Preparation of highly stable porous SiC membrane supports with enhanced air purification performance by recycling NaA zeolite residue

NaA zeolite membrane which exhibits remarkable selectivity for dehydration of organic compounds has been widely applied in industrial scale. Typical preparation of NaA zeolite membrane involves the hydrothermal synthesis of the NaA zeolite and the formation of a zeolite membrane layer on a substrate. However, the preparation of NaA membrane generates large quantity of zeolite residues in the synthesis solution. In this paper, the NaA residues from the preparation of the NaA zeolite membrane was recovered and reused as fillers for the fabrication of porous SiC membrane support (PSCS). The effect of loading of NaA residue and sintering temperature on the porosity, pore size, gas permeability and bending strength of PSCS were investigated. The results showed that the addition of 8% of NaA residue in PSCS led to the decrease in sintering temperature from 2000 to 1200 °C, as compared to sintering pure SiC powder. Also, the gas permeability and the bending strength were significantly increased to 1200 m³ / (m² h kPa) and 25 MPa, respectively compared to 600 m³ / (m² h kPa) and 2.5 MPa of the pristine PSCS without NaA residue. Furthermore, because of the high temperature reaction to form NaAlSi₃O₈, the PSCS loaded with NaA residue showed remarkable thermal shock resistance and resistance to acid and alkali corrosion. The successful use of NaA residue in the preparation of the PSCS provided a more economical process for the fabrication of PSCS using lower cost raw material and more thermally efficient sintering condition.