正庚烷和正辛烷在无黏结剂5A分子筛上的吸附动力学特性

采用重量法研究正庚烷和正辛烷在无黏结剂和有黏结剂5A分子筛上的吸附动力学，采用简化的扩散模型计算扩散系数，并估算扩散活化能。结果表明，正构烷烃在无黏结剂5A分子筛颗粒上的扩散时间常数大于有黏结剂的5A分子筛，黏结剂的存在降低了正构烷烃在5A分子筛上的扩散速率。在300～480 K，正庚烷和正辛烷在无黏结剂5A分子筛上的微孔扩散系数分别为(20.84~85.77)×10-14、(3.80～23.44)×10-14 cm2/s，在有黏结剂5A分子筛上的大孔扩散系数分别为(4.87～38.58)×10-7、(4.28～14.65)×10-7 cm2/s。正庚烷和正辛烷在无黏结剂5A分子筛上的扩散活化能分别为10.74、12.71 kJ/mol，在有黏结剂分子筛上的扩散活化能分别为14.16、16.35 kJ/mol。

ADSORPTION KINETICS OF n-HEPTANE AND n-OCTANE ON BINDER-FREE 5A MOLECULAR SIEVE

Adsorption kinetics of n-heptane and n-octane on 5A molecular sieve pellets with/without binder was studied using gravimetric method. Diffusivities were derived from the simplified model and diffusion activation energies were evaluated. Results show that the diffusion time constants of n-paraffins on binder-free pellets are larger than those of adsorbates on pellets with binder. In the temperatures range of 300-480 K, the micropore diffusivities of n-pentane and n-hexane on binder-free pellets are (20.84~85.77)×10-14 and (3.80-23.44)×10-14 cm2/s, respectively; the macropore diffusivities of n-pentane and n-hexane on pellets with binder are (4.87-38.58)×10-7 and (4.28-14.65)×10-7 cm2/s, respectively. The diffusion activation energies of n-pentane and n-hexane are 10.74 and 12.71 kJ/mol on binder-free 5A molecular sieve respectively, 14.16 and 16.35 kJ/mol on 5A molecular sieve with binder respectively.