarbons on their sooting tendencies, and on the physical and chemical properties of soot produced from them are not well understood. In this work, the effect of the presence of methyl groups on aromatic hydrocarbons on their sooting propensity, and on the oxidative reactivity, morphology, and chemical composition of soot generated from them in diffusion flames is studied using benzene, toluene, and m- xylene as fuels. Several experimental techniques including high resolution transmission electron microscopy and X-ray diffraction are used to identify the morphological changes in soot, whereas the elemental and thermo-gravimetric analyses, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy are used to study the changes in its chemical properties and reactivity. The activation energies for soot oxidation are calculated at different conversion levels, and a trend in the reactivity of soots from benzene, toluene and m- xylene is reported. It is observed that the sizes of primary particles and graphene-like sheets, and the concentrations of aliphatics and oxygenated groups in soot particles decreased with the addition of methyl group(s) on the aromatic ring. The physicochemical changes in soot are found to support the oxidative reactivity trends. [ABSTRACT FROM AUTHOR]

Catalytic performances of soluble Co, Co/Mn, Co/Mn/Br, and Co/Mn/Ce catalysts for m-xylene (MX) oxidation without acetic acid (HAc) solvent were studied, comparing with Co/HAc catalysts. In m-toluic acid (MTA) production, a Ce-salt promoter could effectively substitute for bromide salts and the recycle alcohol/aldehyde liquid mixture acts as a more efficient promotor than either peroxides or MTA itself. The Co/Mn/Ce system, free of acetic acid and Br, was a superior catalyst in terms of activity and selectivity to MTA. Just as for p-xylene oxidation using Co/Mn/Br catalysts, both the MX reaction rate and the MTA selectivity increased with temperature when using Co/Mn/Ce catalysts. Unlike p-xylene oxidation however, MX oxidation resulted in more coupling products. For MX oxidation catalyzed by a supported Co-imide complex in supercritical CO, the activity was lower by more than an order of magnitude, but the MTA selectivity was greater. Graphical Abstract: The selectivity behavior of the catalyst systems indicate that the Co/Mn/Ce system, free of acetic acid solvent and corrosive Br, was a superior catalyst, both in terms of overall activity and selectivity for MTA. [ABSTRACT FROM AUTHOR]

A new correlation for the viscosity of meta-xylene is presented. The correlation is based upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory. It is applicable in the temperature range from 273 to 673 K at pressures up to 200 MPa. The overall uncertainty of the proposed correlation, estimated as the combined expanded uncertainty with a coverage factor of 2, varies from 1% for the viscosity at atmospheric pressure to 5% for the highest temperatures and pressures of interest. Tables of the viscosity, generated by the relevant equations, at selected temperatures and pressures, and along the saturation line, are provided. [ABSTRACT FROM AUTHOR]