硫酸铝法制备拟薄水铝石过程研究

采用硫酸铝法制备拟薄水铝石，设计正交试验考察多种因素对拟薄水铝石物化性质的影响。用X 射线衍射、氮吸附脱附、扫描电镜等方法分析了制备样品的三水铝石含量、晶相结构、孔结构以及微观形貌。正交试验结果表明：样品的三水铝石含量与成胶pH值密切相关；在所考察的因素中，成胶pH值、成胶温度、酸浓度、碱浓度、成胶时间、老化时间是影响拟薄水铝石孔性质的主要因素；制备比表面积大于280 m2/g且孔体积大于0.70 mL/g的拟薄水铝石，需控制成胶pH值在8.5左右，成胶温度高于70 ℃，硫酸铝的浓度大于130 g/L，偏铝酸钠的浓度200 g/L左右，成胶时间60 min，老化时间5 min；本试验得到的高比表面积、大孔体积的拟薄水铝石微观晶粒为棍棒状，这些晶粒的疏松堆积形成了较大的空隙。

PREPARATION OF PSEUDO-BOEHMITE BY ALUMINIUM SULFATE METHOD

Pseudo-boehmite was prepared by NaAlO2-Al2(SO4)3 method. The effect of process parameters on the physicochemical properties of pseudo-boehmite was studied by the orthogonal test. Techniques such as XRD, BET, and SEM were employed to characterize the content of gibbsite, crystal phase, pore structure, and apparent morphology. The results of orthogonal test show that the contents of gibbsite of the samples were closely related to the gelation pH. The main factors affecting the pore properties of pseudo-boehmite were the gelation pH value, the gelation temperature and time, the content of Al2(SO4)3 and NaAlO2, and the aging time. Under the conditions of pH value around 8.5, the gelation temperature higher than 70℃, the content of Al2(SO4)3 larger than 130 g?L-1, the content of NaAlO2 around 200 g?L-1, the gelation time of 60 minutes, and the aging time around 5 minutes, the pseudo-boehmite with specific surface area larger than 280 m2?g-1 and pore volume larger than 0.70 mL?g-1 are obtained. The grain shape of pseudo-boehmite with high specific surface area and large pore volume likes rods which are loosely stacked and form large gaps.