Highly selective extraction of aromatics from aliphatics by using metal chloride-based ionic liquids

The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.

Controllable Condensation of Aromatics and Its Mechanisms in Carbonization

In order to obtain liquefied products with higher yields of aromatic molecules to produce mesophase pitch,a good understanding of the relevant reaction mechanisms is required.Reactive molecular dynamics simulations were used to study the thermal reactions of pyrene,1-methylpyrene,7,8,9,10-tetrahydrobenzopyrene,and mixtures of pyrene with 1-octene,cyclohexene,or styrene.The reactant conversion rates,reaction rates,and product distributions were calculated and compared,and the mechanisms were analyzed and discussed.The results demonstrated that methyl and naphthenic structures in aromatics might improve the conversion rates of reactants in hydrogen transfer processes,but their steric hindrances prohibited the generation of high polymers.The naphthenic structures could generate more free radicals and presented a more obvious inhibition effect on the condensation of polymers compared with the methyl side chains.It was discovered that when different olefins were mixed with pyrene,1-octene primarily underwent pyrolysis reactions,whereas cyclohexene mainly underwent hydrogen transfer reactions with pyrene and styrene,mostly producing superconjugated biradicals through condensation reactions with pyrene.In the mixture systems,the olefins scattered aromatic molecules,hindering the formation of pyrene trimers and higher polymers.According to the reactive molecular dynamics simulations,styrene may enhance the yield of dimer and enable the controlled polycondensation of pyrene.

Effect of Steam Treatment on the Catalytic Performance of ZSM-5 in the Co-conversion of Methanol and n-Hexane to Aromatics

Steam pretreatment is a widely used method for modifying the acidity and structure of zeolites,thereby enhancing their catalytic properties.This study systematically investigated the effects of steam treatment on ZSM-5 zeolites at varying treatment temperatures and durations.The structural evolution of the catalysts was monitored using N2 adsorptiondesorption,X-ray diffraction,inductively coupled plasma optical emission spectroscopy,scanning electron microscopy,NH3 temperature-programmed desorption,in situ pyridine infrared spectroscopy,and thermogravimetric analysis.The characterization results revealed that mesopores were introduced into the ZSM-5 zeolite catalysts through dealumination induced using steam treatment at moderate temperatures(400 and 500℃).Moreover,compared with the parent catalyst,the steam-treated catalysts exhibited a lower amount of acid sites and relative crystallinity,while the n(Si)/n(Al)ratio increased.In the co-conversion of methanol and n-hexane in a fixed bed reactor at 400℃and 0.5 MPa(N2 atmosphere),with a weight hourly space velocity of 1 h−1 and a stoichiometric ratio of 1:1(CH3OH to n-hexane),the steam-treated catalysts displayed a prolonged catalyst lifetime.Particularly,the parent zeolite had a lifetime of 96 h,while the catalyst treated at 500℃for 12 h had a lifetime of up to 240 h.Additionally,the steam-treated catalysts maintained stable n-hexane conversion and improved aromatic selectivity.Notably,these treated catalysts exhibited a lower deactivation rate than the parent catalyst,and would be conducive to industrial scale-up production.

The dynamic catalysis of Ga/ZSM-5 catalysts for propane-CO_(2) coupling conversion to aromatics and syngas

Alkane coupling with CO_(2) by metal-containing zeolites catalysis is found to be a promising way to produce aromatics and syngas in recent years,but the real active sites and the role of CO_(2) are still unclear owing to the quick evolution of the metallic active sites and the complex reaction processes including direct propane aromatization,CO_(2) hydrogenation,reverse water-gas shift reaction,and propane-CO_(2) coupling aromatization.Herein,Ga/ZSM-5 catalysts were constructed to study the dynamic evolution of the metallic active sites and the role of CO_(2) during the propane and CO_(2) coupling reaction.After optimizing the reaction conditions,a notable propane conversion rate of 97.9%and an impressive aromatics selectivity of 80.6%in hydrocarbons can be achieved at the conditions of 550℃and CO_(2)/C_(3)H_(8) of 4.^(13)CO_(2)isotope experiments illustrate that C-atoms of CO_(2) can enter into CO(86.5%)and aromatics(10.8%)during the propane-CO_(2) coupling reaction process.In situ XANES and FTIR spectroscopies at 550℃and H_(2)/C_(3)H_(8) atmosphere reveal that GaO_(x) species can be gradually dispersed into[GaH_(2)]^(+)/[GaH]^(2+)on the Bronsted acid sites of ZSM-5 zeolite during H_(2) and/or C_(3)H_(8) treatment,which are the real active sites for propane-CO_(2) coupling conversion.In situ CO_(2)-FTIR experiments demonstrate that the[GaH_(2)]^(+)/[GaH]^(2+)species can react with CO_(2) and accelerate the propane and CO_(2) coupling process.This work not only presents a cost-effective avenue for CO_(2) utilization,but also contributes to the active site design for improved alkane and CO_(2) activation in coupling reaction system.

