Role of ball milling during Cs/X catalyst preparation and effects on catalytic performance in side-chain alkylation of toluene with methanol

Ball milling modification was performed on Cs/X catalysts before or after cesium ion exchange.Multiple characterization results(such as pyridine-FTIR,XPS,and solid-state NMR)demonstrated that ball milling played a distinct role in these two different preparation procedures of the catalyst.Ball milling performed after the cesium modification has a strong influence on the Cs/X structure and acid-base properties,which results in the enhancement of the catalytic performance for side-chain methylation of toluene with methanol.Detailed studies revealed that ball milling intensified the interactions between oxides and molecular sieves,which not only increased the dispersion of the Cs species but also generated some weaker basic centers.It is proposed that the new basic centers could be Si-O-Cs and Al-O-Cs,which are produced by breaking of the Si-O-Al bonds of the zeolite framework under the synergetic effect of ball milling and alkali treatment.These new active sites may help to promote the side-chain methylation reaction.However,excessive ball milling will lead to the vanishing of zeolite micropores,thus deactivating side-chain methylation activity,which indicates that microporosity plays a key role in side-chain methylation and individual basic centers cannot catalyze this reaction.

Synthesis of spherical nano-ZSM-5 zeolite with intergranular mesoporous for alkylation of ethylbenzene with ethanol to produce m-diethylbenzene

Catalytic synthesis of m-diethylbenzene(m-DEB)through alkylation of ethylbenzene(EB)may be a promising alternative route in comparison with traditional rectification of mixed DEB,for which the top priority is to develop efficient and stable heterogeneous catalysts.Here,the spherical nano-ZSM-5 zeolite with abundant intergranular mesoporous is synthesized by the seed-mediated growth method for alkylation of EB with ethanol to produce m-DEB.The results show that the spherical nano-ZSM-5 zeolite exhibits better stability and higher alkylation activity at a lower temperature than those of commercial micropore ZSM-5.And then,the spherical nano-ZSM-5 is further modified by La_(2)O_(3) through acid treatment followed by immersion method.The acid treatment causes nano-ZSM-5 to exhibit the increased pore size but decreased the acid sites,and subsequent La_(2)O_(3) loading reintroduces the weak acid sites.As a result,the HNO_(3)-La_(2)O_(3)-modified catalyst exhibits a slight increase in EB conversion and DEB yield in comparison with unmodified one,and meanwhile,it still maintains high m-DEB selectivity.The catalyst after acid treatment achieves higher catalytic stability besides maintaining the high alkylation activity of EB with ethanol.The present study on the spherical nano-HZSM-5 zeolite and its modification catalyst with excellent alkylation ability provides new insights into the production of mDEB.

Enhancing the side-chain alkylation of toluene with methanol to styrene over the Cs-modified X zeolite by the assistance of basic picoline as a co-catalyst

Side-chain alkylation of toluene with methanol is a green pathway to realize the one-step production of styrene under mild conditions,but the low selectivity of styrene is difficult to be improved with by-products of ethylbenzene and xylene.In this study,a new way is introduced to improve the catalytic performance by means of assisting basic compounds as co-catalysts during the toluene side-chain alkylation with methanol to styrene.As a result,high activity of side-chain alkylation appears over the basic Cs-modified zeolite catalysts prepared by ion exchange and impregnation methods.This high performance should be mainly attributed to two co-catalysis actions:(1)the promotion of basic compounds for methanol dehydrogenation to formaldehyde as the intermediate for side-chain alkylation;(2)the suppression of the styrene transfer hydrogenation on basic Cs-modified zeolites to avoid the formation of ethylbenzene.Especially for Cs_(2)O/CsX-ex catalyst,the addition of 2%mol/mol 2-picoline in reaction mixture could achieve both 12.3%toluene conversion and 84.1%styrene selectivity.Whereas the higher concentration of 2-picoline(>6%mol/mol)caused an inhibition to the catalytic activity because the excessive basic compound poisoned the combined acid-base pathway required for the side-chain alkylation process.In addition,two possible side-chain alkylation reaction routes on Cs-modified zeolite under the different 2-picoline absorption were described.

Adsorption and Diffusion Properties of Ethylene, Benzene and Ethylbenzene in the Cylindrical Pore under Alkylation Reaction near Critical Regions by DCV-GCMD Simulation

Abstract A cylindrical pore model was used to represent approximately the pore of β-zeolite catalyst that had been used in the alkylation of benzene with ethylene and spherical Lennard-Jones molecules represented the components of the reaction system-ethylene, benzene and ethylbenzene. The dual control volume-grand canonical molecular dynamics (DCV-GCMD) method was used to simulate the adsorption and transport properties of three components under reaction in the cylindrical pore at 250℃ and 270℃ in the pressure range from 1 MPa to 8 MPa. The state map of the reactant mixture in the bulk phase could be divided into several different regions around its critical points. The simulated adsorption and transport properties in the pore were compared between the different near-critical regions. The thorough analysis suggested that the high pressure liquid region is the most suitable region for the alkylation reaction of benzene under the near-critical condition.

