ZSM-5/MCM-41复合分子筛的微波合成及催化性能

用微孔沸石硅源法微波合成ZSM-5/MCM-41复合分子筛,采用XRD、BET和NH₃-TPD技术对合成分子筛进行表征。结果表明,复合分子筛具有类MCM-41 的典型六方介孔结构,同时具有中孔和微孔结构,复合分子筛的总酸量介于HMCM-41酸量与HZSM-5酸量之间。利用脉冲微反装置考察合成分子筛的邻二甲苯异构化催化性能。结果表明,ZSM-5/MCM-41复合分子筛具有高于同硅铝比的MCM-41、ZSM-5和ZSM-5/MCM-41的机械混合物的催化活性。     

WO3-ZSM-5/MCM-41催化剂的合成 及其催化氧化脱硫研究

以氢氧化钠溶液处理微孔沸石ZSM-5来提供硅铝源,合成了ZSM-5/MCM-41复合结构型分子筛。采用XRD、N2吸附脱附、TEM等方法对其进行了表征,考察了其水热稳定性。实验结果表明,碱处理合成的ZSM-5/MCM-41同时具有微孔孔道和介孔孔道结构,并具有优于介孔MCM-41分子筛的水热稳定性。以ZSM-5/MCM-41为载体负载三氧化钨后应用于噻吩/正辛烷模拟油体系,双氧水为氧化剂,催化氧化脱硫,WO3-ZSM-5/MCM-41（三氧化钨质量分数为10%）表现出良好的催化性能,脱硫率可达到93.6%。     

改性ZSM-5分子筛催化合成哌嗪

研究了不同金属离子改性得到的M-ZSM-5分子筛在以乙二胺(EDA)为原料合成哌嗪反应中的催化性能。通过NH3-TPD和BET法对催化剂进行表征,结果表明,经过离子交换后HZSM-5的骨架结构没有发生变化,仅仅是表面酸性发生了变化。重点考察了催化剂酸性对反应的影响,实验表明,提高弱酸和中强酸中心所占比例有利于哌嗪(PA)和三乙烯二胺(TEDA)生成。以Zn-ZSM-5和Zn/K-ZSM-5为催化剂,在常压,t=360℃,空速为0.25 g/(min.h),m(EDA)∶m(H2O)=4∶6的反应条件下,原料EDA的转化率分别为94.1%和82.6%;产物PA和TEDA的选择性分别为45.5%,42.1%和29.4%,50.1%。     

新型复合分子筛L/ZSM-5的合成与表征

在一定的SiO₂与Al₂O₃物质的量比和pH条件下,采用水热晶化法合成了L/ZSM-5新型复合分子筛。并通过X射线衍射（XRD）、扫描电镜（SEM）和红外光谱（IR）对样品进行了表征。讨论了酸量对合成的影响。结果表明,优化的加酸量为(0.802 0～0.939 9) g,在一定的酸性范围,酸性越强越有利于ZSM-5的生成,合成出的复合分子筛中ZSM-5所占的比率越高。     

Synthesis of mesoporous ZSM-5 zeolites through desilication and re-assembly processes

ZSM-5 zeolite crystals with secondary mesopores were synthesized by alkaline desilication and surfactant-induced re-assembly of dissolved species (i.e., silicates, aluminosilicates and zeolite crystal fragments) originating from the parent ZSM-5 crystals. The meso-zeolite products exhibit a dual-mesopore structure in which the smaller mesopores (ca. 3 nm) are attributed to surfactant-induced micelle formation involving dissolved species, and larger mesopores (ca. 10-30 nm) result from desilication processes occurring under the alkaline reaction conditions. The external surface area (i.e., the surface area due to mesopores, macropores and the external particle surface) of the meso-zeolite materials depends on the Si/Al ratio, the hydroxide concentration and the presence of surfactant, and it reaches values as high as 327 m² g⁻¹ when a surfactant is used. The crystallinity of the highest surface-area meso-zeolite is well preserved, maintaining values of ca. 83% (on the basis of micropore volume) or ca. 77% (on the basis of X-ray diffraction intensities) of the parent zeolite structures. Further physicochemical characterization by ²⁷Al and ²⁹Si magic-angle-spinning solid-state NMR spectroscopy, scanning and transmission electron microscopy, temperature-programmed ammonia desorption measurements, and inductively coupled plasma elementary analysis support the hypothesis that re-assembly of dissolved species of zeolite crystals occurred by surfactant-induced micellization, resulting in the high external surface area of the meso-zeolite materials.     

