杂原子(B、Ti、Fe)进入Y型分子筛骨架的表征

应用X射线粉末衍射(XRD)、傅立叶变换红外光谱(FT-IR)、固体核磁共振(NMR)、紫外可见漫反射(UV-Vis-DRS)和热重(TG)等多种表征方法对合成的杂原子Y分子筛(BY、TiY、FeY)的结构进行了表征. 根据引入杂原子后分子筛的晶胞常数、骨架伸缩振动吸收峰、杂原子的特征电子跃迁峰、还原的热重曲线以及杂原子所处的微观配位环境等多种性质的变化, 得出结论：杂原子B、Ti、Fe均已进入Y分子筛骨架.     

两种杂原子复配对Y型分子筛结晶性能的影响

分子筛作为催化剂或催化剂的载体材料广泛应用于各种催化反应过程中,将杂原子引人分子筛骨架中形成杂原子分子筛,可在较大的范围内调节分子筛表面的酸性中心和氧化还原催化活性中心.     

脱铝八面沸石的催化行为——非晶格铝的影响

经水热处理和SiCl4处理得到了两个系列的脱铝Y沸石USY（W）和USY（T）。经X射线衍射分析、化学分析和ESCA研究确定USY（W）中包含有非晶格铝，通过TPD、IR研究发现，沸石中非晶格铝屏蔽了沸石中的强酸中心，同时产生部分弱酸中心，经异丙苯裂化反应和DTA实验发现非晶格铝的存在虽使反应活性降低，但却提高了抗积碳能力。     

含NiY分子筛的加氢裂化催化剂载体研究

采用水热晶化法,合成出了含骨架杂原子Ni的NiY分子筛。分别以Y分子筛和NiY分子筛作为载体,通过等体积浸渍法担载金属活性组分Ni、Mo,制备加氢裂化催化剂。通过NH₃-TPD表征催化剂的表面酸性、固定床反应器评价催化剂的加氢裂化性能。结果表明,将Ni引入分子筛骨架中,可以调变催化剂的表面酸性,提高其裂化和脱硫活性,并减少催化剂上的积炭。     

ZSM-5/Y复合分子筛在烃类催化裂化催化剂中的应用研究

以大庆减压蜡油为原料，考察了水热脱铝ZSM-5/Y复合分子筛的催化裂化性能，并与经同样条件水热脱铝的ZSM-5和Y型沸石的机械混合分子筛进行了对比研究。结果表明，与机械混合样品相比，复合分子筛具有较大的柴油产率和气体产率，汽油产率降低。从复合分子筛结构和ZSM-5的择形催化两方面分析了复合分子筛和机械混合分子筛裂化性能差别的原因。复合分子筛的聚集体结构不利于大分子进入分子筛结构中进行裂化，有利于汽油组分的裂化。气体数据分析支持了复合分子筛的结构特点。     

Potentiometric Sensing of Heavy Metal Ions Using a Novel Zeolite Y Membrane

The application of zeolite Y membranes to the potentiometric sensing of heavy metal ions is described. Membranes are prepared from a pressed disk of zeolite Y, treated using tetraethyl orthosilicate (TEOS) as a silica source. The resulting silica‐zeolite Y composite membranes are characterized by powder X‐ray diffraction, MAS NMR and their potentiometric response to cations with a diameter greater than the zeolite Y pore. The initial response to cadmium (Cd²⁺) and lead (Pb²⁺) ions obeys the Nernst equation, including appropriate corrections for non‐ideality, although the responses decay over a time‐scale of several hours for higher concentration ratios.     

超稳丫沸石制备技术对沸石铝分布的影响 Ⅰ.两种典型超稳Y沸石表面-体相组成的XPS研究

用XPS考察了USY和FSY超稳Y型沸石及其起始原料NH_4Y沸石的表面组成,并结合Ar~+刻蚀技术与其体相组成进行了比较。结果表明,NH_4Y沸石的铝分布基本均匀一致,经超稳化处理后,沸石表面组成发生了很大的变化。用(NH_4)_2SiF_6液相脱铝补硅法制备的FSY表面呈缺铝特征,其表面铝原子浓度比体相低8～10％;而用传统水热法制备的USY具有典型的富铝表面,其表面铝原子浓度比体相高30％左右。USY表面富铝主要是由于USY“次表面”(Subsurface)附近的非骨架铝类迁移到表面所致。内层的非骨架铝类在常规水热超稳处理条件下一般则很难迁移,仍然留有在USY晶体内部。     

ZSM-5/Y复合分子筛的酸性及其重油催化裂化性能

 ZSM-5/Y是本研究组合成的一种新型复合分子筛材料. 用“两次交换,两次焙烧”和磷 酸氢二铵浸渍方法对该复合分子筛材料进行了改性,采用红外光谱表征了复合分子筛的酸性,研究了磷改性对复合分子筛样品羟基区谱学性质的影响,并与相应的机械混合分子筛样品进 行了对比. 红外光谱数据表明,磷改性后复合分子筛的B酸(主要是中强酸)增加,而机械混合分子筛在各个酸强度区域的B酸量和L酸量都减少. 以新疆重油为原料考察了改性后复合分子 筛样品和机械混合分子筛样品的催化裂化性能. 与相应的机械混合分子筛催化剂相比,磷改 性复合分子筛催化剂具有较高的柴油选择性,其柴油产率增加了4.1个百分点,柴汽比增加了0.11,总轻油产率与机械混合分子筛相当. 用气体产物中的CMR(裂化机理比)和C3/C4比 值分析了复合分子筛的催化性能与其聚集体结构的关系.     

