JPS6147794A - Method of cracking to produce petrochemical product from hydrocarbon - Google Patents

Abstract

PURPOSE:To produce petrochemical products such as olefins, aromatic hydrocarbons, etc. in high yield in high seletivity, by cracking catalytically light hydrocarbons, and cracking thermally prepared cracked oils in the presence of steam, hydrogen, and methane. CONSTITUTION:Light hydrocarbons comprising mainly hydrocarbons having <=350 deg.C boiling point is fed to the first reactor 1, and cracked catalytically. Then, the formed cracked oils together with other raw material hydrocarbons are fed to the second reactor 2, and thermally cracked in the presence of steam, hydrogen, and methane in such a way that the initial cracking temperature is a high temperature of >=1,000, to give petrochemical products.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention decomposes one carbon and one hydrogen to produce olefins and aromatic raw coal (hereinafter referred to as BTX (B: benzene, T: toluene, X: This invention relates to a method for producing petrochemical products such as xylene in high yield and with high selectivity.

(Prior art) Conventionally, as a method for converting light gaseous hydrocarbons such as ethane, propane e, and liquid hydrocarbons such as naphtha and kerosene into olefins, a tube heating system called steam clara kink has been used. It is well known that the minute calendar system is used.

In this method, the heat necessary for the reaction is supplied from the outside through the entire tube wall, so there are limits to the heat transfer rate and reaction temperature, and the reaction conditions are usually 850°C or less and a residence time of α1 to α5 seconds. It's visible.

In addition, a method has been proposed that uses a vessel (small-diameter tube) that allows for shorter residence time decomposition by increasing the degree of decomposition severity, but in this method, the inner diameter is smaller by V decreases in a short period of time, and as a result, the pressure loss in the reaction tube increases, the partial pressure of hydrocarbons increases, and the selectivity of ethylene deteriorates. For this reason, it is necessary to shorten the interval between decokings, but as a result, this has the major disadvantage of causing damage to the equipment due to a decrease in the operating rate of the cracking furnace and an increase in heat cycles due to decoking.

Due to such restrictions on equipment and reaction conditions, the raw material that can be used is limited to light oil at most, and cannot be applied to heavy hydrocarbons such as residual oil. In addition, in a reaction at a temperature applicable to a tube cracking furnace, a side reaction of polycondensation occurs, causing severe coking, and the desired gasification rate (from the amount of hydrocarbons supplied to the reactor to ETX t- Excluding < Os Charcoal IF
This is because the weight ratio of the amount of hydrocarbons heavier than hydrogen to the feedstock hydrocarbons cannot be achieved, and as a result, the yield of useful components is low. '1. fc, once the raw material is selected, that single raw material and product.

Basically, specific decomposition conditions and specific equipment are required depending on the requirements. For this reason, there is a drawback that the selectivity of raw materials and products is poor and flexibility is lacking. For example, in the current typical naphtha tube cracking furnace, the main focus is on ethylene production, so the co-produced propylene, C4 fraction and
It is difficult to arbitrarily vary the product yield of basic chemicals such as TX to match the supply and demand balance. On the other hand, in order to use naphtha raw materials to secure ethylene, which can be obtained at a high rate through high-severity cracking of heavy hydrocarbons, the C4 residues such as propylene and butadiene, which naphtha inherently has, are increasing. It can be seen that this is at the expense of a large potential for BTX products.If an attempt is made to increase the ethylene yield, the yield of propylene and C4 fractions will decrease, and by-product methane will increase. This is the reality of thermal decomposition reactions.

Several methods have been proposed to alleviate such constraints in terms of both raw materials and products. One method is to generate high-temperature gas using liquid carbon IL hydrogen such as crude oil as fuel, which thermally decomposes hydrocarbons under pressure of 5 to 70 bar, reaction temperature of 1515 to 1575 °C, and residence time of 5 to 10 milliseconds. This is the way to do it. In this method, Co! gas is directed from the combustion zone into the reactor. By supplying inert gas such as , N, etc. in the form of a film, coking can be suppressed and heavy oil such as residual oil can be decomposed.

The second method involves partially combusting hydrogen to produce high-temperature hydrogen gas, and using a heavy hydrogen gas under a hydrogen atmosphere at a reaction temperature of 800-1800°C, a residence time of 1-10 milliseconds, and a pressure of 70 bar. This is a method for producing olefins from various hydrocarbons including quality oil.

