Synthesis, characterization and CO2 adsorption of NaA, NaX and NaZSM-5 from rice husk ash

Abstract

NaA, NaX and NaZSM-5 zeolites were prepared by using silica extracted from rice hull ash as a raw material, and they were investigated for CO2 adsorption performance as an adsorbent in order to solve the problem of suppressing the global warming. Three zeolites were synthesized by hydrothermal methods with seed technology, and a series of characterization methods, including XRD, FTIR, nitrogen adsorption-desorption and SEM, were used to demonstrate their advantages compared to traditional hydrothermal methods. The maximum equilibrium adsorption capacity of NaA-RS, NaX-RS and NaZSM-5-RS was 1.46, 3.12 and 2.20 mmol/g at 0 °C and 101.3 kPa, respectively. The CO2 and N2 adsorption isotherms recorded at different temperatures were perfectly fitted by the Dual-site Langmuir model. The CO2/N2 selectivity and Henry's law constants were calculated to demonstrate that the samples have a stronger affinity for CO2, especially at low pressures. The isosteric heat of CO2 and N2 adsorption of the three zeolites was calculated, which was indicated that they were in an excellent potential for adsorption and separation of CO2 in industrial flue gas.