Removal of Thiophenic Sulfur Compounds from Oil Using Chlorinated Polymers and Lewis Acid Mixture via Adsorption and Friedel-Crafts Alkylation Reaction

For efficient removal of thiophenic sulfur （S-） compounds from oils, a novel method is proposed here, i.e. one-pot alkylation desulfurization （OADS）, in which oil insoluble chlorinated polymer such as polyvinyl chlo- ride （PVC） is used as the alkylating regent with Lewis acid as catalyst. The aromatic S-compounds are grafted to the polymer through Friedel-Crafts reaction and removed facilely along with the polymer. The OADS mechanism is identified by scanning electron microscope and analyzer with surface area and pore size of the polymer. The influ- ence of some factors on the OADS is studied, e.g. the type and amount of chlorinated polymers and Lewis acids. It is nroved that thionhene and benzothioDhene can be removed efficiently from oil by PVC＋AlCl3 mixture even in the presence of 25% （by mass） of benzene due to the synergetic effects of the adsorptive desulfurization of AlCl3 and the alkylation desulfurization of PVC.

Alkylation of naphthalene with n-butene catalyzed by liquid coordination complexes and its lubricating properties

With the development of coal chemical industry,large amounts of naphthalene and n-butene are produced,and converting them into high value-added products through alkylation has gained particular importance and interest.In this work,liquid coordination complexes(LCCs)were used as acid catalysts for the first time in the naphthalene alkylation reaction under mild conditions to obtain multibutylnaphthalenes with high yield.Various reaction conditions were thoroughly investigated.The LCC consisting of urea and AlCl_(3) showed excellent catalytic performance under optimal reaction conditions,giving 100%conversion of naphthalene and 99.66%selectivity towards multi-butylnaphthalenes.Combining the catalyst properties and catalytic results,a plausible reaction mechanism was proposed.The lubricating properties of the synthesized products were investigated for their potential application as lubricating base oils.The synthesized multi-butylnaphthalenes showed comparable physicochemical properties and tribological performances as the commercial cycloalkyl base oil.

Regioselechve Reaction of α－（Alkoxydimethylsilyl）allyl Carbanions with Alkyl Halides and Aldehydes

The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied. α-Alkylation with alkyl halides was favoured, whereas γ-selection was achieved in the reaction with aldehydes.

REACTIONS OF ORGANODILITHIUM COMPOUND WITH ALKYL HALIDES

The mechanism of the electron transfer reaction of 1,4-dilithio- tetraphenyl-1,3-butadiene with methyl iodide was studied.

A Facile Synthesis of N-alkyl-4'-methyl-1,1'-biphenyl-2-sulfona-mide via Linking DoM Reaction with Suzuki Reaction

Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki reaction.The structures of the new compounds synthesized were confirmed by elemental analysis,IR,1H NMR and MS.This new method makes a feature of low cost and readily available starting material,fewer steps,mild condition,easiness to operate and higher yield.

烷基水杨酸盐清净剂合成工艺研究进展

近年来,随着节约能源和保护环境的要求逐渐提高,发动机设计日益向小型化,大功率和高速度方向发展,因此对内燃机油的高温清净性能提出了越来越苛刻的要求,低硫低磷及低灰分型内燃机油将是未来发展的方向。烷基水杨酸盐具有优异的清净作用及酸中和性能,且具备一定的抗氧化和抗腐蚀能力,是内燃机油的主要添加剂之一,可满足内燃机油低硫低磷及低灰分的要求。对烷基水杨酸盐的传统及改进的合成工艺进行了综述。传统合成工艺严重制约了烷基水杨酸盐的应用和发展,探索新的合成工艺是烷基水杨酸盐发展的主要方向。

1-取代-3-碘-1H-吡唑并[3,4-d]嘧啶-4-胺的合成

本研究报道一类1-取代-3-碘-1H-吡唑并[3,4-d]嘧啶-4-胺(1a~1e)的合成方法。以3-碘-1H-吡唑并[3,4-d]嘧啶-4-胺(2)为原料,分别与碘乙烷(3a)、碘甲烷(3b)、2-碘丙烷(3c)、碘代环丁烷(3d)及碘代环戊烷(3e)发生N-烷基化反应,得到5种1-取代-3-碘-1H-吡唑并[3,4-d]嘧啶-4-胺(1a~1e),产物结构经^(1)H NMR和ESI-MS确证。然后考察并确定该N-烷基化反应的适宜反应条件为:物料比为n(3a)∶n(2)=4∶1,N,N-二甲基甲酰胺为反应溶剂,碱为Cs_(2)CO_(3),反应温度为110℃。

