液氮温度下分子筛的真空吸附特性试验研究

Experimental Study on Vacuum Adsorption Characteristics of Molecular Sieves at Liquid Nitrogen Temperature

为探究低温容器夹层所用分子筛吸附剂的吸附特性,采用静态膨胀法进行试验,获得了平衡压力为10-3Pa~103Pa范围内4A、5A和13X分子筛对N2、O2单一组分以及空气的吸附等温线,比较了不同分子筛对气体的吸附能力差异,探究了分子筛的吸附机理。研究结果表明:液氮温度下,5A和13X分子筛在真空条件下对N2及O2的吸附性能强,吸附量能达到104Pa·L/g量级,4A分子筛对O2的吸附量也能达到104Pa·L/g量级,然而4A分子筛在平衡压力高时吸附N2能力较差,饱和吸附量仅达到300Pa·L/g左右;三种分子筛对空气的吸附能力为13X分子筛>5A分子筛>4A分子筛,且在液氮温度下,5A分子筛对空气的吸附速率高于13X分子筛。研究分子筛在低温下的真空吸附特性,有助于指导分子筛在低温容器中的应用,同时为低温分子筛的设计提供参考。

In order to investigate the adsorption characteristics of molecular sieve adsorbents used in the interspace of cryogenic vessels, the adsorption isotherms of the 4A, 5A and 13X molecular sieves for N2, O2 single components and air were obtained by static expansion method. In the range of 10-3~103 Pa, the differences in adsorption capacity of different molecular sieves for gases were compared, and the adsorption mechanism of molecular sieves was explored. The results show that the 5A and 13X molecular sieves have strong adsorption performance for N2 and O2 under vacuum conditions at liquid nitrogen temperature, the absorption capacity can reach 104 Pa·L/g magnitude. The adsorption capacity of O2 in the 4A molecular sieve can also reach 104 Pa·L/g magnitude, while the 4A molecular sieve has poor nitrogen adsorption ability when the equilibrium pressure is higher, the saturated adsorption capacity reaches only about 300 Pa·L/g. The adsorption capacity of the three molecular sieves for air follows 13X molecular sieve >5A molecular sieve >4A molecular sieve, and at liquid nitrogen temperature, the adsorption rate of 5A molecular sieve on air is higher than that of 13X molecular sieve. Studying the vacuum adsorption characteristics of molecular sieves at low temperatures helps to guide the application of molecular sieves in cryogenic vessels, which also provides a reference for the design of low temperature molecular sieves.