无黏结剂5A分子筛吸附分离正构烃的结焦失活

COKING DEACTIVATION OF BINDERLESS 5A MOLECULAR SIEVES USED IN ADSORPTION FOR NORMAL HYDROCARBONS

对比了己烯-1、正己烷和环己烯在无黏结剂5A分子筛上吸附分离时的结焦情况。探讨了吸附温度、吸附质分压及黏结剂对结焦的影响。分析了5A分子筛上的结焦机理。并研究了己烯-1在无黏结剂5A分子筛上的结焦动力学。结果表明,己烯-1更易引起5A分子筛的结焦失活,结焦量和失活度随温度和吸附质分压的增加而增加。有黏结剂5A分子筛上的结焦量和失活度大于无黏结剂5A分子筛。当温度623 K、时间30 min、吸附质分压40 kPa时,己烯-1在无黏结剂和有黏结剂5A分子筛上的结焦量分别为0.019 g/g和0.026 g/g,相应失活度分别为16.4%和28.2%。烯烃分子通过氢转移和聚合等反应生成焦炭。结焦过程遵循连串反应机理。

The coking properties of hexene-1, n-hexane and cyclohexene on binderless 5A molecular sieves were compared. The influences of temperature, adsorbate pressure and binder on coke content and deactivation degree were investigated and discussed. Also the coke formation mechanism was analyzed. Furthermore, the coking kinetics of hexene-1 on binderless 5A molecular sieves was studied. The results indicated that hexene-1 had more obvious coking trend compared to n-hexane and cyclohexene. The coke content and deactivation degree increased with temperature or adsorbate pressure. The coke content and deactivation degree on 5A molecular sieves with binder were higher than these on binderless samples, respectively. Under adsorption temperature of 623 K, adsorption time of 30 min and hexene-1 pressure of 40 kPa, the coke contents on binderless 5A molecular sieves and the sample with binder were 0. 019 g/g and 0. 026 g/g, respectively, and the corresponding deactivation degrees were 16.4% and 28.2%. Coke was formed through hydrogen transfer and polymerization of olefin molecules. Coke formation processes can be explained by using consecutive reaction mechanism.