JP3450940B2 - Desulfurization method of catalytic cracking gasoline - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for desulfurizing catalytically cracked gasoline. Specifically, in a device for hydrodesulfurization of catalytically cracked gasoline containing sulfur compounds and olefin components using a catalyst, desulfurization of catalytically cracked gasoline that can control the exothermic reaction from the beginning of the reaction and perform a stable reaction It is about the method.

[0002]

2. Description of the Related Art In the field of petroleum refining, there is catalytic cracking gasoline as a high octane gasoline material source containing a large amount of olefin components. This is a gasoline fraction obtained by catalytically cracking heavy petroleum fractions, for example, feedstock oil such as vacuum gas oil or atmospheric residual oil, and recovering and distilling catalytic cracking products. It is used as one of the sources.

However, the catalytically cracked feedstock oil originally has a relatively large content of sulfur compounds, and if this is directly subjected to catalytic cracking treatment, the content of sulfur compounds in the catalytically cracked product also increases. If this is used as a mixed source of automobile gasoline, environmental impact may become a problem. For this reason, it is usual that the feedstock oil of the catalytic cracking apparatus is desulfurized in advance.

As the desulfurization treatment, a hydrodesulfurization treatment which has been conventionally carried out in the field of petroleum refining is generally used. This is an appropriate 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 vacuum gas oil or atmospheric residual oil, which is a feedstock for catalytic cracking, the hydrodesulfurization catalyst is VIII.
Group I and Group VI elements such as chromium, molybdenum, tungsten, cobalt, nickel and the like supported on a suitable substrate such as alumina are used. In addition, the conditions for the hydrodesulfurization treatment are generally a temperature 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 vacuum gas oil and atmospheric residual oil, which are feedstocks for catalytic cracking, the processing conditions are high temperature and high pressure as described above, so 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. Although it is possible to directly hydrodesulfurize catalytically cracked gasoline, in this case, the olefin component contained in the catalytically cracked gasoline is hydrogenated and the content thereof is reduced, resulting in a decrease in octane number. There is. The heat generated by this hydrogenation reaction is 30 kcal / m.
It is very large as ol, and it is quite difficult to suppress the hydrogenation reaction and proceed the desulfurization reaction. Especially in the initial stage of the reaction, the hydrogenation activity of the catalyst is extremely high, and even if a heat removal / cooling measure such as hydrogen quenching is taken, meticulous attention is required for the control of the apparatus in order to prevent the runaway reaction.

The catalyst used in the apparatus for hydrodesulfurizing catalytically cracked gasoline containing a sulfur compound and an olefin component is, like other desulfurization catalysts, a group VIII and group VI element,
For example, chromium, molybdenum, tungsten, cobalt,
An appropriate base material such as nickel supported on nickel is used. This catalyst is activated by pre-sulfurization, and the same method as the naphtha desulfurization catalyst can be used as the pre-sulfurization method. That is, a method is generally used in which naphtha is mixed with a sulfur compound such as dimethyl disulfide, heated to 150 to 350 ° C. with hydrogen, and then passed through a reaction tower filled with a catalyst. A sulfur compound such as dimethyl disulfide reacts with hydrogen on the surface of the active metal of the catalyst to be converted into hydrogen sulfide, and the hydrogen sulfide and the active metal further react to become a metal sulfide active in the desulfurization reaction.

[0007]

The desulfurization catalyst usually passes the feedstock oil after this pre-sulfurization, but the catalyst after the pre-sulfurization has a remarkably high hydrogenation activity, and when catalytically cracked gasoline is passed through the oil. Has a problem that not only the olefin component is hydrogenated to lower the octane number, but also the reaction temperature is difficult to control due to the heat generated by the hydrogenation. Further, there is a possibility that the reaction locally progresses to raise the temperature and the catalyst deteriorates rapidly. Normal catalytically cracked gasoline contains about 30% by volume of olefins, but the temperature rises up to 1
It is a big thing which reaches 00 degreeC. In order to prevent this, measures such as heat quenching and cooling such as hydrogen quenching are taken, and oil containing no olefin such as naphtha is passed through for a certain period of time after the completion of pre-sulfurization to perform a leveling operation to activate the product. It completely sulfides the metal and removes strong hydrogenation active points where the olefin component is hydrogenated, and also deposits a certain amount of coke on the catalyst surface, contributing to the olefin hydrogenation reaction. It is necessary to reduce the function of the acidic point of the catalyst carrier.

