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.

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%.

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.

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.

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.

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.

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.

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%).

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

EU-1分子筛的快速合成及表征

采用固相原位转化法在HMBr2-Na2O-Al2O3-SiO2-H2O体系中快速合成出高结晶度的EU—1分子筛，晶化时间明显缩短，从水热合成时的168h缩短至28h；考察了水添加量对晶化过程的影响，发现在较低的液固比（n（H2O）：n（SiO2）：4．2～6．9）条件下，产物具有较高的结晶度。利用X射线衍射、扫描电子显微镜、热重-差热分析、N2吸附及红外光谱等测试手段对EU—1分子筛的物化性能进行了表征。表征结果显示，固相原位转化法与水热法合成的EU—1分子筛具有相同的EUO拓扑结构，为1～5μm的团聚体，由0．3～0．8μm的亚微米级颗粒团聚而成；比表面积为336m^2／g，孔体积为0．33cm^3／g；固相原位转化法与水热法合成的EU—1分子筛经历不同的晶化过程。

一步合成核壳结构ZSM-5/EU-1复合分子筛及其表征

在添加适量柠檬酸的条件下采用双模板剂一步法,一次晶化合成ZSM-5/EU-1核壳共生复合分子筛,对其物理化学性质进行表征,结果显示：核壳分子筛中存在ZSM-5和EU-1两种分子筛晶相,且EU-1分子筛在ZSM-5分子筛表面缺陷处外延生长;复合以后核壳分子筛为微孔–介孔多级孔道结构,且其微孔孔径达到0.94 nm;相比于单一分子筛,核壳分子筛的强酸量相对提高,酸性质有所改善。通过对柠檬酸加入量、晶化时间影响因素的分析,得到合成核壳共生结构的最佳条件为：n（citrate）/n（Al_2O_3）=0.8~1.2,晶化时间为72~96 h,并推测核壳分子筛可能的生长过程。

B、Al、La同晶取代EU-1分子筛酸性的密度泛函理论计算

采用量子力学的密度泛函理论(DFT)方法,研究了B、Al、La同晶取代EU-1分子筛骨架的Si后可能的存在位置,确定了与平衡电荷质子结合的骨架O位置,考察了杂原子B、La进入骨架后对EU-1分子筛Brnsted酸(B酸)强度的影响。计算所采用的26T簇模型均在DFT的BLYP方法和DNP基组下完成。对合成的分子筛进行了NH3-TPD表征。能量分析表明,Al和B取代EU-1分子筛骨架最可能的位置为T(1)、T(2)、T(3)、T(6)、T(7)和T(8)位,La取代最可能的位置为T(1)、T(2)和T(8)位。B酸落位点分别为Al(1)-O(12)H-Si(2)和Al(1)-O(13)H-Si(6)位,B(8)-O(29)H-Si(10)位,La(1)-O(12)H-Si(2)、La(1)-O(13)H-Si(6)、La(2)-O(12)H-Si(1)位。与硅铝EU-1分子筛相比,B和La进入骨架会导致EU-1分子筛的B酸强度有所减弱,Al-EU-1、La-EU-1、B-EU-1三者中,Al-EU-1的B酸强度最强,B-EU-1的最弱。B和La进入EU-1分子筛骨架后,酸性减弱,弱酸量增加,理论计算与实验结果一致。

甲醇定向转化制二甲苯的复合分子筛ZSM-5/EU-1的合成及其应用

以硅溶胶、硫酸铝、氢氧化钠、四丙基溴化铵以及硼酸和九水硝酸铁为原料，采用EU-1晶种，通过水热法合成了2种含杂原子的微孔结构ZSM-5／EU-1复合分子筛。采用XRD、SEM、N2吸附-脱附和NH3-TPD对合成样品进行了表征，并在连续流动固定床反应器上考察了该分子筛催化剂对甲醇N-甲苯反应的催化性能。结果表明-含杂原子微孔结构的ZSM-5／EU-1复合分子筛同时具有ZSM-5和EU-1的特征衍射峰，结晶度较好，平均孔径明显增大，当催化剂的酸强度和酸量增大时，有利于甲醇芳构化趋势以及二甲苯优先扩散。B-ZSM-5／EU-1催化产物中芳烃在油相中的选择性达到84-70％；B-ZSM-5／EU-1和Fe-ZSM-5／EU-1两种分子筛催化产物的芳香烃中二甲苯的含量最高，分别为41-32％～45-88％和33-88％～39-16％。由于B-ZSM-5／EU-1较高的酸性、酸量和相对较小的孔道内径（0-8060nm），较Fe-ZSM-5／EU-1更有利于产物中二甲苯的生成；不仅如此，B-ZSM-5／EU-1复合分子筛催化产物中对二甲苯在二甲苯中选择性范围为29-75％～47-47％；不过，Fe-ZSM-5／EU-1产物中对二甲苯在二甲苯中的含量最高可达53.75％，这是由于Fe-ZSM-5／EU-1复合分子筛的粒径较大，为催化反应提供了较长的孔道结构，易使产物中邻、间二甲苯在扩散过程中异构化转化为对二甲苯的缘故。

导向剂法合成EU-1分子筛

将导向剂法引入EU-1分子筛合成体系，所加入的导向剂为自主研发的硅铝酸盐溶胶（或凝胶）。合成导向剂时，仅在其中加入少量有机模板剂溴化六甲双铵（HMBr2），而在配制反应混合物时不再加入HMBr2。按照m（SiO2）：m（Al2O3）：m（Na2O）：m（HMBr2）：m（H2O）为（40～50）：1：（2．0～4．5）：（9～12）：（60～80）质量比配制导向剂，适宜的陈化温度为370～450K，陈化时间为18～24h。合成EU-1分子筛适宜的反应混合物质量比m（SiO2）：m（Al2O3）：m（Na2O）：m（H2O）为（30～40）：1：（1．7～4．9）：（50～70），导向剂用量为8％～10％，晶化时间为2～3d，温度区间为430-450K。采用XRD、SEM、和IR等表征手段对样品进行表征。结果表明，采用该法成功地合成了高纯度、高结晶度的EU-1分子筛，且模板剂用量较常规合成法降低70％以上，降低了制造成本。

以EU-1分子筛为晶种合成ZSM-11分子筛及其表征

以EU-1分子筛为异质晶种，采用不同模板剂和硅源合成两种不同粒度尺寸的ZSM-11分子筛。采用XRD，FT—IR，SEM，Nz吸附-脱附等手段对合成的ZSM-11分子筛样品进行表征。结果表明，当晶种加入量（W）为1％～10％时，一定温度下水热晶化处理1～10天，均可以得到结晶度高、无杂晶的ZSM11分子筛。采用不同方法合成的两种ZSM11分子筛在形貌、晶粒尺寸及硅铝比上存在较明显区别，微米尺寸的ZSM11分子筛呈椭球状，由许多板条状粒子团聚而成，尺寸约为200nm×700nm，硅铝比较高；纳米尺寸的ZSM—11分子筛为清晰的球状晶体，是由许多球状纳米级粒子团聚形成的，粒径在100nm以下，硅铝比较低。