以哌啶为模板剂静态合成MCM-22和MCM-36分子筛

以来源易得的哌啶(PI)取代六亚甲基亚胺(HMI)为模板剂,采用静态合成的方法制备MCM-22分子筛,并进一步以十六烷基三甲基氯化铵(CTMACL)、四丙基氢氧化铵(TPAOH)作为溶胀剂,以正硅酸乙酯(TEOS)为柱撑剂合成MCM-36分子筛,以探索MCM-22和MCM-36的新合成途径。通过XRD、IR、SEM、N2吸附-脱附、NH3-TPD、正丁胺回滴法对MCM-22和MCM-36结构形貌、比表面积、孔径、表面酸量进行表征。结果表明,采用静态法以哌啶为模板剂是合成MCM-22和MCM-36的有效途径,MCM-22结晶度达到98.5%。合成的MCM-22比表面积为382 m2?g-1,孔容为0.25 cm3?g-1,外表面酸量为0.78 mmol?g-1;合成的MCM-36比表面积为468 m2?g-1,孔容为0.39 cm3?g-1,外表面酸量为0.94 mmol?g-1,介孔孔径达2.7 nm。     

无硼体系MCM-22分子筛的合成

以哌啶(PI)为模板剂,在不添加晶化助剂下,采用动态水热晶化法合成MCM-22分子筛,考察了晶化时间、PI和Si O2、OH-和Si O2、Si O2和Al2O3的物质的量之比等对晶化产物的影响,结果表明,PI和Si O2,OH-和Si O2,Si O2和Al2O3的物质的量之比为0.50~0.70,0.09~0.10和30~40,晶化时间48~72 h的条件下,能较好地合成MCM-22分子筛。在苯与乙烯液相烷基化制乙苯反应中,以哌啶为模板剂与采用六亚甲基亚胺为模板剂合成的MCM-22分子筛的催化性能相当。     

咪唑改性MCM-22分子筛的制备及甲烷无氧芳构化性能

以硅溶胶为硅源,环己亚胺为模板剂,在动态条件下利用水热合成法合成了MCM-22分子筛,并在该体系下以咪唑为添加剂合成了咪唑改性MCM-22-I分子筛,考察了咪唑对MCM-22-I分子筛合成的影响,利用FTIR、XRD、SEM、ICP、BET、NH₃-TPD、H₂-TPR和TG/DTG等手段分别对咪唑改性前后分子筛的物化性质进行了表征。结果表明,咪唑改性能够增大MCM-22的比表面积、孔容和酸性,同时可有效降低模板剂HMI的用量。采用等体积浸渍法制备了6Mo/MCM-22和6Mo/MCM-22-I双功能催化剂,在连续流动固定床反应器上,反应温度700℃、反应压力1.01×10⁵Pa（1atm）、空速1500mL/(g-cat·h)的反应条件下,考察了催化剂催化甲烷无氧芳构化合成苯的催化剂性能。结果表明,与6Mo/MCM-22催化剂相比,咪唑改性的6Mo/MCM-22-I催化剂具有更高的择形性能和催化活性,甲烷的平均转化率提高了24.1%,苯的平均生成速率和选择性分别提高了24.3%和10.0%。     

MCM-22、MCM-49和MCM-56三种分子筛的合成

MWW结构分子筛是一类新型的催化材料,具有独特的10元环孔道和12元环孔穴结构,在多种反应中表现出良好的催化活性。以六亚甲基亚胺作为模板剂,合成了MCM-22、MCM-49和MCM-56三种分子筛,并详细考察了不同硅源、凝胶配比、晶化温度和晶化时间对合成过程的影响。结果表明,凝胶配比和晶化温度对分子筛物相的影响较大。以硅胶粉为硅源,无论在何种晶化时间下都不能得到MCM-56,只能合成出MCM-49。而以碱性硅溶胶为硅源,在较短的晶化时间内就可以得到MCM-56。     

