多孔玻璃粉在蒸汽相中自转晶合成含硼CF-2沸石

在甲胺和水的蒸汽相中，多孔玻璃粉自转晶为高结晶度纯相含硼TON类型的CF- 2沸石。~(11)B MAS NMR证明硼原子基本上进入了沸石骨架。扫描电镜照片显示， 合成的CF-2沸石中既有单个晶体，也有由许多单个晶体构成的扇形聚集体。单个晶 体呈长条形。     

高硅FAU沸石与甲胺吸附物的相互作用

合成高硅沸石中所用的模板剂胺类分子与沸石骨架 Si—O基团间的相互作用机理尚不清楚 .迄今为止 ,沸石与吸附胺之间的相互作用的研究还只限于测定沸石酸性质 [1,2 ]、表面羟基活性位或了解模板分子在沸石骨架中的位置和状态 [3,4 ] .甲胺、乙胺在骨架完美的高硅 FAU(Y型 )沸石上的亲和性指数 AT 值 ,即被吸附有机物脱附峰温与该有机物的沸点之差分别高达 1 60与 1 5 0℃[5] .而在高硅 MFI(Silicalite-1 )沸石上为 1 60与 1 2 7℃ [6 ] .与大多数有机物不同 ,被吸附的胺类脱附时的吸热效应十分明显 .上述现象表明胺与高硅沸石骨架 O2 -…     

蒸汽相中含硼多孔玻璃自转变合成沸石Ⅰ.固相表面反应

以xRD、化学成分分析、SEM为主要手段,观察含硼多孔玻璃粉或玻璃板在有机胺与水的混合蒸汽相中自转变合成MFI型沸石与沸石膜,以及TON型沸石的结晶行为.结果表明该结晶行为属固相表面反应过程.     

硅烷对HZSM－5沸石分子筛的改性研究Ⅱ．硅烷化改性对HZSM－5表面酸性、吸附性能和催化性能的影响

以硅烷气体作为改性剂，对ＨＺＳＭ－５沸石进行了改性研究，并用ＮＨ＿３－ＴＰＤ，表面羟基和吡啶吸附态红外光谱的手段表征了改性样品。发现随着硅烷化程度的加深，强酸和弱酸开始降低，硅烷化程度ｗ％＞１．８３％后，酸性基本保持不变，这时改性只起到明显的缩孔作用。通过对改性沸石探针分子吸附行为的研究分析得知，硅烷化开始时，硅烷分子进入了孔道内，与内表面羟基反应，致使部分孔道堵塞，孔道变窄。硅烷化程度ｗ％＞１．８３％后，硅烷分子扩散进孔内受阻，转换到与外表面羟基反应，只起到改性外表面缩小孔径的作用。这种改性的ＨＺＳＭ－５沸石对甲醇胺化反应的活性和选择性都有很好的促进作用。     

蒸汽相中含硼多孔玻璃自转变合成沸石I.固相表面反应

以XRD、化学成分分析、SEM为主要手段,观察含硼多孔玻璃粉或玻璃板在有机 胺与水的混合蒸汽相中自转变合成FMI型沸石与沸石膜,以及TON型沸石的结晶行为 。结果表明该结晶行为属固相表面反应过程。     

甲胺改性酸碱双功能Y沸石的制备和表征

以甲胺水溶液为改性剂, H-Y沸石可在416 K下经水热反应制备酸碱双功能甲胺杂化H-Y沸石. X 射线粉末衍射(XRD), 固体29Si魔角核磁共振(29Si MAS NMR)表征表明甲胺分子与H-Y相互作用导致沸石晶胞体积明显增大, 骨架产生新的Si—N键. 以热重(TG/DTG)及差热分析(DTA), NH3, CO2程序升温脱附(NH3-TPD和CO2-TPD)研究杂化H-Y沸石的酸-碱性质及其经不同温度焙烧后的变化, 结果表明, 杂化后沸石的酸/碱量, 尤其是后者增加甚大. 与H-Y相比, 随焙烧温度变化, 该酸-碱双功能沸石材料的酸/碱量可分别提高3至7倍和1.5至26倍.     

新型两亲性HZSM-5沸石催化剂对环己烯水合相界面反应的催化研究

采用三甲基氯硅烷对HZSM-5沸石样品进行外表面修饰,制得两亲性沸石样品,该类两亲性沸石能分布于水、油两相界面处.改性后样品的红外光谱中末端硅羟基峰的强度明显降低,并出现CH₃基团的C_H伸缩振动吸收峰,证实部分亲水性表面硅羟基被亲油性硅烷基团取代.这类两亲性样品在不加共溶剂及静置条件下,对环己烯水合相界面催化反应的催化活性远远高于改性前的HZSM-5沸石.由于该相界面反应是以孔道内为主的反应,三甲基氯硅烷经改性制备出的亲油性HZSM-5沸石也呈现出较高的活性.     

