Mineral oils: processes and products – Chemical conversion of hydrocarbons – Plural serial stages of chemical conversion
Reexamination Certificate
1999-08-27
2001-07-24
McAvoy, Ellen M. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Plural serial stages of chemical conversion
C208S015000, C208S143000, C208S144000
Reexamination Certificate
active
06264827
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manufacturing process of a diesel gas oil with a high cetane number and a low sulfur. More particularly, the present invention relates to a manufacturing process of a diesel gas oil with a high cetane number, a low sulfur content, and a superior storage stability from a petroleum distillate oil with a low cetane number and a high sulfur content.
2. Background Art
Presently, diesel gas oil used in Japan is prepared by mixing a straight-run gas oil cut, a straight-run kerosene cut, a gas oil cut obtained from a cracking apparatus, or the like, with a desufurized gas oil cut which is obtained mainly by treating a straight-run gas oil with a general desulfurization apparatus. Considering that a clean oil will be required much more in the future, it is expected that in the diesel gas oil a content ratio of the gas oil cut obtained from the cracking apparatus will increase more and more. However, since the gas oil cut obtained from a fluid catalytic cracking (FCC) apparatus or a thermal cracking apparatus contains a lot of aromatic components, the cetane number thereof is low as it is. Additionally, the sulfur content thereof is usually at least 500 ppm, and there is not any less than 350 ppm. Furthermore, when the gas oil cut is hydrogenated, unstable substances are generated and the storage stability (hue and sludge amount) gets worse.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a manufacturing process of a diesel gas oil with a high cetane number and a low sulfur, where the cetane number thereof is at least 45, the sulfur content thereof is less than 350 ppm, and the storage stability thereof is superior, from a petroleum distillate oil with a low cetane number and a high sulfur content.
In order to solve the aforesaid problems, the inventors have intensively studied and found that the diesel gas oil with a high cetane number, a low sulfur content, and a superior storage stability can be manufactured by a two-stages hydrogenation of the petroleum distillate oil with a low cetane number and a high sulfur content using a specific catalyst and condition.
Namely, the present invention provides a manufacturing process of a diesel gas oil with a high cetane number and a low sulfur content, comprising a first stage of contacting hydrogen with a petroleum distillate oil with a cetane number of at least 20 and less than 45, a sulfur content of at least 350 ppm, and a boiling point in the range of 200 to 430° C. in the presence of a hydrogenation catalyst of a porous solid acid carrier carrying one or more hydrogenation-active metals selected from the group consisting of chromium, molybdenum, tungsten, cobalt, and nickel, under a temperature from 320 to 500° C. and a pressure from 30 to 110 kg/cm
2
to obtain a hydrogenated oil with a cetane number of at least 45 and a sulfur content of less than 350 ppm; and
a second stage of contacting hydrogen with the hydrogenated oil in the first stage in the presence of a hydrogenation catalyst of a porous solid acid carrier carrying one or more hydrogenation-active metals selected from the group consisting of chromium, molybdenum, tungsten, cobalt, and nickel, under a temperature from 200 to 400° C. and a pressure from 30 to 110 kg/cm
2
to obtain a hydrogenated oil with a superior storage stability without changing the cetane number and the sulfur content.
In the aforesaid process of the present invention, it is preferred that the porous solid acid carrier in the first stage be two or more oxides (complex oxide) selected from the group consisting of silica, alumina, titania, zirconia, boria, and magnesia, or one or more oxides selected from the oxides and zeolite or clay compounds.
In the aforesaid process of the present invention, it is preferred that the porous carrier in the second stage be alumina.
With the two-processes hydrogenation of the present invention, the diesel gas oil with the high cetane number and the low sulfur content, where the cetane number thereof is at least 45, the sulfur content is less than 350 ppm, and the storage stability is good, can be easily manufactured from the petroleum distillate oil where the cetane number thereof is at least 20 and less than 45, the sulfur content thereof is at least 350 ppm, and the boiling point thereof is in the range of 200 to 400° C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be explained in detail with reference to the preferred embodiments, but it will be understood that the invention is not limited thereto.
The petroleum distillate oil used as raw material oil in the present invention is the petroleum distillate oil whose cetane number is at least 20 and less than 45, whose sulfur content is at least 350 ppm, and whose boiling point is in the range of 200 and 430° C. Examples of the petroleum distillate oil include distillate oil obtained by fluid catalytic cracking (FCC), distillate oil obtained by thermal cracking, distillate oil obtained by distillation of crude oil under atmospheric pressure, distillate oil obtained by distillation of crude oil under reduced pressure, and a mixture of two or more of them.
In the present invention, the distillate oil with the cetarie number of at least 20 and less than 45, the sulfur content of at least 350 ppm, and the boiling point in the range of 200 to 430° C., is preferably used; where the distillate oil is a mixture of the distillate oil obtained by fluid catalytic cracking (FCC) and the distillate oil obtained by distillation of crude oil under atmospheric pressure,
In accordance with the present invention, what is mainly performed in the first stage is the improvement of the cetane number by the ring opening with hydrogenation of the petroleum distillate oil and the lowering of the sulfur content by hydrodesulfurization. In the second stage, unstable substances with polycyclic aromatic structures which are mainly generated in the first stage and make worse the storage stability are removed. The unstable substances with specific polycyclic aromatic structures make the hue of the hydrogenated oil worse and generate sludge.
For the measurement of the storage stability, for example, ASTM method D-4625 is used for the hue (Saybolt color value) and the acceleration test in conformity to ASTM method D-2274 (the amount of the sludge) is for the sludge.
The hydrogenation temperature in the first stage of the invention is in the range of from 320 to 500° C., and preferably of 330 to 450° C. If the temperature is lower than 320° C., it is difficult to achieve the cetane number of at least 45. If the temperature is above 500° C., decomposition reaction occurs strikingly and induces the yield lowering.
The hydrogenation temperature in the first stage means the mean temperature of the reaction column (WABT).
The hydrogenation pressure in the first stage is in the range of 30 to 110 kg/cm
2
, preferably of 35 to 80 kg/cm
2
, and more preferably 40 to 65 kg/cm
2
.
The hydrogenation pressure in the first stage means a hydrogen partial pressure.
The supply amount (liquid hourly space velocity: LHSV) of the petroleum distillate oil in the first stage is preferably in the range of 0.1 to 10 h
−1
, and specially preferably in the range of 1 to 5 h
−1
.
The hydrogen/oil ratio in the first stage is preferably in the range of from 200 to 5000 scf/bbl, and particularly preferably in the range of from 400 to 5000 scf/bbl.
In order to increase the cetane number in the first stage, not only the hydrogenation of the aromatic ring but also the ring opening is required. For the progress of the hydrogenation ring opening reaction, it is necessary for the catalyst to have an ability to cut the carbon-carbon bond of the ring, and therefore it is desirable to provide the solid acidity to the carrier.
The carrier is preferably one including two or more oxides (complex oxides) selected from the group consisting of silica, alumina, titania, zirconia, boria, and magnesia. Alternatively, the carrier is one
Adachi Michiaki
Ishikawa Katuhiko
Okazaki Hajime
Waku Toshio
McAvoy Ellen M.
Nippon Mitsubishi Oil Corp.
Ostrolenk Faber Gerb & Soffen, LLP
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