Poly-functional Catalyst Development for Benzene Production from Alkyl-aromatic Mixture via Hydrodealkylation

Abstract

Development of a poly-functional catalyst that has higher hydrodealkylation activity based on 15% Cr/γ -Al 2 O 3 was researched for benzene production from an alkyl-aromatic mixture via hydrodealkylation. For this goal, the effects of the promoters like Fe, Co, or Ni and their concentrations on the activity of a Cr/Al 2 O 3 catalyst were investigated. Toluene + n-heptane + tetrahydrotiophene (89:10:1 w%) model mixture, which has the same content as industrial aromatics, was used as feedstock. The activities of catalysis in reactions of hydrodealkylation, hydrocracking, and hydrogenolize with respect to conversions of toluene, heptane, and tetrahydrotiophene were tested, respectively. As to the obtained results, the catalyst including 5% Fe has a higher hydrodealkylation activity, compared to the catalyst including Co, and especially to the alumocrom catalyst not including a promoter, while it has a lower coke formation and reduced activity to the catalyst including Ni.

Aromatic Hydrocarbon Production from Eucalyptus urophylla Pyrolysis over Several Metal‐Modified ZSM‐5 Catalysts

“…[55] Ni has been used previously as ap romotero naCr 2 O 3 /Al 2 O 3 catalyst for the hydrodealkylation of toluene at atmospheric pressure. [56] In this case,i ti sp ossible that Ni-ZSM-5 promotest his pathway using H 2 presentf rom the reforming reactionst oc onvert xylenesa nd toluenet o benzene,w hich forms CH 4 concurrently.T he Zn-modified ZSM-5 catalystsp roduce methane at higherl evels than Gamodified or unmodified ZSM-5 but less than that of the Nimodified catalyst and they also produce the highests electivity to toluene. TheZ n-modified catalystsa ppear to act in the same mannera st he Ni-modifiedc atalysts but are poorer promoters of the second step of the demethylation of toluene to benzene because either they are less active catalysts for hydrogenolysis and/or because of the lower H 2 availability (because Ni is am ore activer eforming catalyst as shown by its high CO yield;T ables 2a nd 3).…”

“…The demethylation of xylenes with hydrogen would proceed in two steps: xylenes to toluene and toluene to benzene . Ni has been used previously as a promoter on a Cr 2 O 3 /Al 2 O 3 catalyst for the hydrodealkylation of toluene at atmospheric pressure . In this case, it is possible that Ni‐ZSM‐5 promotes this pathway using H 2 present from the reforming reactions to convert xylenes and toluene to benzene, which forms CH 4 concurrently.…”