The invention is directed to a multimetallic catalyst and its use in a reactor system in a C9+ aromatics conversion process in order to reduce the saturation of aromatic species, reduce the production of C6+ non-aromatics byproducts, and achieve higher benzene purity. The multimetallic catalyst exhibits improved selectivity towards aromatic hydrocarbons in comparison to a traditional Pt/ZSM-5 catalyst and comprises ZSM-5, a Group 6-10 metal, and an additional metal not in Group 6-10. The C9+ aromatics conversion reactor system comprises a top bed containing the multimetallic catalyst for dealkylation of ethyl and propyl side chains, a second bed containing a catalyst comprising a hydrogenation component for transalkylation, and an optional third bed containing a catalyst without a hydrogenation component to convert non-aromatic hydrocarbons to gas products.