Morphology,Nanostructure,and Oxidation Reactivity of Particulate Matter Emitted by Diesel Blending with Various Aromatics

This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were tested on a 11.6 L direct-injection diesel engine.The raw particulate matter(PM)before the after-treatment devices was collected using the thermophoresis sampling system and the filter sampling system.A transmission electron microscope and Raman spectrometer are used to analyze the physical properties of the soot particles,including morphology,primary particle size distribution,and graphitization degree.A Fourier transform infrared spectrometer and thermogravimetric analyzer are used to characterize the surface chemical composition and oxidation reactivity of soot particles,respectively.The results show that as the PAH content in the fuel decreases,the size of the primary soot particles decreases from 29.58 to 26.70 nm.The graphitization degree of soot particles first increases and then decreases,and the relative content of the aliphatic hydrocarbon functional groups of soot particles first decreases and then increases.The T_(10),T_(50),and T_(90) of soot from high-PAH fuel are 505.3,589.3,and 623.5℃,while those from low-PAH fuel are 480.1,557.5,and 599.2℃,respectively.This indicates that exhaust PM generated by the low-PAH fuel has poor oxidation reactivity.However,as the PAH content in fuel is further decreased,the excessively high cetane number may cause uneven mixing and incomplete combustion,leading to enhanced oxidation reactivity.

Selective Hydrogenation of Polycyclic Aromatics to Monocyclic Aromatics over NiMoC/HβCatalysts in a Methane and Hydrogen Environment

To obtain high yields of monocyclic aromatic hydrocarbons with methyl side chains,such as toluene and xylene,methane(CH_(4))can be introduced into the hydrocracking of polycyclic aromatic hydrocarbons.CH_(4)can participate in the reaction,supply methyl side chains to the product,and improve product distribution.In this study,the hydrogenation reaction of polycyclic aromatic hydrocarbons over a carbonized NiMo/Hβcatalyst in a CH_(4)and hydrogen(H_(2))environment was investigated to study the promotional effect of CH_(4)on the hydrocracking of polycyclic aromatics.Under conditions of 3.5 MPa,380℃,volume air velocity of 4 h^(-1),gas-oil volume ratio of 800,and H_(2):CH_(4)molar ratio of 1:1,the conversion rate of naphthalene was 99.97%,the liquid phase yield was 93.62%,and the selectivity of BTX were 17.76%,25.17%,and 20.47%,respectively.In comparison to the use of a H_(2)atmosphere,the selectivity of benzene was significantly decreased,whereas the selectivity of toluene and xylene were increased.It was shown that CH_(4)can participate in the hydrocracking of naphthalene and improve the selectivity of toluene and xylene in the liquid product.The carbonized NiMo/Hβcatalyst was characterized by a range of analytical methods(such as X-ray diffraction(XRD),ammonia-temperature-programmed desorption(NH3-TPD),hydrogen-temperature-programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)).The results indicated that Ni and Mo carbides were the major species in the carbonized NiMo/Hβcatalyst and were considered to be active sites for the activation of CH_(4)and H_(2).After loading the metal components,the catalyst displayed prominent weak acidic sites,which may be suitable locations for cracking,alkylation,and other related reactions.Therefore,the carbonized NiMo/Hβcatalyst displayed multiple functions during the hydrocracking of polycyclic aromatic hydrocarbons in a CH_(4)and H_(2)environment.These results could be used to develop a new way to efficiently utilize polycyclic aromatic hydrocarbons and natural gas resources.

