Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
2002-02-28
2004-11-23
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S213000, C208S21600R, C208S217000, C502S325000, C502S332000, C502S333000, C502S334000, C502S339000
Reexamination Certificate
active
06821412
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a catalyst for hydrotreatment of gas oil and a method for hydrotreating gas oil. More particularly, the present invention relates to a method for obtaining gas oil having a sulfur content of 10 ppm or lower from a feedstock oil which is straight-run gas oil or blend oil comprising the straight-run gas oil and at least one other hydrocarbon oil.
BACKGROUND ART
Recently, there is a global trend toward stricter quality regulation values for gas oil so as to improve the atmospheric environment. In part of the north-European countries, a quality regulation for gas oil has already been strengthened so as to include a sulfur content of 50 ppm or lower and an aromatic content of 5% or lower. Such strengthened regulations are expected to become even stricter in the future.
In our country also, the regulation for gas oil is expected to be strengthened in the near future so as to include a sulfur content of 50 ppm or lower.
Sulfur content in gas oil is regarded as the primary property to be more strictly regulated, because there is a fear that the sulfur may adversely influence the durability of after-treatment technologies expected as the countermeasure against the diesel exhaust gas, such as oxidation catalysts, nitrogen oxide (NO
x
) reduction catalysts, and diesel particulate filters.
For the reasons given above, there is a desire for a further sulfur content reduction in gas oil, and the conventional deep desulfurization techniques and ultra-deep desulfurization techniques are required to be further improved.
A subject in the ultra-deep desulfurization of gas oil is how to efficiently remove heavy refractory sulfur-containing compounds unsusceptible to desulfurization, such as 4,6-dimethyldibenzothiophene (4,6-DMDBT).
It is thought that the reason why those substances are less apt to be desulfurize is that the alkyl substituents are located near the sulfur atom and hence cause a steric hindrance when the molecule comes into contact with an active site of a catalyst.
Consequently, an important subject in efficiently carrying out a desulfurization reaction in an ultra-deep desulfurization region is to design catalysts which enable the desulfurization of such substances having a steric hindrance to desulfurization-active sites to proceed efficiently and how to use these catalysts, namely, how to design a desulfurization process using these catalysts.
In addition, in view of the recent economic situation in the world including our country, it is of urgent necessity to design a catalyst or process which enables the deep desulfurization or ultra-deep desulfurization such as those described above to be carried out at a lower cost.
One technology for this cost reduction is catalyst regeneration. To develop a catalyst capable of being repeatedly regenerated and to develop a regeneration technology giving a regenerated catalyst having the same performance as the fresh catalyst also are important subjects.
DISCLOSURE OF THE INVENTION
An object of the present invention, in view of the points described above, is to provide a catalyst for hydrotreatment which can highly desulfurize straight-run gas oil so as to have a sulfur content of 10 ppm or lower.
Another object of the present invention is to provide a method for hydrotreating a gas oil fraction at a high efficiency using the catalyst described above.
Still another object of the present invention is to provide a method by which the catalyst described above can be converted to a regenerated catalyst.
The present invention relates to the following (1) to (15).
(1) A catalyst for hydrotreatment of gas oil, comprising from 0.1 to 10% by weight platinum, from 0.1 to 20% by weight palladium, and from 0.05 to 1.2% by weight halogen in terms of the respective elements based on the catalyst in a support comprising an inorganic oxide containing an alumina,
wherein the alumina comprises a crystalline alumina having a crystallite diameter of from 20 to 40 Å.
(2) The catalyst according to (1), wherein the weight ratio between the platinum and the palladium is from 0.5 to 0.8 in terms of (palladium)/(palladium+platinum) ratio.
(3) The catalyst according to (1) or (2), wherein the support contains at least one inorganic oxide selected from silica, boria, titania, and zirconia in an amount of from 5 to 60% by weight.
(4) The catalyst according to any one of (1) to (3), which has an acid amount as determined by the ammonia-TPD (temperature programmed desorption) method of from 0.4 to 3 mmol/g.
(5) The catalyst according to any one of (1) to (4), wherein the metal dispersion degree of the catalyst as determined by the CO pulse method after a hydrogen reduction treatment is from 40 to 100%.
(6) A method for hydrotreating gas oil, comprising carrying out a catalytic reaction of a gas oil fraction containing an aromatic compound in the presence of the catalyst according to any one of claims
1
to
5
at a hydrogen partial pressure of from 3 to 8 MPa, a temperature of from 200 to 370° C., a liquid hourly space velocity of from 0.3 to 5.0 h
−1
, and a hydrogen/oil ratio of from 100 to 1,000 L/L.
(7) A method for hydrotreating gas oil, comprising:
carrying out, as a first desulfurization step, a catalytic reaction of straight-run gas oil having a boiling point of from 160 to 400° C. or blend oil comprising the straight-run gas oil and at least one other hydrocarbon oil at a hydrogen partial pressure of from 3 to 7 MPa, a temperature of from 200 to 400° C., a liquid hourly space velocity of from 0.5 to 5.0 h
−1
, and a hydrogen/oil ratio of from 100 to 1,000 L/L in the presence of a catalyst comprising from 10 to 25% by weight at least one metal selected from the Group 6a of the periodic table and from 0.1 to 6% by weight at least one metal selected from the Group 8 of the periodic table in terms of the respective oxides based on the catalyst in a support comprising an inorganic oxide to thereby regulate the oil so as to have a sulfur-containing compound content of 0.2% by weight or lower after the step; and then
carrying out, as a second desulfurization step, a catalytic reaction of the oil after the first desulfurization step at a hydrogen partial pressure of from 3 to 8 MPa, a temperature of from 150 to 370° C., and a liquid hourly space velocity of from 0.3 to 5.0 h
−1
in the presence of a catalyst comprising from 0.1 to 10% by weight platinum, from 0.1 to 20% by weight palladium, and from 0.05 to 1.2% by weight halogen in terms of the respective elements based on the catalyst in a support comprising an inorganic oxide containing an alumina.
(8) The method according to (7), wherein after the first desulfurization step, the oil is subjected to a degassing step.
(9) The method according to (7) or (8), wherein the alumina contained in the support of the catalyst for use in the second desulfurization step comprises a crystalline alumina having a crystallite diameter of from 20 to 40 Å.
(10) The method according to any one of (7) to (9), wherein in the catalyst for use in the second desulfurization step, the weight ratio between the platinum and the palladium is from 0.5 to 0.8 in terms of (palladium)/(platinum+palladium) ratio.
(11) The method according to any one of (7) to (10), wherein the support of the catalyst for use in the second desulfurization step contains at least one inorganic oxide selected from silica, boria, titania, and zirconia in an amount of from 1 to 60% by weight.
(12) The method according to any one of (7) to (11), wherein the catalyst for use in the second desulfurization step has an acid amount as determined by the ammonia-TPD method of from 0.4 to 3 mmol/g.
(13) The method according to any one of (7) to (12), wherein the catalyst for use in the second desulfurization step, after a hydrogen reduction treatment, has a metal dispersion degree as determined by the CO pulse method of from 40 to 100%.
(14) The method according to any one of (7) to (13), wherein the catalyst for use in the second desulfurization step is one regenerated by carrying out a reac
Fujukawa Takashi
Godo Hideki
Kimura Hiroshi
Mizuguchi Hirofumi
Cosmo Oil Co. Ltd.
Griffin Walter D.
LandOfFree
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