Zeolite Catalyst Composition for Benzene Purity

The patent modifies the catalyst's chemical composition parameters by incorporating specific zeolite structures (mordenite and ZSM-5) with controlled silica-to-alumina ratios (10-60 for mordenite, 5-50 for ZSM-5) and metal components (Group 10 metals like Pt, Pd, Ni) at controlled loadings (0.01-10 wt%). These parameter changes in catalyst composition enable selective conversion that produces benzene with purity ≥99.0 wt%, eliminating the need for additional extraction steps to remove benzene co-boilers.

The patent replaces the mechanical distillation separation system with a catalytic conversion system. Instead of relying on physical property differences (boiling points) for separation, the catalyst selectively converts ortho-xylene and meta-xylene into para-xylene through isomerization, and converts ethylbenzene into benzene through dealkylation. This substitution of mechanical separation with chemical transformation achieves separation efficiency without the time and energy costs of distillation.

The catalyst performs preliminary selective conversion of feedstock components before any separation steps. By pre-converting ortho-xylene and meta-xylene to para-xylene and ethylbenzene to benzene with high selectivity, the catalyst ensures that benzene co-boilers are not formed in significant quantities in the first place. This preliminary selective action eliminates the need for subsequent extraction steps to remove co-boilers, maintaining both high purity and high productivity.