Studies on sulfinatodehalogenation ⅩⅩⅣ.Further study on sodium dithionite-initiated perfluoroalkylation of electron-rich aromatics

The application ot the sulfinatodehalogenation reaction system for the perfluoroalkylation of electron-rich aromatics is further studied.It was shown that perfluoroalkyl iodides reacted with polyhydric phenols,N,N-dialkylanilines,2,5-dimethylpyrrole,N-methylpyrrole initiated by Na_2S_2O_4- NaHCO_3 gave the corresponding perfluoroalkylated products in moderate to good yields.

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.

Tuning of the textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acid catalysts for alkenylation of diverse aromatics to their corresponding α-arylstyrenes

The textural features and acidic properties of sulfated mesoporous lanthana‐zirconia solid acids （SO42？/meso‐La0.1Zr0.9Oδ） were efficiently tuned by modifying the conditions used to prepare the meso‐La0.1Zr0.9Oδcomposites, such as the molar ratio of the template to La and Zr metal ions （Nt/m）, molar ratio of ammonia to La and Zr metal ions （Na/m）, hydrothermal temperature （Thydro）, and hy‐drothermal time （thydro）. The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p‐xylene with phenylacetylene was investi‐gated. Various characterization techniques such as N2 physisorption, X‐ray diffraction, NH3 temper‐ature‐programmed desorption, and thermogravimetric analysis were employed to reveal the rela‐tionship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso‐La0.1Zr0.9Oδcomposite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t‐ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42？/meso‐La0.1Zr0.9Oδcatalyst exhibited much superior catalytic activity and coke‐resistant stabil‐ity. Moreover, the developed SO42？/meso‐La0.1Zr0.9Oδcatalyst demonstrated excellent catalytic per‐formance for alkenylation of diverse aromatics with phenylacetylene to their correspondingα‐arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42？/meso‐La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production ofα‐arylstyrenes through clean and atom efficient solid‐acid‐mediated Friedel‐Crafts alkenylation of diverse aromatics with phenylacetylene.

Characterization of nitrogen-containing aromatics in Baiyinhua lignite and its soluble portions from thermal dissolution

Soluble portions(SPs) 1-4(SP1-SP4) were afforded from sequentially dissolution and alkanolyses of Baiyinhua lignite(BL) in cyclohexane,CH3OH,CH3CH2OH,and(CH3)2CHOH at 300℃.They were analyzed with a gas chromatograph/mass spectrometer and quadrupole exactive orbitrap mass spectrometer(QEOTMS) with an atmosphere pressure chemical ionization source in positive-ion mode,while BL was characterized with an X-ray photoelectron spectrometer(XRPES).The results show that the yields of SP2 and SP3 are much higher than those of SP1 and SP4,and the total SP yield is ca.39.0%.According to the analysis with XRPES,pyrrolic nitrogen atoms are the most abundant nitrogen existing forms in BL.Thousands of nitrogen-containing aromatics(NCAs) were resolved with QEOTMS and their molecular masses are mainly in the range of 200-450 u.The main NCAs are N1O1 and N1O2 class species with double bond equivalent values of 4-18 and carbon numbers of 7-30.The nitrogen atoms appear in pyridine s,quinolines,benzoquinolines or acridine,and dibenzoquinolines or naphthoquinolines,while the oxygen atoms exist in methoxy and furan rings.

Catalytic performance of imidazole modified HZSM-5 for methanol to aromatics reaction

A facile approach was developed for the preparation of nano-sized HZSM-5 with a hierarchical mesoporous structure by adding imidazole into conventional zeolite synthesis precursor solution. The physicochemical properties of modified HZSM-5 were characterized by X-ray diffraction（XRD）, N;adsorption–desorption isotherms, scanning electron microscopy（SEM）, NH;-temperature-programmed desorption（NH;-TPD） and pyridine adsorption infrared spectroscopy（Py-IR）. The coke in spent catalysts was characterized by thermogravimetry（TG）. The results showed that hierarchical HZSM-5 zeolites with excellent textural properties, such as abundant porous structure, uniform particle size and suitable acidity, could be synthesized by the recipe of one-pot synthesis routes. Moreover, the obtained HZSM-5 exhibited higher selectivity of total aromatics as well as longer lifetime in the catalytic conversion of methanol to aromatics, comparing with conventional HZSM-5. It is expected that the synthesis approach demonstrated here will be applicable to other zeolites with particular textural properties and controllable particle sizes, facilitating the emergence of new-type porous materials and their related applications in catalysis and separation.

