Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Reexamination Certificate
2001-01-31
2004-04-06
Stoner, Kiley (Department: 1725)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
C208S111350, C208S111010, C502S066000, C502S068000, C502S074000, C502S079000, C502S080000, C502S084000
Reexamination Certificate
active
06716337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a carrier suitable for use in a hydrocracking catalyst that has a high selectivity for middle distillates, in particular diesel, and to a hydrocracking process in which such a catalyst is used.
2. Prior Art
The oil refining industry commonly employs hydrocracking processes to convert hydrocarbonaceous feedstocks into products of a lower boiling range. Such processes entail contacting the feedstock with hydrogen at elevated temperature and pressure under the influence of a catalyst, with the catalyst containing at least a hydrogenation component and an acidic component, the latter effecting the actual cracking. Conventional acidic components include zeolitic acidic components, in particular Y-zeolites, and amorphous acidic components, in particular silica-aluminas.
Nowadays, the conversion of heavy hydrocarbon feedstocks into middle distillates, in particular diesel, is becoming more and more important, and there is a continuing focus on developing catalyst compositions with a high selectivity for diesel.
A catalyst suitable for the production of diesel has been described, e.g., in EP0540123. This reference discloses carrier compositions which contain less than 25 wt % of a zeolite Y with a unit cell size below 2.437 nm, more than 25 wt % of a binder selected from alumina, silica, magnesia, titania, clays, zirconia, silica-zirconia, and silica-boria, and at least 30 wt % of a dispersion of silica-alumina in an alumina matrix. In the one Example of this publication a catalyst is described which comprises nickel and tungsten on a carrier comprising 4 wt % of Y-zeolite, 30 wt % of an alumina binder, and 66 wt % of a silica-alumina. Although this catalyst shows good results in diesel production, there is still need for a catalyst showing a higher selectivity in this application.
A further trend in the field of hydrocracking is the development of alternative acidic components. This development is reflected, e.g., in WO 96/07477. This reference describes carrier compositions which comprise elemental clay platelets with an average diameter of 1 &mgr;m or less and an average degree of stacking of 20 platelets per stack or less. If so desired, the carrier can also contain a matrix material selected from, int. al., amorphous materials such as silica, alumina, silica-alumina, titania and/or zirconia, and optionally, in addition, a zeolite. The carrier composition is used in catalysts suitable for hydroprocessing applications. These catalysts contain the carrier composition as defined above and at least a hydrogenation metal. The term “hydroprocessing” in this reference encompasses all processes in which a hydrocarbon feed is reacted with hydrogen at elevated temperature and elevated pressure. These processes include hydrodesulfurisation, hydrodenitrogenation, hydrodemetallisation, hydrodearomatisation, hydroisomerisation, hydrodewaxing, hydrocracking, and hydrocracking under mild pressure conditions, which is commonly referred to as mild hydrocracking.
The trend towards alternative cracking components is further reflected in the non-prepublished international patent application No. PCT/EP99/05818 filed with the European Patent Office on Jun. 24, 1999 with the title “Cogel Containing Oxidic Compounds of Tetravalent, Trivalent, and Divalent Metallic Elements” (inventors: J. Nieman, and S. Janbroers), claiming priority of EP 98202600.7 and EP 98202185.9. This reference discloses carrier compositions comprising a cogel of oxidic compounds of one or more di-, tri-, and tetravalent metallic elements, which apart from optionally present saponite is essentially X-ray amorphous and which has a B.E.T. surface area of at least 400 m
2
/g, a cation-exchange capacity of at least 0.5 wt %, and a saponite content C
A
of less than 60%, with the total of sodium and potassium amounting to less than 0.5 wt %, based on the total weight of the cogel. If so desired, the carrier can also contain a support material selected from, int. al., amorphous materials such as silica, alumina, silica-alumina, titania and/or zirconia, and optionally, in addition, a zeolite. This carrier composition is described as suitable for use in hydroprocessing catalysts in general. The amount of zeolite in the catalysts of both WO 96/07477 and the above-mentioned non-prepublished international patent application, if present at all, is specified to be 3-55 wt %, based on the total weight of the catalyst. This corresponds to 3-92 wt %, based on the total weight of the carrier composition, if 3-40 wt % of hydrogenation metal is present in the catalyst. No catalysts containing both a zeolite and a clay or cogel component, respectively, are disclosed in the Examples of these references. Neither is there any indication of any specific suitability of these cracking components for the production of diesel.
SUMMARY OF THE INVENTION
The carrier composition of the present invention comprises
a) at least 30 wt % of a synthetic cracking component, based on the total weight of the carrier composition, which comprises oxidic compounds of one or more trivalent metallic elements, tetravalent metallic elements, and divalent metallic elements, said cracking component comprising elemental clay platelets with an average diameter of 1 &mgr;m or less and an average degree of stacking of 20 platelets per stack or less, and/or comprising a cogel with a saponite content C
A
of less than 60%, and in which the total of sodium and potassium (calculated as metal) amounts to less than 1 wt %, based on the total weight of the cogel, and
b) 1-25 wt % of a zeolite Y, based on the total weight of the carrier composition, with a unit cell size below 24.35 å.
Other embodiments of the present invention encompass further details relating to further ingredients in the catalyst composition, and details concerning the process for preparation of the composition and processes in which the catalyst is used, all of which are hereinafter disclosed in the following discussion of each of those facets of the invention.
DETAILED DISCRIPTION OF THE INVENTION
We have surprisingly found that the diesel selectivity of a hydrocracking catalyst can be significantly increased when the carrier composition of the present invention is used in the catalyst instead of carrier compositions conventionally used in this field which are based on, e.g., the combination of zeolite with silica-alumina as amorphous cracking component as disclosed in EP0540123.
The invention will be further described below.
Preferably, the carrier composition of the present invention comprises 2-20 wt % and more preferably 2-12 wt % of the zeolite, based on the total weight of the carrier composition. Further, it is preferred that the carrier composition comprises at least 40 wt % and more preferably at least 50 wt % of the synthetic cracking component, based on the total weight of the carrier composition. Optionally, the carrier composition additionally comprises an amorphous support material.
Clay Platelets
The clay platelets that may be used in the carrier composition of the present invention as the synthetic cracking component comprise elemental clay platelets with an average diameter of 1 &mgr;m or less and an average degree of stacking of 20 platelets per stack or less.
Preferably, the average diameter of the clay platelets used in the carrier composition of the present invention is between 1 nm and 0.5 &mgr;m, more preferably in the range of 1 nm to 0.1 &mgr;m, and most preferably in the range of 1 to 50 nm. The average degree of stacking of the clay platelets is preferably not more than 10 platelets per stack, more preferably not more than 5 platelets per stack, and most preferably not more than 3 platelets per stack. The lower limit is constituted by unstacked clay platelets, which have a “degree of stacking” of 1. The two parameters are easily determined by means of transmission electron microscopy.
The counter-ions in the interlayer between the clay platelets can be replaced by H
3
O
+
ions. H
3
O
+
ions can be introdu
De Kroes Bas
Maria Sonnemans Johannes Wilhelmus
Nieman Jan
Ildebrando Christina
Morris Louis A.
Stoner Kiley
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