Phosphotungstic acid immobilized on amino-functionalized TS-1 zeolite as a solid acid catalyst for the synthesis of tributyl citrate

The amino-functionalization of TS-1 zeolite followed by immobilization of phosphotungstic acid(HPW)was presented to prepare a strong solid acid catalyst for the synthesis of bio-based tributyl citrate from the esterification of citric acid and n-butanol.γ-Aminopropyltriethoxysilane(APTES)was first grafted on the TS-1 zeolite via the condensation reactions with surface hydroxyl groups,and subsequently the HPW was immobilized via the reaction between the amino groups and the protons from HPW-forming strong ionic bonding.The Keggin structure of HPW and MFI topology of TS-1 zeolite were well maintained after the modifications.The amino-functionalization generated abundant uniformly distributed active sites on TS-1 for HPW immobilization,which promoted the dispersity,abundance,as well as the stability of the acid sites.The tetrahedrally coordinated framework titanium and non-framework titania behaved as weak Lewis acid sites,and the protons from the immobilized HPW acted as the moderate or strong Brønsted acid sites.An optimized TBC yield of 96.2%(mol)with a conversion of-COOH of 98.1%(mol)was achieved at 150℃for 6 h over the HPW immobilized on amino-functionalized TS-1.The catalyst exhibited good stability after four consecutive reaction runs,where the activity leveled off at still a relatively high level after somewhat deactivation possibly caused by the leaching of a small portion of weakly anchored APTES or HPW.

Elucidating the effect of oxides on the zeolite catalyzed alkylation of benzene with 1-dodecene

In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides herein, and obvious decrease of lifetime could be caused by only trace amount of oxides added in the feedstocks. However, the deactivated catalysts were difficult to be regenerated by extraction with hot benzene. Additionally, coke-burning was also proved to be incapable to regenerate the deactivated catalysts mainly for the dealumination during calcination. Further characterizations complementary with DFT calculations were conducted to demonstrate that the deactivation was mainly due to the firm adsorption of oxides on the acid sites.

Titanium-rich TS-1 zeolite for highly efficient oxidative desulfurization

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.

无溶剂快速合成S-1和TS-1分子筛

Silicalite-1(S-1)和Titanium Silicalite-1(TS-1)沸石分子筛因其良好的疏水性、热稳定性和择形性等特点,作为环境友好的绿色催化剂在工业应用上极具优势和价值.采用无溶剂法成功合成了TS-1分子筛,并利用X-射线衍射仪、全自动比表面和孔隙分析仪、紫外可见光谱仪和扫描电镜等表征仪器研究了晶化时间和硅钛摩尔比对所制备TS-1分子筛的物化性质的影响.结果表明,合成的TS-1沸石分子筛具有较高的结晶度和纯度、均一的晶粒大小、高的比表面积和在分子筛骨架中四配位和六配位的钛物种.无溶剂合成TS-1沸石具有低成本、环境友好和高效的优点,研究将为工业上沸石的规模合成提供一定的理论借鉴.

Pt supported on Zn modified silicalite-1 zeolite as a catalyst for n-hexane aromatization

Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Lewis and Bronsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment,which were identified as mostly weak and medium ones.Besides,Pt and Zn species showed strong interaction,as revealed by the TPR(Temperature-programmed reduction)and XPS(X-ray photoelectron spectroscopy)experiments.Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane.Pulse experimental study showed that 75.6%of n-hexane conversion and 76.8%of benzene selectivity were obtained over Pt0.1-Zn60/S-l catalyst at 550℃ and under atmospheric pressure.By spectroscopy tests and pulse experimental results,it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism.Furthermore,with the assistance of Zn,the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.

The synthetic strategies of hierarchical TS-1 zeolites for the oxidative desulfurization reactions

With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show great potential as catalysts for ODS reactions,due to its remarkable oxidation activity at low temperatures and pressure.However,the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds.Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability.In recent years,abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite,thereby improving its catalytic performance in the ODS process.This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions.In addition,some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised.We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.

