Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Halogen or compound containing same
Reexamination Certificate
2000-11-09
2002-07-23
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Halogen or compound containing same
C502S230000, C502S328000, C502S330000, C502S243000, C502S245000, C502S250000, C502S252000, C585S269000, C585S270000, C585S275000, C585S277000
Reexamination Certificate
active
06423664
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a supported catalyst based on a group VIII metal and an additional metal and comprising at least two halogens. The invention also relates to the use of this catalyst in a process for hydrotreating hydrocarbon-containing feeds containing small amounts of sulphur and in particular for hydrogenating aromatic compounds contained in such feeds.
Hydrotreatment processes are routinely used in operations for refining petroleum cuts to improve the characteristics of the finished products in terms of the specifications required to satisfy product quality and pollution requirements. Currently, gas oil cuts, whether from distillation or from a conversion process such as catalytic cracking, contain non negligible quantities of aromatic compounds, nitrogenated compounds and sulphurated compounds. The current legislation in the majority of industrialised countries requires that fuel for use in engines must contain less than 500 parts per million (ppm) of sulphur. In the very near future, this maximum quantity will be reduced to 350 ppm by 2000 then to 50 ppm for 2005 for the member states of the European community. Regarding the polyaromatic compound content in gas oils, this amount is in danger of being reduced to a very low level (of the order of 1% to 2%) from 2005. Thus hydrogenating the polyaromatics contained in gas oil cuts is becoming increasingly important because of the new sulphur and aromatic compound specifications for that type of fuel.
Desulphurisation is generally carried out under conditions and for catalysts that are not capable of simultaneously hydrogenating aromatic compounds. Thus a first treatment of the cut has to be carried out to reduce the sulphur content followed by a second treatment to hydrogenate the aromatic compounds contained in that cut. That second step is generally carried out by bringing the cut into contact with a catalyst generally based on a noble metal, in the presence of hydrogen. However, because the desulphurisation process can never completely eliminate the sulphurated and nitrogenated compounds, the catalysts used must be capable of operating in the presence of such compounds and as a result must have active phases with good thio-resistant properties.
The aim of the present invention is to provide a novel catalyst for desulphurising petroleum cuts and hydrogenating aromatics and polyaromatics present in those cuts.
PRIOR ART
Catalysts with thio-resistant properties which are known to the skilled person essentially include catalysts based on a noble group VIII metal or on a combination of such metals supported on an alumina type acid support (United States patent U.S. Pat. No. 3,943,053), silica alumina and zeolite (U.S. Pat. Nos. 4,960,505, 5,308,814 and 5,151,172). However, noble metals are extremely sensitive to the presence of sulphur that is a powerful inhibitor of the activity of noble metals. To avoid poisoning by the sulphur in the hydrogenating phase, it appears preferable that the metals are deposited on an acid support. Thus the use of a limited quantity of halogen such as chlorine or fluorine to increase the acidity of platinum/alumina type catalysts has been reported (J. P Frank, J. C. Marquis and M. Derrien, CR Acad. Sci. Paris, Series C, 1284 (1977), 297, and J. Cosyns, J. P. Frank and G Marin-Gil, CR Acad. Sci. Paris, Series C, t284 (1978) 85).
When using an alumina type support (U.S. Pat. No. 3,943,053), it has been reported that the quantities of metal have to be precisely controlled as well as the preparation conditions. This constraint causes obvious problems as regards flexibility when extrapolating such formulations to an industrial scale. The use of supports based on silica-alumina has also been reported. Examples which can be cited are U.S. Pat. Nos. 4,960,505, 5,308,814 and 5,151,172. Those different documents disclose that the type of zeolite for producing the desired properties is highly specific. Further, the use of such supports has some major disadvantages, including preparation, which includes a forming step requiring the use of mineral binders such as aluminas. The preparation methods must thus allow selective deposition of noble metals on the zeolitic material over deposition on the binder, which has an additional specificity linked to such a catalyst type.
Many patents describe metal catalysts comprising at least one halogen for use in processes for hydrogenating aromatic compounds. In particular, European patent application EP-A-0 751 204 describes a process for hydrogenating aromatic compounds with injection of chlorine into a catalyst based on a noble metal and containing at least 1% of a halogen to increase the hydrogenating activity of the catalyst.
U.S. Pat. No. 3,943,053 describes a method for hydrogenating aromatic compounds using a catalyst comprising two noble metals, namely platinum and palladium, and a quantity of chlorine in the range 1.2% to 2.5% by weight.
European patent application EP-A-0 955 090 describes a catalyst comprising two noble metals (Pt and Pd), fluorine and chlorine. The catalytic composition is such that the fluorine content is in the range 0.5% to 1.5% by weight and the chlorine content is in the range 0.3% to 2% by weight.
SIGNIFICANCE OF THE INVENTION
The Applicant has discovered that a catalyst used in hydrotreatment processes and in particular for hydrogenating aromatic compounds, comprising at least one metal from group VIII of the periodic table, at least one additional metal, at least two halogens, including chlorine and fluorine, and at least one amorphous oxide matrix, the catalytic composition being such that the quantity of fluorine represents at least 1.5% by weight of the total catalyst mass results in better performances as regards the degree of hydrogenation of the aromatic compounds than prior art catalysts comprising either a single metal or a small amount of halogen. The high degree of conversion of the aromatic compounds to the corresponding saturated compounds obtained with the catalysts of the invention is linked to the surprising synergistic effects of the combination of metals on the one hand and the combination of halogens present in higher quantities than in the prior art on the other hand. This high degree of hydrogenation results in very good resistance to sulphur for the catalyst, such that the activity of the catalyst is not affected by small residual amounts of sulphur in the teed to be treated.
The additional metal can be a metal from group IB of the periodic table, a metal from group IIB or a metal from group VIIB.
The catalyst of the present invention can advantageously be used to carry out hydrodesulphurisation and hydrogenation of aromatic compounds present in hydrocarbon feeds comprising sulphurated compounds. More particularly, the hydrocarbon feeds which can be treated using the catalyst of the invention are hydrocarbon feeds containing aromatic compounds, more particularly gas oil cuts from distilling crude oil and various processes for converting cuts known as cycle oils from catalytic cracking processes.
The invention also concerns the use of the catalyst in a process for hydrogenating aromatic compounds present in hydrocarbon cuts comprising sulphur. The sulphur content of feeds that can be treated using the process of the invention is less than 2000 ppm by weight, preferably 0.01 to 500 ppm by weight.
This catalyst may also be suitable for any process aimed at hydrogenating all or a portion of the aromatic compounds of a feed containing traces of sulphurated compounds, such as hydrogenating aromatic compounds in food oils and in solvents.
DESCRIPTION OF THE INVENTION
The catalyst of the invention contains at least one amorphous oxide matrix, at least one metal from group VIII of the periodic table, at least one additional metal and at least two halogens, including chlorine and fluorine.
The term “amorphous oxide matrix” as used below means a matrix with no elements that are catalytically active contained in its structure.
The catalyst of the invention is characterized in that the qua
Kasztelan Slavik
Marchal-George Nathalie
Bell Mark L.
Hailey Patricia L.
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
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