NaAlO_2-CO_2法制备拟薄水铝石过程中的转化机理

STUDIES ON CONVERSION MECHANISM IN PREPARATION OF PSEUDOBOEHMITE THROUGH NEUTRALIZATION OF NaAlO2 SOLUTION BY CO2

探讨了ＮａＡｌＯ２ＣＯ２法制备拟薄水铝石（Ｐｓｅｕｄｏｂｏｅｈｍｉｔｅ（ＰＢ），即αＡｌＯ（ＯＨ），也称一水氧化铝，也有写Ａｌ２Ｏ３·Ｈ２Ｏ）过程中的转化机理，经大量实验证实在ＮａＡｌＯ２ＣＯ２法成胶过程中存在两种生成水合氧化铝的平行反应，即ＮａＡｌＯ２溶液的中和反应和水解反应，中和反应可以制备拟薄水铝石，水解反应则生成三水氧化铝（Ｂａｙｅｒｉｔｅ，即β１Ａｌ（ＯＨ）３或β１Ａｌ２Ｏ３·３Ｈ２Ｏ）．此外，若在成胶过程中终点ｐＨ值控制得较低，则发生复合反应生成丝钠铝石．

The conversion mechanism of neutralization of NaAlO2 solution by CO2 for preparation of PB (pseudoboehmite) was discussed. Experimental results proved that there were two parallel reactions during precipitation, which could produce aluminium hydroxide. The two kinds of reaction were the neutralization and the hydrolysis of NaAlO2 solution. PB could be prepared through neutralization and the product of the hydrolysis of NaAlO2 solution was aluminium trihydroxide. Besides, if the end pH was too low, sidereaction would occur which produced dawsonite.