Synthesis of CHA zeolite with low Si-Al ratio from rice husk ash for CO2 capture

Abstract

In order to simplify the synthesis route and reduce environmental hazards, this article exploreed an environmentally friendly method to synthesize low silicon to aluminum ratio chabazite using rice husk ash. For the prepared chabazites(CHA), the effects of crystallization time, crystallization temperature, mineralizer/material ratio, and Si/Al element ratio were systematically studied. The structure, morphology, element distribution, and thermal stability of CHA zeolite were characterized using XRD, SEM, Raman spectroscopy, STEM, and thermogravimetric analysis. According to the experimental results, the ideal conditions for synthesizing chabazite are: the mineralizer/material ratio is 2, the Si/Al element ratio is 2, the calcination temperature is 550 °C, the hydrothermal crystallization is 4 days, and the crystallization temperature is 90 °C. The environmentally friendly method reported in this paper can successfully prepare chabazite with low silicon to aluminum ratio and exhibit excellent CO₂ capture performance, reaching 3.02 mmol/g, with excellent CO₂/N₂ separation performance, reaching 20. In addition, chabazite also has excellent regeneration performance, and the adsorption capacity does not decrease significantly after ten cycles of adsorption. This method is beneficial to improve the recycling efficiency of rice husk ash, reduce the cost, and maintain a significant CO₂ adsorption capacity under flue gas conditions.

Graphical Abstract