高铝粉煤灰制备拟薄水铝石的比表面积与孔隙特性分析

Specific Surface Area and Pore Characteristics Analysis of Pseudo-boehmite Prepared by High-alumina Fly Ash

高铝粉煤灰熟料经预脱硅—碱石灰烧结、溶出、二次脱硅后的溶液经碳分及种分后得到拟薄水铝石产品,并采用低温氮气吸附法分析其比表面积以及孔结构。结果表明,碳分法和种分法制备拟薄水铝石的等温吸附线均属Ⅳ类,晶粒之间的孔隙以中孔为主,等温吸附曲线滞后环类似于H4型,是狭缝孔。碳分产品的BET比表面积略大于种分产品,然而其BJH吸附累积总孔孔容与BJH吸附平均孔径略低于种分产品,两种产品的物化指标均优于普通拟薄水铝石样品。

Pseudo-boehmite （PB） product was prepared from sintered high-alumina fly ash clinker. Fly ash clinker was pretreated by deep desilication and sintering with soda lime, and twice-desilication solution was decomposed （carbonation decomposition and seed precipitation） to prepare PB. Specific surface areas and pore distribution of PB were analyzed by low-temperature nitrogen adsorption. The results show that adsorption isotherm curve of PB prepared by carbonation and seed precipitation process presents as type IV. Most of pores between grains are mesopore. Hysteresis loop of adsorption isotherm curve presents as slit pores similar to H4 type. BET specific surface area of carbonation decomposition product is bigger than that of seed precipitation. However, BJH pore volume and BJH pore size are smaller than those of seed precipitation product. Physical chemical indexes of two products are superior to common PB products.