水在ZSM-5型分子筛中吸附的Monte Carlo模拟

构建了ZSM-5型分子筛物理模型,采用Connoly表面方法和Solvent表面方法对ZSM-5型分子筛的几何结构和性质进行了模拟分析。通过巨正则系综蒙特卡罗方法(GCMC)模拟研究了水蒸气在ZSM-5型分子筛上的吸附特性。通过模拟方法看到了实验难以表征的水蒸气在分子筛中具体吸附位,研究了压力、温度和硅铝比对ZSM-5型分子筛吸附性能的影响及其吸附热的变化规律。     

超细ZSM-5分子筛的制备及其形貌表征

对比考察了模板剂的种类、晶化温度以及铝含量等影响因素对超细ZSM-5分子筛晶化行为的影响,采用扫描电镜（SEM）、透射电镜（TEM）和X射线衍射光谱（XRD）技术对所制备的超细产物的结构及形貌进行了表征。结果表明,模板剂的种类对分子筛的晶化过程有重要影响,四丙基氢氧化铵是优良的制备超细ZSM-5分子筛的模板剂;以四丙基氢氧化铵为模板剂,适宜采用静态法制备超细ZSM-5分子筛的晶化温度为70～ 120 ℃;凝胶体系中铝的存在抑制ZSM-5分子筛晶核的生长,无铝条件下,分子筛的晶化速度最快;随着铝含量的增加,分子筛的晶化速度变慢,在相同的晶化时间内,生成的分子筛的粒径更小。     

石蜡/MCM-41复合相变材料的结构及热性能

以石蜡为相变材料、SiO2介孔分子筛MCM-41为载体,采用溶液浸渍法制备了石蜡/MCM-41复合相变储能材料。应用SEM与TEM测试了复合材料的微观结构,利用TG-DSC测定了复合材料的相变温度、相变潜热及相变可逆性,通过FTIR对复合材料的兼容性进行了表征。实验表明,复合材料表面孔结构改善了相变可逆性,复合相变储能材料中石蜡的适宜质量分数为40%,相变温度为66.6℃,相变潜热为135.3 J/g。石蜡与MCM-41间是简单的嵌合关系,复合材料具有良好的热稳定性和兼容性。     

低成本合成介孔ZSM-5沸石及其负载CoMo催化剂的加氢脱硫活性

以廉价的水玻璃、硫酸铝为原料,以阳离子聚季铵盐为介观尺度模板剂,通过水热合成方法制备了较高结晶度的介孔ZSM-5沸石(MZSM-5)。采用等体积浸渍法制备MZSM-5负载CoMo金属硫化物催化剂(CoMo/MZSM-5),考察了其对4,6-二甲基二苯并噻吩加氢脱硫活性。与传统的γ-Al2O3负载的CoMo(CoMo/γ-Al2O3)催化剂相比,CoMo/MZSM-5表现出更高的加氢脱硫活性。     

