JP3398273B2 - Desulfurization method of catalytic cracking gasoline - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for desulfurizing catalytically cracked gasoline. More specifically, when catalytically cracking a catalytically cracked gasoline containing a sulfur compound and an olefin using a catalyst, the terminal olefin in the catalytically cracked gasoline is isomerized to an internal olefin in advance, and then hydrodesulfurized. By doing so, the present invention relates to a method for desulfurizing catalytically cracked gasoline capable of suppressing a decrease in octane number due to hydrogenation of terminal olefins.

[0002]

In the field of petroleum refining, as a high octane gasoline material source containing a large amount of olefin components,
There is catalytic cracking gasoline. This is a heavy petroleum fraction, for example, catalytic cracking of feedstock oil such as vacuum gas oil or atmospheric residual oil,
It is a gasoline fraction obtained by collecting and distilling catalytic cracking products, and is used as one of the main sources of blending materials for automobile gasoline. However, the catalytically cracked feedstock oil originally has a relatively large content of sulfur compounds, and if the catalytic cracking treatment is carried out as it is, the content of sulfur compounds in the catalytically cracked products will also increase. If used as a mixed material source, the environmental impact may become a problem. For this reason, it is usual to use, as the feedstock oil for the catalytic cracking apparatus, vacuum desulfurization oil / atmospheric pressure residual oil which has been desulfurized in advance, or atmospheric pressure residual oil having a low sulfur content.

As the desulfurization treatment, a hydrodesulfurization treatment which has been conventionally carried out in the field of petroleum refining is generally used. This is a suitable hydrogenation of a feed oil to be desulfurized in a high temperature and pressurized hydrogen atmosphere. The catalyst is brought into contact with the desulfurization treatment catalyst. In the case of hydrodesulfurization treatment of reduced pressure gas oil or atmospheric residual oil, which is a feedstock for catalytic cracking, the hydrodesulfurization catalyst is a group VIII or VI element such as chromium, molybdenum, tungsten, cobalt or nickel. A suitable substrate, for example one supported on alumina, is used. The conditions for the hydrodesulfurization treatment are generally temperatures of about 300 to 400.
C, hydrogen partial pressure of about 30 to 200 kg / cm ² , and liquid hourly space velocity (LHSV) of about 0.1 to 10 1 / hr are adopted.

However, in the case of hydrodesulfurization of heavy petroleum fractions such as reduced pressure gas oil and atmospheric residual oil which are feedstocks for catalytic cracking, the treatment conditions are high temperature and high pressure as described above, and therefore There is a problem that the construction cost is high when a device is added in order to cope with a strict design condition and a lack of the device capacity. Therefore, a large amount of capital investment is required for the recent tightening of fuel oil quality regulations.

On the other hand, the catalytically cracked gasoline can be directly hydrodesulfurized, but in this case, the olefin component contained in the catalytically cracked gasoline is hydrogenated, and the octane number decreases as the content decreases. There is a problem that it ends up. In the conventional technique, for example, the temperature is about 200 to 3
When the catalytically cracked gasoline is directly hydrodesulfurized under the conditions of 50 ° C., hydrogen partial pressure of about 5 to 50 kg / cm ² , and LHSV of about 1 to 10 1 / hr, the octane number decreases. Although research has been conducted to improve the decrease in octane number by improving the catalyst and reaction conditions, the problem has not been solved yet at this time. Therefore, a process that can directly hydrodesulfurize catalytically cracked gasoline containing a sulfur compound and an olefin component while suppressing the olefin hydrogenation reaction as much as possible is expected.

[0006]

As described above, when hydrodesulfurizing catalytically cracked gasoline, there is a big problem that the octane number is lowered, and the major problem is that the commercial value of automobile gasoline is lowered. was there. An object of the present invention is to provide a catalytically cracked gasoline containing a sulfur compound and an olefin component, which is subjected to a hydrodesulfurization treatment using a catalyst, to control the olefin hydrogenation reaction and to suppress a decrease in octane number. It is to provide a desulfurization method.