NiMo/Al_2O_3 catalyst containing nano-sized zeolite Y for deep hydrodesulfurization and hydrodenitrogenation of diesel

Two mixed-matrix NiMo/Al2O3 catalysts containing nano-and micro-sized zeolite Y have been prepared to explore the size effect of zeolite Y particle on the hydrodesulfurization(HDS)and hydrodenitrogenation(HDN)activities of fluid catalytic cracking(FCC)diesel.They were characterized by SEM,BET,XRD,H2-TPR,NH3-TPD and HRTEM.The results show that the catalyst containing nano-sized zeolite Y possesses larger average pore diameter,higher pore volume,weaker and lesser acid sites,more easily reducible metal phases,shorter MoS2 slabs and more slab layers than the catalyst containing micro-sized zeolite Y.The catalysts were also evaluated with a high-pressure fixed-bed reactor using real FCC diesel as feed.The results display that the catalyst containing nano-sized zeolite Y bears higher HDS and HDN activities and exhibits higher relative rate constant for the removal of total sulfur or nitrogen than the one containing micro-sized zeolite.     

The role of mesopores in intracrystalline transport in USY zeolite: PFG NMR diffusion study on various length scales

PFG NMR has been applied to study intracrystalline diffusion in USY zeolite as well as in the parent ammonium-ion exchanged zeolite Y used to produce the USY by zeolite steaming. The diffusion studies have been performed for a broad range of molecular displacements and with two different types of probe molecules (n-octane and 1,3,5-triisopropylbenzene) having critical molecular diameters smaller and larger than the openings of the zeolite micropores. Our experimental data unambiguously show that, in contrast to what is usually assumed in the literature, the intracrystalline mesopores do not significantly affect intracrystalline diffusion in USY. This result indicates that the intracrystalline mesopores of USY zeolite do not form a connected network, which would allow diffusion through crystals only via mesopores.     

Ethylenediamine effect on the sorption of cesium on zeolites ZSM-5 and Y

The sorption of cesium was studied on zeolites ZSM-5 and Y. It was found that the sorption is much higher on zeolite Y than in ZSM-5 and it depends on the crystalline network of the zeolite. It was found as well that the main uptake mechanism involved in both zeolites for cesium was ion exchange.     

HCl处理后局部有序Y沸石的二次晶化

将商品 Y 型沸石用 HCl 处理后, 运用 X 射线粉末衍射, 透射电镜和扫描电镜、红外光谱及 27Al 和 29Si 魔角旋转核磁共振对其进行了表征. 结果表明, 酸处理后 Y 沸石接近无定形, 其长程有序性遭到破坏, 但还保留部分局部结构. 以不同浓度酸处理后的 Y 沸石为前驱体, 在 150 oC, 0.3 mol/L NaOH 条件下采用蒸汽辅助干胶转化法进行二次晶化, 可以获得丝光沸石, 其相纯度与前驱体的 Si/Al 密切相关. 随 Si/Al 比不同, 所得丝光沸石形貌由纳米针状堆积逐渐向微米单块状变化, 且其比表面积可达 400 m2/g 以上, 微孔孔容在 0.19 cm3/g.     

LaDAIY型沸石的裂解活性和抗氮性能

采用脉冲微反技术,以含吡啶的正庚烷为原料,考察了LaDAlY型沸石的裂解和抗氮性能。结果表明,LaDAlY型沸石的裂解与抗氮性能均优于其母体样品DAlY。结合NH_3-TPD的数据,讨论了酸性与裂解和抗氮性能之间的关系,对吡啶中毒的机理进行了探讨。     

高硅Y沸石的合成研究进展

Y沸石的合成及在流化催化裂化中的应用在现代石油化学工业中具有里程碑意义. Y沸石的骨架硅铝比直接影响材料的热/水热稳定性及催化性能. 提高Y沸石的骨架硅铝比、 合理减少酸中心密度、 提高酸强度, 进而改善催化裂化反应性能一直是学术界和工业界关注的重要课题. 目前工业使用的高硅Y沸石均是通过复杂的后处理方法获得的. 与复杂的后处理方法相比, 直接合成高硅Y沸石是更理想的方式, 但其难度大, 为分子筛领域具有挑战性的课题. 本文系统总结了高硅Y沸石的直接合成研究进展, 分别对无机合成体系和有机模板剂合成体系进行综合评述, 并介绍了Y沸石的晶化机理研究进展.     

