Chemistry of hydrocarbon compounds – Adding hydrogen to unsaturated bond of hydrocarbon – i.e.,... – Hydrocarbon is aromatic
Reexamination Certificate
2000-08-01
2002-09-03
Silverman, Stanley S. (Department: 1754)
Chemistry of hydrocarbon compounds
Adding hydrogen to unsaturated bond of hydrocarbon, i.e.,...
Hydrocarbon is aromatic
C585S269000, C208S143000, C208S217000, C208S178000
Reexamination Certificate
active
06444865
ABSTRACT:
The present invention relates to a catalyst composition and to its use in hydroconversion processes, wherein a hydrocarbon oil comprising aromatic compounds is contacted with hydrogen in the presence of such a catalyst composition. A process for the preparation of the catalyst composition also forma part of the present invention.
Hydrotreating catalysts are well known in the art. Conventional hydrotreating catalysts comprise at least one Group VIII metal component and/or at least one Group VIB metal component supported on a refractory oxide support. The Group VIII metal component may be either based on a non-noble metal, such as nickel (Ni) and/or cobalt (Co), or may be based on a noble metal, such as platinum (Pt) and/or palladium (Pd). Useful Group VIB metal components include those based on molybdenum (Mo) and tungsten (W). The most commonly applied refractory oxide support materials are inorganic oxides such as silica, alumina and silica-alumina and aluminosilicates, such as modified zeolite Y. Specific examples of conventional hydrotreating catalysts are NiMo/alumina, CoMo/alumina, NiW/silica-alumina, Pt/silica-alumina, PtPd/silica-alumina, Pt/modified zeolite Y and PtPd/modified zeolite Y.
Hydrotreating catalysts are normally used in processes wherein a hydrocarbon oil feed is contacted with hydrogen to reduce its content of aromatic compounds, sulphur compounds and/or nitrogen compounds. Typically, hydrotreating processes wherein reduction of the aromatics content is the main purpose are referred to as hydrogenation processes, whilst processes predominantly focusing on reducing sulphur and/or nitrogen content are referred to as hydrodesulfurization and hydrodenitrogenation, respectively. Current environmental standards require that both aromatic content and sulphur and nitrogen content of i products are very low and it is generally expected that specifications for aromatics, sulphur and nitrogen will become more and more severe in the future. Accordingly, in the refining of hydrocarbon oil fractions the ability to deeply hydrogenate, deeply hydrodesulphurise and deeply hydrodenitrogenate will become increasingly important.
Effective hydrogenation of monoaromatic compounds normally is difficult to achieve with the traditional hydrotreating catalysts. Conventional, dedicated aromatics hydrogenation catalysts, on the other hand, generally have a relatively low sulphur and/or nitrogen tolerance, so that they exhibit poor hydrogenation activity in the presence of substantial amounts of sulphur- and/or nitrogen-containing compounds. For this reason the conventional way for reducing the amounts of aromatics and sulphur- and nitrogen-containing compounds is a two-stage process with a first hydrodesulfurization and/or hydrodenitrogenation stage and, normally after removal of the hydrogen sulphide and ammonia formed, a second stage for hydrogenating the aromatics still left.
The present invention aims to provide a hydrotreating catalyst which exhibits an excellent aromatics hydrogenation activity, whilst at the same time having an excellent hydrodesulfurization and/or hydrodenitrogenation activity. This, consequently, implies that the catalyst composition should be able to effectively promote the hydrogenation of aromatics in the presence of substantial quantities of sulphur- and nitrogen-containing compounds. The present invention moreover aims to provide a hydrotreating catalyst exhibiting an excellent hydrogenation activity towards monoaromatics. It will be understood that the use of such a catalyst in a hydrotreating process offers an increased potential for meeting future low-content specifications for (mono)aromatics, sulphur and nitrogen.
Accordingly, the present invention in a first aspect relates to a catalyst composition comprising from 0.1 to 15% by weight of a noble metal selected from one or more of platinum, palladium and iridium, and from 2 to 40% by weight of manganese and/or rhenium, said weight percentages indicating the amount of metal based on the total weight of carrier, supported on an acidic carrier.
Manganese and rhenium both belong to Group VIIB of the Periodic Table of Elements. The third Group VIIB metal, technetium, is not useful due to its instability as will be appreciated by those skilled in the art. The catalytically active metals, i.e. platinum and/or palladium and/or iridium on the one hand and manganese and/or rhenium on the other hand, may be present in elemental form, as an oxide, as a sulphide or as a mixture of two or more of these forms. As will be discussed in detail hereinafter, a suitable preparation method used to prepare the present catalyst includes a final step of calcination in air, which will cause the catalytically active metals to be at least partially converted into their oxides. Usually such final calcination step will cause substantially all catalytically active metals to be converted into their oxides. If the catalyst is subsequently contacted with a sulphur-containing feed, then at least a part of these oxides will be sulphided and hence converted into the corresponding sulphides (“in situ” sulphidation). Very good catalyst performance has been observed in this situation and therefore it is considered a preferred embodiment of the present invention to have the catalytically active metals at least partly present in the catalyst as sulphides. Accordingly, the catalyst may also be subjected to a separate presulphiding treatment prior to being contacted with the feed. The degree of sulphidation of the metal oxides can be controlled by relevant parameters such as temperature and partial pressures of hydrogen, hydrogen sulphide, water and/or oxygen.
The metal oxides may be completely converted into the corresponding sulphides, but suitably an equilibrium state between the oxides and sulphides of the catalytically active metals will be formed, so that the catalytically active metals are present both as oxides and as sulphides.
As will be discussed in more detail below, the catalyst according to the present invention can suitably be used in a variety of hydroconversion processes. The catalyst has been found to be particularly useful in the hydrotreatment of gas oils, thermally and/or catalytically cracked distillates (such as light cycle oils and cracked cycle oils) and mixtures of two or more of these. These oils usually contain a relatively large amount of aromatic compounds, sulphur-containing compounds and nitrogen-containing compounds. The amounts of such compounds must usually be reduced in view of environmental regulations. Aromatic compounds reduction may also be desirable for reaching certain technical quality specifications, such as cetane number in the case of automotive gas oils, smoke point in the case of jet fuels and colour and stability in the case of lub oil fractions. When using the catalyst according to the present invention in the hydrotreatment of gas oils, thermally and/or catalytically cracked distillates and mixtures of two or more of these, the required reduction for e.g. meeting automotive gas oil specifications can be attained in a single stage. It has been found that the catalysts of the present invention are especially active in reducing the amount of mono-aromatics in the final product, even in the presence of substantial amounts of sulphur- and nitrogen-containing compounds.
The catalyst according to the present invention comprises as catalytically active metals from 0.1 to 15% by weight of platinum and/or palladium and/or iridium and from 2 to 40% by weight of manganese and/or rhenium. If lower amounts of catalytically active metals are applied, the activity of the catalyst becomes too low to be commercially attractive. If, on the other hand, the amount of catalytically active metals is higher than the upper limits indicated, the further increase in catalytic activity does not warrant the costs of the extra amount of metal. This applies in particular for platinum and palladium. Good results can be obtained with catalysts comprising from 3 to 10% by weight of noble metal, i.e. platinum and/or palladiu
Barre Guy
Mahtout Taous Grandvallet
Nguyen Cam N.
Shell Oil Company
Silverman Stanley S.
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