Insights into the size effect of ZnCr_(2)O_(4)spinel oxide in composite catalysts for conversion of syngas to aromatics

Direct conversion of syngas to aromatics(STA)over oxide-zeolite composite catalysts is promising as an alternative method for aromatics production.However,the structural effect of the oxide component in composite catalysts is still ambiguous.Herein,we investigate the size effect by selecting ZnCr_(2)O_(4)spinel,as a probe oxide,mixing with H-ZSM-5 zeolite as a composite catalyst for STA reaction.The CO conversion,aromatics selectivity and space-time yield(STY)of aromatics are all significantly improved with the crystal size of ZnCr_(2)O_(4)oxide decreases,which can mainly attribute to the higher oxygen vacancy concentration and thus the rapid generation of more C1oxygenated intermediate species.Based on the understanding of the size-performance relationship,ZnCr_(2)O_(4)-400 with a smaller size mixing with H-ZSM-5 can achieve32.6%CO conversion with 76%aromatics selectivity.The STY of aromatics reaches as high as 4.79 mmol g_(cat)^(-1)h^(-1),which outperforms the previously reported some typical catalysts.This study elucidates the importance of regulating the size of oxide to design more efficient oxidezeolite composite catalysts for conversion of syngas to value-added chemicals.

Molecular Characterization of C_(9+)Aromatics in Gasoline by Gas Chromatography-Mass Spectrometry

The comprehensive characterization of heavy aromatic hydrocarbons in gasoline is important to optimize the blending process and understand the correlation between aromatics content and engine particulate emissions.However,most current analysis methods can only provide the composition of C_(8)/C_(8-) aromatics.In this study,a simple and fast gas chromatography-mass spectrometry(GC-MS)method to identify and quantify C_(9+)aromatics in gasoline was developed.A selected ion monitoring model was employed to eliminate interference from non-aromatic compounds in the detection of target compounds,as well as that between target compounds with different molecular formulas.The identification of C_(9+)aromatics was based on the retention time of model compounds,combined with characteristic mass fragment ions,boiling points,and retention indexes.Seventy-nine C_(9)–C_(12)aromatic compounds were quantified based on the calibration of representative model compounds,and the method demonstrated good linearity,and high accuracy and precision.Furthermore,the developed methodology was successfully applied to the analysis of gasoline fractions from the reforming,pyrolysis,straight-run,delayed coking,and catalytic cracking processes,as well as commercial gasolines.The results showed that C_(9)aromatics were the predominant aromatics in all gasoline samples,followed by C10 aromatics.Alkylbenzenes such as C_(9)H_(12)and C_(10)H_(14)were the main components in the reforming,straight-run,delayed coking,and catalytic cracking gasoline fractions,as well as in the commercial gasolines,in which 1,2,4-trimethylbenzene and 3-ethyltoluene were dominant;in contrast,aromatics with higher degrees of unsaturation such as indene were the most abundant aromatics in the pyrolysis gasoline fraction.

Fabrication of a sinter-resistant Fe-MFI zeolite dragonfruit-like catalyst for syngas to aromatics conversion

Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence.Here,a unique structured hybrid catalyst composed of Fe_(3)O_(4) nanoparticles intimately dispersed inside an acidic zeolite is developed.1 to 4 nm sized Fe_(3)O_(4) nanoparticles end up evenly dispersed in an acidic and slightly mesoporous Al-ZSM-5 based on Fe_(3)O_(4) restructuring during co-hydro thermal synthesis using organosilane modification.A very high aromatic productivity of 214 mmolaromatics h^(-1) gFe^(-1) can be obtained with a remarkable 62%aromatic selectivity in hydrocarbons.This catalyst has excellent sintering resistance ability and maintains stable aromatics production over 570 h.The synthetic insights that postulate a mechanism for the metastable oxide-zeolite reorganization during hydrothermal synthesis could serve as a generic route to sinter-resistant oxide-zeolite composite materials with uniform,well-dispersed oxide nanoparticles in close intimacy with-and partially confined in-a zeolite matrix.