用TG/DTG/DTA研究硅沸石与有机分子的主体/客体相互作用

用TG/DTG/DTA法研究无阳离子与Si—OH缺陷、结构完美的硅沸石上烃类、烷基醇、烷基胺的热脱附行为.有机分子从硅沸石上脱附的温度低于300℃其亲和性值A_T=T_d-T_b,式中T_d为有机分子在DTG上的失重峰温,T_b为该有机物在标准压力下的沸点.饱和烷烃的A_T值为60～90,而苯、甲苯、对二甲苯等的A_T值为6～13.电负性较强的羟基使烷基醇与硅沸石的亲和性明显下降.多羟基醇的A_T值为负值.对二甲苯、烷基醇、烷基胺在脱附时有明显吸热效应.A_T值及脱附热效应的不同是硅沸石骨架0~(2-)微孔表面与有机分子C—H基因,其它极性基因之间相互作用不同,以及受到硅沸石骨架空间限制的被吸附分子间缔合情况不同所致,反应了不同类型的主体/客体超分子相互作用.     

硅烷对HZSM—5沸石分子筛的改性研究：Ⅱ.硅烷化改性对HZSM—5表面酸…

以硅烷气体作为改性剂，对ＨＺＳＭ－５沸石进行了改性研究，并用ＮＨ３－ＴＰＤ，表面羟基和吡啶吸附态红外光谱的手段表征了改性样品。发现随着硅烷化程度的加深化，强酸和弱酸开始降低，硅烷化程度Ｗ％＞１．８３％后，酸性基本保持不变，这时改只起到明显的缩孔作用。通过对改性沸石探针分子吸附行为的研究分析得知，硅烷化开始时，硅烷分子进行了孔道内，与内表面羟基反应，致使部分孔道堵塞，孔道变窄。硅烷化程度Ｗ％＞１．８     

PHBV/Sol-gel Bioglass多孔材料在模拟生理溶液中的化学反应研究

3-羟基丁酸-co-3-羟基戊酸共聚物(PHBV)/生物活性玻璃(SGBG)是一种用于骨和软骨组织工程支架的新型多孔复合材料,本文探讨了PHBV/SGBG在模拟生理溶液中的一系列化学反应,以及多孔材料在模拟生理溶液中浸泡后的成分和结构变化.研究结果表明,在SBF溶液中浸泡后,SGBG与SBF溶液的离子交换反应和PHBV的降解反应使SBF溶液的离子浓度发生变化,并在PHBV/SGBG表面形成了结晶态类骨碳酸羟基磷灰石.     

蒸汽相中含硼多孔玻璃自转变合成沸石——Ⅱ．自转变动力学

以XRD为表征手段详细研究了408—453K温度范围、多孔玻璃粉在乙胺和水的蒸 汽相中自转变为B-Al-MFI型沸石的自转变动力学。由动力学曲线计算得到的成核活 化能和晶体生长活化能分别是102．0kJ／mol和34．7kJ／mol。沸石的结晶速率显 著受温度影响，低温有利于晶体成核和形成小晶体，高温有利于晶体生长和形成大 晶体。不同反应温度下的结晶速率几乎在相同时间内(cα．132h)达到最大值(νm) 。     

Transport properties of alkanes through ceramic thin zeolite MFI membranes

Polycrystalline randomly oriented defect free zeolite layers on porous α-Al₂O₃ supports are prepared with a thickness of less than 5 μm by in situ crystallisation of silicalite-1. The flux of alkanes is a function of the sorption and intracrystalline diffusion. In mixtures of strongly and weakly adsorbing gases and a high loadings of the strongly adsorbing molecule in the zeolite poze, the flux of the weakly adsorbing molecule is suppressed by the sorption and the mobility of the strongly adsorbing molecule resulting in pore-blocking effects. The separation of these mixtures is mainly based on the sorption and completely different from the permselectivity. At low loadings of the strongly adsorbing molecules the separation is based on the sorption and the diffusion and is the same as the permselectivity. Separation factors for the isomers of butane (n-butane/isobutane) and hexane (hexane/2,2-dimethylbutane) are respectively high (10) and very high (> 2000) at 200°C. These high separation factors are a strong evidence that the membrane shows selectivity by size-exclusion and that transport in pores larger than the zeolite MFI pores (possible defects, etc) can be neglected.     

Dye-modified nanochannel materials for photoelectronic and optical devices

Artificial photonic antenna systems have been realised by incorporating organic dyes into zeolite L. The size and aspect ratio of the cylindrically shaped zeolite crystals can be tuned over a wide range, adding to the versatility of this host material. A 600 nm sized crystal, for example, consists of about 96 000 one-dimensional channels oriented parallel to the cylinder axis. Geometrical constraints imposed by the host structure lead to supramolecular organisation of the guests, allowing high concentrations of non- or only very weakly interacting dye molecules. A special twist is added to these systems by plugging the channel openings with a second type of fluorescent dye, a so-called stopcock molecule. The two types of molecules are precisely tuned to each other; the stopcocks are able to accept excitation energy from the dyes in the channels, but cannot pass it back. The supramolecular organisation of dyes in the zeolite channels corresponds to a first stage of organisation, allowing light-harvesting within the volume of a cylindrical crystal and radiationless energy transport to either the cylinder ends or centre. The second stage of organisation represents the coupling to an external acceptor or donor stopcock fluorophore at the channel entrances, which can then trap or inject electronic excitation energy. The third stage of organisation is realised by interfacing the material to an external device through a stopcock intermediate. We observed that electronic-excitation-energy transfer in dye-zeolite L materials occurs mainly along the channel axis and we have shown that macroscopically organised materials can be prepared. The new materials offer unique possibilities as building blocks for optical, electro-optical and sensing devices.     

