以具有一定活性的偏高岭土兼作铝源与硅源,正磷酸作磷源,三乙醇胺和十六烷基三甲基溴化铵为复合模板剂,采用分段晶化的方法水热合成了高硅磷酸硅铝分子筛(SAPO-5). 利用X射线衍射分析(XRD)、红外光谱分析(FTIR)、扫描电镜(SEM)、29Si, 27Al MAS-NMR (固态核磁共振)、X光电能谱(XPS),吸附氨的程序升温脱附(NH3-TPD)等手段对产物进行了表征. 研究结果表明:采用十六烷基三甲基溴化铵复合三乙醇胺作模板剂,可以促进SAPO-5晶体产物的形成,其产物形貌为尺寸大约20μm×5μm×5μm的规则柱状晶体. IR、MASNMR及XPS分析表明,反应后结构中的Si、Al的配位环境发生了较大的变化,形成了较多Al(OP)4及Si(AlO)4两种四配位结构,其Si/Al为0.56. 产物分子筛中的总酸量为0.578mmol/g,中强酸与弱酸比例为0.684.
Highsilica silicoaluminophosphate (SAPO-5) molecular sieves were hydrothermally synthesized using metakaoline with a certain activity as the silicon and aluminum sources, phosphoric acid as the phosphorus source and triethanolamine combined with cetyltrimethylammonium bromide (CTMABr) as the template agents. The sample was characterized by means of X-ray diffraction spectroscope (XRD), Infrared spectrum (IR), scanning electron microscope (SEM) and 29Si, 27Al MAS-NMR and X-ray photoelectron spectroscope (XPS), temperatureprogrammed desorption of adsorbed NH3. The results show that the crystallization of the SAPO-5 can be promoted by the addition of CTMABr. The synthesized SAPO-5 reveals pillarlike morphology with dimension of 20μm×5μm×5μm. The local environment of Si and Al changs greatly after reaction and many fourcoordinated structures such as Al(OP)4 and Si(AlO)4 are produced with the Si/Al ratio of 0.56. The acidity amount of the product is 0.578mmol/g and the ratio of the strong acid sites to the weak acid sites is 0.684.
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