Study on Coke Formation during Liquid Adsorption of Hydrocarbons and Regeneration for 5A Molecular Sieves

Abstract

Coke formation on 5A molecular sieves from hydrocarbons during liquid adsorption and subsequent oxidation regeneration were investigated. Among linear olefin, cycloolefin, and linear paraffin, the coke formation from the linear olefin was proved to be the most severe, and the sequence was linear olefin > cycloolefin > linear paraffin, the reason of which was discussed. Influence of temperature on the coke formation on 5A molecular sieves was then investigated by taking linear olefin as the adsorbate; the coke was found to be increasing with the temperature and the sieves were almost deactivated at 533 K. The infrared spectrum analysis of the coke indicated that its composition was the saturated high polymer generated by the polymerization of the olefin molecules. The result of the oxidation regeneration showed the influences of oxygen partial pressure and temperature on the coke removal rate on the deactivated 5A molecular sieves. By the comparison of the pore distribution, the regenerated 5A molecular sieves were found to be similar to the fresh 5A molecular sieves.

Keywords::

• 5A molecular sieves
• coke
• liquid phase
• pore volume distribution
• regeneration