吸附分离正构烃结焦失活的无粘结剂5A分子筛氧化再生研究

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

  • 摘要: 在固定床吸附器上模拟无粘结剂5A分子筛的失活过程,并对失活分子筛进行氧化再生研究。结果表明,焦炭会堵塞部分分子筛孔道,导致失活分子筛的比表面积和孔容减小、平均孔径增加。焦炭含量增加,分子筛的失活度增加,但增加的速率逐渐减小。氧化反应温度由582K升至787K,焦炭脱除率由64%增至100%。失活分子筛于787K下氧化处理后,其上焦炭被完全脱除,分子筛的吸附活性完全恢复。氧化再生后分子筛的比表面积和孔容增加,但难以恢复至新鲜分子筛的水平。在685K~884K,实验得到的无粘结剂5A分子筛上焦炭的氧化脱除宏观动力学方程为:ln(C0/C) = 0.013exp(-28122.1/T) (pO2)0.32t

     

    Abstract: 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 (ABET), smaller pore volume (vp) and larger pore diameter (dp) 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, ABET 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) (pO2)0.32t.

     

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