[0008] As described above, when the reaction is started in the hydrodesulfurization apparatus using the catalytically cracked gasoline as a raw material, there is a big problem of heat generation. Therefore, a large amount of equipment is required for heat removal and cooling. However, there was a big problem that the production volume decreased due to long-term break-in operation.
An object of the present invention is a catalytic cracking apparatus capable of controlling the exothermic reaction from the initial stage of the reaction and performing a stable reaction in an apparatus for hydrodesulfurizing catalytically cracked gasoline containing a sulfur compound and an olefin component using a catalyst. It is to provide a method for desulfurizing gasoline.

[0009]

The above object of the present invention can be achieved by the following constitution. 1. When catalytically cracking gasoline containing sulfur compounds and olefin components is hydrodesulfurized with a catalyst, catalytic cracking gasoline is passed through the catalyst while the catalyst is wet with petroleum fractions to start the reaction. It is a desulfurization method, and as the reaction time elapses, the petroleum fraction that had previously wet the catalyst is volatilized and the catalyst becomes dry. The petroleum fraction used is in the boiling range of 200 to 400 ° C., and the proportion of the olefin component in the composition of the petroleum fraction used for wetting the catalyst is 10% by volume or less. Desulfurization method. 2. 200 to 300 petroleum fractions used to wet the catalyst
2. The method for desulfurizing catalytically cracked gasoline according to the above 1, which is in a boiling point range of ° C. 3. When presulfiding a catalyst, a petroleum fraction is passed along with a sulfiding agent to wet the catalyst, and after presulfiding treatment, catalytic cracking gasoline is passed through the catalyst while the catalyst is wet with a petroleum fraction to start the reaction. 3. The method for desulfurizing catalytically cracked gasoline according to 1 or 2 above. 4. When oil is passed through catalytic cracking to start the reaction,
The above-mentioned 1, 2 wherein the petroleum fraction is passed through along with the catalytically cracked gasoline to start the reaction in a wet state of the catalyst.
Or the method for desulfurizing catalytically cracked gasoline according to item 3. In order to solve the above problems, the present inventors have conducted extensive studies and as a result, in a device for hydrodesulfurizing catalytically cracked gasoline containing a sulfur compound and an olefin component using a catalyst, the catalyst is a petroleum fraction. The invention has led to the epoch-making invention of initiating the reaction by passing catalytic cracking gasoline in a wet state. The wet state means that a part or all of the petroleum fraction is in a liquid phase under the reaction conditions, whereby the catalyst surface is covered with the liquid phase of the petroleum fraction. Hereinafter, the present invention will be described in detail.

The boiling point of catalytically cracked gasoline is usually 20 to 22.
It is about 0 ° C., and is in a gas phase under the reaction temperature condition of the desulfurization reaction of 220 to 350 ° C. The desulfurization reaction also proceeds in the gas phase, but on the other hand, the olefin component in catalytically cracked gasoline directly contacts the hydrogenation active site on the catalyst surface and reacts with hydrogen in the gas phase to rapidly produce hydrogen. Will be converted. Further, the reaction heat is a catalyst having a small specific heat (about 0.
The temperature of 25 cal / g · ° C) rises rapidly.

The present invention is characterized in that the reaction is started using a catalyst wet with a petroleum fraction. In this case,
The olefin component and hydrogen in the gas phase cannot directly contact the hydrogenation active site on the catalyst surface, and dissolve in the petroleum fraction on the catalyst surface to reach the catalyst active site. Therefore, the hydrogenation reaction is suppressed, and the calorific value becomes mild. Also,
The specific heat of the petroleum fraction (about 0.5 cal / g · ° C at room temperature) is larger than the specific heat of the catalyst, and acts to mitigate the rapid temperature rise of the catalyst. Further, when excessive heat is locally generated, the petroleum fraction is vaporized to suppress a rapid temperature rise.

In order to prevent a rapid exothermic reaction, a method of reacting catalytically cracked gasoline in a liquid phase may be considered, but sufficient desulfurization activity cannot be obtained at a temperature below the boiling point of catalytically cracked gasoline. There is also the idea of increasing the reaction pressure to carry out the liquid phase reaction, but under high pressure the hydrogenation reaction proceeds more than the desulfurization reaction, and the heat generation is large and the octane number is lowered, which is not preferable. Further, the catalytically cracked gasoline to be desulfurized has a wide boiling point range, and it is difficult to desulfurize it under the condition that the whole fraction is in the liquid phase. On the other hand, when only a part of the fraction is subjected to the liquid phase reaction, the residence time of the liquid phase on the catalyst surface becomes long, and coking deactivation due to the polymerization of the olefin content contained in the catalytically cracked gasoline is also a concern. That is, the desulfurization reaction of catalytically cracked gasoline is efficiently carried out in the gas phase, and it is not preferable to carry out it in the liquid phase from the viewpoint of the life of the catalyst. On the other hand, the present invention can be easily carried out by selecting a petroleum fraction having a low olefin content, without deterioration of the catalyst.