Quasi-solid state synthesis of EU-1 zeolite and its catalytic properties for the isomerization of C_8 aromatics

In this study,EU-1 zeolite was successfully synthesized via a quasi-solid state approach and assembled to catalyst for the C 8 aromatics isomerization process.The catalytic properties were tuned through careful modification of the acidity of EU-1 zeolites and metal-doping of the catalyst.It was shown that EU-1 was an excellent candidate for the C 8 aromatics isomerization process due to its unique structure.In addition,steam treatment of EU-1 at 450-500 ℃ could optimize the acidic properties of the catalyst,hence enhance its catalytic performance.The effect of the amount of Pt on ethylbenzene conversion was studied and the optimum amount was determined to be about 0.3-0.4 wt%.It was confirmed that EU-1 zeolite prepared via a quasi-solid state approach and then dealuminated by steam treatment had better activity and selectivity than conventional mordenite（MOR） zeolite and could be an excellent candidate for C 8 aromatics isomerization.

MCM-36 zeolites tailored with acidic ionic liquid to regulate adsorption properties of isobutane and 1-butene

Adsorption properties of an adsorbent or a catalyst towards adsorbates are crucial in the process of adsorption separation or catalytic reaction. Surface morphology and structure of adsorbents have a significant impact on the adsorption properties. In this study, a novel acidic ionic liquid, 1-butyl-3-(triethoxysilylpropyl)imidazolium hydrogen sulfate(i.e., [BTPIm][HSO_4]), was synthesized and subsequently grafted onto the MCM-36 zeolite for the regulation of its adsorption properties towards isobutane and 1-butene. The resultant [BTPIm][HSO_4]-immobilized MCM-36(i.e., MCM-36-IL) was characterized by FT-IR, XPS, XRD, SEM, TG/DTG and N_2 adsorption–desorption measurement. It was found that the specific surface area, micropore volume and mesopore volume of the MCM-36 support underwent a reduction upon the immobilization of ionic liquid,while the surface density of acid increased from 0.0014 to 0.0035 mmol·m^(-2). The adsorption capacity of isobutane and 1-butene on the MCM-36-IL was determined by a static volumetric method. Results demonstrated that the interaction between isobutane and MCM-36-IL was enhanced and the interaction between 1-butene and MCM-36-IL was reduced. As a result, a tunable adsorption ratio of isobutane/1-butene on MCM-36 was achieved.With the increase in surface density of acid and the tunable adsorption ratio of isobutane and 1-butene on the functionalized MCM-36, the acidic ionic liquid-immobilized zeolites are beneficial to obtain an improved reaction yield and a prolonged catalyst life in the reactions catalyzed by solid acid.

Synthesis, characteristics of hierarchical EU-1 zeolite for xylene isomerization probe reaction

Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.

过渡金属负载Silicalite-1分子筛的制备及其催化糠醛加氢性能研究

糠醛是一种重要的生物质平台分子,研发具有高活性和稳定性的糠醛加氢催化剂是当前的研究焦点,但贵金属催化剂的高成本问题使得其难以满足大规模工业生产的需求。利用一步水热法成功地合成了过渡金属负载Silicalite-1分子筛催化剂,并探讨了引入不同类型的过渡金属(如Ni、Co、Cu和Fe)对Silicalite-1分子筛结构产生的影响。研究结果表明:低金属负载量并不会对分子筛结构的形成产生影响,同时金属物种在分子筛载体的表面也能均匀分布。在糠醛的加氢转化过程中,Ni基催化剂S-Ni2展现出优异的糠醛转化能力,糠醛的转化率高达96%,产物呋喃的选择性保持在71%左右。Cu基催化剂S-Cu1表现出优异的糠醇选择性,产物选择性接近100%,这一性能明显优于通过浸渍法制得的铜基催化剂(76%)。因此,与浸渍法相比,采用一步水热法可以获得具有高选择性的催化剂,且该方法简单易操作。本研究为寻找高效、稳定且经济的金属加氢催化剂开辟了新的方向,并促进了生物质资源的高值化应用。

Experiment and Modeling of Pure and Binary Adsorption of n-Butane and Butene-1 on ZSM-5 Zeolites with Different Si/Al Ratios

Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and butene-1 and their mixtures on these catalysts at 300K and p=0—100kPa were measured using the intelligent gra- vimetric analyzer.The experimental results indicate that the presence of Al can significantly affect the adsorption of butene-1 than that of n-butane on ZSM-5 zeolites.Then,the double Langmuir(DL)model was applied to study the pure gas adsorption on ZSM-5 zeolites for pure n-butane and butene-1.By combining the DL model with the ideal adsorbed solution theory(IAST),the IAST-DL model was applied to model the butene-1(1)/n-butane(2)binary mixture adsorption on ZSM-5 zeolites with different Si/Al ratios.The calculated results are in good agreement with the experimental data,indicating that the IAST-DL model is effective for the present systems.Finally,the adsorp- tion over a wide range of variables was predicted at low pressure and 300K by the model proposed.It is found that the selectivity of butene-1 over n-butane increases linearly with the decrease of Si/Al ratio.A correlation between the selectivity and Si/Al ratio of the sample was proposed at 300K and p=0.08MPa.

A convenient synthesis of 1,5-diarylpyrazoles from Baylis-Hillman adducts using HY-zeolite

A facile and convenient protocol was developed for the synthesis of 1,5-diarylpyrazoles using Baylis-Hillman adducts in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst in reasonable reaction times(1.5-2.5 h) and high yields (78-90%).

Modification and sequential treatment of EU-1 zeolite in mild alkali and alkaline-acid conditions

EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),N_2 adsorption/desorption,temperature programmed desorption of NH_3(NH_3-TPD),solid state^(27)A1 nuclear magnetic resonance(^(27)A1 NMR),and the catalytic performances of the treated samples were tested in the xylene isomerization reaction.The results showed that the external surface area and mesoporous volume of the sample sequentially treated with 0.05 mol·L^(-1) Na_2CO_3 and 0.1 mol·L^(-1) HCl solutions reached73.9 m^2·g^(-1) and 0.162 cm^3·g^(-1),respectively.The catalytic performances of EU-1 zeolites were significantly improved,that the activity of the probe reaction increased from 23.03%to 23.61%and the selectivity increased from85.09%to 87.14%compared with those of parent sample.Furthermore,it was found that only amorphous silica and alumina species was dissolved during the post-treatment process,but the framework structure and the acidic properties of EU-1 zeolite remained intact.

Studies of Cyclohexane Catalytic Oxidation Processes over Titanium Silicate-1 Zeolite

The catalytic oxidation processes for cyclohexane/H2O2/acetone system over the TS-1 zeolite was studied. Study results have revealed that the cyclohexane conversion was 27% after the reaction proceeded at 100C for 2 hours at a cyclohexane/H2O2 molar ratio of 0.8. The cyclohexanol/cyclohexanone molar ratio was 1.3along with a certain amount of organic acids and esters, the formation of which was closely associated with the oxidation of reaction solvent and deep oxidation of cyclohexanone and cyclohexanol contained in the reaction products. With respect to the catalytic oxidation of cyclohexane/H2O2 system the selection of appropriate solvent was critically important.

Skeletal Isomerization of 1-Hexene over MCM-22 Zeolite Catalyst

The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure on the performance of MCM-22 zeolite for catalytic skeletal isomerization of 1-hexene was examined. The experimental results showed that at a steam treatment temperature of 500℃, a reaction temperature of 270℃, a space velocity of 1.0 h-1 and a reaction pressure of 0.2 MPa, the MCM-22 zeolite exhibited excellent performance for catalytic skeletal isomerization of 1-hexene with the i-hexene yield reaching 66.15%. Compared with other commonly used molecular sieve catalysts, the MCM-22 zeolite catalyst exhibited better catalytic performance for skeletal isomerization of 1-hexene.

