Porous mullite-bonded SiC filters prepared by foaming-sol-gel-tape casting for high-efficiency hot flue gas filtration

Porous mullite-bonded SiC filters was prepared by combining foaming-sol–gel-tape casting and in situ mullite reaction bonding. Silica sol served two main functions: (i) it was used to create a sol–gel reaction at room temperature to consolidate foam, and (ii) it was used as a silicon source for in-situ mulletization reactions with alumina at high temperatures to bind silicon carbide to produce high mechanical strength. In this study, gelation process, reaction bonding behavior and hot flue gas filtration were thoroughly investigated. The produced filters comprise a high number of interconnected big pores with sizes ranging from 50 to 150 µm. The size of the pores connecting channels with filtration functionality was less than 10 µm. High porosity of 64.8 to 80.5 % and high N2 permeation of 4.82 × 107 to 7.44 × 107 Lm−2 h−1 bar−1 were attained by adjusting the amount of foaming agent. In hot flue gas filtration, the unique structure of the filter allows for high filtration efficiency (>89.6% for PM2.5), ultra-low pressure drop (30 Pa), and exceptional cyclic stability.