Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
2000-05-16
2004-01-20
Nguyen, Ngoc-Yen (Department: 1754)
Mineral oils: processes and products
Refining
Sulfur removal
C208S25400R, C208S143000, C208S108000, C585S266000, C585S446000, C585S467000, C585S520000, C585S671000, C585S709000, C585S734000, C585S940000, C502S321000, C502S325000, C502S305000, C502S337000, C502S339000, C502S349000, C502S242000
Reexamination Certificate
active
06679986
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a catalytic support particularly appropriate for the manufacture of catalysts for the treatment of hydrocarbons, and comprises in particular at least one oxide of a metal from the SVI group of the Periodic Table of the Elements, in which is incorporated a small quantity of silica. The invention also comprises preferred methods for the preparation of such a support. Lastly, the invention comprises catalysts prepared from such a support, as well as the uses of these catalysts in reactions for the treatment of hydrocarbons, such as, for example, hydrodesulphurization, hydrodenitrogenation, hydrogenation, hydroisomerization reactions etc.
It is well known that the oil industry resorts to many procedures whose object is to selectively transform certain compounds that are present in the oil cuts in order to obtain products whose properties are suitable for the sought use. These procedures usually call for one or more solid catalysts which must be specifically adapted to the chemical transformation we wish to complete and to the requirements tied to the implementation of the procedure.
Many of these reactions are done in the presence of a somewhat significant quantity of hydrogen. This is the case, for example, in the hydrodesulphurization and hydrodenitrogenation reactions that are aimed at eliminating the undesirable compounds, sulphuretted and nitrogenated hydrocarbons respectively, from the oil cuts. It is also the case in reactions that take place in the isomerization procedure of paraffins, which applies essentially to high-gravity gasolines, whose octane number is higher.
In most of these procedures for the treatment of oil cuts, the catalysts traditionally used today consist essentially of a high porosity alumina support, on which is deposited an active phase that corresponds to the active sites of the catalyst. This active phase often consists of a function that favors the transfers of hydrogen (in particular a group VIII metal of the Periodic Table of the Elements), usually combined with another compound, specific to the sought activity, namely the reaction to be catalyzed.
However, in general, the activity of the traditional catalysts is now proving to be insufficient, taking into consideration the increasing requirements as far as performance of the industrial procedures are concerned. For example, nowadays it is essential to increase the efficiency of the hydrodesulphurization procedures in response to stricter and stricter environmental standards concerning the maximum content of sulphuretted compounds in fuels.
This is why many researches have been undertaken in order to develop new, more active catalysts that would make it possible to meet these objectives without having to significantly modify the existing units, which would then make it possible to avoid costly investments.
It is well known that the nature and properties of the support have a significant influence on the activity of a catalyst, and among other things the researchers have tired to replace the traditional alumina based supports with new supports, capable of conferring a greater activity on the catalysts. In particular, the oxides of the SVI group metals of the Periodic Table of the Elements, such as zirconia for example, quickly proved to be relatively interesting potential candidates.
As early as 1970, U.S. Pat. No. 3,686,095 mentions the theoretical possibility of replacing the alumina with zirconia or magnesia. However, this patent limits itself to describing a hydrodesulphurization catalyst consisting of an active phase (hydrogenating metal combined with a group VI metal) deposited on a support with a very high porosity consisting of an alumina mixed with silica, meaning a completely traditional type of alumina base catalyst. If it mentions, in a theoretical manner, the possible use of alternative oxides, it in no way describes how to effectively prepare supports consisting of such oxides that have enough porosity to serve as a base for the preparation of industrial catalysts.
Indeed, if the zirconia type oxides do have interesting properties, to date they have not proved to be very appropriate for the manufacture of supports of industrial catalysts, to the extent that obtaining an adequate porosity is the result of the loss of specific properties brought on by these oxides. Therefore, many attempts have been made to try and improve supports with bases of such oxides in order to turn them into catalytic supports that can be used in the industry.
Thus, U.S. Pat. No. 5,021,385 proposes a catalyst that consists of a support with a high porosity made of co-precipitated zirconia and titanium oxide, on which are deposited molybdenum oxide (2 to 30% by weight) and nickel or cobalt oxide (1 to 10% by weight) and possibly phosphorus.
The FR patent number 2,661,171 describes a synthesis procedure of a stabilized zirconia with a high specific surface, designed to serve as a support for a hydrotreating catalyst. The high porosity of this catalyst is obtained thanks to the impregnation, before the calcination, of the amorphous zirconia by a solution of a stabilizing element chosen from among yttrium, nickel, aluminum, titanium, and phosphorus.
U.S. Pat. No. 5,262,373 recommends the method called melted salt method for the preparation of a support with a zirconia, alumina, silica or titanium oxide base, alone or mixed; the preferred support contains zirconia, alone or mixed with alumina, and is designed, after depositing the nickel and the molybdenum, to serve as a hydrotreating catalyst.
FR patent number 2,709,432 claims a catalyst that contains a support with a specific surface that is greater than or equal to 150 m
2
/g, consisting of 60 to 99% by weight of zirconia and 1 to 40% by weight of oxide of at least one metal chosen from the group consisting of the metals of groups V, VI, VII, the noble metals such as ruthenium, osmium, rhodium, iridium, uranium, the phosphorous, arsenic and sulfur compounds. This support, essentially designed for hydrocarbon hydrotreating catalysts, is also prepared by the melted salts method.
In general, the catalysts proposed in the prior art as alternatives to the traditional catalysts on an alumina support have not proved to very satisfying because of their insufficient level of activity, meaning it is less than that of the traditional catalysts. Indeed, obtaining a high porosity of the support is done to the detriment of the additional activity brought by the metal oxide that is the alternative to the alumina. In other words, when we want to obtain a support that is sufficiently porous (which is indispensable to guarantee a good accessibility of the active sites to the molecules to be converted), we loose the specific catalytic properties that are the entire interest of theses metal oxides. This is why in general such catalysts are not currently used in industrial reactors.
SUMMARY OF THE INVENTION
In pursuing research in the field of catalysts with a zirconia base or other equivalent oxide base, the applicant has sought to act on the properties of these oxides. In doing so, it has been discovered that, surprisingly so, the zirconia or titanium oxide can become a material of choice that makes it possible to create excellent catalytic supports, provided its structure is of the crystalline type and is doped in an appropriate way with a small quantity of silica. Indeed it becomes possible to rigorously control all the characteristics of porosity without however losing the specific activity brought by these alternatives oxides. Thus the applicant has been able to develop industrial catalysts from a high porosity matrix, consisting essentially of metal oxides of the SVI group (of which zirconia and titanium oxide), where said catalysts have proved to have a level of activity that is greater when compared to the catalysts of the prior art.
Applicant has also discovered an original method of preparation that makes it possible to obtain such supports by controlling their porosity so as to obtain the desired active structures.
Thu
Bisson Marc
Da Silva Pedro
Decker Sebastien
Denayer Joeri
Milan Alain
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