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Here, catalytic fast pyrolysis (CFP) was studied as a method to valorize rice husk (RH). Specifically, the effects of RH pretreatment, i.e., NaOH treatment, on the CFP efficiency and selectivity over a Ga-loaded HZSM-5 (SiO2/Al2O3 ratio = 38) were investigated. In addition to NaOH pretreatment, it was investigated how pyrolysis medium (N2, CH4, or a gas stream evolved from ex-situ CH4 decomposition over a Ni/La2O3/CeO2/Al2O3 catalyst (Ni/La2O3/CeO2 = 2/1/1) at 923 K (d-CH4)) influences the CFP of pretreated RH. The NaOH treatment reduced the content of ash and increased the content of cellulose in the RH sample. Thus, the effect of pyrolysis medium on the CFP of cellulose was studied at first, followed by that on CFP of NaOH-treated RH. With regard to the pyrolysis medium, the yield of aromatic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) achieved with both cellulose and the NaOH-treated RH enhanced in an order; d-CH4 > CH4 > N2. The removal of ash from RH with the NaOH pretreatment increased the BTEX yield up to 22.3 wt% as ash (mineral impurities) affects pyrolytic behavior of cellulose and lowers accessibility of pyrolytic volatiles to acid sites on zeolite. This study gives helpful information about how different parameters influence the conversion of RH into BTEX via CFP process.

A series of ZnO-ZrO2 solid solutions with different Zn contents were synthesized by the urea co-precipitation method, which were coupled with H-ZSM-5 zeolite to form bifunctional catalysts. As a new benzene alkylation reagent, syngas was used instead of methanol to realize the efficient conversion of syngas and benzene into toluene and xylene. A suitable ratio of ZnO-ZrO2 led to the significant improvement in the catalytic performance, and a suitable amount of acid helped to increase the selectivity of toluene/xylene and reduce the selectivity of the by-products ethylbenzene and C9+ aromatics. The highest benzene conversion of 89.2% and toluene/xylene selectivity of 88.7% were achieved over 10% ZnO-ZrO2H hence, the conversion of benzene is higher. H-ZSM-35 and H-MOR zeolites exhibited small eight-membered-ring channels, which were not conducive to the passage of benzene; hence, the by-product ethylbenzene exhibits a higher selectivity. The distance between the active centers of the bifunctional catalysts was the main factor affecting the catalytic performance, and the powder mixing method was more conducive to the conversion of syngas and benzene.

Silica chemical vapor deposition (Si-CVD) technique was applied in the silylation of ZSM-5 zeolite to enhance para isomer product selectivity in the disproportionation of toluene (TDP) and ethylbenzene (EBDP). A threshold value in Si-CVD deposition for enhancement in para isomer selectivity in TDP and EBDP was determined. Beyond the threshold value, the para selectivity increased with increasing silica deposition amount. Upon Si-CVD modification, while the micropore size of the MFI zeolite stayed the same with the parent MFI zeolite, the enhancement in para selectivity could be due to the passivation of external active sites. The p-diethylbenzene isomer selectivity of>99 % was demonstrated at EB conversion up to 35 %. Nevertheless, p-xylene isomer product selectivity of around 83 % was obtained only at a reasonable conversion level of 20 %. The difference in selectivation efficiency between TDP and EBTDP reactions could be attributed to the difference in the relative ratio of reaction kinetics rate to the diffusion rate in associated with different reaction temperature range.

Styrene-acrylonitrile-copolymer (SAN) and acrylonitrile-butadiene-styrene-copolymer (ABS) are gaining in importance as food contact materials. Oligomers and other non-intentionally added substances can migrate into foodstuffs. Five SAN and four ABS samples from the German market and manufacturers were extracted and the extractable oligomers were characterised by high performance liquid chromatography-mass spectrometry/ultraviolet detection/chemiluminescence nitrogen detection/fluorescence detection and gas chromatography-mass spectrometry. Trimers, formed from acrylonitrile and styrene units, were determined to be the dominating group of extractable oligomers in SAN and ABS in concentrations of about 4900���15800 mg/kg material. Furthermore, styrene-acrylonitrile dimers, styrene oligomers, styrene monomer and ethylbenzene were identified in the sample extracts. Migration testing with three consecutive migrations for multiple use articles was performed for two SAN articles. Migration of trimers into water, 3% acetic acid, 10% and 20% ethanol under hot-fill conditions (70��C, 2 h) was not detectable above 9 ��g/dm2, while 50% ethanol acting as a food simulant for milk (124 ��g/dm2 trimers during the third migration) was shown to overestimate the actual migration into milk (< 11 ��g/dm2 trimers at 70��C, 2 h). 2-Amino-3-methyl-1-naphthalenecarbonitrile (AMNC), an oligomer degradation product and a primary aromatic amine, was detected in all material sample extracts (0.3���17.1 mg/kg material) and was released into food simulants in low amounts (< 0.014 ��g/dm2 during the third migration into 50% ethanol at 70��C, 2 h).

