Desorption rate curves of n-pentane on 5A zeolites at 418 K and 10-0.03 kPa were determined, and the effects of different macropore structure on desorption performance were analyzed. Results show that macropore distribution of 5A-1 concentrates in 0.25-1.25 μm, while that of 5A-2 ranges from mesopore category to 0.3 μm, but 5A-3 contains both pores of 0.01-0.1 μm and 0.2-2 μm inside, reflecting a broadest distribution; 5A-3, 5A-1 and 5A-2 reach desorption equilibrium after 1100 s, 1400 s and 2000 s respectively at 0.03 kPa, indicating that abundant macropores make n-pentane fastest desorbed from 5A-3, but this advantage gradually disappears with the increasing pressure; the effective desorption diffusion coefficients of n-pentane on 5A-1, 5A-2 and 5A-3 are 4.2×10-15-2.2×10-14 m2/s, 2.0×10-15-2.3×10-14 m2/s, 7.4×10-15-2.4×10-14 m2/s respectively, suggesting that plenty macropores make the diffusivity less affected by the changes of pressure, which can guarantee a fast diffusion rate of n-pentane even at low pressure.
Ultrathin, fine-tuned microporous coating modified 5A zeolite for propane/propylene adsorptive separation
