The carbon molecular sieve (CMS) is a sorbent desiccant developed in the 1970s that has no polarity. The primary purpose of carbon molecular sieve desiccant is to separate nitrogen from air. It has the performance to absorb oxygen in the air under changing pressure of normal temperature, so it can gain rich nitrogen gas. Traditional rich nitrogen in plant air is produced to adopt deep freezing method, that is to make air liquefy under low temperature, separate oxygen and nitrogen through rectification. Its most remarkable characteristic is that N2 has little impurity content, N2 concentration and air current can be adjusted according to the requirements, and can gain high purity N2 with less than 5ppm O2 content and lower than -60¡æ dew point through refine.