Background In the traditional ethylbenzene dehydrogenation process, much superheated steam is needed to ensure the activity and stability of the catalyst, inevitably leading to high energy consumption. Methods A novel ethylbenzene dehydrogenation process based on a circulating fluidized bed (CFB) reactor was used for the ethylbenzene dehydrogenation reaction under a low steam-to-oil ratio. In this work, a series of Fe-Al-based catalysts were prepared by a sol-gel method and the effect of alumina content on the catalytic performance of Fe-Al-based catalyst for ethylbenzene dehydrogenation was investigated. Significant findings Among a series of Fe-Al-based catalysts, the FeAl40 catalyst (the Fe-Al-based catalyst with 40 wt. % alumina) had the highest dehydrogenation activity and suitable attrition resistance for the CFB reactor. Further investigation found that the adding alumina could inhabit the formation of KFe11O17, leading to poor stability. Interestingly, the high activity of the FeAl40 catalyst could be completely recovered through a reaction-regeneration operation. Compared with the conventional ethylbenzene dehydrogenation process, the CFB process benefits from high activity, low steam-to-oil ratio and no induction period. Consequently, the FeAl40 catalyst had high dehydrogenation activity (∼51 wt. % yield of styrene) and low preparation cost, showing an extraordinary potential for industrial application.

A detailed reaction mechanism and kinetic model have been developed to study the catalyzed oxidation of ethylbenzene. The model is used to compute the time profiles of ethylbenzene and three products: acetophenone, benzaldehyde, and benzoic acid. The kinetic model is evaluated on three different reported studies for ethylbenzene oxidation with iron- and cobalt-based catalysts using tert-butyl hydrogen peroxide as an oxygen source, in solventless condition and at various experimental conditions. The model shows good fit for the concentration profiles with time and with the change in parameters like ethylbenzene-to-tBHP ratio and temperature. Activation energy and pre-exponential factors are calculated from Arrhenius plots using the values of rate constants derived using the proposed model. It was established that the excess amount of oxidant in the reaction mixture leads to over-oxidation products, which was not captured experimentally. The hypothesis is supported with the simulation results from modified model.

A bizeolite catalyst based on ZSM-5 and ZSM-12 was designed to maximize the yield of valuable aromatics from ethylbenzene (EB) rich feedstocks for the first time. The catalyst Pt/ZSM-5:ZSM-12/Al2O3 was characterized by X-ray diffraction (XRD), nitrogen physisorption, temperature-programmed desorption of ammonia (TPD-NH3), transmission and scanning electron microscopy (TEM and SEM), X-ray fluorescence analysis (XRF), Fourier-transformed infrared spectroscopy (FTIR) and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The catalyst and its components were tested in isomerization of an industrial C-8 aromatic cut (C8-Ar) and feedstocks with high EB content. The catalyst demonstrated higher conversion of EB and m-xylene (MX) compared with an industrial catalyst and higher selectivity to dealkylation products.

The breathing phenomenon in metal-organic frameworks (MOFs) has revealed supramolecular host-guest interactions that could be beneficial for chemical separation in numerous industrial applications. The cost-effective purification of C8 alkyl aromatics such as o-xylene, m-xylene, p-xylene, and ethylbenzene remains challenging owing to their similar molecular structures, boiling points, kinetic diameters, polarities, etc. Herein, we report two Zn-based pillar-bilayered MOFs, denoted [Zn2 (aip)2 (pillar)] (aip=5-aminoisophthalic acid; pillar: bpy=4,4'-bipyridine or bpe=1,2-bis(4-pyridyl)ethane) that exhibit a breathing effect depending on the adsorbed guest molecules. Guest-dependent sorption studies in organic solvents such as N,N-dimethylformamide, methanol, benzene, and water vapor display reversible structural flexibility through the breathing effect in both framework compounds. The experiments conducted on C8 -alkyl aromatics resulting in both MOF compounds can access these isomers in the shrunken pores, and thereby expand the pore size by framework breathing. In C8 binary mixtures, these Zn-MOFs exhibit selective sorption properties based on the different interactions between guest C8 aromatics and the framework structure.

Roof-shaped host compounds trans-α,α,α′,α′-tetraphenyl-9,10-dihydro-9,10-ethanoanthracene-11,12-dimethanol H3 and trans-α,α,α′,α′-tetra(p-chlorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dimethanol H6 were assessed for their host potential and selectivity behaviour when presented with single or mixed guest solvents comprising o-xylene, m-xylene, p-xylene and ethylbenzene (o-Xy, m-Xy, p-Xy and EB). H3 included each solvent with 3:1 host:guest ratios, while the ratios preferred by H6 were more varied (4:3, 1:1 and 3:2). More importantly, the selectivity behaviour of these two host compounds was observed to be entirely different: H3 possessed only a very modest preference for o-Xy (37.9–68.2%) when recrystallized from various equimolar binary, ternary and quaternary guest mixtures, while H6 was considerably more selective, preferring m-Xy (the least favoured guest of H3) with selectivities ranging from 57.7 to 91.4% in analogous conditions. The latter result was obtained in o-Xy/m-Xy mixtures and demonstrates that H6 may be employed as a purification tool for mixtures of these two xylenes via host–guest chemistry protocols. A single crystal diffraction experiment on 3(H3)·o-Xy (containing the preferred guest of H3) revealed that the guest was retained in the host crystal by means of a singular (host)m-Ar–H···π(guest) interaction that measured 2.73 A (148°) as well as numerous other host···guest interactions involving only the aromatic protons of the free host phenyl groups and the guest methyl protons or aromatic carbons and protons (2.20–2.54 A, 121–125°). Thermal analyses explained the preference of H3 for o-Xy, while these were less informative for the complexes of H6.

