Zeolite Molecular Sieve

Zeolite molecular sieve

Zeolite is an aluminosilicate composed of AlO4 tetrahedra replacing SiO4 tetrahedra, resulting in a negative charge that is balanced by exchangeable cations located in the pores and cavities throughout the structure. Generally speaking, CO2 capture by zeolites depends on factors such as the structure and composition of the zeolite framework, cations, and functional groups. Among porous materials for CO2 separation, zeolites have gained popularity in adsorption technology due to their advantages such as good availability, low cost, high CO2 capture rate, fast kinetics, and good chemical and thermal stability.

Wide range of applications. Adjusting the framework structure, cations, chemical modification and material compounding are considered to be effective methods for the CO2 adsorption and desorption performance of high zeolites. used molecular simulation to simulate 13X
Cation exchange with different Li+, K+ and Ca2+ contents in zeolites. The adsorption performance of various cation exchange zeolites for CO2 was evaluated from the aspects of pore volume, adsorption isotherm, adsorption heat and CO2/N2 selectivity. It was found that the CO2 molecule has a quadrupole moment. , which can be used with smaller cationic zeolites such as Li+, the silicon-to-aluminum ratio also has a significant impact on the adsorption selectivity of CO2. Calleja et al. explored the effect of the Si/Al ratio on zeolite polarity and CO2 adsorption by adjusting the zeolite Si/Al ratio. It is found that as the Si/Al ratio decreases, the selectivity of the adsorbent for CO2 increases.

A binder-free zeolite material with a hierarchical structure was prepared using 3D printing technology, which showed excellent mechanical stability and an adsorption capacity of CO2 of 245.52 mg/g under normal temperature and pressure conditions. A kind of zeolite material was prepared at 25 The copper-doped RHO zeolite has a CO2 capacity of 3.2 mmol/g at ℃, making it a potential pressure swing adsorption carbon capture technology. Chemical modification effectively improves the adsorption selectivity of zeolite for CO2. Monoethanolamine (MEA) and ethylenediamine (ED) are chemically fixed to the zeolite framework through ionic bonds to overcome the degradation problem of amines. The prepared amine@HY The sample has excellent CO2 adsorption selectivity, and has excellent cycle thermal stability under the conditions of an adsorption temperature of 90°C and a desorption temperature of 150°C. Amines such as monoethanolamine, tetraethylpentbutylamine, and morpholine were loaded on NaY zeolite. The research results show that at normal pressure and 323 K temperature, the interaction between the amine groups on the surface of NaY zeolite and CO2 is the main mechanism of its adsorption. Compared with activated carbon, zeolite has better capture capacity and higher CO2/N2 selectivity in flue gas with low CO2 partial pressure (15% CO2, 85% N2). However, there is also the problem of significant decrease in adsorption capacity under high temperature conditions, and the CO2 adsorption capacity is negligible above 200 °C. The trade-off between the adsorption capacity, adsorption kinetics and mechanical stability of zeolites remains a great challenge in their industrial applications. Z Pilot run tests were conducted on a single-stage VPSA unit packed with 5A zeolite and 13X zeolite. For the capture of dehumidified flue gas with a CO2 concentration of 15.0%, 5A zeolite can reach an enrichment concentration of 71% to 81%, and the recovery rate is 86% to 91%; although13X zeolite has better CO2 adsorption capacity, but showed similar performance to 5A zeolite in pilot operation tests, with an enrichment concentration of 73% to 82% and a recovery rate of 85% to 95%. The main reason is that the stronger polarity of 13X makes desorption more expensive. Therefore, in application, the selection of zeolite needs to be based on the actual feed gas conditions and the adsorption and desorption kinetic characteristics of the zeolite.