Preparation of porous mullite ceramic for high temperature flue gas filtration application by gel casting method

In this study, porous mullite ceramics were prepared by gel-casting using fused mullite particles as the raw materials, ρ-Al2O3 and polysilicon waste as the binders, and starch as the pore forming agent. In addition, the effects of pore forming agent content on the apparent porosity, compressive strength, pore size distribution, thermal analysis, and pressure drop of porous mullite ceramics were studied. The results show that the as-prepared porous mullite ceramics have high apparent porosity, compressive strength, and gas permeability. Mullite phase formed in situ by adding polysilicon waste and ρ-Al2O3, which bonded the fused mullite particles and improved the performance of porous mullite ceramics. With increasing soluble starch content, the apparent porosity of the samples increased from 49.50 to 62.67%, and the compressive strength decreased from 4.98 MPa to 1.35 MPa. Furthermore, uniform pore size distribution and high gas permeability fully meet the requirements for the application of high-temperature flue gas filtration.