Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2002-05-03
2003-02-25
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S327000, C502S332000, C502S333000, C502S334000, C502S339000, C502S340000, C502S407000, C502S439000, C502S252000
Reexamination Certificate
active
06524993
ABSTRACT:
TECHNICAL FIELD TO WHICH THE INVENTION BELONGS
The present invention relates to a hydrogenation catalyst for aromatic hydrocarbons contained in hydrocarbon oils, and relates particularly to a hydrogenation catalyst for aromatic hydrocarbons contained in hydrocarbon oils which has a low hydrocracking ratio, high resistance to poisoning by sulfur hydrocarbons and the like, and high hydrogenation activity.
BACKGROUND OF THE INVENTION
The light gas oil used for fuel in diesel engines is prepared as a blend of mainly a light gas oil obtained by performing hydrodesulfurization and denitrogentation processing on a straight run light gas oil fraction having a specific boiling point range obtained by atmospheric distillation of crude oil, and a light gas oil fraction obtained by vacuum distillation.
However, because the volume of the light gas oil fraction in the crude oil is limited, and crude oil becomes heavier over time, the straight run light gas oil fraction obtained by atmospheric distillation tends to reduce in volume. Furthermore, because the demand for light gas oil is increasing in accordance with an increase in the production of diesel engines, a shortage in the supply of light gas oil is anticipated in the near future.
As a result, measures such as adding a cracked or hydrogenated and desulfurized heavy gas oil to the light gas oil fraction, or increasing the production of blend oils which can be added to straight run light gas oil fractions are being considered.
In the case of blend oils which can be added to a straight run light gas oil fraction, light cycle oil having a specific boiling point range obtained from a fluid catalytic cracker is drawing considerable attention as a new blend oil for light gas oil.
However, because the light cycle oil contains a large amount of aromatic hydrocarbons, adding the light cycle oil with these characteristics directly to the straight run light gas oil fraction causes the cetane index of the thus obtained light gas oil to be lowered substantially.
Furthermore, in terms of the standards for aromatic hydrocarbon content within light gas oil fuel, it is anticipated that, in the future, a further reduction of the amount of aromatic hydrocarbons included in light cycle oil to below current levels will be required by law. This is because air pollutants such as particulates in the exhaust gas of diesel engines which contains aromatic hydrocarbons, and specifically the particulate matter which occurs due to the incomplete combustion of a portion of the aromatic hydrocarbons, cause environmental problems. Strict regulations are already in place in Sweden and in California, USA regarding the content of aromatic hydrocarbons in light gas oil.
In order to use the light cycle oil as a blend oil, it is desirable that the aromatic hydrocarbon content be reduced by performing catalytic hydrogenation on the light cycle oil. The sulfur compound content of light cycle oil is low compared with straight run light gas oil fractions, but the hydrogen sulfide produced during hydrogenation of the sulfur compound in there oils may cause a deterioration in activity by inhibiting the hydrogenation of the aromatic hydrocarbons and poisoning active sites of the hydroprocessing catalyst. Consequently, a hydrogenation catalyst for light cycle oil must have high hydrogenation activity and sulfur resistance with respect to aromatic hydrocarbons, and also have desulfurization capabilities.
Among hydrogenation catalysts, catalysts wherein a Group VIII metal is supported by a carrier such as alumina generally have high hydrogenation activity and are effective catalysts, but they suffer in that they deactivate early by being poisoned by the sulfur compounds and the like in the hydrocarbon oils. In order to overcome this problem, an attempt to perform hydrogenation using a catalyst containing zeolite in the carrier is described in Japanese Patent Publication No. Toku Kai Sho 64-66292, and Japanese Patent Publication No. Toku Hyo Hei 8-509999. However, although zeolite is a catalyst with high hydrocracking activity, in hydroprocessing, a hydrocracking occurs at the same time. Because the liquid yield of the light gas oil fraction decreases if a hydrocracking occurs during the hydroprocessing of light cycle oil, it is necessary to suppress hydrocracking activity as much as possible. In addition, the catalyst is poisoned by the high concentration of sulfur compounds and the like contained in the crude oil, and the hydrogenation activity with respect to the aromatic hydrocarbons remains unsatisfactory.
Furthermore, an attempt to perform hydroprocessing using a catalyst comprising a crystalline clay mineral having silicon and magnesium as its main components is disclosed in Japanese Patent Publication No. Toku Kai Hei 8-283746. However, while this method did have the effect of suppressing hydrocracking and raising the yield of the oil product, the hydrogenation activity with respect to the aromatic hydrocarbons remains unsatisfactory.
Generally, catalysts are formed with either comparatively large pores of greater than several dozen nm, or conversely with small pores of less than several dozen nm, and/or with a combination of comparatively large pores of greater than several dozen nm and small pores of less than several dozen nm. The balance of these pore capacities has a large influence on the targeted hydrogenation activity.
The pore characteristics are measured using a mercury porosimetry method for sizes ranging from 4 to 46800 nm, a nitrogen adsorption-DH method for sizes ranging from 2 to 200 nm, and a nitrogen adsorption-t-plot method for sizes ranging from 0.7 to 2 nm. The nitrogen adsorption-DH method and the nitrogen adsorption-t-plot-method are analysis methods based on adsorption isotherms obtained by nitrogen adsorption measurements, and the term “measurement” in the present specification includes obtaining physical properties by means of this type of analysis.
The pore characteristics of the catalyst, for example, the total volume of pores sized from 0.7 to 2 nm contained in 1 g of catalyst is referred to as “the 0.7 to 2 nm pore volume” and is expressed in units of ml/g.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a catalyst which resolves the problems described above associated with conventional catalysts, which is suitable for hydrogenation of hydrocarbon oils containing sulfur compounds and the like, and particularly light gas oil fractions, to reduce the aromatic hydrocarbon content, and which has high resistance to sulfur compounds, high hydrogenation activity, and moreover produces an oil product with a high liquid yield.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A hydrogenation catalyst of the present invention is a hydrogenation catalyst for hydrocarbon oils containing aromatic hydrocarbons, wherein the catalyst comprises a carrier and an active metal, and the pore characteristics of the catalyst are such that the volume of pores with a pore size of at least 4 nm as measured by a mercury porosimetry method is within a range from 0.3 to 0.6 ml/g, the volume of pores with a pore size of at least 200 nm is no more than 0.05 ml/g, the volume of pores with a pore size from 0.7 to 2 nm as measured by a nitrogen adsorption-t-plot method is within a range from 0.2 to 0.3 ml/g, and the volume of pores with a pore size from 2 to 4 nm as measured by a nitrogen adsorption-DH method is within a range from 0.15 to 0.2 ml/g.
Preferably the hydrocarbon oil contains 80 weight percent or more of a fraction with a boiling point of 170 to 390° C.
Preferably the hydrogenation catalyst for hydrocarbon oils containing aromatic hydrocarbons comprises a carrier and an active metal, wherein the carrier is composed of silica-magnesia, the active metal is a noble metal selected from the group VIII of the periodic table, and the magnesia content of the silica-magnesia is within a range from 25 to 50 weight percent, calculated in terms of the metal oxide.
Preferably the proportion of the noble metal selected from the group VIII of the periodic t
Kanai Yuki
Yamaguchi Toshio
Yokozuka Hideharu
Katten Muchin Zavis & Rosenman
Nguyen Cam N.
Silverman Stanley S.
Sumitomo Metal & Mining Co., Ltd.
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