Ultra-high steaming stability of Cu-ZSM-5 zeolite as naphtha cracking catalyst to produce light olefin

H-ZSM-5 is an excellent catalyst to produce light olefin in naphtha cracking. But it is difficult to avoid the deactivation by coke formed, so the frequent regeneration of H-ZSM-5 by calcination is necessary. A little steam is generated during the calcination, resulting in the permanent deactivation by dealumination. We found that Cu-ZSM-5 exhibited an ultra-high steaming stability in the presence of oxygen and a comparable activity for heptane cracking in the reductive atmosphere, compared with H-ZSM-5. These results are attributed to a low Brønsted acidity in the presence of oxygen and a high Brønsted acidity in the reductive atmosphere.

► Exchange degree of Cu2+ was determined to be 194 % by ICP-AES measurement.
► The Cu-ZSM-5 oxidized had a very low Brønsted acidity.
► The Cu-ZSM-5 exhibited an ultra-high steaming stability in the presence of oxygen.
► The Cu-ZSM-5 reduced had a similar Brønsted acidity to H-ZSM-5.
► The Cu-ZSM-5 reduced exhibited a similar activity to H-ZSM-5.