Typically xylene isomerization catalysts convert ethylbenzene (EB) to benzene. But for example, IFP's Oparsi plus catalyst convert EB to xylenes isomers.
It is a big help if anybody tells me what promoter can do this reaction.
I know hydrogenation metals like Pd can convert EB to naphthenes and acid sites of zeolite support are suitable for the conversion of naphthenes to xylene. But I think conventional catalysts have noble metals like Pd and they convert EB to benzene.
Today´s industrial catalysts for isomerization of xylenes (more precisely C8-aromatic fraction from reforming after p-xylene separation, that contains also ethylbenzene) are based on ZSM-5 zeolites, which isomerize m- and o-xylenes to p-xylenes, and ethylbenzene is dealkylated to benzene. This kind of catalysts are mostly acidic, but contain also a metal component that prevent against coking. Older industrial catalysts for isomerization of C8-aromatic fraction were typical bifunctional catalysts (Pt/mordenite) where isomerization of ethylbenzene to xylenes proceeds via hydrogenation of ethylbenzene into all C6 and also C5 cyclanes (over Pt), isomerization of C8-cyclanes (over acidic mordenite) and back dehydrogenation into C8 aromatics. Of course, at the present of hydrogen. So answer to your question is - you must use bifunctional catalyst with acid and metal component.
Both suggested catalysts - Pt/HY and Pt/H-mordenite are bifunctional catalysts, you must work in atmosphere of hydrogen (industrial conditions were about 1.5-2 MPa) and temperature of about 380-400 °C. You must take into account that quite a lot saturated by-products will be created (as intermediates during hydrogenation-isomerization-dehydrogenation cycles). If you work at atmospheric pressure, the quantitiy of such by-products could be lower. My experiences showed that Pt/H-mordenite is more selective catalysts than wide-pore Pt/HY where much more disproportionation of xylenes into toluene and trimethylbenzenes proceeded.
Pavol Hudec
Thanks for your attention.
Your advice is helpful and practical.
you can test with Al-Fe pillared clays catalyst, HY zeolite or ZSM-5 Zeolite.
Good luck
The present invention relates to a method for converting a feed mixture comprising an aromatic C8 mixture of xylenes and ethylbenzene in which the para-xylene content of the xylene portion of the feed is less than equilibrium to produce a product mixture of reduced ethylbenzene content and a greater amount of para-xylene, which method comprises contacting the feed mixture at conversion conditions with a first catalyst having activity for the conversion of ethylbenzene, and with a second catalyst having activity for the isomerization of a xylene.
Ethyl benzene conversion to xylene by isomerization processes and the catalyst catalysts used is aluminosilicate zeolite.