Oxidative regeneration of deactivated binderless 5A molecular sieves for the adsorption-separation of normal hydrocarbons

The deactivation of binderless 5A molecular sieves for the adsorption-separation of normal hydrocarbons was investigated on a fixed bed adsorber. The deactivated molecular sieves were regenerated by removing the coke deposited through oxidation under various conditions. The deactivated molecular sieves exhibited lower surface area (A_BET), smaller pore volume (vp) and larger pore diameter (d_p) than the fresh sample, because certain passages in the molecular sieves were blocked by the coke deposited. With the increase of the coke content in the molecular sieves, the deactivation rate decreased gradually. With the increase of oxidation temperature from 582K to 787K, the coke removal efficiency was elevated from 64% to 100%. At 787K, coke deposited in the molecular sieves was completely removed and the adsorption activity of the molecular sieves was recovered; however, A_BET and vp of the regenerated molecular sieves could not be restored to the original values of the fresh samples. Under 685K~884K, the removal of coke from the binderless 5A molecular sieves by the oxidative treatment could be expressed with a macrokinetic formula：ln(C₀/C) = 0.013exp(-28122.1/T) (p_O2)0.32t.