磷酸铝分子筛溶样及含量测定方法的探讨

INVESTIGATION ON THE METHODS OF DISSOLUTION OF SAMPLE AND DETERMINATION OF CONTENT FOR ALUMINOPHOSPHATE MOLECULAR SIEVES

用廉价的无机酸作溶剂来溶解稳定性很强的磷酸铝分子筛以便测定其化学组成,最适宜的酸浓度为HNO_3/H_2O=1∶3(体积比),溶样仅需5min.这种新的溶样法明显地优于传统的碱熔法,操作简便、溶样快、完全,且对溶样后分子筛中磷、铝含量的测定无影响,所得结果的相对平均偏差比碱熔法的小,重现性好,此外,本文并对磷酸铝分子筛中磷、铝含量的多种测定方法进行了比较,发现用PAN作指示剂的Cu(Ⅱ)盐返滴法测定铝含量比二甲酚橙作指示剂的Zn(Ⅱ)盐返滴法好;用二甲酚橙作指示剂的Bi(Ⅲ)盐滴定法测定磷含量比重量法更好.

A cheap solvent,inorganic acid has been utilized for the dissolution of thealuminophosphate molecular sieves with high stability in order to determined theircemical composition.The optimal acid concentration is HNO_3/H_2O=1/3(Volume/Volume).The time needed for the complete dissolution of the sample is only fiveminutes at the optimal acid concentration.In addition,it has been discoveredthat the back titration of Cu(Ⅱ)salt using PAN as an indicator is better thanthat of Zn(Ⅱ)salt using dicresol orange as an indicator for the determination ofAl content,and It has been found that the Bi(Ⅲ)salt titration using dicresolorange as an indicator is better than gravimetric method for the determination ofP content by the comparison of various methods of determining P and Al contentsin the aluminophosphate molecular sieves.