制备条件对MCM-22分子筛催化异丁烯气相齐聚性能的影响

以六亚甲基亚胺为模板剂,硅溶胶为硅源,偏铝酸钠为铝源,采用动态水热法合成了MCM-22分子筛,并考察了MCM-22分子筛的Si与Al之比和制备条件对其催化异丁烯气相齐聚反应性能的影响.结果表明:Si与Al之比对其催化性能影响较小;MCM-22分子筛适宜的制备条件为晶化温度175 ℃、晶化时间72 h、焙烧温度500 ℃和离子交换浓度2 mol/L.异丁烯气相齐聚反应的实验结果表明, MCM-22分子筛具有较好的异丁烯齐聚活性,在反应温度225 ℃和体积空速240 h-1条件下, 异丁烯转化率大于50%,C8烯烃选择性大于95%.     

六亚甲基亚胺在MCM-22分子筛合成中的导向作用及分解行为研究

对以六亚甲基亚胺为模板剂合成MCM-22分子筛的方法进行了优化，并对模板剂在合成中的作用及焙烧分解行为进行了研究。结果表明，采用合适的水与硅物质的量比和晶化温度能有效降低六亚甲基亚胺用量；六亚甲基亚胺在MCM-22分子筛合成过程中起结构导向和平衡电荷的作用；在干燥焙烧过程中无气相六亚甲基亚胺外排，烟气中含氮化合物以NH₃、NO和NO₂为主。     

2-羰基丙酸异烟酰腙功能化MCM-41吸附水中镍离子研究

以十六烷基三甲基溴化铵为模板剂,金尾矿为硅源制备MCM-41分子筛,将合成的2-羰基丙酸异烟酰腙(H2L)修饰在MCM-41分子筛上制备出2-羰基丙酸异烟酰腙功能化MCM-41分子筛(H2L/MCM-41).采用红外光谱法、XRD和热重分析对酰腙功能化MCM-41进行了表征.采用紫外可见分光光度法测试了酰腙功能化MCM...     

硅基纳米材料结合阿司匹林的缓释作用研究

本文在碱性条件下,硅酸钠作为硅源,十六烷基三甲基溴化铵(CTAB)作为结构模板剂,利用水合晶化法合成了纯硅源的MCM-41介孔分子筛.采用浸渍法将阿司匹林组装在MCM-41六方形孔道中,制备出新型载药Aspirin/MCM-41复合物。采用X射线粉末衍射(XRD)和傅里叶红外光谱(FT-IR)表征手段对合成的新型功能化介孔材料进行表征。MCM-41分子筛与阿司匹林的相互作用为研发以MCM-41分子筛为载体的载药体系提供了理论依据。     

MCM-22和MCM-49分子筛的合成

在Na2O-Al2O3-SiO2-HMI-H2O体系中。对MCM-22和MCM-49分子筛的静态晶化过程进行了研览。结果表明，晶化温度和硅铝比对MCM-22和MCM-49分子舜合成至关重要。晶化温度低（150℃）时，只能合成硅铝比鞋低的MCM-49分子筛；晶化温度高（180℃）时，可以合成较高硅铝比的MCM-49分子筛。同时发现碱庹高有和利于MCM-49分子筛的合成．而Na＋浓度以及模板剂的用量影响不大．     

硅铝胶气相法合成MCM-22分子筛工艺条件的影响

以硅酸和偏铝酸钠为硅源和铝源制备硅铝胶,采用气相法合成MCM-22分子筛.考察了硅铝比、钠离子含量、模板剂六亚甲基亚胺(HMI)和水用量等工艺条件对合成的影响.结果发现,与水热晶化法相比,气相法合成中硅铝比范围变窄,所需Na 含量大大降低,合成的MCM-22分子筛结晶更完整,晶粒直径较大.原料组成为SiO2:(0.02～0.033)Al2O3:(0.085～0.1)Na :1.2HMI:20H2O,晶化温度和时间分别为150 ℃和5～7 d的实验合成条件较为适宜.     

