Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component
Reexamination Certificate
2000-08-21
2003-09-02
Dunn, Tom (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And additional al or si containing component
C502S066000, C502S074000
Reexamination Certificate
active
06613709
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst which can, for example, be used in aromatic hydrocarbon transformation reactions. More precisely, it concerns a catalyst for alkylaromatic hydrocarbon transalkylation, preferably transalkylation of toluene and aromatic compounds containing at least 9 carbon atoms, to produce xylenes. The present invention also relates to the preparation of said catalyst and to its use in an alkylaromatic hydrocarbon transalkylation process.
PRIOR ART
A number of catalysts for dismutation and/or transalkylation have already been described in the prior art, and are based on mordenite (United States patents U.S. Pat. No. 3,506,731, U.S. Pat. No. 4,151,120, U.S. Pat. No. 4,180,693, U.S. Pat. No. 4,210,770, U.S. Pat. No. 3,281,483, U.S. Pat. No. 3,780,121 and U.S. Pat. No. 3,629,351) or based on omega zeolite (U.S. Pat. No. 5,210,356, U.S. Pat. No. 5,371,311).
European patent EP-B1-0 378 916 describes NU-87 zeolite, a zeolite with structure type NES, and a method for its preparation in the presence of a salt of a polymethylene diammonium cation, for example decamethonium bromide. In that patent, rhenium is cited among numerous other elements for its hydrodehydrogenating properties.
U.S. Pat. No. 5,641,393 concerns SSZ-37 zeolite with a SiO
2
/Al
2
O
3
ratio for the as synthesised zeolite of more than 400. The synthesis of that zeolite is different from that of NU-87 in that the template is the N,N-dimethyl-4-azoniatricyclo[5.2.2.0
(2.6)
]undec-8-ene for the SSZ-37 zeolite. The importance of NU-87 zeolite with structure type NES for dismutation and/or transalkylation of alkylaromatic hydrocarbons has been demonstrated in the Applicant's French patent FR-A-2 752 568. That patent also mentions the importance of adding a metal such as nickel.
In EP-A1-0 731 071, the use of a catalyst based on mordenite zeolite and rhenium is described for transalkylation of aromatic C9 cuts comprising an aromatic compound containing at least one ethyl group. While rhenium is the preferred metal, other metals (Ni, Co, Mo, Cr and W) are cited as being suitable.
SUMMARY OF THE INVENTION
The catalyst of the present invention contains at least one zeolite with structure type NES, preferably NU-87, comprising silicon and at least one element T selected from the group formed by aluminium, iron, gallium and boron. Preferably, element T has been extracted so that the overall atomic ratio Si/T is more than 20. This zeolite is at least partially in its acid form. The binder is preferably alumina. The catalyst also contains at least one metal selected from the group formed by group VIIB and group VIB from the periodic table and iridium, preferably rhenium. Finally, the catalyst optionally also contains at least one metal selected from the group formed by elements from groups III and IVA of the periodic table, preferably indium or tin. The present invention also concerns the use of the catalyst in a process for transalkylating alkylaromatic hydrocarbons such as toluene and alkylaromatic compounds containing at least 9 carbon atoms. In particular, this catalyst is highly effective in treating C9+ aromatic feeds containing more than 5% by weight of aromatic olefins containing 10 carbon atoms and more, this feed possibly also containing benzene.
IMPORTANCE OF THE INVENTION
It has been discovered that a catalyst containing at least one zeolite with structure type NES, preferably NU-87 zeolite, preferably dealuminated so as to obtain a Si/T ratio of more than about 20, at least partially and preferably practically completely in its acid form, and at least one metal selected from the group formed by metals from groups VIIB, VIB and iridium, preferably rhenium, leads to catalytic performances, in particular activities, stabilities and selectivities, which are improved for transalkylation reactions of alkylaromatic hydrocarbons such as toluene and alkylaromatic compounds containing at least 9 carbon atoms with respect to prior art catalysts. In particular, this catalyst is very effective in treating C9+ aromatic feeds containing a high percentage of aromatic molecules containing 10 carbon atoms and more (over 5% by weight), meaning that these heavy molecules (such as dimethylethylbenzenes, diethylbenzenes . . . ) can be upgraded to xylenes, with selectivities and stabilities which are improved over the prior art, and also producing benzene with an improved purity.
DESCRIPTION OF THE INVENTION
The invention thus concerns a catalyst containing at least one zeolite with structure type NES, preferably a NU-87 zeolite, in an amount of 30% to 90%, preferably 60% to 85% by weight, and at least one matrix (or binder) making up the complement of the catalyst to 100%. In a preferred embodiment, said zeolite, preferably NU-87, comprising silicon and at least one element T selected from the group formed by aluminium, iron, gallium and boron, preferably aluminium, is dealuminated and at least partially, preferably practically completely in its acid form. The overall Si/T atomic ratio of said zeolite, when it is dealuminated, is generally over 20, preferably over 25, more preferably in the range about 25 to about 350, still more preferably in the range 25 to 250, or yet still more preferably in the range about 25 to about 150. When it is included in the catalyst of the invention, the zeolite with structure type NES is at least partially, preferably practically completely in its acid form, i.e., in its hydrogen form (H
+
). The sodium content is less than 0.1% by weight, preferably less than 0.05% by weight with respect to the total weight of dry zeolite.
Said catalyst also comprises at least one metal selected from the group formed by metals from groups VIIB, VIB and iridium, preferably rhenium, in an amount in the range 0.01% to 5%, preferably in the range 0.05% to 3% by weight, and optionally at least one element selected from the group formed by groups IIIA and IVA of the periodic table, preferably selected from the group formed by indium and tin in an amount in the range 0.01% to 5%, preferably in the range 0.5% to 3% by weight. Highly preferably, iridium is the only group VIII element which may be is included in the catalyst of the invention.
The matrix, present in an amount in the range 10% to 60% , preferably in the range 15% to 40% by weight with respect to the total catalyst weight, is generally selected from the group formed by clays (for example natural clays such as kaolin or bentonite), magnesia, aluminas, silicas, titanium oxide, boron oxide, zirconia, aluminium phosphates, titanium phosphates, zirconium phosphates, silica-aluminas and charcoal, preferably selected from the group formed by aluminas and clays, more preferably from aluminas.
The present invention also concerns the preparation of the catalyst.
The NES zeolite included in the catalyst of the present invention is preferably NU-87 zeolite prepared in accordance with EP-B1-0 378 916. Thus the NU-87 zeolite is prepared by mixing a source of silicon and a source of an element T, an alkali cation and an organic template selected from salts of polymethylene diammonium cations, for example decamethonium bromide. The NES zeolite used in the catalyst of the present is preferably such that the element T has been extracted from the framework.
In order to prepare the dealuminated NU-87 zeolite with structure type NES of the invention, in the preferred case where element T is aluminium, two dealumination methods can be used starting from an as synthesised zeolite with structure type NES comprising an organic template. They are described below. However, any other method which is known to the skilled person can also be used in the invention.
These methods described for aluminium can also be suitable for other elements T.
The first method, direct acid attack, comprises a first calcining step carried out in dry air, at a temperature which is generally in the range 450° C. to 550° C., which eliminates the organic template present in the micropores of the zeolite, followed by a step in which the zeo
Alario Fabio
Ferrer Nathalie
Martin Olivia
Merlen Elisabeth
Dunn Tom
Ildebrando Christina
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
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