A kinetic analysis of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the iron(IV)-oxo complex [(N4Py)FeIV(O)]2+ and to the phthalimide N-oxyl radical (PINO) has been carried out. The results indicate that a higher activating effect of α-heteroatoms toward the HAT from C-H bonds is observed with the more electrophilic PINO radical. When the N-hydroxy precursor of PINO, N-hydroxyphthalimide (NHPI), is used as a HAT mediator in the oxidation promoted by [(N4Py)FeIV(O)]2+, significant differences in terms of selectivity have been found. Product studies of the competitive oxidations of primary and secondary aliphatic alcohols (1-decanol, cyclopentanol, and cyclohexanol) with alkylaromatics (ethylbenzene and diphenylmethane) demonstrated that it is possible to modify the selectivity of the oxidations promoted by [(N4Py)FeIV(O)]2+ in the presence of NHPI. In fact, alkylaromatic substrates are more reactive in the absence of the mediator while alcohols are preferably oxidized in the presence of NHPI.

A series of ZSM-5@MCM-41 core–shell composite materials prepared via a multi-cycle-sol–gel coating strategy is investigated as the catalyst for benzene alkylation with ethylene, in which both ethylbenzene and para-diethylbenzene (p-DEB) are aimed as the target products. With multi-cycle-sol–gel coating, the external acid sites on the samples are gradually passivated by the inert MCM-41 shell. As a result, the shape selectivity to p-DEB is greatly enhanced. Nevertheless, the coating of mesoporous MCM-41 shell on ZSM-5 accelerates deactivation of the catalyst only due to the dilution effect of ZSM-5 content in the catalyst at the same space velocity, which is a reason that core–shell ZSM-5@MCM-41 will potentially be a practical catalyst in shape selective alkylation of benzene. In order to enhance the yield of p-DEB on ZSM-5@MCM-41, the reaction conditions at the fixed bed reactor including temperature, the molar rate of benzene to ethylene and GHSV, are also optimized.

The aerobic, selective oxidation of hydrocarbons via C H bond activation is still a challenge. This work shows the achievement of the room temperature visible light driven photocatalytic activation of benzylic C H bonds with N-hydroxysuccinimide over BiOBrxI1-x (0 ≤ x ≤ 1) solid solutions, whose valance bands were engineered through varying the ratio of bromide to iodide. The optimal BiOBr0.85I0.15 catalyst exhibited over 98% conversion ratio of ethylbenzene, which was about 3.9 and 8.9 times that of pure BiOBr and BiOI, respectively. The excellent photocatalytic activity of BiOBr0.85I0.15 solid solution can be ascribed to the orbital hybridization of the valence band containing both Br 4p and I 5p orbitals, which could promote photo-induced charge carrier separation and improve the generation of singlet oxygen. This work shed some light on the rational design of photocatalysts for targeted organic transformation.

Polymer-silica hybrid support (SA-2-AMPS-SiO2) was synthesized and Co (II), Cu (II) metals were loaded over hybrid support by incipient impregnation technique. Oxidation of ethylbenzene was carried out for testing catalytic activity of catalysts at different reaction conditions i.e. the mole ratio of ethylbenzene to TBHP and reaction temperature. The main oxidation product was acetophenone along with benzaldehyde as the minor product and the highest ethylbenzene conversion (83.65 %) was attained at a 1:4 mol ratio of ethylbenzene to TBHP and temperature at 100 °C. The reusability of the catalysts was also determined and results showed that they can be easily reused three times without much loss in their structural and catalytic properties.

The objective of this study is to evaluate the catalytic performance of pellet-type Ru/γ-Al2O3 as a catalyst during liquid-phase hydrogenation of the aromatic hydrocarbon. The Ru/γ-Al2O3 catalyst was prepared using a wet impregnation method. After adding a binder to Ru/γ-Al2O3, a pellet-type catalyst was obtained through an extrusion method. Nanoporous structures are well developed in the pellet-type Ru/γ-Al2O3 catalyst. The average pore sizes of the Ru/γ-Al2O3 catalysts were approximately 10 nm. The catalytic performance of the pellet-type Ru/γ-Al2O3 catalyst during ethylbenzene hydrogenation was evaluated in a trickle-bed reactor. When the ruthenium loading increased from 1 to 5 wt%, the number of active sites effective for the hydrogenation of ethylbenzene increased proportionally. In order to maximize the conversion of ethylbenzene to ethylcyclohexane, it was necessary to maintain a liquid phase hydrogenation reaction in the trickle bed reactor. In this regards, the reaction temperature should be lower than 90 °C. The conversion of ethylbenzene to ethylcyclohexane on the Ru(5 wt%)/γ-Al2O3 catalyst was highest, which is ascribed to the largest number of active sites of the catalyst.

In order to create a more efficient process for the production of styrene from ethylbenzene by selective oxidation of the resulting hydrogen, model aluminum-chromium catalysts with different modifier (Cu) contents were prepared, and O2, CO2 and a mixture of CO2:air were used as an oxidant. It has been es-tablished that the process of obtaining of styrene from ethylbenzene on alumochromic catalysts is characterized by a high intensity. Alumochromic catalysts modified by Cu and promoted by 15 mass.% K2CO3 in the presence of carbon dioxide increase the conversion of ethylbenzene by 14%, and the selectivity of the formation of styrene by 10% as a result of the transferring dehydrogenation of compaction products to the products of oxidative compaction. The presence of oxygen in the oxidizing mixture CO2:air blocks the participation of carbon dioxide in the selective oxidation of hydrogen isolating at the dehydrogenation of ethylbenzene. It has been established that the most selective alumochromic catalysts in the oxidative dehydrogenation of ethylbenzene to styrene contain 1.5–2.5 mass.% of the modifying component (Cu)

