Parametric study of dealkylation-transalkylation reactions over mordenite-based bi-functional catalysts

Transalkylation of heavy reformate (96% A₉ and 4% A ₁₀) without addition of toluene was conducted over four bifunctional mordenite-based catalysts at various process conditions using a flow reactor. The effects of (i) molybdenum content (3 vs. 1 wt.%); mordenite content (80 vs. 67 wt.%); and (iii) metal type (Re vs. Mo) were assessed. The composition of products and their trends was scrutinized to determine the influence of the aforesaid parameters on dealkylation-transalkylation reactions. Higher molybdenum content enhanced the methylethylbenzene (MEB) dealkylation as well as trimethylbenzene (TMB) transalkylation, resulting in increased toluene and xylene formation. Higher mordenite content had little effect on either MEB or TMB conversion. Compared to molybdenum-containing catalysts, rhenium-containing catalyst not only exhibited higher MEB dealkylation and TMB transalkylation, but also resulted in higher hydrogen consumption and methane formation. A reaction scheme for the transalkylation of heavy reformate without the addition of toluene is proposed. Among several reactions that occur during this type of a process, de-ethylation of MEBs is kinetically controlled and probable rate-determining step in the overall reaction scheme. A linear correlation between MEB conversion and xylene yield was observed, which also supports the above rationale.