Direct conversion of syngas to aromatics: A review of recent studies

The direct catalytic conversion of syngas to aromatics offers a promising route to manufacture fine chemicals by employing non-petroleum carbon resources,because aromatic constituents are the key platform for producing polymers.However,this remains a great challenge due to the low yield of aromatics and poor catalyst stability,which restrict further development.In recent years,extensive research has been reported on the design of effective catalysts and the optimization of operating conditions to obtain better catalytic performance.In this review,we focus on these related achievements and present a comprehensive overview of different kinds of catalysts,mainly including modified Fischer-Tropsch(FT)catalysts and composite catalysts,as well as their performance and reaction mechanisms.The thermodynamic analysis of the reactions involved in this innovative conversion process and the comparison of different methods are also described in detail in this updated review.Finally,the challenges and prospects for direct syngas conversion are discussed to provide general guidelines for the construction of a well-designed reaction route.

Formaldehyde intermediate participating in the conversion of methanol to aromatics over zinc modified H-ZSM-5

Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics(MTA)reaction,which is often attributed to the metal promoting the aromatization of intermediate olefins.However,the effect of methanol dehydrogenation on aromatics formation over these catalysts is rarely studied.Here,we report that HCHO,which is formed by methanol dehydrogenation over Zn/H-ZSM-5 prepared by Zn impregnation,can participate in the synthesis of aromatics.Methanol conversion can produce more aromatics than olefins(propylene or ethylene)conversion over Zn/H-ZSM-5,indicating the conventional MTA pathway including methanol-to-olefins and olefins-to-aromatics is not complete.Moreover,an MTA mechanism including the conventional pathway and the methanol and HCHO coupling pathway is systematically proposed.

[Bmim]Br_3 as a New Reagent for Regioselective Mono-bromination of Activated Aromatics under Solvent-free Conditions

Reaction of activated aromatics containing phenobs, naphthol, methoxynaphthalenes,anisole etc. with 1-butyl-3-methylimidazolium tribromide （[Bmim]Br3） under solvent-free conditions, selectively gave the corresponding monobromination products with excellent yields.

Effect of the Structure of Cations and Anions of Ionic Liquids on Separation of Aromatics from Hydrocarbon Mixtures

The effects of the structure of typical cations and anions of ionic liquids on the separation of benzene and toluene from aromatic/paraffin mixtures were studied. The .results showed that the corresponding separation factors were considerably larger than those of the traditional solvents （Benzene＋Hexane＋sulfolane）, and that the ionic liquids could be used as novel solvents for the separation of aromatics from hydrocarbon mixtures. The key parameters governing the ability of ionic liquids for separating aromatics from hydrocarbon sources were investigated. It was found that the effectiveness of the ionic liquids, based on the same anion, changed in the cation order of [BIqu]^＋〈 [BPy]^＋〈 [BMIM]^＋. The selectivity of the ionic liquid toward aromatics decreased apparently with the increasing length of the substituted alkyl chain of its cationic head ring. The separation factors, based on the same cation, changed in the anion order of [Tf2N]^-〈[PF6]^-〈[BF4]^-〈[C2H5SO4]^-. The solubilities of the aromatics were greater in the ionic liquids based on the former three anions than that in the ionic liquids involving [C2H5SO4]^-.

SSHT Process -a Low Cost Solution for Low Sulfur and Low Aromatics Diesel

The need for cleaner fuels has resulted in a continuing worldwide trend to reduce diesel sulfur and aromatics. There are many approaches to reducing sulfur and aromatics in diesel. Most of them have a common drawback of high cost because of adopting two stages of hydrotreating and using noble-metal catalyst, especially for reducing aromatics. The attempt to resolve this issue has led to the recent development of the Single Stage Hydrotreating (SSHT) process by Research Institute of Petroleum Processing (RIPP), SINOPEC.The SSHT process is a single-stage hydrotreating technology for producing low sulfur and low aromatics diesel. The process uses one or two non-noble-metal catalysts system and operates at moderate pressure. When revamping an existing unit to meet low aromatics diesel specification, the only thing to do is to add a reactor or replace the existing reactor, In pilot plant tests, the SSHT technology has successfully treated SRGO (Straight Run Gas Oil), LCO (Light Cycle Oil) or the blend of them. It is shown that by using the SSHT process diesel with sulfur of 30 ppm and aromatics of 15 m% can be produced from Middle-East SRGO and diesel with aromatics content of 25 m% can be produced from cracked feed, such as FCC-LCO. High diesel yield and cetane number gain (from cracked feed stocks) give the SSHT technology a performance advantage compared to conventional hydrocracking and hydrotreating processes.The lower investment and operating cost is another advantage. The first commercial application of the SSHT technology has been in operation since September 2001.