Selective chemical detection of aniline vapor from benzene, toluene, ethylbenzene, and xylene (BTEX) is still a challenge. Here, we deliberately design a hydroxyapatite (HAP) nanorods nanobiomaterial modifying on the quartz crystal microbalance transducer for highly efficient detection of aniline from aniline/BTEX mixture. Besides, at room temperature, HAP nanorods perform excellent sensitivity of aniline, and the corresponding detection limit can reach down to 5 part per billion (ppb). The stability of HAP nanorods in the sensing process is also satisfactory. The sensing mechanism, as unveiled by the theoretical basis and the enthalpy extraction experiment, is due to the moderate acid–base absorptive interaction between aniline molecule and the HAP structure. The molecular formula of hydrate C6H7N·βH2O existing in wet air (with 50–90% relative humidity) can be obtained as C6H7N·1.36∼1.93H2O based on quantitatively measurement data.

Alkylbenzenes constitute a significant portion of middle-distillate transportation fuels, and they are judged as the key contributors to the extent of soot production and consequent exhaust particulate emissions in combustion engines. Because of the uncertainties involved in engine experiments due to boundary condition variation among test platforms and the difficulties involved in controlling engine variables independently, benchmark information on pressure dependence of sooting propensities of alkylbenzenes is essential to understand their influence on particulate emissions and provide a more consistent interpretation of engine data. One of the approaches to acquire such benchmark data is to investigate laminar diffusion flames doped with alkylbenzenes under tractable conditions at elevated pressures. Here, we study the influence of doping a methane laminar diffusion flame with alkylbenzenes having eight carbon atoms, namely ethylbenzene, p-xylene, and o-xylene and compare their sooting characteristics to that of n-octane at pressures up to 10 bar. Liquid hydrocarbons added to methane replaced 3% of the carbon in the base fuel keeping the carbon mass flow in the fuel stream fixed, at all pressures considered, to have tractable measurements. The flames of base fuel methane and those doped with liquid C 8 hydrocarbons were stabilized on a laminar co-flow diffusion burner positioned inside a combustion chamber capable of elevated pressures and has suitable optical access. Radially resolved temperatures and soot volume fractions were evaluated from spectral emission of soot radiation from the flames. Soot yields, inferred from the radial distributions of soot volume fractions, of ethylbenzene, p-xylene, and o-xylene doped flames were found to be a factor of about 2.6–3.2 higher than that of n-octane at 2 bar; however, this difference gradually disappeared with increasing pressure and soot yields were almost the same above 6 bar. It appears that pressure dependence of sooting propensities of ethylbenzene, p-xylene, and o-xylene is weaker than that of n-octane within the pressure range of 2 to 10 bar.

The extraction of valuable components (methyl phenyl carbinol, acetophenone, ethylbenzene, phenol, propylene glycol) from industrial wastewater formed during styrene–propylene oxide coproduction by the hydroperoxide method at PAO Nizhnekamskneftekhim was used as an example to formulate and discuss approaches to increasing the efficiency of the extraction process performed under supercritical fluid conditions beyond the binodal for the systems desired component–extractant with type I and II phase behavior. The assumptions were experimentally confirmed by studying the extraction of methyl phenyl carbinol and phenol from their aqueous solutions with such extractants as carbon dioxide in the liquid and supercritical fluid state and also a supercritical propane/butane mixture. The phase equilibrium of the thermodynamic system propane/butane–propylene glycol was experimentally investigated at 403, 423, and 443 K.

CaCO3 obtained from Sporosarcina pasteurii isolated from agricultural soils has been employed as catalytic support for Pd that was subsequently loaded on CaCO3 by wet impregnation with a metal loading of 0.5 wt.% using Palladium acetate as precursor. The materials were characterized via nitrogen physisorption measurements, X-ray diffraction, X-ray photoelectronic spectroscopy, TGA Analysis and TEM microscopy. Pd0.5/CaCO3 was able to successfully hydrogenate phenylacetylene into styrene and ethylbenzene as products. Thus, through the proper optimization of the reaction conditions (flow rate, temperature, pressure) it was possible lead the reaction towards the selective production of styrene, a monomer widely used in the polymer industry, from phenylacetylene as starting material in yields up to 65 %.

A headspace-hollow fiber solid-phase microextraction (HS-HFSPME) as a selective and sensitive procedure was developed to extract benzene, toluene, ethylbenzene, and p-xylene (BTEX) prior to their determination with gas chromatography-flame ionization detection. δ-Al2O3@SiO2@CTAB core–shell was synthesized as a novel sorbent for the BTEX extraction and enforced into the surface pores on the polypropylene hollow fiber (HF) using sol–gel procedure. The preparation of an HF device for HS-HFSPME can be highly regarded for creating a cheap disposable tool with no memory effects. A chemometric approach, including the Plackett–Burman design and the central composite design, was utilized to optimize the effective factors due to a low number of experiments and investigate the factor interaction. The method shows low LODs (≤ 0.01 ng ml−1), wide linearity, high preconcentration factor (≥ 265), and suitable RSDs (≤ 5.2%) toward the BTEX determination. The method was finally applied to measure BTEX in Buxus leaves and wastewater samples with high recoveries in the range of 89.7–103.4 and low RSD% in the range of 4.64–6.20%, showing the method has suitable recoveries and repeatability. The results confirm that the HS-HFSPME-GC/FID method is an excellent procedure to measure BTEX in various real samples such as plant and wastewater samples with great benefits such as low organic solvent consumption, simple operation, and high sensitivity for the BTEX determination.

