Modification Of Low Silicon-aluminum Ratio X-type Molecular Sieve And Its Oxygen Adsorption Properties

At high altitudes,the thinness of the air and the low oxygen content make human activities extremely limited,so the development of oxygen technology is particularly inportant.The pressure swing adsorption technology has the characteristics of miniaturization,rapid oxygen production,and easy portability,and has been widely used.The adsorbent is the core of pressure swing adsorption,and the excellent adsorbent can quickly separate the air to make oxygen.The low silicon-aluminum ratio X-type molecular sieve is an excellent adsorbent.The molecular sieve in the molecular sieve and the molecular sieve pore structure are changed by the coordination cation,and the molecular sieve has strong selective adsorption.In this paper,the optimal experimental process was determined by orthogonal experiments with coordination cation-modified low silica-alumina ratio X-type molecular sieves,and multiple exchanges were carried out by aqueous solution cation exchange method to explore the molecular structure and oxygen adsorption properties of molecular sieves after different cation modification.influences.Furthermore,the effects of different exchange degrees on the pore structure and oxygen adsorption performance of molecular sieves under the same cation were investigated.The main contents and conclusions are as follows:X-ray diffraction(XRD),infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),inductively coupled plasma spectroscopy(ICP),X-ray energy spectroscopy(EDS),specific surface area analysis(BET))Characterization of molecular sieves.The effects of different cations on pore structure and oxygen adsorption performance were investigated.After modification,the crystallinity of the molecular sieve structure is reduced and the peak of the skeleton is weakened.However,the modified molecular sieve still has the skeleton structure and crystal configuration of the X-type molecular sieve.After modification,the surface of the molecular sieve particle is slightly corroded and partially agglomerated.As the number of exchanges increases,the degree of exchange decreases and the difficulty of the exchange increases.Ce3＋modified molecular sieve has the largest specific surface area and pore volume,and the highest oxygen adsorption capacity.Ce3+ modified molecular sieve can achieve better oxygen adsorption perfornance,indicating that the charge intensity is higher and the molecular sieve modification is more favorable.Under the same cation,with the increase of the degree of exchange,the crystallinity of the modified molecular sieve decreased,the characteristic peaks weakened,the surface of the molecular sieve was severely corroded,and the molecular sieve showed obvious agglomeration.It shows that the higher the cation exchange degree,the lower the crystallinity of the molecular sieve,the weaker the skeleton characteristic peak,the coarser the morphology and the weaker the dispersibility.As the degree of exchange increases,the pore size of the molecular sieve increases,and the specific surface area and pore volume generally increase first and then decrease.Excessive exchange degree has a great influence on the internal pore structure of the molecular sieve,resulting in poor dispersion of the molecular sieve,resulting in a decrease in specific surface area and pore volume,which is not conducive to oxygen adsorption.From the ion exchange degree to the molecular sieve pore structure,the Ce3+ exchange degree is 39.96%,the specific surface area is 457.2616 m2/g,the pore volume is 0.5315 mL/g,the oxygen adsorption amount is 7.3284 mL/g,and the oxygen-argon separation ratio is 3.0545.,higher than Ag+,Ca2+modification.According to the gas adsorption performance test,the larger the specific surface area and the pore volume of the molecular sieve,the higher the oxygen adsorption amount,and the better the molecular sieve dispersibility is,which is more favorable for the adsorption of oxygen.