Role of rare earth cations in Y zeolite for hydrocarbon cracking

Reaction kinetics data were collected for isobutane conversion over a series of ultra stable Y (USY) zeolite catalysts with and without rare earth cations and subjected to various extents of dealumination by steaming. We conducted these reaction studies at low temperatures (523-573 K) using isobutane feed streams containing known levels of isobutylene (100-400 ppm) so that the kinetics were controlled by bimolecular hydride transfer and oligomerization/beta-scission processes with little or no participation of monomolecular initiation reactions. These experimental conditions led to stable catalyst performance with the main products of isobutane conversion being propane, n-butane, and isopentane, with smaller amounts of propylene, trans-2-butene, and cis-2-butene. The rates of formation of these products per Br?nsted acid site (as counted by pyridine adsorption) depended exponentially on Br?nsted acid site density, regardless of whether the catalyst contained rare earth cations. Kinetic modeling showed an exponential dependence of hydride transfer and oligomerization/ beta-scission reaction rates on Br?nsted acid site density which translated into composite activation energies for these reactions having a linear relationship with site density. Based on results in the literature from theoretical calculations, we suggest that increasing Br?nsted acid site density in zeolite Y leads to larger zeolite elasticity, increased stabilization of cationic transition states, and lower composite activation barriers for hydride transfer and beta-scission steps. The role of rare earth cations, therefore, is to ensure the retention of high Br?nsted acid site density under hydrothermal conditions, such as in fluid catalytic cracking (FCC) regenerators, where steam would dealuminate the Y zeolite framework and reduce this site density. It is for this reason that hydride transfer reaction rates are high in the presence of rare earth cations and lead to higher yields of less olefinic gasoline during FCC.     

Sorption of Co and Cd by zeolite Y

The sorption behavior of cobalt and cadmium by zeolite Y has been investigated. Cobalt and cadmium solutions were exchanged with the zeolite at different pH's. Cobalt, cadmium and sodium in the samples were determined by neutron activation analysis. The sorption of cadmium was higher than that of cobalt, however, the selectivity for both cations by the zeolite was low.     

La 或 Ce 增强 Y型分子筛结构稳定性的机制

 采用 X 射线粉末衍射、²⁹Si 固体核磁共振、X 射线光电子能谱和扫描电镜及能谱等方法研究了 La, Ce 增强 Y 分子筛结构稳定性的差异. 结果表明, La 和 Ce 的引入均可稳定 Y 分子筛的骨架结构, 但 La 离子比含量相当的 Ce 离子更容易进入分子筛内部和抑制骨架铝的脱除, 因而对分子筛结构的稳定作用更优. 结合量子力学密度泛函计算方法, 从理论上阐述了这种增强机制, 即La 或 Ce 的引入能显著增加分子筛骨架 Al 和相邻 O 原子的作用力, 有效稳定分子筛骨架 Al 位, 并且稀土离子与分子筛间存在较强的作用力; 与 Ce 相比, La 与分子筛的相互作用更大, Al–O 作用力更强, 因此, La 比 Ce 更有利于稳定分子筛的骨架结构.     

CuCl改性Y型分子筛的CO吸附性能研究

利用自发单层分散原理,讨论了在NaY,NH4Y,CuY分子筛上CuCl分散改性情况,并对所得到的改性分子筛进行了CO吸附性能研究。实验结果表明,在低CuCl担载量时,CuCl可在这三种载体表面达到原子水平分散,其分散容量分别为0.58g/gNaY,0.68g/gNH4Y和0.41g/gCuY。由于CO与Cu^+可生配位化合物,经CuCl改性的Y型分子筛对CO显示出较高吸附性能。其中,0.6gCuCl/gNH4Y分子筛表现出最高的CO吸附容量,在室温、常压下可达123mL/gNH4Y.     

Synthesis of Mesopore Y Zeolite

Y zeolite has been widely used in the petroleum processes, especially in the fluid catalytic cracking and hydrocracking catalysts. The catalytic performance of the Y zeolite depends strongly on the modification; it is well recognized that the mesopore Y zeolite with diameters between 0.8-60 nm is good for cracking large molecules. To obtain this kind of Y zeolite, chemical modification in hydrothermal treatment is one of effective methods.     

利用Taguchi法以高岭土为原料制备高硅NaY分子筛

采用Taguchi试验方法优化出了以高岭土为原料制备高硅NaY分子筛的最佳合成参数,考察了硅溶胶的加入量、反应体系的碱度、加水量以及晶化时间对NaY分子筛硅铝比和结晶度的影响。结果表明,高硅NaY分子筛的最佳合成条件是：反应体系各组分的物质的量比为7.5SiO₂∶1.0Al₂O₃∶2.2Na₂O∶120H₂O,晶化时间为16 h。同时发现,对合成样品性能的影响最为显著的因素是硅溶胶的加入量和碱度。采用X射线衍射、N₂静态容量吸附法和扫描电镜对利用最佳条件所合成样品的硅铝比、比表面积、孔分布以及表观形貌进行了表征。结果显示,以高岭土原料制备的NaY分子筛比参考样品拥有更高的硅铝比和更大的比表面积。