The xylene isomerization is a well-established process in the aromatic-based petrochemical complex. This process aims to convert ethylbenzene (EB), meta- and ortho-xylene to para-xylene (PX). Active metal such as platinum (Pt) on the zeolite support is a commonly used catalyst for isomerization reactions. Different catalysts with different acidic strength of zeolite (Si/Al ratios = 32, 50, and 150) are synthesized in this study. The physical and chemical properties of the synthesized catalysts are characterized using X-ray diffraction (XRD), inductively coupled plasma (ICP), and Brunauer, Emmett, and Teller (BET) surface area analyses. Then, the effect of catalyst types and operating parameters such as temperature (370, 375, 380, and 385 °C), hydrogen partial pressure (2.4, 2.6, 2.8, and 3.0), and weight hourly space velocity (3.2, 3.4, 3.8 and 4.1 h−1) investigated on the xylene isomerization process. Indeed, the variation of EB conversion, xylene loss, and the ratio of PX produced to the PX in equilibrium condition (PXATE) by these influential factors is experimentally monitored in a laboratory-scale xylene isomerization reactor. Results show that the catalyst with a small Si/Al ratio of 32 has higher acidic strength and provides the best isomerization performance. Moreover, the temperatures of 375 °C, hydrogen partial pressure (H2/hydrocarbon) of 2.6, and weight hourly space velocity (WHSV) of 3.5 h−1 are the optimum operating conditions for the xylene isomerization process.

Poly(methacryloyloxy quinoline) microparticles were synthesized and used as reducing and stabilizing agents to prepare Au/Pt bimetallic nanoparticle (NP) decorated microparticle (MP) hybrid catalyst systems. These newly reported hybrid catalyst systems were used for reduction of styrene into ethylbenzene. Gold precursor was essential to prepare bimetallic NPs due to its great interaction with PMAQ resulting in the reduction to AuNPs on the surface of PMAQ MPs. Pt is also contrubute to NP formation thanks to this superior interaction between Au and PMAQ MPs. The bimetallic nanoparticle contents on the PMAQ MPs were determined as Au0.85Pt0.15 via XRD analysis. Au and Pt amounts were also determined with ICP-MS analysis. Although the metal amount in the sample was quite low, the catalytic effect was remarkable for hybrid system. AuNP decorated MPs had no catalytic activity for the reduction of styrene. Thus, it is clear that Pt was the active part of hybrid catalyst system for this reaction. On the other hand, gold precursor had been determined as crucial for the simultaneous synthesis of bimetallic NP decorated MPs as well. New microparticles decorated with bimetallic nanoparticles have been synthesized and used effectively as a catalyst systems in the hydrogenation of styrene. While it is reported in the literature that such particles have successful catalytic activity in various oxidations, our particles stand out with reducing activities, reusabilities and easy production/removal properties.

The isobaric binary vapor–liquid equilibrium (VLE) data for the mixture of 2-phenylethanol (2PEA) with 1-phenylethanol (1PEA), 2-phenylpropan-2-ol (2P2P), ethylbenzene (ETB), and isopropylbenzene (...

Air quality policy in the Los Angeles megacity is a guidepost for other megacities. Over the last 2 decades, the policy has substantially reduced aerosol (OA) concentrations and the frequency of high aerosol events in the region. During this time, the emissions contributing to, and the temperature associated with, high aerosol events have changed. Early in the record, aerosol concentrations responded to a variety of different sources. We show that emission control has been effective with a strong decrease in temperature-independent sources. As a result, the response of aerosol to temperature has become a dominant feature of high aerosol events in the basin. The organic fraction of the aerosol (OA) increases with the temperature approaching 35% at 40 °C. We describe a simple conceptual model of aerosol in Los Angeles, illustrating how benzene, toluene, ethylbenzene, and xylenes (BTEX) and isoprene, along with molecules for which these are plausible surrogates such as monoterpenes, are sufficient to explain the observed temperature dependence of PM 2.5.

In conventional ethylbenzene dehydrogenation process, abundant superheated steam is consumed to supply reaction heat and inhibit coke formation, thereby a high operation cost is resulted. In this work, Fe2O3 promoted TiO2-ZrO2 catalyst demonstrated outstanding dehydrogenation performance in the absence of steam. The catalyst composition and preparation method have both been studied and optimized. The high specific surface area, well dispersion of Fe2O3 species, and appropriate acid-base properties are all necessary for ethylbenzene dehydrogenation. Ascribed to the reduction of Fe2O3 species, an induction period to reach the highest styrene selectivity was observed. For the catalyst after pre-reduction, an outstanding initial dehydrogenation performance can be obtained and kept stable in eight reaction-regeneration cycles. Further, a conceptual fluidized-bed ethylbenzene dehydrogenation process composed of a reactor, a regenerator and a reduction section was proposed to realize continuous reaction-regeneration operation. This work not only provides a class of ethylbenzene dehydrogenation catalyst efficient in the absence of steam, but also presents the concept of fluidized bed process obviously reducing the operation cost and achieving self-heat balance.

A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups. The porous structure of the catalyst was characterized by a specific surface area of 94.7 m2 g−1. The presence of Pd(II) and Pd(0) in Pd/S-DVB was evidenced by XPS and TEM. Pd/S-DVB catalyzes the hydrogenation of acetophenone (APh) to 1-phenylethanol (PhE) and ethylbenzene (EtB). The highest conversion of APh was obtained in methanol (MeOH) and in 2-propanol (2-PrOH), while in water it was lower. The conversion of APh correlates well with the hydrogen-bond-acceptance (HBA) capacity of the solvent. However, in all binary mixtures of alcohol and water the APh conversion and the yield of products significantly decreased. The observed inhibiting effect can be explained by the microheterogeneity of these mixtures and the blocking of the catalyst surface restricting access of the substrates to the Pd centers.