Synthesis and Catalytic Reactivity of MCM-22/ZSM-35 Composites for Olefin Aromatization

A series of MCM-22/ZSM-35 composites has been hydrothermally synthesized and characterized by XRD, SEM, particle size distribution analysis, N₂ adsorption and NH₃-TPD techniques. Pulse and continuous flow reactions were carried out to evaluate the catalytic performances of these composites in aromatization of olefins, respectively. It was found that MCM-22/ZSM-35 composites could be rapidly crystallized at 174 °C with an optimal gel composition of SiO₂/Al₂O₃=25, Na₂O/SiO₂=0.11, HMI/SiO₂=0.35, and H₂O/SiO₂=45 (molar ratio), of which the weight ratio of ZSM-35 zeolite in the composite relied on the crystallization time. The coexistence of MCM-22 and ZSM-35 in the composite (MCM-22/ZSM-35=45/55 wt/wt) was observed to exert a notable synergistic effect on the aromatization ability for butene conversion and FCC gasoline updating, possibly due to the intergrowth of some MCM-22 and ZSM-35 layers.     

合成混合物中NaOH含量对MCM - 22分子筛的合成及其特性的影响

本文用硅溶胶、异丙醇铝、六亚甲基亚胺(HMI)、NaOH和H2O反应体系动态水热合成法合成MCM-22分子筛,并采用XRD、SEM测试手段对所制样品进行表征。结果表明:NaOH含量直接影响水热合成的周期,其含量越高,合成周期越短,同时合成混合物中六亚甲基亚胺也相应增加。     

Multinuclear MAS NMR studies of zeolites MCM-22 and MCM-49

MCM-22 and MCM-49 comprise a new class of molecular sieves that crystallizes as thin sheets or platelets and has many unusual structural features. MCM-22 is first synthesized hydrothermally as a precursor, MCM-22(P), that condenses upon calcination to a three-dimensional framework (MCM-22). Its framework topology is comprised of two independent pore systems, both accessible through 10-membered rings. One of these pore systems is defined by two-dimensional sinusoidal channels, which maintain an effective 10-ring diameter throughout the structure. The other consists of large supercages whose inner free diameter, 7.1 Å, is defined by 12 rings with inner height of 18.2 Å. MCM-49 has the same framework topology as MCM-22, but is synthesized directly in the reaction gel and therefore still contains the organic template. Multinuclear MAS NMR studies of MCM-22 (P), MCM-22, and MCM-49 are presented and discussed in light of the proposed structure and provide new insights into this novel class of materials. The structural information obtained from this NMR investigation is complementary to and consistent with the structure proposed from X-ray diffraction measurements. ¹³C NMR data support the existence of different dual pore systems within both MCM-22(P) and MCM-49. ²⁷Al MAS NMR spectra exhibit three distinct T_d resonances that can be interpreted in terms of the proposed framework topology. ²⁹Si MAS studies of a highly siliceous MCM-22 prepared by hydrothermal dealumination confirm the presence of at least one buried T-site in its framework structure that is not accessible to a channel wall, favor the orthorhombic form of the proposed structure, and support the presence of the modified dodecasil-1H cage.     

新型MCM-22/MCM-41复合分子筛上FCC汽油降烯烃芳构化反应

采用纳米组装法合成MCM-22/MCM-41微孔/介孔复合分子筛,分别以H-MCM-22和H-MCM-22/MCM-41为催化剂,在固定床微反装置上对FCC汽油进行降烯烃芳构化的对比考察。结果表明,在反应时间2 h内,与MCM-22相比, MCM-22/MCM-41具有高的芳构化性能和持久的初始活性,复合分子筛汽油改质的产物中,芳烃体积分数由28.58%上升至51.1%,烯烃体积分数由34.04％降至5.8％。探讨了新型H-MCM-22/MCM-41复合分子筛用于FCC汽油改质的操作条件以及催化剂失活再生性能。结果表明,最佳反应条件为：反应温度400 ℃,压力2 MPa,空速3 h^-1。失活催化剂经过两次再生,降烯烃芳构化性能基本不变。     