[0007]

The present inventors have overcome the above-mentioned drawbacks in the conventional hydrodesulfurization method of catalytically cracked gasoline containing a sulfur compound and an olefin component, and have an excellent desulfurization method for suppressing a decrease in octane number. As a result of earnest researches for developing the above, by using a double bond regioisomerization catalyst before hydrodesulfurization, an effect of suppressing a decrease in octane number was found, and the present invention was completed. . That is, in the present invention, an acidic isomerization catalyst having the ability to move the double bond position of a terminal olefin to the inside and isomerize to an internal olefin is used in the first stage, and subsequently, a desulfurization catalyst is used in the second stage. As a result, the present invention relates to a method for desulfurizing catalytically cracked gasoline capable of suppressing a decrease in octane number as much as possible.

The catalytically cracked gasoline contains an aromatic content, an olefin content and a saturated content, and the olefin content is 15 to
50% by volume, of which about 1-10% by volume is terminal olefin having a double bond at the end. The ratio of this terminal olefin can be determined by ¹ H-NMR analysis or the like.

In the conventional hydrodesulfurization process of catalytic cracking gasoline, group VIII and VI elements such as molybdenum, tungsten, cobalt and nickel are presulfurized on a suitable base material such as alumina. Only is used as a catalyst. However, since these catalysts have hydrogenation ability, they will hydrogenate the olefin content contained in the catalytically cracked gasoline. Depending on the catalyst and reaction conditions, etc., when catalytically cracked gasoline containing sulfur compounds is hydrodesulfurized under normal conditions,
Studies by the inventors have revealed that terminal olefins are more easily hydrogenated than internal olefins.

The fundamental difference of the present invention from the existing technology is the use of a double bond regioisomerization catalyst prior to this process. As a result, the terminal olefin is converted into an internal olefin that is less susceptible to the hydrogenation reaction, and the olefin hydrogenation reaction that occurs during the subsequent hydrodesulfurization treatment is suppressed. It is also well known that the octane number generally increases when the terminal olefin changes to the internal olefin by the isomerization reaction at the double bond position. For example, when isomerizing 1-octene to 2-octene,
The Lisathioctan number increases by about 28.

From the above two points, when the proportion of the terminal olefin in the catalytically cracked gasoline is 2% by volume or more,
By isomerizing the double bond position to the internal olefin, while suppressing the hydrogenation of the olefin component, it is possible to sufficiently compensate the decrease in the octane number due to the hydrodesulfurization treatment, and as a result, it is possible to suppress the decrease in the octane number. . The present invention can be applied to the case where the proportion of the terminal olefin in the catalytically cracked gasoline is less than 2% by volume, but the decrease in the octane number generated during hydrodesulfurization treatment is isomerized at the double bond position. Makes it much more difficult to make up for it.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst applicable in the first stage of the present invention must have sufficient acid performance to internally isomerize the double bond position of the terminal olefin. It is known that the catalyst has an isomerization ability at the double bond position,
Silica-alumina, zeolite-based catalysts and the like can be used, but since silica-alumina catalysts tend to be deactivated due to the precipitation of coke due to the polymerization of olefins, a zeolite-based catalyst with a uniform acid strength at the active site is used. It is preferable to use. Examples of zeolite-based catalysts include aluminosilicates, and crystalline structures in which aluminum or silicon of aluminosilicate is replaced with a metal such as phosphorus, boron, gallium, or iron. These zeolite-based catalysts may be used alone or in the form of a mixture in the present invention, but among them, it is preferable to use an aluminosilicate zeolite-based catalyst which has high activity and is generally inexpensive and easily available.

Examples of the aluminosilicate zeolite-based catalyst applicable to the present invention include X-type zeolite, Y-type zeolite, β-type zeolite, ZSM-5 type zeolite,
Mordenite and the like can be used, and these can be used alone or in the form of a mixture. The aluminosilicate zeolite-based catalyst may be used after being ion-exchanged into a proton type, but since the proton-type zeolite-based catalyst has a strong acid strength, deactivation due to the precipitation of coke is likely to occur. It is desirable to use zeolite after ion exchange with various metal ions. As the metal to be used, various transition metals can also be used, but highly active alkaline earth metals and rare earth metals are preferable. Alkaline earth metals include magnesium, calcium, strontium,
Lanthanum, cerium, europium and the like can be used as the rare earth metal.