The petroleum fraction used to pre-wet the catalyst is
Since it is necessary to maintain the liquid phase under the reaction conditions at the start of the reaction, the boiling point is in the range of 200 to 400 ° C. Specifically, a kerosene fraction or a light oil fraction can be used. Further, as the oil passage time elapses, coke is deposited on the catalyst, which causes the hydrogenation activity to rapidly decrease. On the other hand, the decrease in desulfurization activity is small. The amount of coke required for stabilization is about 3% or more. As the reaction time elapses, the petroleum fraction that had previously wet the catalyst also volatilizes little by little, and eventually the catalyst becomes dry, but until the stabilization, the petroleum fraction will be wet as if the catalyst was wet. The boiling point must be set as above.

After the catalyst is stabilized and the hydrogenation activity of the catalyst is sufficiently reduced, it is efficient to contact the catalytically cracked gasoline directly with the catalyst to carry out the desulfurization reaction. As the reaction time elapses, the petroleum fraction that had previously wet the catalyst will also volatilize little by little and eventually the catalyst will be in a dry state, so it is possible to continue the reaction as it is, but after stabilization, catalytic decomposition should be carried out early after stabilization. In order to carry out the desulfurization reaction by directly contacting the gasoline with the catalyst, the oil circulation of the catalytic cracking gasoline is stopped, the temperature is raised to volatilize and remove the petroleum fraction, the temperature is lowered again, and then the catalytic cracking gasoline is passed through. Just add oil. In this case, the boiling point range of petroleum fraction is 20
Select a petroleum fraction with a slightly low boiling point in the range of 0 to 300 ° C.

The composition of the petroleum fraction used for pre-wetting the catalyst should be as free of olefin components as possible,
The content is set to 10% by volume or less, and preferably it is substantially free. As the petroleum fraction containing no olefin component, there are straight-run kerosene, gas oil fraction, hydrocracked oil, hydrotreated oil and the like. Also, substances that poison the catalyst, such as heavy metals and basic substances, are not preferable.

The method of pre-wetting the catalyst is not particularly limited, but it is sufficient to pass the petroleum fraction before or after the pre-sulfurization of the catalyst. At the time of pre-sulfurization, a sulfurizing agent is added to the petroleum fraction. If the sulfurating operation is carried out by the above method, the sulfurizing and the wetting operation can be carried out simultaneously. Further, a petroleum fraction having a boiling point higher than that of the catalytically cracked gasoline may be blended with the catalytically cracked gasoline in advance and fed to the reactor, or the catalytically cracked gasoline and the petroleum fraction may be separately fed to the reactor for reaction. You may. In this case, it is necessary to carry out a fractional distillation operation after completion of the reaction to separate the gasoline and the petroleum fraction used for wetting.

As the catalyst used in the hydrodesulfurization apparatus to which the present invention can be applied, a hydrodesulfurization catalyst, which is a porous inorganic oxide carrier on which a desulfurization active metal is supported, and which is generally used in the field of petroleum refining, is used. You can Examples of the porous inorganic oxide carrier include alumina, silica, titania,
Magnesia and the like can be used, and these can be used alone or in the form of a mixture. Alumina and silica-alumina are preferably selected.

Examples of the desulfurization active metal include chromium, molybdenum, tungsten, cobalt and nickel, which 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.

The form of the hydrotreating reaction tower may be any of a fixed bed, a fluidized bed and a boiling bed, 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 220 to 350 ° C. and a hydrogen partial pressure of about 5 to 50 kg.
/ Cm ² , hydrogen / oil ratio 300 to 3000 scf / bb
1, liquid hourly space velocity (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.

[0020]

EXAMPLES The present invention will be described in more detail by way of examples. (Example 1) In a fixed bed / cocurrent downflow type small reactor, 5% by weight of CoO and 17% by weight of MoO ₃ were loaded on an alumina carrier.
2.8g (4.0g) of 16-inch extruded commercial catalyst
ml). Using JIS No. 1 naphtha containing 5% by weight of dimethyl disulfide, 300 ° C., pressure 15
kg / cm ² , hydrogen / oil ratio of 500 scf / bbl, LH
Presulfiding was carried out for 5 hours at SV21 / hr. After the completion of sulfidation, the temperature was lowered to 250 ° C., and a straight-run light oil fraction having a boiling point range of 250 to 350 ° C. was passed through LHSV51 / hr for 24 hours to wet the catalyst surface. Then, as a catalytically cracked gasoline, 80 was obtained by catalytically cracking a raw material oil containing atmospheric residual oil.
A desulfurization reaction test was carried out using catalytically cracked gasoline of ˜210 ° C. fraction. The density is 0.776 g / cm ³ @ 15 ° C., the sulfur content is 192 ppm by weight, the olefin content is 33% by volume, and the Lisa-thioctan number is 87.5. The reaction conditions are: reaction temperature 250 ° C., hydrogen partial pressure 12 kg / cm ² , LHSV7.
The ratio was 1 / hr and the hydrogen / oil ratio was 2000 scf / bbl. As a result, the sulfur content was 67 ppm by weight and the olefin content was 2
A hydrodesulfurization catalytically cracked gasoline having a 9% by volume and a Lisa-thiooctane number of 86.3 was obtained.