Carbon isotopic compositions of mono-, di-, tri-aromatics provide insights into the source of sulfur-rich crude oils in the Huanghekou Depression, Bohai Bay Basin

The stable carbon isotope compositions (δ13C) of individual aromatic hydrocarbons have been analyzed in sulfur-rich and sulfur-lean crude oils from the Huanghekou Depression, Bohai Bay Basin. The δ13C values of individual aromatic hydrocarbons, including alkylbenzenes, alkylnaphthalenes, alkylphenanthrenes, alkylfluorenes and alkyldibenzothiophenes, are reported. The main aims are to find out the origin of these oils and their relationship to paleoclimate. The distribution of aromatic hydrocarbons and maturity parameters show the oils all stay in the low-mature to mature stage. Meanwhile, aromatic hydrocarbons are mainly derived from the diagenetic/catagenetic origin. The δ13C values for 1,2,4-trimethylbenzene (−30.7‰ to −28.8‰) and 1,2,3,4-tetramethylbenzene (−32.4‰ to −26.3‰) indicate the algae-derived organic matter for alkylbenzenes. Some isomers, such as 1,7-+1,3-+1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,5,6-+1,2,3,5-tetramethylnaphthalene, 1,10-+1,3-+3,10-+3,9-dimethylphenanthrenes, 1,6-+2,9-+2,5-dimethylphenanthrenes and 4,9-+4,10-+1,9- dimethylphenanthrenes show isotopic depletion (−34.9‰ to −25.2‰), indicating the major contribution of algae for these compounds. Meanwhile, isotopically depleted (−33.6‰ to −26.7‰) alkyldibenzothiophenes represent the algae input. δ13C values for mainly algae-derived naphthalene to trimethylnaphthalenes of sulfur-rich oils are more enriched than those of sulfur-lean oil, with the most significant difference of 4.4‰, indicating that the aridity of the environment and stratified water column result in the enrichment in 13C.

CO_(2)utilization in syngas conversion to dimethyl ether and aromatics:Roles and challenges of zeolites-based catalysts

Several studies have proven a strong correlation between global warming and CO_(2)emissions.Annually,38 billion tons of CO_(2)are approximately emitted into the atmosphere.Utilizing CO_(2)via chemical conversion to clean fuels and value-added aromatics can substantially contribute to controlling the problem.Considering the thermodynamic and environmental limitations of hydrogenation of CO_(2)alone to value-added aromatics and fuels,CO_(2)utilization has currently emerged as a promising and practical approach for the production of fuels and aromatics with simultaneous utilization of both CO and CO_(2)wastes.As such,the approach is economically preferable.CO_(2)could be converted directly to fuels by the hydrogenation process or as a part of a syngas mixture.Dimethyl ether(DME)is a clean fuel with a higher energy density,which could be used as a substituent for several fuels such as diesel.In the same vein,value-added aromatics such as benzene,toluene,and xylene(BTX)can be produced from a similar process.Herein,we report a review that collects the most recent studies for the conversion of CO_(2)to DME and aromatics via zeolite-based bifunctional catalysts.We highlighted the main routes for producing DME and aromatics,as well as thoroughly discussed the conducted studies on CO_(2)hydrogenation and CO_(2)-rich syngas utilized as feedstock for conversion to DME and aromatics.The CO_(2)hydrogenation mostly occurs through the methanol-mediated reaction route but is most often limited by low selectivity and catalyst deactivation,particularly in the utilization of CO_(2)alone for the reduction reaction.The review takes an overview of the progress made so far and concluded by identifying the roles and challenges of zeolite-based catalysts for CO_(2)utilization and conversion to DME and aromatics.Accordingly,despite the incredible growth the field received in the last couple of years,however,many research challenges and opportunities associated with this process are still abounded and required to be addressed.Special attention is required for the development of approaches to block diffusion of H2O through zeolite to suppress the excess formation of CO_(2)in CO_(2)-rich syngas hydrogenation to DME and aromatics,exceed the product distribution limits,and suppress catalysts deactivation.

An innovative classification system for ranking the biological effects of marine aromatic hydrocarbons based on fish embryotoxicity

Petroleum hydrocarbon pollution is a global concern,particularly in coastal environments.Polycyclic aromatic hydrocarbons(PAHs) are regarded as the most toxic components of petroleum hydrocarbons.In this study,the biomonitoring and ranking effects of petroleum hydrocarbons and PAHs on the marine fish model Oryzias melastigma embryos were determined in the Jiulong River Estuary(JRE) and its adjacent waters in China.The results showed that the levels of petroleum hydrocarbons from almost all sites met the primary standard for marine seawater quality,and the concentrations of the 16 priority PAHs in the surface seawater were lower compared with those in other coastal areas worldwide.A new fish expert system based on the embryotoxicity of O.melastigma(OME-FES) was developed and applied in the field to evaluate the biological effects of petroleum hydrocarbons and PAHs.The selected physiological index and molecular indicators in OME-FES were appropriate biomarkers for indicating the harmful effects of petroleum hydrocarbons and PAHs.The outcome of OME-FES revealed that the biological effect levels of the sampling sites ranged from level Ⅰ(no stress) to level Ⅲ(medium stress),which is further corroborated by the findings of nested analysis of variance(ANOVA) models.Our results suggest that the OME-FES is an effective tool for evaluating and ranking the biological effects of marine petroleum hydrocarbons and PAHs.This method may also be applied to evaluate other marine pollutants based on its framework.

