部份层无序铝交联蒙脱土结构的研究

应用非完整晶体的XRD衍射及阳离子交换量的测定等实验数据, 得出了铝交联蒙脱土的三维结构模型. 结构中Al(III)多数以十三聚体形式进入层间, 层间距为1.97 nm, 几率为0.65, 少数以六聚体形式进入层间, 层间距为1.5 nm, 几率为0.25, 其余10%的层间仅为水分子. 并给出了交联柱子在层间的分布与层单元之间的连接方式. 目前通用的以Bragg公式计算所得的d_(001)值来表征交联浆脱土的层间距是不确切的.     

聚萘并噁嗪/蒙脱土纳米复合材料的制备与表征

用原位插层反应法地制备了聚萘并嗪 蒙脱土纳米复合材料 .采用X ray衍射 (XRD)及透射电镜(TEM)研究复合材料中蒙脱土硅酸盐片层间距 ,发现硅酸盐片层间距由 1 2 6nm扩增至 5 88nm以上 .同时研究了该复合材料的耐热性 ,并探讨了复合材料的结晶行为     

Al_2O_3-交联蒙脱土的合成及其对甲苯丙烯烷基化的催化性能

本文研究了蒙脱土在交联前后的面间距、比表面及酸性的变化,并与甲苯丙烯烷基化制伞花烃(Cymene,IPT)的催化活性和关联。当原土经Al_2O_3处理成Al_2O_3交联蒙脱土后,其层间距扩大到0.89nm,比表面增加七倍,酸量增加四倍,成为甲苯丙烯烷基化反应较好的催化剂。在连续进料及常压、低温(50～70℃)的温和条件下,甲苯转化率为～46％,IPT选择率为～68％。     

三聚苯撑乙烯/蒙脱土发光光谱的时间依赖性

用原位插层法制备了插层型的三聚苯撑乙烯/蒙脱土(TPV/MMT)纳米复合材料. 研究了新制备及在室温储存180天后的TPV/MMT纳米复合材料的荧光光谱及蒙脱土层间距的变化情况. 荧光光谱分析表明, 储存180天后, TPV/MMT纳米复合材料的最大发射峰由494 nm蓝移到438 nm, 半峰宽由77 nm增加到104 nm. X射线衍射结果表明, 与新制备的复合材料相比, 蒙脱土的层间距由1.52 nm减小到1.22 nm. 红外光谱分析表明, 室温储存180天后的三聚苯撑乙烯苯环的某些特征峰由1598 和1554 cm-1分别红移到1506和1462 cm-1. 依据相关实验和理论数据探讨了储存180 天前后TPV在蒙脱土中聚集态结构的变化方式.     

不同有机离子表面活性剂改性蒙脱土结构与性能比较

分别用阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）、阴离子表面活性剂十二烷基磺酸钠(SDS)以及二者混合物(CTAB-SDS)的水溶液处理天然蒙脱土。 用红外光谱和X射线衍射比较了它们对蒙脱土结构的影响。 证明CTAB及CTAB-SDS处理蒙脱土的层间距分别由1.5420 nm增大至2.1946和1.8935 nm。 表明CTAB插入蒙脱土层间,且CTAB及CTAB-SDS处理蒙脱土在苯乙烯中分散性能明显提高,对有机物表现出良好的吸附性;而阴离子表面活性剂未进入蒙脱土层间,蒙脱土的结构和性能几乎未变。     

高抗冲聚苯乙烯/蒙脱土复合材料的阻燃性研究

用经十六烷基三甲基溴化铵有机化改性的蒙脱土 (OMMT)与高抗冲聚苯乙烯 (HIPS)通过熔融插层法制备了HIPS OMMT复合材料 ,用X ray衍射技术对材料结构进行了表征 ,发现钠基蒙脱土 (Na+ MMT)和有机蒙脱土的层间距分别为 1 5 1nm和 2 18nm ,HIPS OMMT(5phr)复合材料中蒙脱土的层间距因聚合物大分子的插入扩大为 3 4 4nm ;而HIPS与Na+ MMT形成的复合材料的层间距与Na+ MMT的层间距相比却没有变化 ,表明未有机化处理土没有形成插层结构 .锥形量热仪的研究结果表明HIPS OMMT复合材料的热释放速率、质量损失速率以及生烟速率等燃烧特性参数均显著降低 ,具有较明显的阻燃性和抑烟性 ,而HIPS Na+ MMT非插层型复合材料只有在Na+ MMT很高填充量下 (>2 0phr)才有一定阻燃效果 .比较了铵盐对HIPS阻燃性的影响 ,结果表明铵盐自身的阻燃作用很小 ,主要是插层复合结构起阻燃作用 .     

