Study on Characterization and Coke Compositions of Deactivated 5 A Molecular Sieve for Adsorption Separation of Industrial Naphtha

The deactivation causes and coke compositions of the deactivated 5 A molecular sieves (5A-E) used in the liquid phase adsorption separation process for industrial naphtha were analyzed. The results showed that 5A-E existed 14 species of C-10 similar to C-11 benzene series, naphthalene series and indans (main components of industrial corrosion inhibitor), which formed coke to block 4.4-4.9 angstrom micropores of 5 A-E. The coke content was similar to 3.72 % and there had a strong exothermic peak at 271 degrees C on the surface of 5A-E. The static adsorption capacity of fresh 5 A molecular sieves for n-hexane reduced by 24.6 % within 90 min in the isooctane/n-hexane mixed solution containing 400 ppm industrial corrosion inhibitor. It indicated that trace corrosion inhibitor would be deposited on the surface of 5 A molecular sieves during industrial long-term operation, resulting in slow deactivation of 5 A molecular sieves. It can provide the guidance for industrial production of liquid phase adsorption separation process of naphtha.