Sensory Phenotypic and Molecular Identification of Aromatic Rice Accessions Cultivated in Benin

Rice is one of the most widely cultivated cereals in the world, and its aroma is increasingly in demand. With the advancement of research, a major rice flavor gene has been identified on rice chromosome 8. It encodes non-functional betaine aldehyde dehydrogenase leading to the accumulation of 2-acetyl-1-pyrroline which is the major olfactory compound that confers the fragrant character to rice. The aroma of rice is considered a special trait of enormous economic importance that determines the prime price in world trade. To satisfy the needs of the population and reduce rice imports into Benin, we conducted this study to identify aromatic rice accessions grown in Benin. Seventy-two rice accessions collected across Benin were PCR amplified with three SSR markers RM 7049, Aro 7, and RM 223, linked to the fgr (fragrance of rice) aroma gene. Molecular analysis revealed that 12 of the 72 accessions, namely Bagou 19, Bagou 22, Tchaka 34, Foun 15, Tchaka 41, Nana 32, Kan 61, Kung 69, Kung 67, Bagou 20, Agbab 101 and Koum 55 possess the fgr gene and can be considered as aromatic rice accessions. A sensory phenotypic test using KOH was carried out on rice accessions carrying fgr gene. Of the twelve positives, only one had the smell of aromatic rice, like the Azucena control. These results show that Benin also has aromatic rice varieties that can be sold on national and international markets.

Physiology of medicinal and aromatic plants under drought stress

Drought poses a significant challenge,restricting the productivity of medicinal and aromatic plants.The strain induced by drought can impede vital processes like respiration and photosynthesis,affecting various aspects of plants’growth and metabolism.In response to this adversity,medicinal plants employ mechanisms such as morphological and structural adjustments,modulation of drought-resistant genes,and augmented synthesis of secondary metabolites and osmotic regulatory substances to alleviate the stress.Extreme water scarcity can lead to leaf wilting and may ultimately result in plant death.The cultivation and management of medicinal plants under stress conditions often differ from those of other crops.This is because the main goal with medicinal plants is not only to increase the yield of the above-ground parts but also to enhance the production of active ingredients such as essential oils.To elucidate these mechanisms of drought resistance in medicinal and aromatic plants,the current review provides a summary of recent literature encompassing studies on the morphology,physiology,and biochemistry of medicinal and aromatic plants under drought conditions.

Hyperbranched polymer hollow-fiber-composite membranes for pervaporation separation of aromatic/aliphatic hydrocarbon mixtures

The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane structure.The obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.

Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area.Currently,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high cost.Herein,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high yield.The active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail.The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'synthesis.This work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

Effect of mesopore spatial distribution of HZSM-5 catalyst on zinc state and product distribution in 1-hexene aromatization

1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and xylene.Besides,the increasing market demand of xylene has put forward higher requirements for new generation of catalyst.For increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was studied.Catalysts with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and recrystallization.It was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst surface.While the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the catalyst.Besides,the state of loaded Zn was also affected by mesopores spatial distribution.On the optimized catalyst,the xylene selectivity was enhanced by 12.4%compared with conventional Zn-loaded parent HZSM-5 catalyst at conversion over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid properties.This work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.

Changes in the Non-targeted Metabolomic Profile of Three-year-old Toddlers with Elevated Exposure to Polycyclic Aromatic Hydrocarbons