聚丙烯/蒙脱土纳米复合材料Ⅰ.制备、表征及动态力学性能

用原位接枝插层法成功地制备了聚丙烯 /蒙脱土纳米复合材料 (PPMNC) .采用X射线衍射研究复合材料中蒙脱土硅酸盐片层间距 ,发现硅酸盐片层间距从 1 94nm升至 4nm左右 .同时研究了PPMNC的动态力学性能 ,结果表明 :PPMNC的动态储能模量明显高于聚丙烯 (PP) ,尤其在T >Tg 高温段 ,甚至可以达到PP基体的 2倍     

铁-锆交联蒙脱土的制备和结构表征

我们首次合成了铁锆复合柱交联蒙脱土, 并用XRD, 比表面及孔径测定和Mossbauer谱学等方法进行了表征。结果表明, 铁锆交联蒙脱土比表面增大为原土的三倍以上, 其层间距可达0.88nm(d001=1.84nm)。热稳定性明显高于单一Fe柱交联蒙脱土。在500℃加热后层间距保持0.63nm~0.71nm。但由于铁柱的坍塌造成微孔减少, 比表面明显下降。Mossbauer谱研究表明, 500℃焙烧单一铁柱转变为α-Fe~2O~3, 而Fe-Zr-PILC中铁仍以超顺磁Fe^3^+存在, 单一铁柱的铁组分在400℃可还原为金属铁, 而铁锆混合柱交联蒙脱土中由于铁与锆之间存在较强的相互作用, 450℃氢气气氛中铁组分仍不能还原为金属铁。     

双单体原位接枝插层法制备聚丙烯纳米复合材料的研究Ⅰ.制备、表征及力学性能的研究

用有机插层剂处理蒙脱土原土 ,制得有机蒙脱土 (O MMT) .采用双单体 (马来酸酐和苯乙烯 )原位接枝插层法 ,制备了聚丙烯 蒙脱土纳米复合材料母料 .将母料与聚丙烯基体在双螺杆上共混挤出 ,制得聚丙烯 蒙脱土纳米复合材料 (PP Montmorillonetenanocomposites,PMNC) .这是制备聚合物纳米复合材料的一种新方法 .通过X 射线衍射测试 (XRD)表明 ,有机蒙脱土片层 0 0 1面间距从原土的 1 4 9nm扩大到 2 96nm ,复合材料中蒙脱土片层 0 0 1面间距由有机蒙脱土的 2 96nm扩大到 4 0nm .力学性能测试表明 ,复合材料的力学性能明显优于PP基体 ,在提高材料拉伸强度的同时 ,缺口冲击强度也得到很大的提高 .用扫描电镜 (SEM)对材料的冲击断面形貌进行了研究 ,并从理论上分析了断裂机理 .随着蒙脱土含量的增加 ,冲击断裂形式逐渐从脆性断裂变成韧性断裂     

聚N-甲基苯胺/蒙脱土纳米复合材料的合成及其协同电流变效应

用插层聚合法制备了聚N 甲基苯胺 蒙脱土纳米复合材料微粒 ,通过IR、XRD及TEM对其结构进行了表征 .观察发现聚N 甲基苯胺插入蒙脱土层间后 ,蒙脱土片层间距由 0 96nm扩大至 1 34nm .将其分散在甲基硅油中 (2 0wt% )配制成无水电流变液 ,该复合材料表现出显著的协同效应 ,具有较好的电流变行为 .实验表明在电场作用下聚N 甲基苯胺 蒙脱土纳米复合材料的电流变效应比聚苯胺、蒙脱土都有显著提高 ,在 3kV mm(DC ,74 5s- 1 )时 ,剪切强度达 6 0kPa ;同时抗沉降性极好 ,静置 6 0天沉淀率小于 3% .介电性能测试表明聚N 甲基苯胺 蒙脱土纳米颗粒的介电常数和介电损耗较蒙脱土和聚N 甲基苯胺明显提高 ,电导率也达到了最佳范围 .     