(Example 2) The same reactor and catalyst as in Example 1 were used. The boiling point range is 200 to 30 with addition of 1% by weight of dimethyl disulfide.
Using a straight distillation kerosene fraction at 0 ℃, 300 ℃, pressure 15kg
/ Cm ² , hydrogen / oil ratio of 500 scf / bbl, LHSV
Presulfiding was carried out for 24 hours at 21 / hr. After the sulfurization was completed, the temperature was lowered to 250 ° C., and the desulfurization reaction test was conducted under the same conditions using the same catalytically cracked gasoline as in Example 1. As a result, the sulfur content was 55 ppm by weight, the olefin content was 28% by volume,
A hydrodesulfurization catalytically cracked gasoline having a L-thiooctane number of 85.8 was obtained. After reacting at 250 ° C for 2 days, the feedstock was switched to straight-run gasoline having a boiling range of 100 to 200 ° C, heated to 300 ° C and passed for 1 day to remove the kerosene fraction that had wet the catalyst surface. did. Then, the catalytically cracked gasoline was again passed at 250 ° C. to obtain a hydrodesulfurized catalytically cracked gasoline having a sulfur content of 46 ppm by weight, an olefin content of 25% by volume, and a Lisa-thiooctane number of 84.9.

Comparative Example Using the same reactor and catalyst as in Example 1, the same presulfurization was performed. The temperature was lowered to 250 ° C., and the same catalytically cracked gasoline as in Example 1 was used.
A desulfurization reaction test was conducted under the same reaction conditions. As a result, a hydrodesulfurization catalytically cracked gasoline having a sulfur content of 35 ppm by weight, an olefin content of 16% by volume, and a lys-thiooctane number of 80.2 was obtained.

[0023]

EFFECTS OF THE INVENTION In the case of hydrodesulfurization of catalytically cracked gasoline, the process of the present invention in which the catalyst is passed through the catalytically cracked gasoline to start the reaction while the catalyst is wet with the petroleum fraction is used to start the reaction from the initial stage of the reaction. Since hydrogenation of the components is suppressed, the exothermic reaction can be controlled and a stable reaction can be performed.

Continuation of the front page (56) References JP-A-54-139607 (JP, A) JP-A-54-88903 (JP, A) JP-A-1-284586 (JP, A) JP-A-4-222638 (JP , A) JP 5-239470 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C10G 45/04-45/12 C10G 45/34-45/40 C10G 65/04 -65/08 C10G 69/04 B01J 23/85 B01J 23/88

Claims (4)

(57) [Claims] 1. When hydrocracking a catalytically cracked gasoline containing a sulfur compound and an olefin component using a catalyst, the catalytic cracking gasoline is passed through the catalyst while the catalyst is wet with petroleum fractions to start the reaction. In the method of desulfurization of catalytically cracked gasoline, as the reaction time elapses, the catalyst is touched during the period until stabilization in which the petroleum fraction that had previously wet the catalyst is volatilized and the catalyst is in a dry state. The petroleum fraction used for wetting the catalyst is in the boiling range of 200 to 400 ° C., and the proportion of the olefin component in the composition of the petroleum fraction used for wetting the catalyst is 10% by volume or less. Method for desulfurization of catalytically cracked gasoline. 2. Petroleum fraction used to wet the catalyst is 200
3. The boiling point range is from 300 to 300 [deg.] C.
The method for desulfurizing catalytically cracked gasoline according to 1. 3. When presulfurizing a catalyst, a petroleum fraction is passed along with a sulfiding agent to wet the catalyst, and after presulfurization treatment, catalytic cracking gasoline is passed through while the catalyst is wet with the petroleum fraction. The method for desulfurizing catalytically cracked gasoline according to claim 1 or 2, wherein the reaction is initiated. 4. When oil is passed through catalytic cracking gasoline to start the reaction, oil fraction is passed through together with catalytic cracking gasoline,
The method for desulfurizing catalytically cracked gasoline according to claim 1, 2 or 3, wherein the reaction is started in a wet state of the catalyst.