超重力连续碳分法制备γ-Al2O3的研究

Preparation of γ-Al2O3 by high-gravity continuous carbonation decomposition

为解决分批操作导致产品孔径分布不均、结晶颗粒大、杂质多等问题,提出了将超重力技术与连续碳分工艺相结合制备拟薄水铝石及γ-Al2O3的新技术。以CO2和NaAlO2为原料,采用错流旋转填料床连续制备拟薄水铝石,考察了NaAlO2溶液浓度、气液比和超重力因子对拟薄水铝石孔隙性能的影响。对拟薄水铝石进行扩孔改性,焙烧制备了大孔γ-Al2O3。随着NaAlO2溶液浓度、气液比和超重力因子的增大,拟薄水铝石的比表面积和孔容呈先增大后减小的趋势,其最佳制备条件为:NaAlO2溶液浓度为0.1mol/L、气液比为3∶1、超重力因子为54。对其进行扩孔改性后焙烧,最终得到比表面积和孔容分别为322m2/g、1.826mL/g的纳米级大孔纤维状γ-Al2O3。研究结果表明,超重力连续碳分法所得产物纯度高、孔径分布均匀、生产效率高,适用于工业放大。

In order to solve the problems such as uneven distribution of pore size,over-large crystal particles and many impurities caused by batch operation in traditional batch carbonation decomposition process,a new technology combining high-gravity technology with continuous carbonization process is proposed for preparing pseudo-boehmite andγ-Al2O3.Pseudo-boehmite is prepared by cross-flow rotating packed bed with CO2and Na AlO2as raw materials.The impacts of the concentration of Na AlO2solution,gas-liquid ratio and high-gravity factor on the pore properties of pseudoboehmite are investigated.Macro-porousγ-Al2O3is prepared through reaming modification and calcination of pseudoboehmite.With the increases of the concentration of Na AlO2solution,gas-liquid ratio and high-gravity factor,the specific surface area and pore volume of pseudo-boehmite increase firstly and decrease then.The optimal preparation conditions are as follows:the concentration of Na AlO2solution is 0.1 mol·L-1,the gas-liquid ratio is 3∶1 and the high-gravity factor is 54.The nanometer macro-porous fibrousγ-Al2O3with specific surface area and pore volume of 322 m2·g-1and 1.826ccl·g-1respectively is obtained after reaming modification and calcination.The results show that the product obtained by the high-gravity continuous carbonation decomposition method exhibits high purity,uniform pore size distribution and high production efficiency,which is suitable for industrial amplification.