Correlation between H-ZSM-5 crystal size and catalytic performance in the methanol-to-aromatics reaction

The porosity of H‐ZSM‐5zeolite is known to facilitate the diffusion of molecules in the methanol‐to‐aromatics(MTA)reaction.The activity and selectivity of the H‐ZSM‐5catalyst in the MTAreaction has been studied as a function of crystal size.ZSM‐5zeolites with different crystal sizeswere successfully synthesized by conventional hydrothermal methods.Tailoring ZSM‐5particle sizewas easily controlled by changes to the sol‐gel composition,and in particular,the deionized waterto tetrapropylammonium hydroxide ratio,and crystallization time.The structure of the H‐ZSM‐5zeolites were characterized by X‐ray diffraction and the morphology of the zeolite particles wasdetermined by scanning electron microscopy.N2adsorption‐desorption measurements establishedchanges to the textural properties,and compositional properties were characterized by X‐ray fluorescencespectroscopy.Acidity measurements of the catalysts were measured by pyridine‐adsorbedFourier transform infrared spectroscopy and the temperature‐programmed desorption of ammonia.After subjecting the catalysts to the MTA reaction,the total amount of coke formed on the spentdeactivated catalysts was determined by thermal gravimetric analysis.The results show that theSiO2/Al2O3molar ratios and acidic properties of the H‐ZSM‐5samples are similar,however,thenano‐sized hierarchical ZSM‐5zeolite with an additional level of auxiliary pores possesses a higher

Zeolite－Catalyzed Friedel－Crafts Acylation of Aromatics．Ⅳ．Nature of the Active Sites of Zeolites

For zeolite-catalyzed Friedel-Crafts acylation of aromatic rings,the Lewis acid sites were found to be active;while the Bronsted acid sites with moderate strength were found to be inactive.

Carboxylation of Aromatics by CO₂under “Si/Al Based Frustrated Lewis Pairs” Catalytic System

Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many catalytic systems employed in the carboxylation, the concept of “Frustrated Lewis Pairs” (FLPs) was scarcely mentioned, which perform excellently in activating small molecules like CO2. The FLPs are combinations of Lewis acids and Lewis bases which failed to form adducts due to their bulky steric congestion. In this paper, we first attempted various Si/Al Based FLPs to catalyze the carboxylation of aromatics through the activation of CO2, and a good yield of 62% - 97% was obtained. The reaction mechanism was proposed, involving the activation of CO2 mainly contributed by AlCl3 in cooperation with organosilane, forming an intermediate consisting of CO2, AlCl3, and R4Si, as well as the subsequent electrophilic attack to aromatics, thus to promote the carboxylation reaction.

Comparison on Commercial Application of Two Types of C_8 Aromatics Isomerization Catalysts

The results of commercial application of two types of C_8 aromatics isomerization catalysts under different feed conditions were compared to gain an insight in the techno-economical basis for selecting proper technological route at the plant.The comparison reveals differences in every aspect of feed consumption,unit capacity,product output,product distribution,and unit process parameters depending upon which catalyst type is adopted by the integrated PX complex.The type of aromatics isomerization catalyst has its influence on the plant scale,the construction cost,the process unit capacity and the product cost,with the magnitude of its impact varying with changing feed conditions.

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.

Tetralin Hydrocracking Reaction Network to Single-Ring Aromatics on Bifunctional Catalysts

Conversion of LCO(light cycle oil)to BTX(benzene,toluene,and xylene)is an economically valuable method for refineries.However,this approach still faces difficulties as the main reactions are not clearly understood.Here we study the detailed hydrocracking pathway of typical reactants,1-methylnaphthalene and tetralin,through molecular simulations and experiments to improve our understanding of the conversion process of LCO to BTX.Molecular simulations demonstrate that the rate-determining step is the isomerization pathway of six-membered ring to five-membered ring in tetralin as its activation energy(ΔEa)is the highest among all the reactions and the order ofΔEa of reactions is isomerization>ring-opening≈side-chain cleavage.The results of experiments show that with the increase in reaction depth,i.e.,through a high temperature(350-370℃)and low LHSV(4.5-6.0 h^(−1)),isomerization,ring-opening,and side-chain cleavage reactions occurred,thus improving the selectivity and yield of alkyl aromatics.

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.