Synthesis and Characterization of Zeolite Hexanediamine-Theta-1

The synthesis of zeolite HXDM-Theta-1(HXDM = hexanediamine) from the reaction mixture HXDM-Al2O3-SiO2-HF-H2O is described. The formation of HXDM-Theta-1 is favoured at 150℃, and a mixture of Theta-1 and ZSM-5 is obtained at a higher temperature. The asynthesized Theta-1 was characterized by means of scanning electron micrography, thermal analysis and 13C MAS NMR techniques. Keywords Theta-1, Hydrothermal crystallization, Hexanediamine template, Thermal analysis, 13C MAS NMR

Fe-MSU-1介孔分子筛的合成及其催化苯酚羟基化性能

以月桂醇聚氧乙烯醚为模板剂,在中性条件下成功合成了Fe-MSU-1介孔分子筛.采用X射线衍射、傅里叶变换红外光谱、紫外-可见吸收光谱、电子自旋共振谱、透射电镜、低温N2吸附和电感耦合等离子体原子发射光谱对样品进行了表征.考察了Fe-MSU-1分子筛在苯酚羟基化反应中的催化性能以及工艺条件对苯酚羟基化反应的影响.结果表明,Fe3+离子进入了分子筛骨架,Fe-MSU-1分子筛具有均一的蠕虫状介孔结构,平均孔径约为2.9nm.在焙烧后的Fe-MSU-1样品中,Fe3+主要以四配位的形式存在,无骨架外Fe2O3物种形成.以水为溶剂,在苯酚/H2O2摩尔比为3,反应温度353K,反应时间7h的条件下,苯酚和H2O2的转化率以及苯二酚的选择性分别达到20.4%,96.9%和99.6%.

窄孔分布介孔分子筛MSU-1的合成(英文)

以水玻璃为硅源,在pH=3以下合成MSU X介孔材料的报道很少,本文将pH范围扩展至0 78,并从廉价的水玻璃和工业级非离子表面活性剂AEO9出发,用二步法合成出介孔分子筛MSU 1。首先将无机前驱体和非离子表面活性剂在介稳态下(pH≈2,t≈2℃)混合,然后调pH至所需值(0 78～3 94),在该pH值下进行二氧化硅缩聚。合成出的MSU 1具有孔分布窄,短程有序度提高,颗粒呈微米级等特点。其中在pH=1 98下合成的MSU 1具有最薄的孔壁、最大的比表面和孔容;在pH=0 78下合成的MSU 1具有最厚的孔壁、最大的孔径和d100值。随着pH值的增大,孔壁厚度先减小后增大。

介孔分子筛MSU-1的合成

Mesoporous MSU1 was synthesized from sodium silicate solution and A(EO)9 surfactant in acid media.Compared with synthesis of MSU1 from TEOS,the former had many features such as low cost silica source,nontoxicity,and short reaction time.Moreover,the products with enhanced shortrange order and narrower pore size distribution were obtained when synthesized in moderate or strong acid media.pH had a large effect on properties of products prepared from sodium silicate solution,such as pore volume,pore wall,pore size and surface area.In near neutral media(pH=608),pore diameter was the smallest and pore wall was the thickest.In the research of two kinds of surfactants(alkylPEO and alkylaryl PEO),system of A(EO)9sodium silicate solution was found good for obtaining products with enhanced shortrange order and narrower pore size distribution.

原料气中乙烷含量对Cr/MSU-1催化剂上CO_2氧化丙烷脱氢反应的影响

研究了原料气中乙烷含量对Cr/MSU-1催化剂上CO_2氧化丙烷脱氢反应的影响,并考察了反应温度和空速的影响。保持总烷烃与CO_2的体积比为1:3,当原料气总空速及烷烃总量恒定时,提高乙烷的含量对丙烷转化率影响不大,但烯烃选择性先升高后降低;当原料气总空速及丙烷含量恒定时,加入乙烷降低了丙烷转化率,提高了丙烯的选择性及收率;随反应温度的升高,丙烷及总烷烃的转化率增大,丙烯及总烯烃的选择性减小,其变化规律与单一丙烷的脱氢过程一致;提高空速丙烷的转化率降低,烯烃的选择性增加。在最佳反应条件即反应温度650℃、丙烷与乙烷的体积比3:2、空速8 400 mL/(h·g)下,总烷烃转化率为50.0%,总烯烃选择性为92.2%,丙烯选择性为83.1%。