基于遗传编程方法的微孔磷酸铝的定向合成研究

根据微孔磷酸铝合成数据的特点,针对合成数据库中合成参数过多和交叉描述等问题,利用改进的遗传编程算法对具有(6,8)元环的微孔磷酸铝合成参数进行特征提取,优化出新的复合特征来更好地描述磷酸铝合成中溶剂和模板剂的特征,并通过参数进化过程的研究,考察了模板剂和溶剂对产物生成的具体影响,从而指导具有特定结构磷酸铝的定向合成.     

spin-lattice relaxation in cobalt-containing aluminophosphate molecular sieves

Phosphorus spin-lattice relaxation was studied in aluminophosphate molecular sieves containing various concentrations of either framework or non-framework cobalt. The behaviour of nuclear magnetisation in the presence of these paramagnetic centres was described successfully in the limit of no spin-diffusion. The diffusionless regime was strongly indicated with non-exponential magnetisation recovery and was therefore easy to recognise. According to the model, spin-lattice relaxation rates depend on the square of cobalt concentration. Measured relaxation rates agreed well with calculations if effective cobalt concentration was considered rather than the average one. The latter was obtained by bulk elemental analysis, while the former was extracted from cobalt concentration depth-profiles measured with Auger electron spectroscopy. These measurements indicated that in impregnated samples containing non-framework cobalt there could be much more cobalt near the crystal surface than within the crystal. Because high cobalt concentration can lead to an invisible phosphorus, only nuclei deep within the crystal contribute to the NMR signal. In such a case, the effective concentration is simply the concentration of cobalt far from the crystal surface. In our case, two impregnated samples with different bulk cobalt concentrations exhibited equal relaxation rates. Previously, such a case was misinterpreted as a case, in which nuclear spin-lattice relaxation was independent of cobalt concentration. AES measurements, however, revealed, that although average concentrations of the two samples were different by a factor of two, their effective concentrations were equal and thus in complete agreement with observed relaxation rates.     

Synthesis, characterization and structure determination of two isotypes of a layered aluminophosphate with a new 2D network topology

Two isotypes of a new layered aluminophosphate, further denoted MDAP-3 and MDAE-1, have been synthesized under hydrothermal conditions using N-methyl-1,3-propanediamine and N-methyl-ethylenediamine, respectively. MDAP-3, with the empirical formula [Al₂(HPO₄)(PO₄)₂](C₄N₂H₁₄)(H₂O), crystallizes in the orthorhombic space group Pna2(1) (No. 33) with , , , Z=4, R₁=0.0498 and wR₂=0.1217. The second solid, MDAE-1, with the empirical formula [Al₂(HPO₄)(PO₄)₂](C₃N₂H₁₂)(H₂O), crystallizes in the same space group with , , , Z=4, R₁=0.0407 and wR₂=0.0954. The two compounds possess the same layer topology. Inorganic layers contain PO₃=O, PO₃OH, AlO₄ and AlO₆ polyhedra, linked together to generate a new 4×8 net. MDAP-3 and MDAE-1 represent the first examples of two-dimensional layered aluminophosphates with the Al₂P₃O₁₂ stoichiometry, and containing AlO₆ octahedra.     

新型三维开放骨架磷酸铝化合物的合成及晶化过程中的共模板效应

以1,2-丙二胺(1,2-DAP)为结构导向剂,在180℃加热摩尔组成为n(Al_2O_3)∶n(P_2O_5)∶n(1,2-DAP)∶n(H_2O)=1∶6∶5.5∶139的初始混合物,合成了具有AlPO-CJ31骨架结构的新型三维开放骨架磷酸铝化合物(1);加热摩尔组成为n(Al_2O_3)∶n(P_2O_5)∶n(1,2-DAP)∶n(H_2O)=1∶6∶7.5∶139的初始混合物,合成了二维层状磷酸铝化合物APDAP_(12)-150.利用X射线粉末衍射分析(XRD)、元素分析、热重/差热分析等表征手段确认了化合物1的分子式为[Al_4P_5O_(20)·H_3O·H_2O]·[H_3NCH_2CHNH_3CH_3],质子化的水分子与双质子化的1,2-丙二胺共同起到了导向化合物1的作用.调变初始混合物中1,2-丙二胺的比例可显著影响其模板效应.1,2-丙二胺比例较低[n(1,2-DAP)=5.5]时,产物为三维开放骨架化合物,而当其比例较高[n(1,2-DAP)=7.5]时,产物为二维层状化合物.     

