共查询到19条相似文献,搜索用时 109 毫秒
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以高岭土为原料合成沸石分子筛的相变规律 总被引:5,自引:0,他引:5
以天然粘土矿物高岭土为原料, 采用水热晶化法合成了NaX, NaP和SOD三类沸石. 利用XRD、 静态饱和水吸附等测试手段详细考察了晶化温度、 初始反应混合物的碱浓度对沸石结晶的影响. 通过实验研究得到了三类沸石的结晶相区和结晶变化规律, 并优化出最佳合成工艺条件和相转变规律. 相似文献
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阐述了沸石作为选择性吸附剂和催化剂在有机合成中的应用,包括杂环化合物的合成、氧化还原反应、傅一克反应、不对称合成、制备高聚物及在萜类化学中的应用进展情况。 相似文献
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ZnO微纳米球的生长机制 总被引:5,自引:0,他引:5
ZnO micro-nano spheres covered with ZnO nanowires were synthesized at 650 ℃ without using cataly-sts. Characterizations of the products by TEM, SEM, XRD, SAED and EDS showed that the ZnO nanowires were of high purity and single-crystalline with hexagonal wurtzite structure. The diameter of ZnO nanowires ranges from 60 to 200 nm and the length is longer than 10 μm. The size of the ZnO micro-nano spheres ranges from hundreds of nanometers to tens of microns. At the same time, the growth mechanism of ZnO micro-nano spheres is discussed. 相似文献
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本文以程序升温脱附(TPD)为主要实验手段,对环己胺在5种不同沸石分子筛上的吸脱附行为进行了研究。结果表明,沸石分子筛对环己胺有着较强的吸附作用,不同的沸石分子筛对环己胺的吸附能力受其结构和表面酸性特征的影响而异。有效吸附部位为与沸石分子筛表面酸性有关的弱化学吸附位;环己胺从不同沸石分子筛表面脱附的动力学与晶内扩散有关,其表观脱附活化能分别为:63.6kJ/mol(5A),68.6kJ/mol(13X),20.1kJ/mol(菱沸石),46.9kJ/mol(NaY)和47.3KJ/mol(ZSM-5)。 相似文献
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在水蒸气气氛中合成沸石分子筛及其特性 总被引:5,自引:0,他引:5
无定型硅铝凝胶-Na2O-Al2O3-SiO2-H2O在水蒸气相中可以晶化合成出LTA,FAU和MOR沸石晶体。本文重点研究了MOR沸石的晶化条件和物理化学特性。 相似文献
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In Situ Synthesis of NaY Zeolite with Coal—Based Kaolin 总被引:3,自引:0,他引:3
XinmeiLiu ZifengYan HuaipingWang YantuoLuo 《天然气化学杂志》2003,12(1):63-73
NaY zeolites were in-situ synthesized form coal-based kaolin via the hydrothermal method. The effects of various factors on the structure of the samples were extensively investigated.The samples were characterized by N2 adsorption,XRD,IR and DTG-DTA methods,and the results show that the crystallization temperature and amount of added water play an important role in the formation of the zeolite structure.The 4A and P zeolites are the competitive Phaes present in the resulting product.However,NaY zeolites wiht a higher relative crystallinity,excluding impure crystals and the well hydrothermal stapore size distribution,and this means that optimization of this process might result in a commercial route to synthesize NaY zeolites form coal-based kaolin. 相似文献