By carrying out thermal decomposition in an atmosphere with a large excess of hydrogen, it is possible to achieve rapid heating, ultra-short residence time decomposition, and suppression of coking, which also makes it possible to decompose heavy oil, but it is also possible to recycle hydrogen. Moreover, the energy required for separation power, make-up, preheating, etc. is an excessive economic burden.

In any case, both of these methods require extremely harsh reaction conditions in order to obtain olefins in high yields even from heavy hydrocarbons. As a result, the olefin composition of the product is extremely biased toward zero ethylene, acetylene, etc., and there is a problem in that it is difficult to perform an operation that simultaneously obtains a propylene mC4 fraction and BTX in high yield.

In the third method, the reactor is divided into two, and parafinic hydrocarbons with a relatively small molecular weight are supplied to the upstream high temperature side to achieve relatively high severity, that is, the decomposition temperature is 815°C or higher, and the residence time is 20 to 150°C. It pyrolyzes in milliseconds to improve ethylene selectivity and then feeds the gas oil fraction to the downstream low temperature side for low severity.

Coking is suppressed by thermal decomposition over a long residence time, that is, at a decomposition temperature of 815° C. or less and a residence time of 150 to 2000 milliseconds. Therefore, the gas conversion ratio is sacrificed, and the purpose is to improve the selectivity of ethylene, similar to the high temperature side. In this method, we aimed to increase the selectivity of ethylene by supplying a raw material that is relatively easy to decompose, a parafinic raw material, to the high temperature section, and an aromatic-rich raw material, which is relatively difficult to decompose, to the low temperature section. There is. However, because aromatic-rich raw materials are decomposed with low severity in a low-temperature reaction zone, there is a problem in that components that could originally be gasified and evaluated as valuable products are only used as fuel.

As described above, in the third method, the raw materials and products are intentionally limited, and there is a problem in that there is a lack of flexibility in terms of raw material selection and product configuration.

The present inventors first burned hydrocarbons with oxygen in the presence of steam, and further supplied methane and hydrogen to the generated high-temperature combustion gas, and then added methane and hydrogen to the high-temperature gas containing methane, hydrogen, and steam. By supplying hydrocarbons and thermally decomposing them, p
1. We found that the yield of useful components such as olefins and BTX from a wide range of feedstock hydrocarbons, from light hydrocarbons such as naphtha to heavy hydrocarbons such as asphalt, could be significantly increased compared to conventional methods. (See Japanese Patent Application No. 58-25797.

(Problems to be Solved by the Invention) Based on the above technology, the present invention furthermore suppresses coking from a wide range of hydrocarbons to selectively obtain desired olefins and BTX in high yields. The present invention provides a method for thermal decomposition of hydrocarbons.

(Means for Solving the Problems) The present inventors have obtained the above desired olefin and BTX i
As a result of intensive research into a thermal decomposition method that can be obtained selectively and in high yield, two reactors were installed, and the first reactor was used to produce light hydrocarbons containing raw hydrocarbons with a boiling point of 550°C or less. Coal 1F and hydrogen are catalytically cracked using a catalyst. In the second reactor, hydrocarbons are first combusted with oxygen in the presence of steam to produce a high-temperature gas stream containing steam, and hydrogen and hydrogen are further added to this high-temperature gas. Methane is supplied, and an arbitrary raw material hydrocarbon and cracked oil produced in the first reactor are supplied into the high-temperature gas containing methane, hydrogen and steam, and the initial decomposition temperature is at least 1000°C or higher. By pyrolysis under such conditions, it is possible to process from light gas or light oil such as naphtha to heavy oil such as asphalt, and to produce olefins, BTX, etc. with high yield and high selectivity. This finding led to the present invention.

