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本文应用^29Si,^27AIMASNMR和XRD技术,测量了四种不同脱铝深度的稀土超稳Y沸石的骨架硅铝比,得到了一致的结果,并研究了稀土超稳Y沸石的脱铝过程和稀土离子和Y沸石骨架铝的机理.发现稀土离子存在时,Y沸石骨架中Si、Al的分布与相同硅铝比的HY不同,在浅、中度脱铝时,主要脱除的是Si(2Al)和Si(3Al)中的铝,深度脱铝时,主要是Si(1Al)和少量Si(2Al)中的铝,而Si(3Al)几乎不变,提出稀土离子最可能是位于方钠的Si(3Al)附近,平衡三个AlO 四面体上的负电荷,起到稳定Si(3Al)结构单元的作用.其次,稀土超稳Y沸石中总的非骨架铝(N~Al)~EF,随脱铝深度的增加而增加,仅只在REUSY-38的^27AIMAS NMR谱中观察到Al^3+非骨架铝的存在.^29Si,^27AIMASNMR 相似文献
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《Composite Interfaces》2013,20(7-9):825-836
The versatility of a process designed to fabricate bicontinuous cellulose–polymer composite has been explored. Bulk samples of bamboo, aspen, black cherry and pine were impregnated with a silicone mixture which was then crosslinked in situ. Incorporation of silicone was confirmed by mass uptake, optical microscopy, infrared spectroscopy, elemental analysis, and thermogravimetric analysis (TGA). Mechanical properties of each material were measured before and after silicone incorporation. In most cases, the density of the composites increases significantly, the ultimate strength of the composite materials is improved, and modulus is unaffected. One notable exception is that pine exhibits a significant increase in both modulus and ultimate strength. Char yield was measured by TGA and all composites exhibit a significant increase of char formation compared to the untreated samples. 相似文献
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