{"title":"Aluminated zeolites β and their properties II. Basicities of aluminated zeolites β: an FTIR study of chemisorbed pyrrole","authors":"Chun Yang , Jian Wang, Qinhua Xu","doi":"10.1016/S0927-6513(97)00044-8","DOIUrl":null,"url":null,"abstract":"<div><p>Zeolite <em>β</em> (with a Si/Al ratio of 15.2) was aluminated with NaAlO<sub>2</sub> solution. The basicities of the aluminated samples were investigated by FTIR spectroscopy with pyrrole as a probe molecule. It was found that the NH-stretching frequency of pyrrole adsorbed on the samples shifts towards lower wavenumbers as the Si/Al ratio is decreased and correlates well with the negative charge on the framework oxygen calculated from the Sanderson electronegativity equalization principle. These results reveal that zeolite <em>β</em> possesses a stronger overall basicity after alumination; hence, the alumination is an effective method to improve the basicity. It is furthermore found that the strength of the basic sites is heterogenous and that stronger basic sites are created by the alumination procedure.</p></div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"11 5","pages":"Pages 261-268"},"PeriodicalIF":0.0000,"publicationDate":"1997-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00044-8","citationCount":"17","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Microporous Materials","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0927651397000448","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 17
Abstract
Zeolite β (with a Si/Al ratio of 15.2) was aluminated with NaAlO2 solution. The basicities of the aluminated samples were investigated by FTIR spectroscopy with pyrrole as a probe molecule. It was found that the NH-stretching frequency of pyrrole adsorbed on the samples shifts towards lower wavenumbers as the Si/Al ratio is decreased and correlates well with the negative charge on the framework oxygen calculated from the Sanderson electronegativity equalization principle. These results reveal that zeolite β possesses a stronger overall basicity after alumination; hence, the alumination is an effective method to improve the basicity. It is furthermore found that the strength of the basic sites is heterogenous and that stronger basic sites are created by the alumination procedure.
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