利用粉煤灰制备多孔氧化硅的实验

Preparation of Porous Silica from Fly Ash:An Experimental Study

利用相分离原理，以粉煤灰经硅铝分离后所得的硅酸凝胶为原料，选用聚乙烯醇为造孔剂，硝酸为催化剂，成功地制备了多孔氧化硅。实验结果表明：制备的多孔氧化硅的孔道发育良好，含有三级孔道。扫描电镜分析显示：大孔孔径为1～2μm，比表面积为12．03m^2／g，这与实际应用的硅藻土助滤剂制品大致相当。对实验制品在啤酒液中的稳定性实验结果显示：多孔氧化硅制品在浸泡于啤酒过程中几乎没有Ca^2＋、Fe^3＋离子溶出，浸泡后的啤酒液的pH值基本不变。上述结果表明：实验制备的多孔氧化硅制品作为硅藻土助滤剂的替代品具有良好的实际应用前景。

The phase-separation theory was used to prepare the porous silica from silicic gel derived from fly ash. Namely the polyvinyl polymer was added into the silicic sol prepared from high-alumina fly ash, and in the gel process of the silicic sol, the polymer phase separation from the siliceous phase occurred. Then the polyvinyl polymer was removed by calcination, and the porous silica formed. Using this method, the porous silica product prepared in this research has three-class pores. SEM observation shows that the pore diameters of the prepared porous silica are around 1 to 2 μm, with the BET surface area of 12.03 m^2/g, corresponding to the diatomite product. The determination of the stability of the prepared porous silica in the Yanjing beer indicated that no ion such as Ca^2＋, Fe^3＋ entered the beer, meanwhile, the pH value of the beer almost kept constant. It is therefore hopeful that the prepared porous silica product, as an equivalence of the diatomite filter, is used in the beer industry.