Objective To investigate changes in the urinary metabolite profiles of children exposed to polycyclic aromatic hydrocarbons(PAHs)during critical brain development and explore their potential link with the intestinal microbiota.Methods Liquid chromatography-tandem mass spectrometry was used to determine ten hydroxyl metabolites of PAHs(OH-PAHs)in 36-month-old children.Subsequently,37 children were categorized into low-and high-exposure groups based on the sum of the ten OH-PAHs.Ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used to identify non-targeted metabolites in the urine samples.Furthermore,fecal flora abundance was assessed by 16S rRNA gene sequencing using Illumina MiSeq.Results The concentrations of 21 metabolites were significantly higher in the high exposure group than in the low exposure group(variable importance for projection>1,P<0.05).Most of these metabolites were positively correlated with the hydroxyl metabolites of naphthalene,fluorine,and phenanthrene(r=0.336–0.531).The identified differential metabolites primarily belonged to pathways associated with inflammation or proinflammatory states,including amino acid,lipid,and nucleotide metabolism.Additionally,these distinct metabolites were significantly associated with specific intestinal flora abundances(r=0.34–0.55),which were mainly involved in neurodevelopment.Conclusion Higher PAH exposure in young children affected metabolic homeostasis,particularly that of certain gut microbiota-derived metabolites.Further investigation is needed to explore the potential influence of PAHs on the gut microbiota and their possible association with neurodevelopmental outcomes.

Enriching Iodine and Regulating Grain Aroma,Appearance Quality,and Yield in Aromatic Rice by Foliar Application of Sodium Iodide

Applying iodine fertilizers to cultivate iodine-rich crops for daily intake is an effective approach for iodine supplementation,especially for aromatic rice.Field experiments were conducted during the early growing seasons of 2021 and 2022 to evaluate the impacts of foliar application of iodine fertilizer on aromatic rice and to explore the optimal iodine fertilizer concentration.At the full heading stage,six different concentrations of sodium iodide solutions of 0%(CK),0.010%(T1),0.025%(T2),0.050%(T3),0.075%(T4),and 0.100%(T5)were applied to indica aromatic rice cultivars Meixiangzhan 2 and Xiangyaxiangzhan.The results showed that sodium iodide treatments significantly increased the iodine and sodium contents in both leaves and grains.Compared with the CK,the T1 and T2 treatments increased the 2-acetyl-1-pyrroline(2-AP)content in mature grains by 8.41%-101.66%and 13.58%-74.60%,respectively.Improvements in the contents of 1-pyrroline-5-carboxylic acid,proline,1-pyrroline,and methylglyoxal,as well as the activity of proline dehydrogenase were also detected.Additionally,sodium iodide treatments remarkably decreased the chalky grain rate,chalkiness area,and chalkiness degree of aromatic rice,with the T2 treatment exhibiting a 17.79%-47.42%decrease in chalkiness degree compared with the CK.Meanwhile,T1 and T2 treatments showed beneficial impacts on chlorophyll content,photosynthetic characteristics,and yield components,while T3,T4,and T5 treatments exhibited adverse effects on leaf and grain yields.The linear discriminant analysis revealed significant differences between treatments.The correlation analysis and piecewise structural equation modeling showed that the iodine and sodium influenced the photosynthetic characteristics and chlorophyll content of the leaves,thereby regulating the 2-AP biosynthesis and yield components,ultimately affecting the 2-AP content and yield.Overall,this study suggests that foliar application of 0.025%sodium iodide is an effective method to enrich the iodine content in rice grains,improve the grain aroma and appearance quality of aromatic rice,without detrimental effects on grain yield.

Mitigation of polycyclic aromatic hydrocarbons(PAHs)in roasted beef patties by cold plasma treatment and products quality evaluation

The cold plasma(CP)technique was applied to alleviate the contamination of polycyclic aromatic hydrocarbon(PAH)in this investigation.Two different CP treatments methods were implemented in the production of beef patties,to investigate their inhibition and degradation capacity on PAHs.With 5 different cooking oils and fats addition,the inhibition mechanism of in-package cold plasma(ICP)pretreatment was explored from the aspect of raw patties fatty acids composition variation.The results of principal component analysis showed that the first two principal components accounted for more than 80%of the total variation in the original data,indicating that the content of saturated fatty acids was significantly positively correlated with the formation of PAHs.ICP pretreatment inhibited the formation of PAHs by changing the composition of fatty acids,which showed that the total amount of polyunsaturated fatty acids decreased and the total amount of monounsaturated fatty acids increased.Sensory discrimination tests demonstrated there were discernable differences between 2 CP treated samples and the controls,utilization of the ICP pretreatment in meat products processing was expected to achieve satisfying eating quality.In conclusion,CP treatment degraded PAHs through stepwise ring-opening oxidation in 2 reported pathways,the toxicity of PAHs contaminated products was alleviated after CP treatment.