Solid‐phase synthesis of silicalite‐1 molecular sieve based on fly ash and its CO₂ adsorption performance

Abstract In this work, an alkali melting‐pickling assisted solid phase synthesis method of S‐1 zeolite molecular sieve with excellent adsorption properties for CO 2 was successfully developed by using solid waste fly ash. SiO 2 with a purity of up to 97.84% was successfully extracted by using alkaline fusion activation, high temperature calcination and pickling. The CO 2 adsorption capacity of the prepared SiO 2 was 0.51 mmol/g at 298 K and 1 bar. Silicalite‐1 molecular sieve was prepared by solid phase synthesis method using SiO 2 extracted from fly ash as silicon source. The results showed that the prepared Silicalite‐1 had good morphology and relatively high crystallinity. The specific surface area is 623.30 m 2 /g, and the total pore volume is 0.31 cm 3 /g. In addition, the adsorption capacity of CO 2 was 2.05 mmol/g at 298 K and 1 bar. Compared with the prepared SiO 2 , the adsorption capacity of CO 2 by Silicalite‐1 molecular sieve increased by four times. Moreover, under the test condition of 298 K, it has a high selectivity coefficient for CO 2 /N 2 mixed gas, and after 10 times of adsorption‐desorption cycle tests, the adsorption capacity of Silicalite‐1 molecular sieve for CO 2 does not change significantly, and its adsorption rate can still be as high as 89.31%. The results indicate that Silicalite‐1 molecular sieve prepared by solid phase synthesis method has good adsorption selectivity and adsorption–desorption cycle regeneration stability, and can be used in the field of CO 2 adsorption, separation and purification. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.