Liquid-phase thiophene adsorption on MCM-22 zeolite and activated carbon

The liquid-phase adsorption of thiophene from thiophene/iso-octane and toluene-rich thiophene/toluene/iso-octane solutions has been investigated in batch conditions at room temperature and atmospheric pressure on MCM-22 zeolite and activated carbon. The adsorption of toluene from toluene/iso-octane solutions has also been investigated on both the adsorbents. These were characterised by X-ray diffraction, nitrogen physisorption, scanning electron microscopy and adsorption microcalorimetry of ammonia. Both MCM-22 and activated carbon were able to adsorb thiophene and toluene from the corresponding single-adsorptive iso-octane solutions. MCM-22 appeared superior to activated carbon for the adsorption of thiophene from toluene-rich thiophene/toluene/iso-octane mixtures. The adsorption data for MCM-22 were correlated with the acid sites and silanol groups concentrations, as determined by microcalorimetric experiments. No such correlation was found for activated carbon. Apparently, on MCM-22 thiophene adsorption occurs first on the acid sites until they are saturated and then continues on the silanol groups. Toluene adsorption also occurs on the acid sites of MCM-22 until saturation, but no further adsorption by interaction of toluene with the silanol groups takes place. GC/MS investigation of the nature of the organosulphur material retained by the adsorbent revealed that the tiophene adsorbed on MCM-22 undergoes transformation into heavy products. Besides thiophene trimers and tetramers, these include other compounds formed by two and three thiophenic rings linked by alkyl groups, as well as a rather high molecular weight product where a trimer is linked to thiophenic ring by a cyclohexadienic ring. Reaction pathways leading to these products have been tentatively outlined.     

MCM-22沸石催化剂的苯与长链烯烃烷基化性能

用NH3-TPD法研究了4种不同硅铝摩尔比的MCM-22沸石的酸性质,在常压间歇式反应器中考察了它们在苯与长链烯烃烷基化反应中的催化性能,并与HY和HZSM-5沸石催化剂进行了比较。实验结果发现MCM-22的催化活性与其强酸量有一致的关系,与其硅铝摩尔比无对应关系;MCM-22的活性比HY低,但对2-P的选择性远远高于HY,这说明了MCM-22对2-P具有形状选择作用。     

Synthesis of the nanosized MCM-22 zeolite and its catalytic performance in methane dehydro-aromatization reaction

A novel and facile synthesis method based on the combination of self-assembly and in-situ crystallization is developed for the preparation of nanosized MCM-22 zeolites (simplified as MCM-22-NZ hereafter) of about 40 nm, where the cationic polymer, PDDA, was added to play a role of protecting agent to avoid the synthesis colloids self-aggregation. MCM-22-NZ was characterized by XRD, TEM, DLS, NH₃-TPD, XRF, TG and N₂ adsorption analysis. The catalytic activity of MCM-22-NZ in methane dehydro-aromatization (MDA) reaction was also studied. Mo/HMCM-22-NZ showed better methane conversion, higher benzene yield and more considerable durability of the catalyst as compared to the conventional microsized catalyst.     

PEG2000对MCM-22分子筛结构特性和催化性能的影响

以六亚甲基亚胺为模板剂,在动态水热合成MCM-22分子筛的过程中,加入有机辅助剂聚乙二醇2000(PEG2000),考察有机辅助剂PEG2000对MCM-22分子筛结构、酸性以及催化性能的影响。由X射线衍射谱图可以看出,合成时加入适量的PEG2000,可以得到结晶较好的MCM-22晶体,但结晶度稍微有些降低。由氮吸附脱附测试结果可以看出,适量助剂PEG2000的加入,改变了分子筛的最可几孔径分布,最可几孔径由0.556 nm提高至0.587 nm,孔容由0.35 m3/g增加到0.59 m3/g,BET比表面积由410 m2/g增加到456 m2/g。NH3-TPD方法测试样品的酸性结果显示,加入适量的PEG2000后,分子筛的强酸位得到加强。另外用合成的分子筛作为催化剂,以苯与丙烯烷基化为模型反应,考察了MCM-22分子筛的活性以及选择性,结果显示催化剂的活性有较大提高,然而对异丙苯的初始选择性降低,随着反应的进行,异丙苯的选择性却很快地增长。