Cogel containing oxidic compounds of tetravalent, trivalent,...

Details Cogel containing oxidic compounds of tetravalent, trivalent,... Cogel containing oxidic compounds of tetravalent, trivalent,...

2001-02-20

2003-03-25

Griffin, Walter D. (Department: 1764)

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Cracking

C208S111100, C208S111250, C208S111300, C208S111350, C208S21600R, C208S2160PP, C208S217000, C208S25100H, C208S25400R, C208S143000, C208S144000, C208S135000, C208S136000, C208S137000, C502S234000, C502S235000, C502S236000

Reexamination Certificate

active

06537442

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
This application is based on PCT International Filing Number PCT/EP99/05818, having International Filing date Jun. 24, 1999 which claims priority from European Application Serial No.: EP98202185.9, filed Jun. 29, 1998 and European Application Serial No. 98202600.7, filed Jul. 31, 1998, all of which are incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to cogels of various metallic elements, alumina process for preparing said cogels, catalysts comprising these cogels, a process for preparing such catalysts, and the use of such catalysts for hydroprocessing applications.
2. Prior Art
In the past, synthetic clays have been synthesized by hydrothermal crystallization of a mixture of clay material precursors. This hydrothermal treatment is carried out in an autoclave at high pressures and temperatures with reaction times in the order of several hours to several days. Such a treatment is described, e.g., in U.S. Pat. No. 3,844,978, EP-A-0224 182, and in J. T. Kloprogge et al.,
Clays and Clay Minerals
, Vol. 41, No. 1, 1993, pages 103-110. The last reference describes materials comprising 36-100% saponite with the balance being an amorphous cogel of oxidic compounds of silicon, aluminum, and magnesium. These materials are characterized by relatively low surface areas in the range of 166-375 m
2
/g (after calcination at 550° C.). Especially the materials with low saponite contents are characterized by very low surface areas below 300 m
2
/g (after calcination at 550° C.).
The synthesis of clay minerals via hydrothermal crystallization is technically relatively difficult and time-consuming. Therefore, in recent years a great deal of research has been done to develop synthetic clay materials, which are obtainable without using hydrothermal crystallization techniques. WO 96/07613 describes the preparation of such synthetic clay minerals by bringing the pH of an aqueous liquid containing precursors for the clay to be prepared to a value of 3-9 and the temperature of the liquid to a value of from 60° to 350° C. Both the temperature and the pH are maintained at said range for the time required for the formation of the clay mineral. The time required depends on the temperature applied: at lower temperatures of 60°-125° C., times of 5 to 25 hours are necessary, whereas at temperatures in the range of 150° C. and higher, times in the order of some minutes to approximately 2.5 hours may suffice. However, as can be deduced from the Examples of said reference, to obtain the desired clay minerals, usually times in the order of 7 to 48 hours must be applied. The resulting clays have a crystalline structure with distinct peaks in the X-ray diffraction pattern at about 2&THgr;≈20°, 2&THgr;≈35° and 2&THgr;≈60°. They are made up of elementary three-layer platelets with dimensions from 0.01 &mgr;m to 1 &mgr;m, which are optionally stacked to up to 20 platelets. One particular example of such a clay material is a saponite, which is a clay in which the tetravalent silicon ions of the tetrahedron layers are at least partly replaced by trivalent aluminum ions and in which the octahedral layer contains divalent ions almost exclusively. The deficiency of positive charge which results from the replacement of the silicon ions by aluminum ions is compensated by including cations (“counter-ions”) between the platelets.
The use of these synthetic clay minerals as cracking component in catalytic applications is described in WO 96/07477. There, catalysts are disclosed which at least comprise a hydrogenation metal component and a swelling synthetic clay. The catalyst is suitable for hydroprocessing of hydrocarbon feeds.
A disadvantage of the clay minerals of WO 96/07613 is their poor filterability, which typically is above 2000 s, expressed as normalized filtration time. Because of this low filterability, the generally required washing step of the resulting precipitated clay mineral is difficult to apply on a technical scale. It is therefore an object of the present invention to provide clay-like materials with good filterability which are suitable as, e.g., cracking components in hydroprocessing catalysts.
If clay minerals are used as cracking component in catalysts, it is essential that they comprise Brønsted acid groups, since these are at least partially responsible for the cracking ability of these compounds. Brønsted acid sites can be achieved by replacing the non-hydrolyzable counter-ions (such as sodium or potassium cations) by ammonium ions which compensate the deficiency of positive charge of the clays and then heating the whole. This process will result in ammonia desorption, leaving a proton to form a Brønsted site. Brønsted sites can also be introduced by replacing the counter-ions with hydrolyzable metal ions. Hydrolysis will then give hydrogen ions.
It must be noted that this introduction of acidic Brønsted sites is only possible if the material possesses an overall negative charge and, consequently, exchangeable counter-ions which can be replaced by ammonium ions or hydrolyzable metal ions. In other words, a material can only be used as cracking component if it is characterized by a cation-exchange capacity (CEC), i.e. if it possesses cations which can be exchanged, e.g., with ammonium ions. To obtain a final catalyst with sufficient cation-exchange capacity, it is therefore necessary that the cracking component which is incorporated into the catalyst has a sufficiently high cation-exchange capacity.
Further, as catalysts to be used in hydroprocessing are generally calcined prior to use and are subject to relatively high temperatures during use and regeneration, it is preferred that the cation-exchange capacity of the cracking components is not dramatically reduced when being subjected to high temperature.
As mentioned above, the clay minerals prepared in WO 96/07477 such as saponites contain exchangeable counter-ions. However, due to the poor filterability of the clay minerals, such an exchange takes a long time and is therefore difficult to perform on a commercial scale. A further object of the present invention therefore consists of the provision of easily filterable clay-like materials with high cation-exchange capacities in which a substantial amount of the counter-ions compensating the deficiency of positive charge: of the clay-like materials has been replaced by hydrogen ions or counter-ions which can generate hydrogen ions.
One further important characteristic of a cracking component is its surface area. For good catalytic performance, a high surface area is essential. To obtain a final catalyst with sufficient catalytic performance, it is therefore necessary that the cracking component which is incorporated into the catalyst has a sufficiently high surface area. Further, for the same reasons as given with respect to the cation-exchange capacity, it is preferred that the surface area of the cracking components is not dramatically reduced when being subjected to high temperature.
References dealing with various cogels include EP0097047, NL 7501204, U.S. Pat. No. 2,935,483 and DD 0152331.
SUMMARY OF THE INVENTION
Cogel of the Present Invention
Surprisingly, it has now been found that all the above-mentioned characteristics can be achieved with a cogel comprising oxidic compounds of one or more trivalent metallic elements selected from the group of aluminum, borium, gallium, chromium, iron, cobalt, manganese, vanadium, molybdenum, tungsten, indium, rhodium, scandium, or mixtures thereof, oxidic compounds of one or more tetravalent metallic elements selected from the group of silicon, titanium, germanium, or mixtures thereof, and oxidic compounds of one or more divalent metallic elements with at least one divalent element not selected from Group VIII non-noble metallic elements, wherein
a) the cogel is essentially X-ray amorphous apart from saponite, if present;
b) the saponite content C
A
of the cogel is less than 60 wt. %;
c) the cogel has a surface area of at least 4

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