静态条件下合成纳米片层ZSM-5分子筛

采用具有双功能导向作用的长碳链双季铵盐作为模板剂,原料配比为n(Na_2O)∶n(Al_2O_3)∶n(SiO_2)∶n(C_(22-6)-6Br_2)∶n(H_2SO_4)∶n(H_2O)=30∶1∶100∶10∶18∶4 000,静态条件下合成有序纳米片层ZSM-5分子筛,并采用XRD、N2吸附-脱附、SEM和TEM等对其进行表征。研究部分晶化条件对合成过程的影响。结果表明,增大填充度至50%,可以提高晶化压强,从而提高分子筛结晶度;随着凝胶碱度的增加,纳米片层分子筛结晶度先增大后降低,多片层有序性也发生同样变化;晶化时间对合成过程的前期影响较大,晶化时间6天,分子筛达到较高结晶度,样品形貌均一,介孔孔径分布集中。     

Acidity and catalytic activity of mesoporous ZSM-5 in comparison with zeolite ZSM-5, Al-MCM-41 and silica–alumina

Acidity of mesoporous HZSM-5 prepared using amphiphilic organosilane template molecules was measured. Brønsted acid sites were observed in the prepared sample, and the number and the strength of Brønsted acid sites were determined quantitatively by a method of infrared-mass spectroscopy/temperature-programmed desorption (IRMS-TPD) of ammonia. ΔH for ammonia adsorption as an index of the strength was ca. 150 kJ mol⁻¹ that was almost the same as on usual HZSM-5, but the number was smaller than that of HZSM-5. From the measured acidity, it was concluded that the mesoporous materials contained a smaller concentration of Brønsted acid site notable on the structure of HZSM-5. Measurements of turnover frequency (TOF) in the catalytic cracking of octane supported the conclusion. Density functional calculations showed that the defect sites Al–OH and Si–OH attached to the Brønsted acid site changed the strength of the acid sites to show some possible structures of the weak and strong Brønsted acid sites included in the mesoporous HZSM-5. Acidities of Al-MCM-41 and silica–alumina were also measured, and the difference in the solid acidities of these materials was discussed.     

多级孔道ZSM-5分子筛的合成及其催化应用

多级孔道ZSM-5分子筛具有微孔沸石分子筛良好的择形催化性能和介孔材料优异的传质扩散性能,在催化领域显示出良好的应用前景。本文综述了近年来多级孔道ZSM-5分子筛的研究进展,重点介绍了多级孔道ZSM-5分子筛的不同合成方法,包括后处理法、硬模板法和软模板法等,同时介绍了不同方法得到的多级孔道ZSM-5分子筛在催化反应中的应用,分析表明多级孔道ZSM-5分子筛以其良好的扩散性能和适宜的酸性提高了反应转化率和目标产物选择性。最后对多级孔道ZSM-5分子筛的发展方向进行了展望,指出研发简单、经济和环保的新合成路线是多级孔道ZSM-5分子筛发展中的重大挑战,深入研究多级孔道分子筛中介孔的形成机理和开发具有多级孔道整体式催化剂以及负载型多级孔道ZSM-5分子筛是今后的研究重点。     

Synthesis of ZSM-5 zeolite from expanded perlite and its catalytic performance in FCC gasoline aromatization

A hydrothermal synthesis method for ZSM-5 preparation was investigated by using expanded perlite as the only alumina source. The effect of crystallization conditions on ZSM-5 zeolite formation, such as temperature, time, pH, chemical composition of the reaction mixture, were studied. The samples were characterized by XRD, IR, SEM, XRF and BET surface area measurements. The ZSM-5 zeolite from expanded perlite showed better catalytic activity for the FCC gasoline aromatization reaction compared to ZSM-5 prepared by the standard method.     

