ZrO_2及SO_4^（2－）／ZrO_2超强酸催化剂的XRD分析

INVESTIGATION OF ZrO_2AND SI /ZrO_2SUPERACID CATALYSTS BY XRD

用ＸＲＤ技术从定性和定量上对ＺｒＯ＿２，特别是超强酸催化剂的物相和四方相ＺｒＯ＿２的含量进行了详细的考察。结果表明，的引入使的晶化温度比ＺｒＯ＿２大约提高了１００Ｋ，并且使亚稳态四方相ＺｒＯ＿２得以稳定。亚稳态四方相ＺｒＯ＿２的含量主要受处理液浓度和焙烧温度的影响。处理液浓度越大，四方相含量越高；焙烧温度越高；四方相含量越低。强酸性的Ｈ＿２ＳＯ＿４溶液比弱酸性的（ＮＨ＿４）＿２ＳＯ＿４溶液对四方相的生成更有利。在无定形ＺｒＯ＿２、四方相ＺｒＯ＿２和单斜相ＺｒＯ＿２上的稳定性依次减小。

The crystal structures of ZrO_2,particularly SO2/ZrO_2 superacid catalystswere studied in detail by XRD technioue. It was found that the incorporation of SO sup-Dresspd the crvstalization and increased the crystalization temperature of ZrO_2.There is aclose relation between the tetragonal ZrO_2 content and calcination temperature and modifingsolution(H_2SO_4 or(NH_4)_2SO_4)concentration. The higher the calcination temperation is,the lower will be the tetragonal content.The higher the modifing solution concentration is,the higher will be the tetragonal content.Strongly acidic H_2SO_4 is preferable to weakly acidic(NH_4)_2SO_4 for the formation of tetragonal ZrO_2.The stability of active sites on ZrO_2 is in thefollowing order:amorphous ZrO_2>tetragonal ZrO_2>monoclinic ZrO_2.