苯甲醇烷基化反应的选择性强化分析

基于苯甲醇烷基化反应动力学,建立了平推流型的固定床反应稳态模型。在验证模型可靠性的基础上,分析了苯烷基化、甲苯烷基化和甲醇转换烯烃的竞争性,并进一步考察了空速(WHSV)、进料温度(T_(inlet))和进料苯醇比(n)对反应过程的影响。反应动力学分析表明:反应温度升高将提高各反应速率,也更有利于二甲苯的生成;但需要适当降低甲醇的浓度,以降低甲醇转换烯烃的反应速率,即提高甲醇的烷基化利用率。固定床反应器模拟显示,高空速可以促使出口的PX选择性超过工业级PX的产品质量分数99%;入口温度T_(inlet)升高有利于提高苯转化率和甲醇有效利用率,但会导致PX选择性的降低;苯醇比n增加会提高甲醇的烷基化利用率,但会极大降低苯转化率和减小PX选择性。在WHSV=32 h^(-1)、n=4和T_(inlet)=500℃时,反应器出口的苯转化率为12.95%,甲醇烷基化利用率是55.43%,PX的选择性99.53%。该研究结果对苯甲醇烷基化过程的反应器设计和进一步工艺优化具有一定的指导价值。

沸石分子筛催化芳烃烷基化反应的研究进展

沸石分子筛具有良好的水热稳定性和酸性,其特有的孔道结构有利于分子的传质,在芳烃的烷基化中表现出良好的催化性能。介绍了近年来芳烃烷基化反应中分子筛通过不同的改性方法来改良自身的结构、孔道、酸性位点提升分子筛在芳烃的烷基化反应中催化性能的研究与应用,主要的改性方法有模板法、后处理法、离子交换法等。以期对研究制备高效绿色环保型分子筛固体酸催化剂在芳烃烷基化反应的工业化应用具有一定的意义。

ZSM-5分子筛结构对苯烷基化反应性能影响的数值模拟研究

以ZSM-5分子筛催化苯和乙烯烷基化为体系,建立并验证了一种三维各向异性扩散-反应数学模型,该模型考虑了分子筛形貌、孔结构和扩散各向异性的影响。模拟发现当分子筛颗粒体积和abc轴尺寸保持不变时,改变分子筛形貌并不会显著影响其表观活性,因而该情况下无须调控分子筛形貌;而当分子筛颗粒体积不变时,仅缩短b轴尺寸才能显著降低扩散阻力,提高催化剂表观活性,因而合成ZSM-5分子筛时缩短b轴尺寸最有利于扩散和反应。在分子筛颗粒中引入大孔可显著提高分子筛催化剂利用率和表观活性,保持大孔孔隙率不变时,减小大孔孔径更有利。存在最优大孔孔隙率以平衡扩散阻力和活性材料含量,当分子筛粒径4μm、大孔孔径300 nm时,最优大孔孔隙率0.16,对应最高表观反应速率80.5 mol/(m^(3)·s)。另外,由于分子筛内扩散各向异性的影响,当大孔取向平行于c轴时最有利。结果可为苯和乙烯烷基化ZSM-5分子筛催化剂乃至其他分子筛催化剂的设计优化提供一定的理论指导。

片状ZSM-5分子筛的合成及其催化苯酚甲醇烷基化反应性能

采用晶种诱导及矿化剂辅助方法合成了一系列具有不同b轴厚度及不同硅铝原子比的片状ZSM-5分子筛,通过SEM、XRD、N_(2)吸附-脱附及NH_(3)-TPD等方法对合成的分子筛进行表征,并将其用于苯酚甲醇烷基化反应中,考察了不同b轴厚度和硅铝原子比对催化反应稳定性及甲酚选择性的影响。实验结果表明,硅铝原子比为100、b轴厚度为20 nm的片状ZSM-5分子筛在该反应中表现出较好的催化性能及良好的容碳能力,苯酚转化率可达43%以上,甲酚选择性达51%,分子筛寿命超300 h。

CDC策略下三氯化铁催化哒嗪酮衍生物N-H烷基化研究

利用FeCl_(3)催化的交叉脱氢偶联反应,在温和反应条件下,建立了哒嗪酮N-H与烷基C(sp^(3))-H之间形成C-N键的方法.不同的哒嗪酮类化合物与氧/硫醚反应,顺利得到了一系列N-氧基/硫烷基哒嗪酮衍生物,收率为44%~83%.该方法为构建具有潜在生物活性的N-取代哒嗪酮类化合物提供了一种新的策略.