The catalyst used in the hydrodesulfurization step, which is the second step of the present invention, is a hydrodesulfurization method commonly used in the field of petroleum refining in which a desulfurization active metal is supported on a porous inorganic oxide carrier. A catalyst can be used. As the porous inorganic oxide carrier, for example, alumina, silica,
Examples thereof include titania and magnesia, and these can be used alone or in the form of a mixture. Alumina is preferably selected.

Examples of the desulfurization active metal include chromium, molybdenum, tungsten, cobalt and nickel, and these can be used alone or in the form of a mixture. Preferably, cobalt-molybdenum or nickel-cobalt-molybdenum is selected. These metals can be present on the support in the form of metals, oxides, sulfides, or mixtures thereof. As a method of supporting the active metal, an impregnation method,
A known method such as a coprecipitation method can be used. Further, in order to suppress the precipitation of coke, it is effective to add an alkali metal such as potassium.

A catalyst for isomerizing the double bond position of the terminal olefin and a catalyst for hydrodesulfurizing the sulfur compound contained in the catalytically cracked gasoline are packed in the same reaction column in two layers,
When carrying out the reaction, the type of reaction tower is limited to a fixed bed. This method is effective when the site area of the device is small. The catalytic cracking gasoline fraction / hydrogen and the catalyst may be brought into contact with each other by any of a cocurrent upflow, cocurrent downflow and countercurrent systems. These individual operations are known in the field of petroleum refining and can be arbitrarily selected and carried out.

The reaction conditions are a temperature of about 200 to 350 ° C., a hydrogen partial pressure of about 5 to 50 kg / cm ² , and a hydrogen / oil ratio of about 300 to.
3000scf / bbl, LHSV about 1 to 10 1 / h
It can be set under the condition that catalytically cracked gasoline becomes a gas phase reaction from r. Although the effect of the present invention can be obtained even when a portion of the fraction of catalytically cracked gasoline is reacted in the liquid phase, it is preferable to react in the gas phase from the viewpoint of the life of the catalyst. It is also possible to carry out the reaction by charging a catalyst for isomerizing the double bond position of the terminal olefin and a catalyst for hydrodesulfurizing the catalytically cracked gasoline into different reaction towers. In this case, a device such as a product tank can be installed between the reaction towers.

The type of the olefin isomerization treatment reaction tower may be a fixed bed, a fluidized bed or a boiling bed. The catalytic cracking gasoline fraction / hydrogen and the catalyst may be brought into contact with each other by a cocurrent upflow method, a cocurrent downflow method, or a countercurrent method. These individual operations are known in the field of petroleum refining and can be arbitrarily selected and carried out. The reaction condition is a temperature of about 200.
˜350 ° C., hydrogen partial pressure 1˜50 kg / cm ² , hydrogen / oil ratio about 100˜3000 scf / bbl, liquid space velocity (L
HSV) About 1 to 101 / hr can be set under the condition that the catalytically cracked gasoline becomes a gas phase reaction. It is possible to carry out the reaction not under a hydrogen stream but under an inert gas stream such as nitrogen, helium or argon, but it is preferable to carry out the reaction under a hydrogen stream in order to prevent deactivation due to the formation of coke. Although the effect of the present invention can be obtained even when a part of the fraction of catalytically cracked gasoline is reacted in the liquid phase, it is preferable to react in the gas phase from the viewpoint of the life of the catalyst.

The type of the hydrodesulfurization reaction tower is a fixed bed,
Either a fluidized bed or a boiling bed may be used, but a fixed bed is particularly preferable. The catalytic cracking gasoline fraction / hydrogen and the catalyst may be brought into contact with each other by any of a cocurrent upflow, cocurrent downflow and countercurrent systems. These individual operations are known in the field of petroleum refining and can be arbitrarily selected and carried out. The reaction conditions are a temperature of about 200 to 350 ° C. and a hydrogen partial pressure of about 5 to 50 kg.
/ Cm ² , hydrogen / oil ratio of about 300 to 3000 scf / bb
1, LHSV of about 1 to 10 1 / hr can be set under the condition that the catalytically cracked gasoline becomes a gas phase reaction. Although the effect of the present invention can be obtained even when a portion of the fraction of catalytically cracked gasoline is reacted in the liquid phase, it is preferable to react in the gas phase from the viewpoint of the life of the catalyst.