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利用简单微乳液自组装体系, 制备了介孔二氧化硅与Y型或Ti-MWW沸石晶体复合形成的沸石/介孔二氧化硅微球(ZMMS). 硅源正硅酸四丁酯与阳离子型季铵盐表面活性剂形成稳定的O/W微乳液形成大颗粒, 沸石颗粒由于疏水作用而进入油相, 同时, 季铵盐表面活性剂和正硅酸四丁酯组装形成介孔材料. 优化合成条件可以有效控制复合微球的沸石/介孔二氧化硅质量比(0~2.3)和直径(186~965 μm). 两种沸石/介孔二氧化硅复合微球材料的介孔孔径分别为3.98 nm(Y型沸石)和3.75 nm (Ti-MWW型沸石). Ti-MWW沸石/介孔二氧化硅复合微球在液相催化环氧化反应中表现出良好的机械强度, 并且能够达到与Ti-MWW沸石原粉相当的催化活性. 相似文献
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二氧化钛纳米棒在空心微球表面的定向生长 总被引:2,自引:0,他引:2
通过表面预处理和水热法开展了用二氧化钛包覆空心微球的研究, 用扫描电子显微镜(SEM)和X射线衍射仪(XRD)等表征了所得产品, 并探索了各种反应参数对产物形貌和结构的调控作用. 实验结果表明, 空心微球的表面溶胶-凝胶预处理至关重要. 采用表面溶胶-凝胶技术预处理空心微球表面, 然后在一定条件下进行水热反应, 我们在空心微球表面上成功地包覆了垂直于微球表面并紧密排列的锐钛矿型二氧化钛纳米棒. 该材料质轻、耐腐蚀, 有望成为一种新型光催化剂, 应用于治理水体表面的大面积污染. 相似文献
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微孔-微孔复合分子筛是指两种(或多种)微孔分子筛的复合晶体,不仅具备单一分子筛的特性,而且由于复合过程中产生的结构畸变使其具有独特的孔道结构和酸性质,进而体现出优异的催化反应特性,成为当今分子筛领域的研究热点。微孔-微孔复合分子筛可分为共晶分子筛和共生分子筛两种,前者通过两种分子筛晶体的无限成分单元重排,有利于构成新的完整的晶体结构,后者则是两种分子筛共生长过程中得到的两相交错生长的复合体,产生微结构畸变和界面效应。本文对微孔-微孔复合分子筛进行归纳和分类,并系统介绍了微孔-微孔复合分子筛的研究进展,着重阐述了共晶分子筛和共生分子筛的合成与微结构特点以及在催化反应领域中的应用。 相似文献
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在改性高岭土催化剂上甲醇脱水生成二甲醚的动力学考察 总被引:4,自引:0,他引:4
采用积分反应器,考察了常压下在改性高岭土(MK)催化剂上甲醇脱水生成二甲醚的反应动力学,根据Langmuir均匀吸附理论,采用R-E机理,推断吸附的甲醇分子与气相主体中的甲醇分子发生的表面反应为速率控制步骤(RDS),得到双曲线型动力学方程为:r=ksbMpM^2/(1+bMpM+bpE)r为反应速率,ks为反应速率常数,bM为甲醇的吸附平衡常数,b为二甲醚和水的吸附平衡常数之和,pM、pE分别为 相似文献
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Long Chen Zuben Bao Jian Pan Weibing Xu Heping Zhang Hongbo Hu Jichao Hu Lili Zhou 《中国化学》2012,30(2):445-448
We report a novel strategy for the green synthesis of calcium carbonate (CaCO3) microspheres by using four vegetables: potato, cucumber, aubergine, and carrot. The products were characterized by scanning electron microscopy, X‐ray powder diffractometry and/or Fourier transform infrared spectroscopy. The results show that the spherical calcite crystals are obtained in the presence of potato, cucumber and aubergine extracts, while uniform vaterite and calcite mixed microspheres are produced with the extracts of carrot. The possible formation mechanism of the CaCO3 microspheres by using vegetables is also discussed, suggesting that the biomolecules especially proteins may induce and control the nucleation and growth of CaCO3 crystals. CaCO3 is an important biomineral and inorganic material. Uniform particles have numerous important applications in many areas. Therefore, this study is very significant not only for expanding the scope of crystal engineering, but also for biomineralization research and green synthesis of functional inorganic materials. 相似文献