That is, the present invention provides a method for producing petrochemical products by decomposing hydrocarbons, in which light hydrocarbons mainly containing hydrocarbons with a boiling point of 550°C or less are first supplied to a first reactor, and then catalytic cracking is carried out. At the same time, in the second reactor,
Hydrogen is produced by first burning any hydrocarbon with oxygen in the presence of steam to produce a hot combustion gas containing steam, and then adding hydrogen and methane to the hot combustion gas stream. Cracked oil produced by catalytic cracking of any raw material hydrocarbon and light hydrocarbons in the first reactor is supplied into high-temperature gas containing methane and steam, and the temperature at least at the initial stage of decomposition is 1000°C or higher. This invention relates to a decomposition method for producing petrochemical products from hydrocarbons, which is characterized by thermal decomposition under conditions such that:

Below, disassembly according to the present invention will be explained in detail.

First, according to the present invention, raw material hydrocarbons are sent to a first reactor or a second reactor and decomposed depending on the purpose. Light hydrocarbons mainly containing hydrocarbons having a boiling point of 3.50° C. or less are supplied to the first reactor and are catalytically cracked by a catalyst. As a result, due to the action of the catalyst, unlike thermal decomposition, the 03 m '4 composition of propylene, butene, etc. increases. The effect of such a catalyst is not limited to light hydrocarbons, but can also occur with heavy hydrocarbons.Heavy hydrocarbons tend to coke onto the catalyst, which lowers the decomposition temperature, resulting in C@e '4 It cannot be expected to obtain the construct in high yield. As for the type of this first reactor, a fixed bed reactor can be used when light paraffin such as LPG is used as a raw material, but when using a hydrocarbon with a relatively high boiling point among light hydrocarbons such as light oil, When used as a raw material, it is preferable to employ a micro-fluidized bed reactor and use a method in which the coking deposited on the catalyst is combusted.

As the catalyst used in the first reactor, for example, when I, PG is used as the raw material hydrocarbon,
-Al40m catalyst, this' K* Mg etc. (D 7
# Catalysts with a dehydrogenation function mixed with potassium or alkaline earth metal oxides can be used. Further, in order to increase butadiene, we and o3 type catalysts can be used. On the other hand, when liquid hydrocarbons such as naphtha and kerosene are used as raw materials, the above catalyst or 810. -It is preferable to use At, O, a catalyst, or zeolite. Further, the decomposition temperature is usually 500 to 700°C, and the pressure is preferably normal pressure. However, if the purpose is to produce gasoline as a by-product from light oil or the like, it is possible to operate at a lower temperature. In other words, the first reactor converts light hydrocarbons into I, PG [by dehydrogenation reaction], and naphtha, etc. by a chain reaction by the carbonium ion mechanism due to the above-mentioned catalytic action, taking into account their decomposition characteristics. The purpose is to obtain 04 components such as propylene and butene in high yield.

On the other hand, the second reactor burns fuel coal<L hydrogen with oxygen in the presence of steam in the upper part of the reactor to generate high-temperature combustion gas, and further supplies hydrogen and methane into this high-temperature gas. It consists of an internal thermal reactor that supplies hydrocarbons to be thermally decomposed into high-temperature gas containing methane, hydrogen, and steam. The fuel hydrocarbon supplied to this internal heating reactor is not particularly limited, and any hydrocarbon can be used as fuel, from light gas such as methane or light hydrocarbons such as naphtha to heavy hydrocarbons such as cracked oil and asphalt. You can choose. Also,
Hydrogen, carbon oxide, etc. can also be used as fuel.

Furthermore, there are no particular restrictions on the hydrocarbons supplied to the second reactor, and a wide range of hydrocarbons can be used, from light paraffin gas to light hydrocarbons such as naphtha, as well as heavy hydrocarbons such as asphalt. Furthermore, the cracked oil produced in the first reactor can also be converted into useful components by being supplied to the second reactor and thermally decomposed. Conventionally, it has been difficult to obtain olefins and BTX in high yield from such heavy hydrocarbons or cracked oil, but in the present invention, hydrogen and methane are added to the cracking atmosphere, and the When employed, it is thermally decomposed under conditions such that the initial decomposition temperature is at least 1000°C or higher. As a result, high yields of olefins are obtained from a wide range of hydrocarbons such as those mentioned above.

In particular, ethylene and BTX can be produced.

That is, the hydrogen added to the second reactor has the following effects. First, hydrogen has a high thermal conductivity compared to other substances, so that even heavy hydrocarbons can be heated quickly. In the thermal decomposition of heavy hydrocarbons, the hydrocarbons are rapidly heated and evaporated to gasify them, and then decomposed in the gas phase diluted with steam, etc. to produce olefins.