The development of a highly efficient strategy for the activation of the C–H bond in hydrocarbons is one of the most challenging tasks facing the chemical industries. The synthesis of novel catalysts with atomically dispersed active centers is highly desirable to achieve the maximized atom efficiency. Here we report the controllable preparation of a Co-based single-atom catalyst anchored on a graphitic carbon nitride support (SACo@g-C3N4) with 3.17 wt% Co content, which is successfully applied for the selective oxidation of ethylbenzene (EB) to derive acetophenone (AcPO) via the activated peroxymonosulfate (PMS) oxidant. The Co atoms are chemically bonded with the N atoms of g-C3N4 and present exceptional stability and reusability to resist the applied acidic-oxidative environment. Both the EB conversion and AcPO selectivity were over 95% in this highly selective SACo@g-C3N4/PMS system under mild reaction conditions. The selective conversion of EB into AcPO is attributed to the oxidative radicals generated from the decomposition of PMS molecules via the electron transfer between Co atoms and PMS. Sulfate radicals (SO4˙−) make a greater contribution than others to activate the C–H bond in EB oxidation. This work uncovers a facile and scalable approach for the synthesis of a robust Co-based single atom catalyst (SAC) on a g-C3N4 support and unveils its potential in the oxidation of hydrocarbons via a highly efficient and environmentally benign PMS activation.

The consumption of acetophenone (AP) is increasing worldwide because of its applications in products such as alcohol, aldehydes, resins, esters, fragrances, and pharmaceuticals. AP is manufactured via several methods like decomposition of cumene hydroperoxide, Hock process, and Friedel–Crafts acylation reaction using homogeneous catalysts with solvent and oxidant. However, it causes several environmental problems that deteriorate the production of AP with these methods. Oxidation of ethylbenzene (EB) is one of the promising methods to synthesize AP in liquid and vapor phases reaction using heterogeneous catalysts, which plays a vital role for selective production of AP. In this review, numerous heterogeneous catalysts are discussed including transition metal nanoparticles, transition metal complexes, and metal free catalysts (carbon nanotubes) used in last 10 years for oxidation of EB. Additionally, catalyst activity along with reaction parameters and its effect, mechanisms, and kinetics study are summarized in this article. The future scope of this reaction is also highlighted. Moreover, this work identifies best catalysts for bulk production of AP with high yield to satisfy global requirement.

Nitrogen-doped carbon materials with hierarchical porous structures have attracted huge attention in the field of catalysis owing to their special structures and properties in past few decades. In this study, a series of metal-free and N-rich porous carbon catalysts (NPCs) were synthesized by a one-step activation-pyrolysis process. The catalytic performance of NPCs obtained from using bean curd as the carbon and nitrogen precursors and activated via pyrolysis in a nitrogen atmosphere with different amounts of K2CO3 was investigated for the selective oxidation of ethylbenzene. The catalysts were characterized using a series of techniques, such as N2 adsorption–desorption isotherms, Raman spectroscopy, TEM, SEM, and XPS. The results presented that the as-prepared samples have specific surface areas as high as 1459 m2 g−1. Furthermore, NPC-10 displayed the optimal catalytic performance among the catalysts. The ethylbenzene conversion of 96.2% over NPC-10 with a selectivity to acetophenone of 97.0% is even comparable to the results of some metal-doped catalysts, which may be attributed to the hierarchical porous structures and plenty of C–NX active sites. This work provides a facile and novel strategy for the construction of metal-free and N-rich carbon materials with excellent catalytic activity for the selective oxidation of ethylbenzene.

This review focuses on recent fundamental insights about methane dehydroaromatization (MDA) to benzene over ZSM-5-supported transition metal oxide-based catalysts (MOx/ZSM-5, where M = V, Cr, Mo, W, Re, Fe). Benzene is an important organic intermediate, used for the synthesis of chemicals like ethylbenzene, cumene, cyclohexane, nitrobenzene and alkylbenzene. Current production of benzene is primarily from crude oil processing, but due to the abundant availability of natural gas, there is much recent interest in developing direct processes to convert CH4 to liquid chemicals. Among the various gas-to-liquid methods, the thermodynamically-limited Methane DehydroAromatization (MDA) to benzene under non-oxidative conditions appears very promising as it circumvents deep oxidation of CH4 to CO2 and does not require the use of a co-reactant. The findings from the MDA catalysis literature is critically analyzed with emphasis on in situ and operando spectroscopic characterization to understand the molecular level details regarding the catalytic sites before and during the MDA reaction. Specifically, this review discusses the anchoring sites of the supported MOx species on the ZSM-5 support, molecular structures of the initial dispersed surface MOx sites, nature of the active sites during MDA, reaction mechanisms, rate-determining step, kinetics and catalyst activity of the MDA reaction. Finally, suggestions are given regarding future experimental investigations to fill the information gaps currently found in the literature.