Supported Atomically Dispersed Pd Catalyzed Direct Alkoxylation and Allylic Alkylation

A new approach to allylic alkylation is realized using an atomically dispersed palladium catalyst(Pd1/TiO2-EG).Unlike conventional methods that require derivation of substrates and utilization of additives,this method allows for direct allylic alkylation from allylic alcohols,producing H2O as the sole by-product.The catalyst's high efficiency is attributed to the local hydrogen bonding at the or-ganic-inorganic interface(Pd-EG interface),facilitating hydroxyl group activation forη3π-allyl complex formation.The system demonstrates successful direct C—O and C—C coupling reactions with high selectivity,requiring no additives.This study highlights the potential of supported atomically dispersed catalysts for greener and more efficient catalysis,meanwhile,offers unique insights into the distinct behavior of atomically dispersed catalysts in comparison to homogeneous or nanoparticle-based catalysts.

Covalently tethering disulfonic acid moieties onto polyoxometalate boosts acid strength and catalytic performance for hydroxyalkylation/alkylation reaction

Solid acid catalysts are widely used in the production of various high-value added and industrially important chemicals.Although the use of organosilicon compounds to modify the vacancy site has been extensively studied,the covalent tethering-SO_(3)H functionalized organosilicon modified polyoxometalates(POMs)has been rarely reported.In this work,two catalysts(TBA_(4)[SiW_(11)O_(39)(O(SiC_(3)H_(6)SO_(3)H)_(2))](compound 2)and TBA_(4)[SiW_(11)O_(39)(O(SiC_(8)H_(8)SO_(3)H)_(2))](compound 3))were synthesized successfully through covalently grafting different sulfonic acid(-SO_(3)H)groups onto[SiW_(11)O_(39)]^(8−)cluster,respectively.Compound 2 was achieved by surface grafting and in situ oxidation(3-mercaptopropyl)-trimethoxysilane,while compound 3 was achieved by surface grafting of 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane.Strong Brønsted acid strength of compounds 2 and 3 can be demonstrated by different methods including potentiometric titration,pyridine adsorption studies,and the ^(31)P trimethylphosphine oxides(TMPO)nuclear magnetic resonance(NMR).The systematic investigation of the relationship among POM structures,acid strength,and electron density was carried out based on density functional theory(DFT)calculation and experimental results,which revealed that covalent modification of compounds 2 and 3 decreased the electron density of the O-H bond,and promoted the release of H^(+).When applied in hydroxyalkylation/alkylation(HAA)reaction of 2-methylfuran(2-MF)with cyclohexanone,compound 2 exhibited better catalytic performance with conversion of ~93%,monocyclic fuel precursors(1a)yield of 79.9% and selectivity of 85.7% than compound 3,which can be attributed to strong Brønsted acid and the intramolecular hydrogen-bonding interactions between the neighboring -SO_(3)H moieties in compound 2.Finally,compound 2 also showed excellent catalytic activity in the HAA reaction of 2-MF with several different aldehydes and ketones(e.g.,furfuraldehyde,5-methylfurfuraldehyde,acetone,butyraldehyde and 4-methoxybenzaldehyde).This result opens a new pathway for design and fabrication of novel solid acid catalysts.

OBC/WPS增容母料的制备及其在三元乙丙橡胶中的应用

利用Friedel-Crafts烷基化反应制备了乙烯-辛烯嵌段共聚物(OBC)/废旧聚苯乙烯(WPS)增容母料,考察了无水AlCl3用量对WPS的接枝率、共混物性能以及增容母料用量对三元乙丙橡胶(EPDM)综合性能的影响。结果表明,WPS可以与OBC发生反应,生成OBC-g-WPS接枝共聚物;当无水AlCl3用量为0.4份时,WPS的接枝率最高,为25.3%,且无凝胶产生,共混物的综合性能最好;将上述共混物作为增容母料应用于EPDM中,添加增容母料的硫化胶,其拉伸强度、撕裂强度和耐热空气老化性能优于纯EPDM硫化胶,且优于添加相同量OBC/WPS简单共混物;添加OBC/WPS增容母料的硫化胶中WPS分散均匀且细小。

银催化的开环Minisci反应——开发适合本科生的教学实验

Minisci反应是利用亲核性的碳自由基中间体对芳杂环进行的取代反应。本研究以1-甲基环丙醇和苯并[d]噻唑为原料在银催化、水相反应条件下发生自由基烷基化,高效合成了4-(苯并[d]噻唑-2-基)-2-丁酮,具有操作步骤简单、反应条件温和及原子经济性的优势。本反应已经本科生进行验证,将有效补充自由基化学相关知识,适合开发成为教学实验。