This is important for producing BTX etc. in high yield. Conversely, if a sufficient heating rate is not achieved, polycondensation in the liquid phase will occur, resulting in a significant reduction in product yield.

Second, in addition to suppressing the aforementioned polycondensation reaction in the liquid phase through hydrogenation, heavy hydrocarbons are gasified by replenishing hydrogen, which is relatively lacking compared to the carbon content. This can promote the production of light gas and increase the amount of light gas produced. Furthermore, the production of coke from the gas phase can be suppressed by reducing the amount of acetylene, which is a precursor of the coking reaction. Thirdly, it has the effect of increasing the concentration of radicals in the reaction system, and a high decomposition rate and gasification rate can be achieved. The above three effects are remarkable at high temperatures and high hydrogen partial pressures. Therefore, when the hydrocarbons supplied to the second reactor are heavy hydrocarbons, the hydrogen partial pressure is high, and when the hydrocarbons supplied to the second reactor are light hydrocarbons, the hydrogen partial pressure is high. It is operated at low partial pressure.

Next, regarding the effect of methane, firstly, it has the effect of suppressing the over-decomposition reaction of olefins caused by hydrogen. For example, when decomposed in a hydrogen atmosphere and in the absence of methane, the hydrogenation reaction of olefins (1) occurs.

H4+ H, →O*Hs, (1) C, H6+
H,→201(4(2)) progresses and the selectivity to olefins deteriorates.

Particularly at high temperatures, the above reaction proceeds rapidly, resulting in a high gasification rate, but there are problems in that selectivity to olefins is low and hydrogen consumption is high.

Such excessive hydrogenation can be suppressed without impairing the above-mentioned advantages of hydrogen by adding methane together with hydrogen as in the present invention. In other words, the effect of methane is that the addition of methane causes the reactions (1) and (2) above, as well as the conversion reaction (3) of methane to ethane, ethylene, etc.
(4) 20B4 → O! E[, + H, (3
)0, H, → 02H4+ Tl@
(4) is produced in competition and can prevent conversion to methane by hydrogenation. Moreover, by adjusting the reaction temperature, pressure, and methane/hydrogen ratio of the atmosphere, methane decomposition can be accelerated and the added methane can be converted into higher value-added ethylene, ethane, and acetylene. Second, as shown in the above reaction, it is also effective as a source of hydrogen, which is lacking in heavy hydrocarbons.

As described above, due to the cooperative action of hydrogen and methane, olefins (especially ethylene chloride) and B'J'X can be obtained in high yield even from heavy hydrocarbons such as asphalt in the second reactor. As described above, the present invention focuses on the fact that the decomposition products of hydrocarbons vary significantly depending on the decomposition conditions, and is characterized in that each hydrocarbon is decomposed under the most suitable decomposition conditions according to the required product composition. . In other words, by catalytically cracking hydrocarbons, the reaction proceeds by a carbonium ion mechanism, so 01* of propylene, butene, etc.
'4 olefin can be obtained in high yield. In this catalytic cracking process, cracked gasoline is produced at the same time, but in order to suppress this and increase the gas yield, the catalytic cracking conditions for the purpose of ordinary gasoline must be
It is preferable to decompose at 0°C. However, if the purpose is to produce gasoline as a by-product, it can also be operated at low temperatures. The raw material hydrocarbon used for this catalytic cracking is L
From PG special light paraffin to light oil, etc., the boiling point is 350.
Light hydrocarbons containing mainly hydrocarbons having a temperature of 0.degree. C. or less are preferred. A method of catalytic cracking by supplying heavier hydrocarbons (e.g. vacuum gas oil) is also known, but the yield of cracked oil or coke is high and the gasification rate is low, so it is difficult to produce gasoline. It is preferable to thermally decompose it at a high temperature and use it for olefin production unless the purpose is for. Furthermore, when probane, butane, etc. are supplied as raw materials, a mourning catalyst having a dehydrogenation function is used as the catalyst. On the other hand, heavy hydrocarbons such as atmospheric residual oil and vacuum residual oil undergo severe coking in catalytic cracking, which rapidly reduces catalyst activity and has a low gasification rate. By thermal decomposition in the coexistence of hydrogen and methane,
Olefins and BTX can be obtained in high yield under a high gasification rate. However, because the decomposition conditions are severe, the product composition has an extremely high ethylene ratio in the olefin.