The catalyst for the isomerization treatment reaction of the terminal olefin and the catalyst for the hydrodesulfurization treatment can be regenerated while they are packed in the reaction tower. That is, the coke adhering to the catalyst can be removed by firing while the reaction tower is filled. Of course, there is no problem even if it is taken out from the reaction tower, baked and regenerated, and then charged again for use in the reaction. The catalyst regeneration condition by calcination can be set in the presence of oxygen at a temperature of about 400 to 650 ° C. at which the catalyst does not deteriorate. Since the temperature of the catalyst layer rises rapidly due to the heat of combustion during firing, it is preferably diluted with an inert gas such as nitrogen or argon so that the concentration of oxygen does not become too high.

[0021]

EXAMPLES The present invention will be described in more detail with reference to comparative examples and examples. (Comparative Example) A 1 / 16-inch extruded commercially available catalyst in which 5 wt% CoO and 17 wt% MoO ₃ are supported on an alumina carrier is used in a fixed bed, cocurrent downflow type small reactor 2.8.
g (4.0 ml) was charged. Using a straight-distilled naphtha fraction having a boiling range of 50 to 200 ° C. to which 10% by weight of dibutyl disulfide was added, the temperature was 300 ° C., the pressure was 12 kg / cm ² G,
Hydrogen / oil ratio 500scf / bbl, LHSV3.5 1
Pre-sulfurization was carried out for 5 hours at / hr. After completion of sulfurization, the straight-distilled naphtha gas oil fraction with a boiling point range of 50 to 200 ° C is subjected to LHSV.
Oil was passed for 48 hours at 3.5 1 / hr. Then, a desulfurization reaction test was conducted using catalytically cracked gasoline of 80 to 220 ° C. fraction obtained by catalytically cracking a feedstock oil containing atmospheric residual oil as catalytically cracked gasoline. Density 0.78 g / cm ³ @
15 ° C, sulfur content 200 ppm by weight, olefin content 3
2.1% by volume (terminal olefin content in catalytically cracked gasoline: 5.0% by volume), and the resosathioctan number is 87.2. The reaction conditions are a reaction temperature of 240 ° C. and a hydrogen partial pressure of 12 kg.
/ Cm ² , LHSV5 1 / hr, hydrogen / oil ratio 2000
It was set to scf / bbl. As a result, a hydrodesulfurization catalytic cracking gasoline having a sulfur content of 22.9 weight ppm, an olefin content of 25.2% by volume (terminal olefin content of 1.6% by volume) and a Lisa-thiooctane number of 85.1 was obtained.

Example 1 Using the same reactor as in the comparative example, β-type zeolite ion-exchanged with lanthanum ions was used as a catalyst. Using the same catalytically cracked gasoline as in Comparative Example, 240 ° C., hydrogen partial pressure 12 kg / cm ² , hydrogen /
A reaction activity test was conducted at an oil ratio of 2000 scf / bbl and LHSV5 1 / hr. As a result, sulfur content 200 p
A catalytically cracked gasoline having pm, olefin content of 32.0% by volume (terminal olefin content of 2.5% by volume) and Lisa-thiooctane number of 87.6 was obtained. Then, the same reactor as the comparative example,
The catalyst for hydrodesulfurization presulfurized in the same manner as in Comparative Example was used as the catalyst, and the sulfur compound contained in the catalytically cracked gasoline treated with the above lanthanum ion-exchanged β-zeolite was added at 240 ° C. and a hydrogen partial pressure of 12 kg. / Cm ² , hydrogen /
A desulfurization reaction test was conducted at an oil ratio of 2000 scf / bbl and LHSV5 1 / hr. As a result, a hydrodesulfurization catalytic cracking gasoline having a sulfur content of 22.8 ppm by weight, an olefin content of 29.5% by volume (terminal olefin content of 2.0% by volume) and a Lisa-thiooctane number of 87.2 was obtained.

(Example 2) In the same reactor as the comparative example,
The catalyst of Example 1 (β-type zeolite ion-exchanged with lanthanum ions) was packed in the upper layer, and the catalyst of Comparative Example (cobalt-molybdenum-based catalyst) was packed in the lower layer in two layers, and the same presulfiding treatment as in Comparative Example was performed. . After that, the temperature is lowered to 240 ° C,
Using the same catalytically cracked gasoline as in the comparative example, a desulfurization reaction test was conducted under the same reaction conditions. As a result, the sulfur content of 22.
9 ppm by weight, olefin content 29.5% by volume (terminal olefin content 2.0% by volume), Lisa-thiooctane number 87.2
A hydrodesulfurization catalytic cracking gasoline was obtained.