交联蒙脱土负载型Cu催化剂用于CH4燃烧反应的研究

在蒙脱土原粉中引入Al-、AlZr-、AlCe-交联剂，分别制备交联蒙脱土。测试表明：与蒙脱土原粉相比，Al-、AlZr-、AlCe-交联蒙脱土的底面间距明显增大，热稳定性显著提高；AlZr-、AlCe-交联蒙脱土的底面间距比Al-交联蒙脱土更大，热稳定性更高。以交联蒙脱土为载体，制得负载型Cu催化剂，考察了它们对甲烷燃烧反应的催化活性。结果表明：AlZr-、AlCe-交联蒙脱土催化剂活性明显高于Al-交联蒙脱土催化剂，反应温度为550 ℃时，甲烷在AlZr-、AlCe-交联蒙脱土催化剂上的转化率约90%。     

层柱人工水热合成皂石的制备与表征(英)

利用具有理想皂石结构的人工水热合成蒙皂石为层原料，通过与羟基聚合铝离子（[Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺）交换反应合成得到了一种层柱粘土。实验对于该铝柱皂石进行了粉末XRD，FT-IR和TG-DTA表征。氮气吸附实验说明其高温活化（773K，2 h）产物具有很高的BET比表面（360 m²·g^-1）。相对于层柱蒙脱土，层柱皂石显示了更高的催化裂解性能和热稳定性。层柱皂石的异丙苯裂解转化率达到了65%；而层柱蒙脱土的转化率只有4%。这说明层材料的四面体取代对于层柱粘土Br?nsted酸位的形成具有重要的决定作用。氨程序升温脱附实验发现铝柱皂石在350～650 ℃区间具有较强的氨脱附量，表明层柱皂石具有层柱蒙脱土所没有的强酸中心。     

Layered cobalt hydroxysulfates with both rigid and flexible organic pillars: synthesis, structure, porosity, and cooperative magnetism.

The synthesis and characterization of two members of a family of porous magnetic materials is described. The structures of Co4(SO4)(OH)6(C2N2H8)0.5*3H2O and Co4(SO4)(OH)6(C6N2H12)0.5*H2O and their thermal stability can be tailored via the choice of organic pillar. The interactions between the pillaring agent and the compositionally complex inorganic layer are discussed. The influences of two pillaring agents i.e., the flexible ethylenediamine and the relatively rigid 1,4-diazabicyclo[2,2,2]octane, on thermal stability, rigidity upon guest loss, and magnetic behavior of the pillared solids are compared. The magnetism of the pillared layered cobalt hydroxides is complex due to the influences of multiple metal sites, inter- and intralayer exchange, spin-orbit coupling, and geometrical frustration. The wide variety of potential pillars, oxyanions, and possible metal substitutions at the octahedral and tetrahedral sites offers the possibility of tailoring the magnetic and porous properties of these materials.     

