Process for the preparation of a catalyst composition

Details Process for the preparation of a catalyst composition Process for the preparation of a catalyst composition

1999-08-02

2001-02-20

Dunn, Tom (Department: 1754)

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Cracking

C502S064000, C502S067000, C502S068000, C502S069000

Reexamination Certificate

active

06190538

ABSTRACT:

The present invention relates to a process for the preparation of a catalyst composition.
BACKGROUND OF THE INVENTION
Of the many conversion processes known in the refining art, hydrocracking has assumed a greater importance over the years since it offers the refiner product flexibility combined with product quality.
There has been considerable effort devoted to the development of hydrocracking catalysts which combine high cracking activity with a low tendency to overcrack towards light products and, in particular, to the less valuable C
1
-C
3
and C
4
gaseous by-products.
Kerosine or gas oil (middle distillates) are often the desired products of a hydrocracking process. However, hydrocracking catalysts with a high selectivity towards middle distillates tend to have a low cracking activity. Such catalysts are typically based on a single, active cracking component such as an aluminosilicate, especially a Y zeolite component.
It is known, e.g. from International (PCT) Patent Specifications Nos. WO 91/17829, WO 92/09366 and WO 97/20016, to form composites of two different cracking components, e.g. Y zeolite and zeolite beta aluminosilicates, for use in hydrocracking, or other hydro or chemical conversion processes. Such composite catalysts are commonly prepared by the conventional techniques of combining the active cracking component(s) with a binder or binder-forming material and then extruding the mixture, drying the extrudates so-formed and calcining. Specifically the combination of materials is carried out by co-mulling the ingredients together in mix-muller equipment, usually with water and a peptising agent.
SUMMARY OF THE INVENTION
It has now been found that by an improved preparation technique, composite catalysts can be obtained having an improved hydrocracking activity coupled with a good middle distillate selectivity and a significantly reduced level of undesirable gaseous (C
1
-C
3
and C
4
) by-products.
The present invention provides a process for the preparation of a catalyst composition which comprises, as first cracking component, a zeolite beta, and a second cracking component selected from (i) crystalline molecular sieves having pores with diameters greater than 0.6 nm, (ii) clays, and (iii) amorphous cracking components, the process comprising the steps of:
(a) preparing a mixture comprising the first cracking component and a gelatin material, and mixing intimately,
(b) mulling with the second cracking component, and
(c) extruding the mixture of step (b) into catalyst extrudates, and calcining the extrudates.
DETAILED DESCRIPTION OF THE INVENTION
The essential ingredient of the improved process of the invention is the use of a gelatin material prior to mulling with the second cracking component in the preparation of the composite catalyst.
Gelatin (also termed gelatine) itself is the preferred material to be used. However, equivalent organic or synthetic materials, which act in a similar manner are also encompassed by the present invention.
By the term “gelatin material” there is therefore to be understood a natural or synthetic polymer material which acts similarly to gelatin, a polymer which swells in the presence of water and becomes fully water-soluble at a temperature of above 35° C. Materials that can be expected to act similarly to gelatin include, for example, complex organic polymeric materials such as polypeptide derivatives, e.g. collagen, and polysaccharide derivatives, e.g. agar. Most commercial gelatins contain molecular species, being complex polypeptide molecules, having a molecular weight in the range of from 15,000 to 250,000, and are derived from animal (bovine or porcine) or fish skin.
Most grades of gelatin or equivalent may be used in the process of the invention, whether as a coarse grained or fine powder, or in a liquid formulated form, or in a natural or synthetic form. It is believed, however, that cross-linked forms would not be useful in the present invention.
The gelatin material may thus be used in the process of the invention in dry form or as a liquid formulation. In the latter, the gelatin material is conveniently used in an aqueous suspension or solution. Water conveniently is used as suspension base or as solvent. Other aqueous materials may be used, e.g. aqueous polyhydric alcohols, but are less preferred. If the gelatin material is used in dry form then a suitable aqueous medium should also be used in step (a) of the process. The preferred aqueous medium for use with the gelatin material is water. When used as a liquid formulation, preferably there is in the range of from 40:60 to 60:40, of gelatin material to aqueous medium, especially about 50:50 gelatin material to medium, on a weight basis. Particularly preferred gelatin material for use in the present invention is a liquid formulation of gelatin in water, especially one containing in the range of from 40 to 60% by weight of gelatin, such as that sold by the Sigma-Aldrich family of companies.
The amount of gelatin material used is not believed to be critical. The preferred aqueous formulation is suitably used in the present process in an amount in the range of from 0.1:1 to 1:1 g/g gelatin formulation to first cracking component; especially in a weight ratio of about 1:2 of aqueous gelatin formulation to first cracking component.
The gelatin material and first cracking component are intimately or vigorously mixed. Such mixing is preferably accomplished using ultrasound techniques, for example at a frequency in the range of 10 to 30 kHz and a power of 220 W for a time period of at least 30 minutes and/or of at most 2 hours; and very suitably for about 40 minutes to about 1 hour. However any method in which mixing at near to molecular level can be achieved is suitable. For example, any method which provides hydrodynamic cavitation, such as high speed, high shear stirring is also suitable. High speed, high shear stirring can be achieved, for example, by use of equipment such as the “ultra-turrax” equipment sold by Janke+Kunkel GmbH.
The further preparation of the composite catalyst of the invention is carried out in conventional manner to incorporate the remaining ingredients. Thus, step (b) of the present process may conveniently be carried out by mulling the mixture from step (a) and the second cracking component, optionally together with binder, in the presence of water and a peptising agent, e.g. acetic acid or nitric acid, to form a mixture which is subsequently extruded into catalyst extrudates in step (c) and then calcined.
Step (c) of the present process may be effected using any conventional, commercially available extruder. In particular, a screw-type extruding machine may be used to force the mixture through orifices in a die plate to yield catalyst extrudates of the required form, e.g. cylindrical or trilobed. The strands formed on extrusion may then be cut to the appropriate length. If desired, the catalyst extrudates may be dried, e.g. at a temperature of from 100 to 300° C. for a period of 30 minutes to 3 hours, prior to calcination in step (c).
Calcination is conveniently carried out in air at a temperature in the range of from 300 to 800° C. for a period of from 30 minutes to 4 hours. Preferably, the calcination is effected at a temperature in excess of 450° C., especially at a temperature in the range of from 500 to 600° C.
The first and second cracking components of the composite catalyst may be any of such components noted as suitable for such composite catalyst formulations.
Thus the first cracking component may be any catalytically active zeolite beta—a crystalline zeolite described in US Patent Specification No. Re 28,341 or known from the Atlas of Zeolite Structure Types, 3rd Edition, published in 1992 on behalf of the Structure Commission of the International Zeolite Association. Particularly good results have been given with small crystal size zeolite beta. Suitably, the zeolite beta has a silica to alumina molar ratio of at least 20, preferably at least 25. Zeolite beta with a higher silica to alumina molar ratio, e.g. up to, and includin

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