Cesium Fluoride on Calcium Oxide as a Strongly Basic Catalyst. Synthesis of Flavones and Tobacco Alkaloids

Niobium containing aluminophosphate materials with AEL structure were prepared by the hydrothermal method. The chemical composition of the hydrogel was: 1 DIPA: 1 Al₂O₃: (1-x) P₂O₅: x Nb₂O₅: 80 H₂O, with x=0.025, 0.050, 0.075 and 0.100. The crystallization was carried out at temperature of 170°C for 72 h. The materials obtained were characterized by XRF, DRX, FTIR, TG and measurements of acidity. The characterization of the catalytic active sites were carried out in the isopropanol dehydration at temperature of 400°C, and WHSV of 1.6, 3.2, 4.8, 6.4 and 8.0 h^-1 . The samples showed good catalytic activity with selectivity to propene. This revised version was published online in June 2006 with corrections to the Cover Date.     

磷酸铝分子筛AlPO4-12的合成与性能研究

用乙二胺作模报剂,在水热体系中合成了磷酸铝分子筛ＡＩＰＯ４－１２,考察了反应混合物的初始ＰＨ值和乙二胺用量对产物结晶相的影响,产品的化学组成与文献值吻合。用ＸＲＤ、ＳＥＭ、ＩＲ、ＤＴＡ、化学分析和吸附等方法,对样品进行了表征及物化性能的研究,用丙酸与正丁醇的酯化为典型反应,考究了ＡＩＰＯ４－１２分子筛的催化性能,实验结果表明,ＡＩＰＯ４－１２具有良好的吸附性能、很高的热稳定性（骨架倒塌温度为９９７     

高性能AlPO4-14分子筛膜的制备及气体分离性能

制备了高性能的AlPO₄-14分子筛膜. 首先通过控制反应溶胶中水和模板剂的含量制备了形貌均一的AlPO₄-14分子筛, 分子筛的尺寸为15~18 mm; 然后采用晶种法即在反应凝胶中加入分子筛作为晶种进一步调控分子筛的大小, 使得AlPO₄-14分子筛的尺寸从15~18 mm减小到2~3 mm, 得到形貌均一的纯相片状晶体, 同时有效缩短了制备时间; 最后以多孔管状莫来石为支撑体, 采用二次生长法制备AlPO₄-14分子筛膜. 考察了2种不同大小的晶种对膜形貌和性能的影响, 发现以大尺寸的分子筛(15~18 mm)作为晶种制备的分子筛膜的分离层存在较多缺陷, 而采用小尺寸的晶种(2~3 mm)制备的膜层较均一致密. AlPO₄-14分子筛膜经高温脱除模板剂后仍然保持着纯相的AlPO₄-14晶型, 表明二次生长法促进了AlPO₄-14晶体在膜层中的生长且使其具有更高的结晶度和热稳定性. 在25 ℃, 100 kPa下, AlPO₄-14分子筛膜对H₂/CH₄, CO₂/CH₄和H₂/CF₄的理想分离因子分别为28, 40和1047, 且H₂和CO₂的渗透速率分别为6.3×10 ^-7和9×10 ^-7 mol·(m ²·s·Pa) ^-1; 对等摩尔CO₂/CH₄混合气体的分离因子为81.5, 且CO₂的渗透速率为8.8×10 ^-7 mol·(m ²·s·Pa) ^-1.     

Synthesis and characterization of a novel crystalline AlPO4 molecular sieve,CFAP-7

The novel crystalline aluminophosphate CFAP-7, having a characteristic X-ray powder diffraction pattern, has been synthesized hydrothermally in a system consisting of di-n-butylamine-(NH₄)₂O–P₂O₅–Al₂O₃–H₂O at 120 to 140°C, the P₂O₅ and Al₂O₃ sources of which were provided by (NH₄)₃PO₄·3H₂O and Al₂(SO₄)₃ in aqueous solution, respectively. Investigations by DTA, TG, DTG, XRD, and IR indicate transformation of the original product (form A) into more stable crystal forms B and C on heating at about 180°C and 240°C, respectively, while liberating water and amine. Isotherms for the adsorption of water and methanol at 23°C show that both form B and form C are molecular sieves with a window dimension of 4.3–4.9 Å, and a methanol volume adsorbtion greater than that of water.     

磷酸铝分子筛骨架结构及其稳定性的模拟计算

采用晶格能极小化技术模拟计算了块磷铝矿和１２种磷酸铝分子筛的骨架晶格，包括ＡｌＰＯ４－３１，ＡｌＰＯ４－１１，ＡｌＰＯ４－８，ＡｌＰＯ４－５，ＡｌＰＯ４－２０，ＡｌＰＯ４－１６，ＡｌＰＯ４－１７，ＡｌＰＯ４－３５，ＡｌＰＯ４－５２，ＡｌＰＯ４－１８和ＶＰＩ－５，预测了它们的几何构型和晶格能，讨论了计算晶格能和骨架结构间的关系，结果表明，随着骨架密度的增大，晶格能呈降低趋势，骨架的相对稳定性增强。