| 何长青,刘中民,蔡光宇,辛勤,应品良.SAPO－34分子筛表面酸性质的研究[J].分子催化,1996,(1): |
| SAPO－34分子筛表面酸性质的研究 |
| Investigation on the Surface Acidity of SAPO-34 Molecular Sieve |
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| DOI： |
| 中文关键词: 分子筛，SAPO－34，TPD，IR，酸性质 |
| 英文关键词:Molecular sieve,SAPO-34,TPD,IR,Acidity, |
| 基金项目: |
| 何长青 刘中民 蔡光宇 辛勤 应品良 |
| 中国科学院大连化学物理研究所，中国科学院大连化学物理研究所催化基础国家重点实验室 |
| 摘要点击次数: 1891 |
| 全文下载次数: 18 |
| 中文摘要: |
| 以水热合成法制备了三个具有不同硅磷铝组成的硅磷酸铝分子筛ＳＡＰＯ－３４样品，采用红外光谱（ＩＲ）和氨法程序升温脱附（ＴＰＤ）两种方法考察了它们的表面酸性质。红外谱图中的３６００ｃｍ－１和３６２１ｃｍ－１谱峰归属于处于ＳＡＰＯ－３４分子筛结构中不同位置的两种桥联羟基（Ｓｉ－ＯＨ－Ａｌ）的振动。ＮＨ３－ＩＲ测定结果显示，这两种羟基具有较强的Ｂ酸特性，并且是分子筛酸性的主要来源；而分子筛具有的Ｌ酸中心的酸性较弱。比较三个样品的ＮＨ３－ＴＰＤ、ＮＨ_３－ＩＲ和骨架组成后发现，ＳＡＰＯ－３４的酸性受其骨架硅含量的强烈影响：当Ｓｉ／Ａｌ摩尔比小于１时，酸性随硅含量增高而变弱；当Ｓｉ／Ａｌ摩尔比大于１时，酸性将随硅含量增高而变强。 |
| 英文摘要: |
| Three samples of silicoaluminophosphate molecular sieve SAPO-34 with different Si-Al-P compositions were synthesized and their surface acidities have been investigated with infrared(IR) spectrometry and temperature-programmed desorption(TPD) of ammonia.The bands at 3621 cm-1 and 3600 cm-1 are possibly assigned to two types of bridging hydroxyl groups Si-OH-Al located at different positions of the frameworks of SAPO-34.The IR spectra of the three samples adsorbed with ammonia show that these two types of bridging hydroxyl groups of SAPO-34 are strong Bronsted acidic centers and the main source of the acidity of the molecular sieve.Lewis acidic centers have also been observed in NH3-IR spectra but their acidities are much weaker than Bronsted ones.The results from NH3-IR,NH3-TPD and chemical elemental analyses reveal that the acidity of SAPO-34 is strongly influenced by the contents of silicon in its framework:the acidity decreases with the increase of silicon contents when the mole ratio of silicon versus aluminum in framework is below 1. |
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