Currently, the aerobic oxidation of ethylbenzene to acetophenone has been found to be efficient and environmentally friendly, but homogeneous N-hydroxyphthalimide (NHPI), being active in the catalytic transformation suffers from separation and recovery. Here, NHPI was covalently anchored on commercial SiO2 using symmetric aromatic dianhydrides and (3-aminopropyl) triethoxysilane as precursors and a linking molecule, respectively, and the grafting bonds formed were convincing based on their IR absorption, chemical state(s) of N atoms, and the decomposition temperatures. Also, the catalyst synthesized using pyromellitic dianhydride (PMDA) as the precursor presented a grafting density of 0.70 mmolN–OH gsilica−1. The immobilized NHPI catalyzed the selective aerobic oxidation of ethylbenzene to acetophenone, and an ethylbenzene conversion of 63.8% and a selectivity to acetophenone of 79.0% were observed under optimal reaction conditions. An excellent catalytic reusability of the grafted NHPI catalyst was observed in repeated evaluations and this could be attributed to the confirmed stability of the structure and composition arising from the robust imide bonds anchoring. The anchoring method and the resulting NHPI catalysts could open access to converting organics with benzylic C–H bond(s) into their oxygenated value-added products, suggesting a promising application prospect.

5-Methyl-4-[(propylsulfanyl)methyl]-2,4-dihydro-3H-pyrazol-3-one was shown to inhibit the radical-chain peroxidation of 1,4-dioxane, ethylbenzene, and methyl oleate. One peroxyl radical is trapped by each (propylsulfanylmethyl)-substituted 2,4-dihydro-3H-pyrazol-3-one molecule. The reaction rate constant of the compound with a peroxyl radical depends on the structure of the latter and decreases in the series: peroxyl radical of 1,4-dioxane, ethylbenzene, and methyl oleate (k7 × 104, L mol –1 s–1, 333 K: 5.7, 4.1, 1.1). The reason for the observed dependence was discussed.

K3PO4/NaX catalysts were prepared by loading potassium phosphate on NaX zeolite, and the catalytic performance was studied for the side-chain alkylation of toluene with methanol to styrene and ethylbenzene. Combined with the characterization of XRD, TPD-NH3, TPD-CO2, and FTIR and the determination of phosphorus content, it is revealed that firstly, the P element loaded on the catalyst surface can prominently promote the percentage of middle base sites, which will accordingly enhance the selectivity of the products (styrene and ethylbenzene) of side-chain alkylation of toluene; secondly, if there are enough middle base sites distributed on the catalysts, the higher percentage of strong base sites benefit the selectivity of styrene, which is confirmed by the performance of the two-stage catalysts.

Here we compare the host behaviour of two roof-shaped compounds, trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid H1 and its dimethyl ester, trans-dimethyl 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylate H4, when presented with mixed xylene (o-Xy, m-Xy and p-Xy) and ethylbenzene (EB) guest solutions. Both host compounds formed complexes with all of these solvents, except H4/EB, where no inclusion occurred. When H1 was recrystallized from the various equimolar combinations of these guests, enhanced selectivities were observed for p-Xy. In fact, equimolar binary mixtures of o-Xy/p-Xy and m-Xy/p-Xy afforded complexes that showed near-complete host selectivity for p-Xy (96.6 and 93.6%, respectively). The selectivity displayed by H4 in analogous experimental conditions, however, was only ordinary at best. The complexes of H1 and H4 with p-Xy were explored in-depth by means of single crystal diffraction analyses. Owing to the scarcity in the number and type of host⋯guest interactions, both complexes may be defined as approaching that of true clathrates. Finally, data from thermoanalytical experiments concurred with the selectivity behaviour of both host compounds.

In the present investigation, we compare the host and selectivity behaviour of two compounds, namely α,α-diphenyl-9,10-dihydro-9,10-ethanoanthracene-11-methanol H1 and α,α-bis(p-chlorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11-methanol H2, when recrystallized from both singular and mixed isomers comprising the xylenes (o-Xy, m-Xy and p-Xy) and ethylbenzene (EB) as potential guest solvents. H1 formed a complex with o-Xy alone in the single solvent experiments, while H2 included all four of these aromatic compounds. In equimolar guest competition experiments, H1 only crystallized from binary mixtures where o-Xy was present, and high selectivities for this guest were observed in these instances (84.5–93.7%). The other binary mixtures ultimately presented as gels, and H1 therefore failed to crystallize from these. In fact, this was true also for all ternary and quaternary experiments with H1, even when o-Xy was present. H2, on the other hand, consistently formed mixed complexes from all of the solutions employed. However, its selectivity for any particular guest was unremarkable. Guest/guest competition experiments using both equimolar and non-equimolar mixtures revealed that H1 may be employed to purify o-Xy/m-Xy, o-Xy/p-Xy and o-Xy/EB binary mixtures, especially when these solutions comprised 50% or more o-Xy (these experiments all favoured o-Xy). SCXRD analyses were employed to understand the moderate preference of H2 for o-Xy: only this guest was involved in contacts with the host compound, two in number, that measured significantly less than the sum of the van der Waals radii of the atoms involved. Additionally, Hirshfeld surface investigations showed that H2, through its chlorine atoms, was involved in the greater number of contacts with the preferred o-Xy guest compound. Thermal analyses, however, proved less useful in understanding these selectivity data.

An ideal catalytic process for the selective oxidation of hydrocarbons should employ an efficient, recyclable, and cost-effective catalyst under solvent- and additive-free conditions with molecular...

