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11.
J. Goldwasser F. J. Machado B. Méndez C. M. López M. M. Ramirez 《Reaction Kinetics and Catalysis Letters》1999,67(2):365-370
Three different molecular sieves were synthesised and characterized using31P and27Al magic angle spinning nuclear magnetic resonance (31P and27Al MAS NMR) spectroscopy and acidity measurement techniques. The synthesized solids were: a silicoaluminophosphate (SAPO-11)
sample, a chromium-substituted silicoaluminophosphate (CrAPSO-11) sample and a chromium-supported SAPO-11 (Cr/SAPO-11) sample.
Significant differences were observed between the CrAPSO-11 MAS NMR spectra and the spectra for the other two solids. The
differences can be understood in terms of a different chemical environment for the Al(III) and P(V) ions in the molecular
sieve framework, as a result of a different type of interaction, probably with substituted chromium ions in the framework.
The acidity measurements were in agreement with the MAS NMR spectroscopy results, providing further evidence for the incorporation
of chromium ions into the molecular sieve framework. 相似文献
12.
The hydroxyl groups and their acidic properties of AlPO_4-5, SAPO-5 and HZSM-5 havebeen examined by means of IR spectroscopy using the adsorption of D_2O and pyridine asa probe. Four hydroxyl groups characterized by the bands near 3745, 3677, 3630 and 3520cm~(-1) are clearly observed and they are acidic on the sample of SAPO-5. Only two very weakbands at 3677 and 3630 cm~(-1) on AlPO_4-5 could be found. The experiments further indicatethat both of Bronsted and Lewis acid sites are present on the SAPO-5. From NH_3-TPD itis found that the HZSM-5 contains two types of acid sites, medium and strong, while theSAPO-5 contains only one type of medium acid sites. The order of a total amount ofacidity and acid strength is HZSM-5>SAPO-5>AlPO_4-5. 相似文献
13.
以Silicate-1晶种为硅源,水热合成了一种新型介孔磷酸硅铝(SAPO-1)分子筛,并且通过X射线粉末衍射、红外光谱、透射电镜、扫描电镜、热重分析、N2吸附/脱附和氨气程序升温脱附(NH3-TPD)等多种手段对产物进行了表征.红外光谱表明,Silicate-1导向剂成功地引入了介孔骨架;氨气程序升温脱附(NH3-TPD)结果表明,SAPO-1具有较强的酸性.催化结果表明,SAPO-1在大分子催化反应中有较高的活性. 相似文献