In the present invention, light hydrocarbons are catalytically cracked in a first reactor to produce 'le'4 compositions such as propylene and butene,
In the second reactor, heavy hydrocarbons are thermally decomposed at high temperatures in the presence of hydrogen and methane to convert them into ethylene and BTX, and by combining the two, the overall product composition is made to a desired value. There is. Therefore, as the raw material hydrocarbon to be supplied to the second reactor, heavy coal fls hydrogen is preferable, but according to the linear invention, it is difficult to use olefin as a raw material in the past, but non-heavy hydrocarbons can also be used as a raw material. It goes without saying that ethylene can be easily produced in the second reactor using other raw materials, such as soot.

When such light hydrocarbons are fed to the second reactor, the addition of hydrogen and therefore methane is not necessarily necessary.

Furthermore, according to the present invention, the cracked oil produced in the first reactor is
Although rich in isoparaffins, naphthenes, and aromatic components, this cracked oil is also sent to the second reactor where it is thermally decomposed at high temperatures in the presence of hydrogen and methane to produce ethylene, B
It can be converted into valuable products such as TX, resulting in a significant increase in overall olefin and BTX yields. Furthermore, the cracked oil from the first reactor may be supplied after removing BTX in advance, or may be supplied while containing BTX. When cracked oil containing BTX is supplied, the high-temperature decomposition in the second reactor increases the yield of benzene in BTX in particular, and increases the purity of BTX in cracked gasoline. This has the advantage that separation costs are significantly reduced. Furthermore, the cracked oil produced in the second reactor is also BTX.
After separation, it is fed again to the second reactor where it is decomposed. The cracked oil supplied to these second reactors is not particularly limited, but may include high boiling point cracked oil, circulating cracking cost (cost of recovering cracked oil, supplying it to the reactor, and heating it to the reaction temperature).
Since the yield of olefin and BTX is lower than that of
It is preferable to supply cracked oil with a boiling point of 550° C. or lower. In addition, the supply position of the cracked oil and raw material hydrocarbon to be supplied to the second reactor is determined by the cracking characteristics of the hydrocarbon. For example, the higher the boiling point hydrocarbon or the hydrocarbon with more aromatic components, the higher the It is thermally decomposed by being supplied in multiple stages to the high-temperature side of the system.

However, hydrocarbons whose decomposition characteristics are not significantly different may be fed to the same position. In addition, if the cracked oil supplied to the second reactor contains a large amount of olefins or diolefins, it is likely to polymerize into a gum-like substance and cause line blockage, so a simple hydrogenation treatment is carried out in the preheating stage. It is preferable to do this to ensure stable operation.

As explained above in detail, the present invention mainly produces C*m'4 olefins such as propylene and butene by separating light hydrocarbons using a catalyst in the first reactor, and in the second reactor. Then, the cracked oil and any hydrocarbons produced in the first reactor are decomposed at high temperature in the presence of hydrogen and methane to mainly produce ethylene and BTX, and the type and amount of raw material hydrocarbons supplied to each reactor are determined. Adjust the ratio of hydrogen and methane in the dilution gas of the second reactor.

It is characterized by obtaining the desired product composition by controlling the steam ratio. Therefore, if the desired ethylene and BTX yields can be achieved by simply feeding cracked oil to the second reactor, there is no need to feed virgin feedstock hydrocarbons to the second reactor.

According to the present invention, ethylene and BTX can be obtained in high yield from heavy oil and cracked oil, which have not been used as raw materials for olefin products in the past. hydrocarbon, its propylene,
It becomes possible to perform decomposition using a catalyst that effectively utilizes the high decomposition ability of butenes and other eC4 olefins, and the selectivity in terms of raw materials and product composition is greatly increased.

Next, the method of the present invention will be explained in detail using embodiment examples. FIG. 1 is an illustrative diagram of an example of an embodiment in which the method of the present invention is applied industrially.

This is merely illustrative and does not limit the invention in any way. In FIG. 1, 1 is a first reactor, and 2 is a second reactor. The first reactor 1 has a boiling point of 550°C.
A light hydrocarbon 3 mainly containing the following hydrocarbons is supplied and decomposed at 500-700°C in the presence of a catalyst to produce a reaction fluid 4 mainly containing 03,04 olefins such as propylene, butene, butadiene, etc. do.