A mathematical description of ethylbenzene dehydrogenation has been developed taking into account the changes in the partial pressures and partial molar volumes of the components of the reaction mixtures. In computational experiments, a steam–ethylbenzene mixture is considered as a system of interacting gases, for which a study is made of the effect of the partial parameters of the components on the change in the component composition of the reaction medium, in the ethylbenzene conversion, in the selectivity toward the desired product, and in the rate of the decrease in the specific rection rates. It is determined that the partial molar volumes and pressures of the substances have a significant effect on the rates of the bimolecular reactions of the process and, as a consequence, on the dynamics of the formation of side products; the sensitivity of the reaction-rate constants to a change in the considered parameters decreases along the length of a reactor stage. The derived mathematical dependences relate the control parameters (ethylbenzene conversion and selectivity toward the desired product) and the physical state quantities of the contact gas. The model can be used to estimate the degree of coking of the catalyst bed during the operation of the reactor.

A robust monolith catalyst has been fabricated involving the combination of nanodiamonds (NDs) and mesoporous carbon modified by nitrogen and phosphorus (ND@NMC-xP, x = amount of ammonium biphosphate) on a β-SiC foam. The ND@NMC-0.02 P/SiC monolith catalyst with 0.2 at.% of P elements exhibits an excellent catalytic performance for oxidative dehydrogenation of ethylbenzene (EB), delivering 90.2% selectivity to styrene (ST) up to 32.6% conversion. The specific conversion rate of monolith catalyst based on the unit weight of NDs and mesoporous carbons (25.3 mmol gact. phase−1 h−1) is 3-fold higher than that of unsupported NDs. The role of nitrogen is believed to enhance the density of active sites and thus offering a high EB conversion, whereas the addition of phosphorus inhibits deep oxidation of EB to carbon oxides and therefore for a high selectivity to ST. The monolith catalyst not only contributes a high utilization efficiency of NDs but also mitigates the high pressure drop across the catalytic bed, which is potentially suitable for a real industrial process.

Nano-sheets Al2O3 supported CeO2-Fe2O3 binary oxides were prepared by the vacuum impregnation method. The structural and textural properties were characterized by pertinent techniques, and the materials were evaluated as catalysts for the oxidative dehydrogenation of ethylbenzene with carbon dioxide (CO2-ODEB). The characterization results show that all samples maintain the hierarchical structure, and CeO2-like and Fe2O3-like solid solutions were formed when changing the Ce-to-Fe molar ratio. The catalytic performances indicate that CeO2-Fe2O3 binary oxides were effective for CO2-ODEB, and the activity is determined by mobile oxygen, which can facilitate the dehydrogenation process. The DFT studies further identified the reaction pathway and rate determining step. The inter-transmission of oxygen species and the presence of CO2 refill the oxygen vacancies and restore the redox cycle of CeO2-Fe2O3 binary oxides.

A multistage synthesis of the catalyst for the gas-phase alkylation of benzene with ethylene is implemented. A highly active catalyst is synthesized from zeolite ZSM-5 using thermal-vapor treatment. The obtained catalyst possesses an optimal acidity, which makes it possible to achieve a higher yield of ethylbenzene compared to the commercial catalyst based on ZSM-5 (88 and 62.7 wt %, respectively), an approximately equal ethylbenzene selectivity, and an almost three times lower concentration of the undesirable xylene impurity in an alkylate (0.004 and 0.011 wt %, respectively) in the gas-phase benzene alkylation with ethylene.

Solubilities of benzene, toluene, and ethylbenzene (BTEX compounds, together with xylene) in poly(ethyl methacrylate) (PEMA) and plasticized PEMA at 298.15 K were measured using a quartz crystal microbalance and are reported in the form of solvent activity versus solvent weight fraction. Two plasticizers, diisononyl cyclohexane-1,2-dicarboxylate (DINCH) and diisooctyl azelate (DIOA), were studied, each at three different concentration levels in the polymer. The presence of a plasticizer increases the solubility of all three compounds. Data were interpreted using a pseudobinary Flory–Huggins model in which the plasticized polymer is considered to be a single pseudocomponent.

The applications of homology and isomerism to the structure of phase diagrams and distillation flowsheets of multicomponent mixtures were considered. Three homologous series of separation flowsheets based on combinations of distillation and splitting were studied for ternary, quaternary and five-component mixtures of water with aromatic hydrocarbons (benzene, toluene, ethylbenzene, propylbenzene). In each series, the flowsheets are ranked according to increasing energy consumption: preliminary splitting—indirect separation sequence—direct separation sequence of the initial mixture. The energy consumption depends linearly on the number of homologous components in the mixture and was shown to be predictable in flowsheets (using the system with butylbenzene as an example). A comparison of isomer flowsheets with the same number of apparatuses but with different sequences of product separation showed that the indirect separation sequence is energetically preferable provided that the water and benzene product flows are separated in the form of equilibrium liquid phases from a decanter.

Highly efficient binder-free catalysts, based on zeolite Y, for the liquid-phase alkylation of benzene with ethylene have been synthesized. The catalysts have been modified by treating with aqueous solutions of hydrochloric and citric acids to remove extra-framework aluminum formed during the partial dealumination of zeolite Y. The synthesized catalysts have been tested in the alkylation of benzene with ethylene at a temperature of 200°C, a pressure of 2.5 MPa, a benzene : ethylene molar ratio of 5 : 1, and a benzene feed space velocity of 5 h−1. Over the modified catalyst, the ethylbenzene (EB) content in the alkylate increases by 27% and the EB selectivity increases by 5% compared to the initial Y zeolite.

Spherical mesoporous carbon (with a particle size in the range of 40–75 μm) was synthesized by nanoreplication of a hard silica template using sucrose as the carbon precursor. The mesoporous carbon...