Effect of steam during catalytic cracking of n-hexane using P-ZSM-5 catalyst.

Phosphorus-modified ZSM-5 (P-ZSM-5) catalyst was active for steam cracking of n -hexane to produce propylene and ethylene; however, the P-ZSM-5 catalyst deactivated because of both dealumination and coke deposition, which were strongly influenced by the steam to n -hexane ratio in the reactant flow. The amount of coke deposition increased with decreasing the steam to n -hexane ratio from the TG-DTA measurement. The steam could reduce the reactions of the light olefins to BTX and coke and enhance the yield of the light olefins; however, the excess steam deactivated the ZSM-5 catalysts irreversibly via dealumination. [ABSTRACT FROM AUTHOR]