As the first reactor 1, a fixed bed reactor can be used, for example, when paraffin, such as LPG, is used as a raw material, but when a hydrocarbon with a relatively high boiling point among light hydrocarbons, such as light oil, is used as a raw material, In this case, a fluidized bed reactor or the like can also be used, which makes it easy to treat the coking material on the catalyst. The catalyst used in the first reactor 1vc varies depending on the properties of the raw material hydrocarbon 3, product composition 9 decomposition conditions, etc., but for example, when using LP() as the raw material, 0rzOB-Al
A catalyst having a dehydrogenation function, such as a TOS catalyst or a catalyst mixed with an oxide of an alkali or alkaline earth metal such as Mg, is used.

Moreover, in order to increase butadiene, a Fe10g catalyst can also be used. On the other hand, when liquid hydrocarbons such as naphtha and kerosene are used as raw materials, the above catalyst or 54o1-A
Z, ol catalysts, solid acid catalysts such as zeolites, etc. are used.

The reaction fluid 4 leaving the first reactor 1 then enters a heat exchanger 5 for heat recovery. The reaction fluid 6 leaving the heat exchanger 5 enters a gas-liquid separator 7 to separate cracked oil 8. The cracked oil 8 is separated from heavy components having a boiling point of 550° C. or higher as a cracked residual oil 9, and then sent to the second reactor 2 where it is thermally cracked. Second reactor 2
has a combustion section 10 in its upper part, and the combustion section 10 contains oxygen 11. Fuel 12 and steam 13 are supplied and the temperature is high.
A combustion gas stream 14 is generated. The fuel 12 includes H,
A wide range of materials can be selected, from combustible gases such as , Co, and 0H4- to heavy hydrocarbons such as asphalt cracked residual oil. Steam 15 is supplied to control the temperature of combustion section 10.

Therefore, when using H,,Co, etc. as fuel, the H,,C0
The steam 15 is not necessarily necessary because the temperature can be controlled by using it as a diluent gas, but when heavy hydrocarbons are used as fuel, it is preferably supplied to improve combustion conditions and prevent coking. This steam may be supplied alone, or mixed with oxygen 11 or fuel 12, or may be supplied along the vessel wall of the combustion section 10 to protect the vessel wall and suppress coking. High temperature combustion gas flow 1
4 then enters the second reactor 2 after being mixed with hydrogen and methane from the line 15, and is sequentially supplied to the first reactor 12. The raw material hydrocarbon 16, the cracked oil 17 from the second reactor and the first These hydrocarbons are sequentially thermally cracked while being in contact with cracked oil 8 from the reactor. As a result, the raw material hydrocarbons and each cracked oil are rapidly heated and cracked, and converted into ethylene, BTX, etc. The reaction fluid 18 discharged from the second reactor 2 enters a quenching device 19 where it is quenched and its heat is recovered. The quenching device 19 includes an indirect quenching heat exchanger, a direct quenching device, and the like.

The reaction fluid 20 that has exited the quenching device 19 then enters the gasoline fractionator 21 and is separated into cracked oil (200°C+) 22, cracked gas and steam 23, and the cracked oil 22 has a boiling point of 550°C.
After the above heavy components are separated as cracked residual oil 24, it is supplied to the second reactor 2 through line 17 and cracked again. On the other hand, the cracked gas and steam 23 enter the high-temperature separation system 25 and are separated into cracked gas 26, process water 27, BTX 28, and cracked gasoline 29. It is sent to reactor 2 and decomposed. Meanwhile, the cracked gas 30 from the first reactor and the cracked gas 26 from the second reactor enter the product separation and purification device 51 either individually or together. The product separation and purification device 51
So, water volume and methane 52. ethylene.

Olefins such as propylene and butadiene, 33° ethane,
Light paraffin gas such as propane and butane 54 and Cs
It is separated into heavier components 35. Among these, hydrogen and methane 32 are partially separated as a product or fuel 66 if necessary, and then supplied to the second reactor 2 through a line 15.

