Synthesis of CO[formula omitted]-adsorbing ZSM-5 zeolite from rice husk ash via the colloidal pretreatment method

Abstract

The novel ZSM-5 zeolite was successfully prepared by the colloidal pretreatment method and using rice husk ash (RHA) and pseudo-boehmite as raw materials of silicon and aluminum. A series of samples (ZSM-5-X) with various colloidal silica usage quantity were characterized by XRD, FTIR, SEM and nitrogen adsorption–desorption methods, and the results indicated that the method can reduce the formation of impurity crystals and increase the micropore volume. The CO2 adsorption measurement showed that the maximum adsorption amount of the samples was 55.01 cm3/g (ZSM-5-25) at 0 °C and 23.08 cm3/g (ZSM-5-75) at 90 °C. The Langmuir, Freundlich and Sips isotherm models were used to fit gas adsorption experimental data and analyze adsorption mechanisms. The three-parameter Sips model with a heterogeneous coefficient was suitable for simulating CO2 adsorption, and the correlation coefficient of the Langmuir model was close to 1 for fitting N2 and O2 adsorption. Higher CO2/N2 and CO2/O2 adsorption selectivity and stable adsorption–desorption regeneration performance have been demonstrated, and it indicated that the adsorbent had a promising application in the adsorption separation of CO2 from industrial flue gas.