ZSM-5分子筛的合成与改性研究进展

ZSM-5分子筛是一种在石油催化裂化过程中常用的择型分子筛,具有良好的热稳定性、耐酸性和择型选择性。催化剂中ZSM-5分子筛的添加可以提高汽油辛烷值和烯烃产率。目前,中国已经形成了以催化裂化为主的重质油加工工艺,2013年原油加工量超过4亿t/a。在未来相当长一段时间,催化裂化加工重质劣质原料油仍是炼油厂的工作重点。综述了近年来国内外ZSM-5分子筛的合成与改性研究进展,为今后ZSM-5分子筛合成与改性方面的研究提供了一定的借鉴和参考。     

Synthesis, characterization, and catalytic properties of a hydrothermally stable Beta/MCM-41 composite from well-crystallized zeolite Beta

A Beta/MCM-41 composite has been synthesized with a new method by using well-crystallized zeolite Beta as silica and aluminum source. The prepared composite was characterized by XRD, FTIR, N₂ adsorption/desorption at 77 K, FE-SEM, DTG, ²⁹Si MAS NMR spectral techniques. It was shown that the composite consisted of a highly ordered mesoporous MCM-41 phase and a zeolite Beta phase. Its hexagonal mesoporous structure was still retained after statically treated for 120 h in boiling water. In contrast, the structure of generally synthesized Al-MCM-41 nearly completely collapsed. This might be attributed to the assembly of the dissolved fragments such as the first and/or secondary structural units of zeolite Beta into the mesoporous structure around surfactant micelles. This is supported by the catalytic result that the prepared composite showed higher activity and selectivity for medium fraction in hydrocracking of Daqing vacuum residue than the parent zeolite Beta, the Al-MCM-41 as well as the mechanical mixture of these two materials.     

ZSM-5分子筛合成及其改性研究进展

ZSM-5分子筛在化学化工中应用广泛.详细阐述了ZSM-5沸石分子筛的各种合成方法,并介绍了常用的高温水热处理、金属改性和磷改性等改性技术现状及其应用,以及近年来的研究和开发应用最新进展,为ZSM-5分子筛的开发利用提供新的思路.     

ZSM-5/EU-1共生分子筛的可控合成及催化裂解性能

采用双模板剂两步晶化法设计合成了ZSM-5/EU-1共生分子筛,通过调整预晶化过程,实现了两种分子筛的共生和晶相比例的可控调变。研究两段凝胶组成的影响发现,第一段凝胶组成,尤其是模板剂浓度对所得共生样品晶相比例具有较大影响。与机械混合和纯相样品相比,ZSM-5/EU-1共生分子筛表现出最大的BET表面积和孔体积尤其是外表面积和介孔体积。而且EU-1相含量为39%的ZSM-5/EU-1共生分子筛在正己烷催化裂解制低碳烯烃反应中表现出比机械混合样品和ZSM-5分子筛更高的反应活性稳定性和低碳烯烃选择性,尤其是丙烯选择性。在反应120 min时,该共生分子筛上低碳烯烃选择性比相同EU-1相含量机械混合样品和ZSM-5分子筛均高出约10.7个百分点,丙烯选择性分别高出8.5和9.1个百分点,P/E比分别高出0.42和0.46。     

ZSM-5沸石合成与改性技术进展

ZSM-5沸石在石油化工过程中得到广泛应用。阐述了ZSM-5沸石的合成、改性技术现状及其应用以及近年来的研究和开发应用最新进展，为ZSM-5沸石的开发利用提供新的思路。     

ZSM-5沸石的改性及其在烷基化反应中的应用进展

ZSM-5沸石在石油化工中的应用非常重要。本文对ZSM-5沸石的改性技术的现状及其近年来在烷基化反应中的开发应用的最新进展进行了综合阐述,ZSM-5沸石的应用已取得了一定的成果,为其今后的开发利用提供了新的思路。     

微波法合成MCM-41介孔分子筛及吸附性能研究

以十六烷基三甲基氯化铵为模板剂,在微波实验条件下合成MCM-41介孔分子筛,缩短了合成时间,降低产品成本。实验考察了多种因素对MCM-41合成的影响,并通过吸附处理亚甲基蓝溶液能力强弱,得到最佳合成条件：摩尔比1TEOS：0.2CTMACl：160H2O,pH为10,晶化时间15 min。通过红外光谱分析,MCM-41分子筛的主要特征吸收峰均已出现,说明合成分子筛MCM-41成功。