The light paraffin gas 34 is used as fuel if necessary, but is normally supplied to the downstream of the second reactor 2 and thermally decomposed, or supplied to the dehydrogenation catalyst reactor and catalytically decomposed. When the first reactor 1 is filled with a dehydrogenation catalyst, it is recycled to the first reactor 1 and decomposed. Also,
Components heavier than Cs 55 together with cracked gasoline 29,
It is fed to a second reactor and thermally decomposed. The cracked residual oils 9 and 24 from the first reactor and the second reactor are transferred to the first reactor 1.
It is also used as a fuel for supplying reaction heat to the second reactor 2 or as a heat source for process steam. Although not particularly shown in FIG. 1, CO, and lli! The acidic gas No. 8 is removed in front of the product separation and purification device 31 as usual.

Above, in Figure 1, BTX is extracted from the cracked oil from the first reactor.
Example 9 shows an embodiment in which BTX is supplied to the second reactor without being separated, but it is also possible to separate BTX and then supply it to the second reactor.

Furthermore, if the amount of components with a boiling point of 550° C. or higher in the cracked oil is small, there is no need to separate the components with a boiling point of 550° C. or higher.

Furthermore, in Figure 1, of the cracked oil supplied to the second reactor,
The cracked oil from the first reactor is combined with the cracked oil in the cracked oil from the second reactor (0,~200°C) and the heavier cracked oil from the second reactor (200°C+). The feedstock hydrocarbons are supplied to the second reactor separately from the feedstock hydrocarbons 16. The order is 17 degrees of heavy cracked oil from the second reactor and 8 degrees of cracked oil from the first reactor. As mentioned above, depending on the type of feedstock hydrocarbon or cracking conditions, cracked oil may be supplied upstream of the feedstock hydrocarbon. The cracked oil from the first reactor can also be separated like cracked gasoline and heavy cracked oil (200°C+) and either together with the cracked oil from the second reactor of the corresponding boiling range or separately. may be fed to the reactor.

Furthermore, if necessary, the cracked gasoline fraction (C, ~200°C) of the cracked oil from the first reactor and the second reactor is converted into BT
The heavy cracked oil (200
℃+) may be supplied to the second reactor and thermally decomposed to produce olefins and BTX.

Further, examples of light hydrocarbons mainly containing hydrocarbons with a boiling point of 550° C. or lower that are supplied to the first reactor include light paraffin gas such as IJPC), naphtha, kerosene, and the like. On the other hand, there are no particular restrictions on the feedstock hydrocarbons supplied to the second reactor, including light hydrocarbons such as TJPG and naphtha, atmospheric residual oil, vacuum residual oil, shale oil, tar sand, bitumen, etc. You can arbitrarily select up to heavy hydrocarbons.

(Effects of the Invention) According to the present invention described in detail above, the following effects can be achieved.

(1) In the first reactor, by decomposing light hydrocarbons with a catalyst, it is possible to take advantage of the high potential of light hydrocarbons into 1104 olefins such as propylene and butene, resulting in high yield. CM with rate
e'4 olefin can be obtained.

(2) In the second reactor, hydrocarbons are thermally decomposed in multiple stages according to their characteristics at high temperatures and in the presence of hydrogen and methane. Ethylene and BTX can be obtained in high yield.

(3) In the first reactor, CmeC such as propylene, butene, etc.
Catalytic cracking for 4-olefins.

The second reactor performs high-temperature pyrolysis to produce ethylene and BTX, and controls the type and quantity ratio of feedstock hydrocarbons supplied to the first and second reactors, as well as hydrogen and methane to the second reactor. By controlling the amount of steam and the amount of steam, a desired product composition can be easily obtained.

(4) By supplying the hydrogen and methane by-produced in the first reactor to the second reactor, hydrogen from light hydrocarbons can be effectively used to produce heavy hydrocarbons. As a result, no special hydrogen source is required for the cracking of the heavy hydrocarbons fed to the second reactor.

(5) By supplying the BTX component to the second reactor without separating it from the cracked oil from the first reactor, the yield and purity of BTX can be increased, and the yield and purity can be increased easily and with high yield. High purity BTX can be produced.

(Example) Examples will be described below, but these are merely for explanation and do not limit the present invention in any way.

