Abstract: ZSM-5 molecular sieve has the unique crystal structure, which has shown excellent performance in the field of catalysis. At the same time, due to the uniform pore size distribution, the molecular sieves have strong internal polarity in their crystal holes, and show good adsorption performance, which can adsorb water and the most of toxic and harmful substances in air, it is a new type of adsorption material which can be regenerated and does not produce secondary pollution. Using thermal activation of kaolin as the aluminum source, the ratio of silica to alumina in the sample was adjusted by increasing the amount of external silica source in the synthetic gel. In the absence of inorganic alkali (NaOH), self-stacking ZSM-5 was efficiently synthesized by using tetrapropylammonium hydroxide (TPAOH) as the template under the interaction of organic template and crystal seeds, and it was used for CO₂ adsorption. The results showed that the optimum synthesis conditions were as follows: the mass fraction of crystalline seed was 3%, the template was TPAOH, n(TPAOH)/n(SiO₂) was 0.3, the crystallization temperature was 170℃, the crystallization time was 2 h, and the ratio of silicon to aluminum was 15. The adsorption of CO₂ on molecular sieve synthesized under the these conditions was better than that of the commercial ZSM-5 molecular sieve.

Key words: kaolin, ZSM-5, synthesis conditions, CO₂ adsorption