Tailoring micropore dimensions in pillared clays for enhanced gas adsorption

A systematic investigation has been undertaken for tailoring the micropore structure of the pillared clay. Besides the type of metal oxide (e.g. Al₂O₃ vs. ZrO₂) being used as the pillars, the important factors for determining the micropore structure are OH/Al ratio (for Al₂O₃-pillared clay), calcination temperature and the starting clay. The effect of the cation exchange capacity (CEC) of the clay on the microporous structure (and consequently the adsorption properties) is reported for the first time. Two clays with widely different CECs are used: Arizona montmorillonite (CEC = 1.40 mequiv./g) and Wyoming montmorillonite (CEC = 0.76 mequiv./g). The interlayer spacings of the pillared clays from these different clays are essentially the same, since the interlayer spacing is controlled by the sizes of the oligomers that intercalate between the clay layers. However, the pillar density in the pillared clay is substantially higher with a high CEC in the starting clay, and is shown to be approximately proportional to the CEC. Consequently, the interpillar spacing is substantially lower resulting from the higher CEC. The CH₄ adsorption on the pillared clay is nearly doubled by the smaller interpillar spacing, due to the back-to-back overlapping potential in the micropores. The N₂ adsorption was not significantly influenced because of its low polarizability (hence low inductive potential). Increasing the calcination temperature of the Al₂O₃-pillared clay from 400°C to 600°C can decrease the interlayer spacing, but only by 1 (from 8.7 to 7.7 ). The CH₄/N₂ adsorption ratio of 2.35 is reached on the Al₂O₃-pillared Arizona clay that is calcined at 600°C. Finally, the surface and pore volume are influenced by the OH/Al ratio (or pH) during pillaring, since this ratio determines the size and charge of the oligomers. A peak surface area is reached at OH/Al = 2.2.     

PLS vs zeolites as sorbents and catalysts. Part 7. The role of oxide pillars and aluminosilicate sheets in alcohol dehydration on PILCs

Reactions of primary aliphatic C2-C8 alcohols on alumina and iron-aluminium-oxides pillared montmorillonite and beidellite indicate that dehydration reaction occurs on Lewis sites of pillars, while clays are responsible of cracking. This revised version was published online in June 2006 with corrections to the Cover Date.     

FTIR investigation of CTAB-Al-montmorillonite complexes

In this study, CTAB-Al-montmorillonite complexes were synthesized by pre-modifying montmorillonite using different concentrations of surfactant (resulting in different surfactant loadings and basal spacings), then pillaring the organoclays with hydroxy-Al cations. The resultant inorganic-organic montmorillonite complexes were characterized using FTIR, with a combination of XRD, TG and chemical analysis. This study indicates that the basal spacings of the CTAB-Al-montmorillonite complexes and the amounts of Al-contained pillars strongly depend on the surfactant loadings in the clay interlayer space, resulted from the mobility variation of the intercalated surfactants. During pillaring hydroxy-Al cations into clay interlayer space, part of the intercalated surfactants were removed, resulting in a decrease of the ordering of alkyl chains and the frequency shifts of Si(Al)-O, Si-O-Al and (M-O)(Td) stretching vibrations. The hydrophobicity of the CTAB-Al-montmorillonite complex also strongly depends on the surfactant loading whereas that of the CTAB-Al-montmorillonite complex is relative lower than that of the corresponding organoclay, indicated by the frequency shift of the vibrations corresponding to the sorbed water and their contents estimated by TG curves. With the decrease of the sorbed water content, the frequency of the band of H-O-H bending (nu(2)) shifts to higher frequency while the O-H stretching vibration (nu(1) and nu(3)) shifts to lower frequency, indicating that H(2)O is less hydrogen bonded. Meanwhile, the ordered conformations of the alkyl chains in CTAB-Al-montmorillonite complex decrease when compared with that of the corresponding organoclay.     

氧化铝柱层状铌酸盐的制备

本文以HNb~3O~8为例, 进一步探讨了用分步交换法来制备氧化铝柱层状金属氧化物的可行性。首次成功地将[Al~13O~4(OH)~24(H~2O)~12]^7+Keggin离子交换进入到层状金属铌酸(HNb~3O~8)的层间。通过焙烧, 制备了首例以氧化铝为柱的层状金属铌酸盐。该化合物具有很高的热稳定性(>700℃)和比较大的层间距(d=1.18nm,700℃), 讨论了不同层板性质对产物结构和性能的影响。     

Al柱层状钛铌酸盐的制备

本文采用分步交换法,首次将[Al~1~3O~4(OH)~2~4(H~2O)~1~2]^7^+Keggin离子交换进入到层状金属钛铌酸盐(KTiNbO~5)的层间.通过焙烧,制备了以Al~2O~3 为柱的层状金属化合物.该化合物具有较高的热稳定性(>500℃)和比较大的层间距(d=1.34nm,500℃)