In this example, Middle Eastern naphtha (
Boiling point: 40 to 180°C), Middle Eastern vacuum residue (specific gravity: 1.02°, 8 minutes, 45 wt%,
Pour point: 40°C) was used to decompose and the results at the time of death were shown.

The type of the first reactor is a fluidized bed, normal pressure, 'L
H8V: 2 was used, and the test was carried out under steam dilution to suppress coking. Moreover, a commercially available zeolite catalyst was used as a catalyst. On the other hand, in the second reactor, the vacuum residual oil is supplied to a normal type combustor installed above the reactor, and while steam preheated to 300°C or higher is blown from the surrounding area, the vacuum residue is The oil was combusted with oxygen to generate high-temperature combustion gas containing steam.Next, hydrogen and methane were blown into the reactor immediately above the combustor and mixed with the high-temperature gas.

Furthermore, this high-temperature gas enters the reactor installed directly below the combustor, contacts the raw material hydrocarbons supplied from the side wall of the reactor, and the cracked oil from the first reactor, and mixes them uniformly. The reaction product after thermally decomposing hydrogen was indirectly cooled with water from the outside, and the product was measured. Also, the residence time is
It was calculated from the reactor volume and reaction conditions.

Table 1 shows the decomposition results in the first reactor.

As is clear from Table 1, when the decomposition temperature is low, the gasification rate is low and the desired C3 * C4 olefin yield is not achieved, and vice versa. At high temperatures, the gasification rate.

% Ca # Although the selectivity to C4 decreases, the coke yield also increases. Therefore, in order to obtain the C3eC4 component in high yield in the first reactor, it is necessary to
It turns out that decomposition at 700°C is preferable.

Table 2 shows the cracking results during running when the cracked oil and vacuum residue obtained in Examples 1 to 4 of Table 1 were fed in multiple stages in the order of vacuum residue 2 cracked oil in the second reactor. .

4) 1 Pressure 15 bar, residence time 15 inches steam:
Hydrogen: methane: vacuum residue = 1.8: (Ll: α4:1 (weight ratio) 4) 2 Examples 5 to 8 are the cracked oils of Examples 1 to 4, respectively, and naphtha: vacuum residue = 1:1 ( Value when supplied so that the weight ratio is 4 $ 3 Combined with the table below, the total yield bone 4 The same conditions as Example 7 except for the temperature (tomato soup, residence time 5
0 milliseconds) Examples 5 to 8 were thermally decomposed under substantially the same decomposition temperature conditions. As is clear from Table 1 and Table 2, by combining catalytic decomposition of light hydrocarbons and high-temperature thermal decomposition of heavy hydrocarbons, 5 Ca e 'j p '4 p
It can be seen that the product composition of each component of x can be varied and a high conversion rate of raw materials into valuable products can be obtained.

In addition, if the decomposition temperature in the second reactor is lower, Example 9 in Table 2
As shown in , the yield is significantly reduced, so it is preferable to decompose at at least 1000°C or higher.

In addition, in the second coating, the ratio of naphtha and vacuum residual oil is 1 by weight.
However, it goes without saying that the range of product selectivity can be further expanded by changing this ratio or changing the type of raw materials. For example, if I and PG are supplied to the first reactor and the dehydrogenation reaction is carried out in a fixed bed, ζ
, compared to naphtha, a significantly higher O@y04 olefin yield is obtained, and the amount of cracked oil supplied to the second reactor is significantly reduced. However, even in this case, as shown in Table 1, the product selectivity decreases as the temperature increases, and thermal decomposition contributes, so ethylene increases, so decomposition occurs under conditions of 500 to 700°C. It is preferable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an embodiment of the method of the present invention. Sub-agent: 1) Akira Sub-agent Ryo Hagi Hara -

Claims (1)

[Claims] In a method for producing petrochemical products by decomposing hydrocarbons, light hydrocarbons mainly containing hydrocarbons with a boiling point of 350° C. or less are supplied to a first reactor and catalytically decomposed,
Next, the cracked oil produced by the catalytic cracking of the light hydrocarbons is fed to a second reactor together with other feedstock hydrocarbons, and the cracked oil and feedstock hydrocarbons are treated in the presence of steam, hydrogen and methane. A decomposition method for producing petrochemical products from hydrocarbons, characterized by performing thermal decomposition such that the initial decomposition temperature is at least 1000°C or higher.