Simple evaluation of the adsorption states of benzene molecule on the hydroxyl,H+ and Na+ sites of Y-zeolite surfaces by using UV absorption spectroscopy

Chemical properties of benzene molecules adsorbed on the hydroxyl, H⁺ and Na⁺ sites of Y-zeolite surfaces were investigated by using UV absorption and FT-IR spectroscopies. The analyses on the IR peaks assigned to a C–H out-of-plane vibration mode revealed two different adsorption states of benzene: (1) a benzene molecule located a little distance from the hydroxyl groups of zeolite inner walls, and (2) a benzene molecule positioned a short distance from the H⁺ or Na⁺ sites of zeolite walls. Furthermore, the electronic properties of benzene molecules adsorbed on these Y-zeolites were investigated by UV absorption measurements. The vibrational splitting in UV absorption spectra of benzene provided the information about IR-inactive skeletal vibrations of the benzene ring, such as C–C–C in-plane bending and breathing modes. The benzene molecules strongly interacting with H⁺ or Na⁺ sites of Y-zeolites showed smaller breathing vibration energy as compared to benzene in gas or liquid phases, clearly indicating the stabilization of the benzene ring. In contrast, the benzene molecules weakly interacting with hydroxyl groups of siliceous USY zeolite were barely stabilized.     

CF-2沸石的表面酸性及催化性能

CF-2是一种新型的高硅沸石。1981年我们实验室首先在二乙醇胺-甘油-Na₂O-SiO₂-Al₂O₃-H₂O体系中制备成功^[1],以后才见到关于Theta-1^[2],ISI-1^[3],KZ-2^[4],NO-10^[5]和ZSM-22^[6]沸石的报道。     

HZSM-5分子筛上甲醇制烯烃典型产物的传质行为研究

分子筛催化甲醇制烯烃反应(MTO)是典型的扩散主导反应过程,运用频率响应技术系统研究了几种典型产物分子(乙烯/乙烷、丙烯/丙烷、苯)在HZSM-5分子筛上的扩散行为。结果表明,频率响应法成功辨析了不同产物分子的传质规律,证实C2和C3烃分子在HZSM-5微孔孔道内具有相近的扩散速率,但由于受晶体表面阻碍效应影响不同,乙烷分子可自由进出HZSM-5分子筛孔道,而丙烷分子则受到较显著的微孔孔道扩散限制。另外,苯分子的扩散速率显著小于C2和C3分子,且苯分子受晶体表面阻抗效应的影响较小。本研究结果可用于解释HZSM-5分子筛在MTO反应中产物选择性的特点及表面结焦原因,进而从传质角度为高活性、选择性以及稳定性的高效甲醇转化制烃催化剂的定向开发提供理论指导。     

Na2O-SiO2-Al2O3-NaCl-H2O体系中ANA和SOD沸石膜的水热合成

Na2O-SiO2-Al2O3-NaCl-H2O体系中，以水玻璃和准一水软铝石为原料，分别在 堇青石和玻璃载体上水热合成方沸石（ANA）和方钠石（SOD）沸石膜。研究水含量 、反应温度、反应时间与多次合成对膜结晶的影响。用XRD，SEM，EDX表征膜的晶 相、形貌和化学组成。堇青石负载方沸石膜在对95％（wt.)乙醇水溶液的渗透蒸发 实验中，水优先透过沸石膜的选择性显示了晶间孔的醇／水分离作用。非计量的 NaCl进入到在玻璃载体上成膜的方钠石笼中，致使该膜显示光致变色效应。     

Na_2O-SiO_2-Al_2O_3-NaCl-H_2O体系中ANA和SOD沸石膜的水热合成

Na2 O SiO2 Al2 O3 NaCl H2 O体系中,以水玻璃和准一水软铝石为原料,分别在堇青石和玻璃载体上水热合成方沸石(ANA)与方钠石(SOD)沸石膜.研究水含量、反应温度、反应时间与多次合成对膜结晶的影响.用XRD,SEM,EDX表征膜的晶相、形貌和化学组成.堇青石负载方沸石膜在对 95 %(wt.)乙醇水溶液的渗透蒸发实验中,水优先透过沸石膜的选择性显示了晶间孔的醇/水分离作用.非计量的NaCl进入到在玻璃载体上成膜的方钠石笼中,致使该膜显示光致变色效应