OH GROUPS AND ACIDIC PROPERTIES OF SAPO-5 AND AIPO₄-5 WITH IR

【摘要】 <正> The hydroxyl groups and their acidic properties of AlPO₄-5, SAPO-5 and HZSM-5 havebeen examined by means of IR spectroscopy using the adsorption of D₂O 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 AlPO₄-5 could be found. The experiments further indicatethat both of Bronsted and Lewis acid sites are present on the SAPO-5. From NH₃-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>AlPO₄-5.更多还原

【Abstract】 The hydroxyl groups and their acidic properties of AlPO₄-5, SAPO-5 and HZSM-5 havebeen examined by means of IR spectroscopy using the adsorption of D₂O 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 AlPO₄-5 could be found. The experiments further indicatethat both of Bronsted and Lewis acid sites are present on the SAPO-5. From NH₃-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>AlPO₄-5.更多还原