Effect of hydrogenative regeneration on the activity of beta and Pt-Beta zeolites during the transalkylation of toluene with 1,2,4-trimethylbenzene

Abstract

Catalyst deactivation remains a main challenge in the transalkylation process. To develop a cost-effective and eco-friendly catalyst, improving the regeneration characteristics of Beta/Pt-Beta catalysts was investigated. The regeneration process was carried out using hydrogen and up to four cycles (30 hours on stream per cycle). A Pt-Beta catalyst with enhanced regeneration and activity characteristic relative to the parent materials is presented, and found to be stable, with the activity fully restored by regeneration with hydrogen at 500 o C. The activity of the parent Beta dropped gradually after each cycle suggesting that the hydrogen alone at 500 o C was insufficiently effective in removing coke precursors. The drop in activity was attributed to the disappearance of Brønsted acid sites over the spent Beta catalyst due to the growth of coke molecules trapped in cavities leading to highly polyaromatic molecules blocking those active sites. This limitation can be effectively overcome by platinum addition.

Alkylbenzene synthesis from benzene and syngas over a ZnCrOx/beta bifunctional catalyst

“…For the alkylation reaction on zeolites, coke deactivation must be considered. 43,44 The benzene–syngas alkylation reaction over the ZnCrOx/beta-11 = 1 : 3 catalyst was carried out to investigate the stability of the bifunctional catalyst. The conversion rates of benzene and CO over time on stream are shown in Fig.…”