5A分子筛吸附剂吸附分离正构烷烃的研究

Study on adsorption and separation of n-alkanes by 5A molecular sieve adsorbent

采用自制无黏结剂5A分子筛吸附剂,通过脉冲实验考察了吸附温度、解吸剂、吸附剂含水率和Ca^(2+)交换度对10~16碳数的正构烷烃吸附分离过程的影响。实验结果表明,提高温度有利于提高12~16碳数的正构烷烃的吸附与脱附速率,较适宜的吸附温度为180℃;正庚烷作为解吸剂时,10~16碳数的正构烷烃对异构烷烃有较高的分离度,且正庚烷对14~16碳数的正构烷烃的脱附效果优于正戊烷和正己烷;吸附剂的含水率(w)在0.2%~6.1%范围内变化时,10~16碳数的正构烷烃的吸附、脱附速率和分离度变化明显,含水率为3.3%时最高;吸附剂的Ca^(2+)交换度在70.8%~91.9%范围内变化时,对正构烷烃吸附分离效果影响不大,但Ca^(2+)交换度过高会降低13~16碳数的正构烷烃的吸附与脱附速率。

The adsorption and separation process of C_(10) to C_(16) n-alkanes was investigated by pulse test using self-made binder-free 5A molecular sieve adsorbent.The influence of separation temperature,desorbent,water content and Ca^(2+)exchange degree of the adsorbent on the separation effect was studied specifically.The results show that the high temperature is beneficial to the absorption and desorption rate of C_(12) to C_(16) n-alkanes,while the suitable temperature is 180℃.The n-heptane desorbent brings a higher separation degree of C_(10) to C_(16) n-alkanes and much better desorption effect of C_(14) to C_(16) n-alkanes compared to that using n-pentane or n-hexane as desorbent.The adsorption rate,desorption rate and separation degree of C_(10) to C_(16) n-alkanes change significantly with the water content of the adsorbent ranging from 0.2%to 6.1%,while optimal separation effect is given when the water content(w)is 3.3%.When Ca^(2+)exchange degree of the adsorbent ranged from 70.8%to 91.9%,no significant influence on the adsorption separation effect of n-alkanes was detected.However,too much Ca^(2+)being introduced could reduce the absorption and desorption rate of C13 to C_(16) n-alkanes.