Chemistry of hydrocarbon compounds – Adding hydrogen to unsaturated bond of hydrocarbon – i.e.,... – Hydrocarbon is aromatic
Reexamination Certificate
1999-05-06
2001-03-27
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Adding hydrogen to unsaturated bond of hydrocarbon, i.e.,...
Hydrocarbon is aromatic
C585S266000, C585S273000, C208S144000
Reexamination Certificate
active
06207870
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst for hydrotreating hydrocarbon containing feeds including at least one noble metal from group VIII and silicon as a doping element.
BACKGROUND OF THE INVENTION
Petroleum cuts, and in particular bases for fuels, gasolines, kerosines and gas oils, contain aromatic compounds the concentration of which has to be further and further reduced under new or future legislation limiting the amount of aromatic compounds in the above fuels.
Current processes for hydrogenating aromatic compounds in solvents or aromatic petroleum cuts such as kerosines or gas oils use noble metal type catalysts, for example platinum, deposited on an alumina support with a high specific surface area. However, such metals are highly sensitive to poisoning by sulphur-containing and nitrogen-containing compounds present in the feeds and thus such feeds have to be desulphurised and denitrogenated to a very great extent before treating them using a catalyst based on a noble metal.
It is thus important to produce aromatic compound hydrogenation catalysts in solvents or in aromatic petroleum cuts such as kerosines and gas oils which are highly active in the presence of sulphur and/or nitrogen and/or oxygen so as to reduce the severity of prior hydrotreatment and to achieve even higher degrees of hydrogenation.
Catalysts based on platinum and palladium have been described for the properties for hydrogenating aromatic compounds. In the case of using an alumina type support (United States patent U.S. Pat. No. 3,943,053), it is reported that it is necessary to precisely control the metal contents, as well as the preparation conditions. The use of supports based on silica-alumina has also been reported. Examples are U.S. Pat. No. 4,960,505, U.S. Pat. No. 5,308,814 and U.S. Pat. No. 5,151,172. Those catalysts are based on a highly specific zeolite and have the disadvantage of requiring selective deposition of noble metals onto the zeolite.
SUMMARY OF THE INVENTION
The present invention relates to a catalyst including at least one noble metal from group VIII (group 8, 9 and 10 in the new notation for the periodic table: Handbook of Chemistry and Physics, 76th edition, 1995, inside front cover), i.e., at least one metal selected from ruthenium, rhodium, palladium, osmium, iridium and platinum, associated with a porous matrix. The catalyst is characterized in that it includes silicon as a doping element. The catalyst also optionally includes boron, optionally phosphorous, optionally at least one group VIB element (group 6) and optionally at least one group VIIA element (group 17, the halogens).
The present invention also relates to processes for preparing the catalyst, and to its use in petroleum cut refining processes.
More particularly, the catalyst of the present invention can be used for hydrogenating aromatic compounds or for dearomatisation of aromatic compounds, or to reduce aromatic compounds in petroleum cuts containing, in particular, aromatic compounds and small quantities of sulphur and/or nitrogen and/or oxygen.
The invention thus relates to a catalyst with a strong hydrogenating phase and moderate acidity. The catalyst comprises at least one group VIII noble metal such as ruthenium, rhodium, palladium, osmium, iridium or platinum. The catalyst also comprises at least one support selected from the group formed by amorphous or low crystallinity supports. The catalyst is characterized in that it also comprises silicon as a doping element. The catalyst can also optionally contain boron, optionally phosphorous, optionally at least one group VIB element, preferably selected from molybdenum and tungsten, and optionally at least one group VIIA element, preferably two group VIIA elements, preferably chlorine and fluorine.
Said catalyst has, for example, an activity for hydrogenation of aromatic hydrocarbons in the presence of sulphur and/or nitrogen and/or oxygen which is higher than known prior art catalytic formulations. Without wishing to be bound to a particular theory, it appears that the improved properties of the catalysts of the present invention are due to reinforcing the acidity of the catalyst by the presence of silicon introduced into the matrix as a dopant. This increased acidity induces a better resistance of the active phase of the catalyst to poisoning by the sulphur and/or nitrogen and/or oxygen and thus improves the hydrogenating properties of the catalyst.
The catalyst of the present invention generally comprises at least one metal selected from the following groups and with the following contents, in weight % with respect to the total catalyst weight:
0.01% to 5%, preferably 0.01% to 2%, of at least one group VIII noble metal, preferably platinum, ruthenium or palladium;
0.1% to 97%, preferably 1% to 95%, of at least one support selected from the group formed by amorphous matrices and low crystallinity matrices, said catalyst being characterized in that it also comprises:
0.1% to 40%, preferably 0.1% to 30%, more preferably 0.1% to 20%, of silicon, (the % being expressed as % of oxides), and optionally:
0 to 20%, preferably 0.1% to 20%, of boron (the % being expressed as % of oxides);
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of phosphorous (the % being expressed as % of oxides);
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one group VIIA element, preferably chlorine and fluorine;
0 to 3 %, preferably 0.1% to 3%, of at least one element selected from group VIB, preferably molybdenum or tungsten (the % being expressed as % of oxides).
The noble group VIII metals and the optional group VIB metals in the catalyst of the present invention can be completely or partially present in the form of the metal and/or oxide and/or sulphide.
The catalysts of the invention can be prepared using any suitable method. Preferably, the silicon and optional boron are introduced into the catalyst already comprising the support and the noble group VIII metal or metals. Preferably, a catalyst is impregnated with a solution, for example an aqueous solution, of silicon and optionally by a solution, for example an aqueous solution, of boron (in any order) or it is impregnated with a common solution, for example an aqueous solution, of boron and silicon when the catalyst contain silicon and boron.
More particularly, the process for preparing the catalyst of the present invention comprises the following steps:
a) weighing a solid hereinafter termed the precursor, comprising at least the following compounds: a porous amorphous and/or low crystallinity matrix, at least one noble group VIII element, optionally at least one group VIIA element, optionally phosphorous, optionally boron, and optionally at least one group VIB metal, the whole preferably being formed;
b) impregnating the solid precursor defined in step a) with at least one solution containing silicon;
c) leaving the moist solid in a moist atmosphere at a temperature in the range 10° C. to 180° C.
d) drying the moist solid obtained in step c) at a temperature in the range 60° C. to 150° C.;
e) calcining the solid obtained from step d) at a temperature in the range 150° C. to 800° C.
The precursor defined in step a) above can be prepared using any conventional methods known to the skilled person.
The silicon, optional boron, optional phosphorous, and optional element selected from group VIIA, the halogens, preferably chlorine and fluorine, can be introduced into the catalyst at various stages of the preparation and in a variety of manners.
The matrix is preferably impregnated using the “dry” impregnation method which is well known to the skilled person. Impregnation can be carried out in a single step using a solution containing all of the constituent elements of the final catalyst.
The phosphorous, boron, silicon, and elements selected from the halogens (group VIIA) can be introduced into the calcined precursor by one or more impregnation operations using an excess of solution.
Thus, for example, in the preferred case where the precursor is a platinum-palla
Harle Virginie
Kasztelan Slavik
Marchal-George Nathalie
Mignard Samuel
Griffin Walter D.
Institut Francais du Pe'trole
Millen White Zelano & Branigan
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