(Embodiment 3) After carrying out Embodiment 1, 650
℃, pressure 1kg / cm ² G, dry air flow rate 1000ml
Under the condition of / hr, the β-type zeolite ion-exchanged with the catalyst lanthanum ion was calcined for 3 hours to regenerate the catalyst. Thereafter, as in Example 1, the same catalytically cracked gasoline as in Comparative Example was used, and the temperature was 240 ° C. and the hydrogen partial pressure was 12 kg /
cm ² , hydrogen / oil ratio 2000 scf / bbl, LHSV
The reaction activity test was conducted at 5 1 / hr. As a result, the sulfur content was 200 ppm by weight, the olefin content was 32.0% by volume (terminal olefin content was 2.6% by volume), and the lysa-thiooctane number was 8
A catalytically cracked gasoline of 7.6 was obtained.

(Embodiment 4) After carrying out Embodiment 3, 650
℃, pressure 1kg / cm ² G, dry air flow rate 1000ml
The two catalysts were calcined and regenerated for 3 hours under the condition of / hr. Then, after performing the same pre-sulfurization treatment as in the comparative example, the same catalytic cracking gasoline as in the comparative example was used in the same manner as in Example 1 at 240 ° C., hydrogen partial pressure 12 kg / cm ² , hydrogen / oil ratio 2000 scf / bbl, LHSV5 1 / hr
The desulfurization reaction test was carried out. As a result, a hydrodesulfurization catalytic cracking gasoline having a sulfur content of 22.8 ppm by weight, an olefin content of 29.5% by volume (terminal olefin content of 2.0% by volume) and a Lisa-thiooctane number of 87.2 was obtained.

[0026]

In the hydrodesulfurization treatment of catalytically cracked gasoline, the terminal olefins in the catalytically cracked gasoline are isomerized into internal olefins in the first step and hydrodesulfurized by a desulfurization catalyst in the second step. By the method, hydrogenation of the olefin is suppressed, so that a decrease in octane number can be prevented.

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-55-155090 (JP, A) JP-A-54-88903 (JP, A) JP-A-55-47145 (JP, A) JP-A-63- 159494 (JP, A) JP 2-172813 (JP, A) JP 7-278567 (JP, A) JP 59-115747 (JP, A) JP 2000-288398 (JP, A) Kaihei 8-311461 (JP, A) JP-A-61-4531 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C10G 69/04 C10G 35/095 C10G 45/04- 45/12 C07C 5/25

Claims (7)

(57) [Claims] 1. A catalytically cracked gasoline containing a sulfur compound and an olefin component is contacted with a catalyst having an acidic functional group in the first step to isomerize a terminal olefin present in the catalytically cracked gasoline to an internal olefin, A method for desulfurizing catalytically cracked gasoline, which comprises contacting with a hydrodesulfurization catalyst in two steps to desulfurize. 2. The method for desulfurizing catalytically cracked gasoline according to claim 1, wherein the proportion of terminal olefins in the catalytically cracked gasoline is 2% by volume or more. 3. The method for desulfurizing catalytically cracked gasoline according to claim 1, wherein the catalyst used for isomerizing the terminal olefin to the internal olefin is a zeolite catalyst. 4. The hydrodesulfurization catalyst is a Group VIII- or Group VI-based metal-supported sulfide catalyst.
[3] The method for desulfurizing catalytically cracked gasoline according to [3]. 5. The reaction is carried out by packing a catalyst for isomerizing a terminal olefin into an internal olefin and a catalyst for hydrodesulfurizing catalytically cracked gasoline in two layers in the same reaction column. The method for desulfurizing catalytically cracked gasoline according to any one of 1 to 4. 6. The reaction is performed by charging different catalysts with a catalyst for isomerizing a terminal olefin to an internal olefin and a catalyst for hydrodesulfurizing catalytically cracked gasoline, to carry out the reaction. Method for desulfurization of catalytically cracked gasoline. 7. The method for desulfurizing catalytically cracked gasoline according to claim 1, wherein the catalyst for isomerizing the terminal olefin to the internal olefin is regenerated while the reactor is charged.