JPS6343995A - Production of aromatic hydrocarbon - Google Patents

Abstract

PURPOSE:To produce an olefin and an arom. hydrocarbon in a high yield, by separating a 5C fraction from a thermally cracked hydrocarbon derived from petroleum and bringing the fraction into contact with crystalline aluminosilicate under particular conditions. CONSTITUTION:A hydrocarbon derived from petroleum (e.g., naphtha) 3 is fed into a steam cracking apparatus 1 to conduct thermal cracking under conditions of a temp. of 750-850 deg.C, a pressure of 0-15kg/cm<2>, and a residence time of 0.1-0.8sec, thereby preparing a reactive fluid 4. The fluid 4 is fed through a heat exchanger 5 into a cracked gasoline separator 7 to separate thermally cracked gasoline 8. The gasoline 8 is fed into a 5C fraction separator 9 to separate it into a 5C fraction 13 and a cyclopentadiene and/or isoprene component 10. The component 10 is fed into a dealkylation apparatus 11 to prepare benzene 12. The 5C fraction 13 is fed into a catalytic cyclization reactor 2 and brought into contact with crystalline aluminosilicate under a conditions of a temp. of 300-600 deg.C and a pressure of 0-60kg/cm<2> to convert it into an arom. compd. 14. The arom. compd. is recycled through a heat exchanger 15 into the separator 7.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention decomposes petroleum hydrocarbons to produce olefins and aromatic hydrocarbons [hereinafter referred to as BTX (B is benzene, T is toluene, and X is xyleph k). This invention relates to a method for producing useful petrochemical products such as (abbreviated as) in high yield and with high selectivity.

(Prior art) Conventionally, the first method for converting light gaseous hydrocarbons such as ethane and propane, and liquid hydrocarbons such as naphtha and kerosene into olefins and BTX is steam cracking. This is a method using a tubular pyrolysis furnace called (91 Ege).

222 to "The Oil and Gas Journal" magazine P220. (described in MAY 12.1969).

The thermal decomposition temperature in this method is generally allowed to range from 750 to 850C. In this method, due to the nature that anti-yakugo proceeds by a radical reaction mechanism, when the decomposition temperature is increased,
Increased yields of ethylene and BTX, propylene,
The yield of C4 fraction decreases, and conversely, if the decomposition temperature + ff1Th is lowered, the amount of propylene collected increases, but ethylene,
It is characterized by a significant decrease in the yield of BTX.

The second method is to use a ZSM-5 zeolite catalyst to produce hydrocarbons particularly rich in BTX components. As this method, for example, (a method in which a liquid hydrocarbon having 5 or more carbon atoms and having an aromatic content of 11 or less by weight is brought into contact with a ZSM-5 zeolite to convert it into an aromatic compound (Japanese Patent Publication No. 56-42659) ), or +21 °C, to +21 °C.

A method of converting paraffins, olefins) into aromatic compounds by contacting them with ZSM-5 zeolite (Japanese Patent Publication No. 1983-
No. 25568), etc. 8 (Problems to be Solved by the Invention) However, in the first method, as the reaction proceeds by a radical reaction mechanism as described above, it is difficult to obtain BTXi in high yield. In addition, harsh reaction conditions are required, and as a result, the progress of so-called coking in the tube heating furnace is accelerated, leading to an increase in pressure loss in the reaction tube, a decrease in reaction selectivity, and decoking. We must shorten the distance between...
There is a problem in that the yield structure in thermal decomposition is biased toward ethylene and BTX, making it difficult to simultaneously obtain propylene and C4 fractions in high yields.

In the second method, hydrogen and light hydrocarbons having 1 to 3 carbon atoms are produced as by-products in addition to aromatic compounds in the catalytic reaction,
In order to recover the desired BTXk, separation and purification equipment is required, and it is inevitable that the equipment investment and energy associated with separation and purification will become an excessive economic burden. Therefore, in order to produce useful petrochemical products, we can selectively produce aromatic hydrocarbons stably and inexpensively while maintaining a flexible yield structure according to demand. Ethylene, propylene, butadiene, BTX from hydrocarbons
The total yield (hereinafter abbreviated as effective product yield) of
There is a strong need for a manufacturing method that allows for more than what can be obtained with any of the conventional methods.

(Means for Solving the Problems) The present inventors have solved the above-mentioned drawbacks of the conventional technology, and have made it possible to achieve an effective product yield from petroleum hydrocarbons as a raw material that is higher than that of the conventional method. As a result of extensive research into a selective method for producing aromatic hydrocarbons that requires less capital investment and less energy, we have discovered that carbon number 4 obtained when petroleum hydrocarbons are pyrolyzed in the ethylene production process.
-5 hydrocarbons at a temperature of 500-600C and 0-5
It is fed into a catalytic cyclization reactor where it is contacted with crystalline aluminosilicate under pressure conditions of 60 kg/dlG to convert it into aromatic compounds, and the reaction products obtained therein are then restarted for pyrolysis of the ethylene production process. Gasoline separator K
This was achieved by 17 cycles and recovering the aromatics as pyrolysis gasoline.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail.

In the drawings, 1 is a tubular heating furnace for the pyrolysis process, and 2 is a reactor for the catalytic cyclization process. First, a liquid hydrocarbon such as naphtha or kerosene, preferably naphtha 3, is supplied to the tube heating furnace 1 at a temperature of 750 to 850C and a normal pressure to 15%.
It is pyrolyzed at a pressure of mG and a residence time of 0.1 to 0.8 seconds to produce a reaction fluid 4 mainly containing ethylene, propylene, and BTX'i. The reaction fluid 4 enters a heat exchanger 5 for heat recovery, passes through the heat exchanger 5 into a higher order reaction fluid 6, and enters a pyrolysis gasoline separator 7 to separate pyrolysis gasoline 8.

The pyrolyzed Ganrin 8 is fed to a 5-carbon fraction separator 9 that separates a 5-carbon fraction therein, which is a 5-carbon fraction 13, which is generally referred to as a no-cut cut rich in BTX components. It is separated into fluid 10. For example, when the fluid 10 is intended to produce benzene, it is supplied to a dealkylation device 11, and benzene 12 is produced by a hydrodealkylation reaction.

On the other hand, the 5-carbon fraction 13 separated by the 5-carbon fraction separator is fed to the catalytic cyclization reactor 2, but preferably the isoprene contained in the 5-carbon fraction 13 is Mayu, catalytic cyclization reactor 2 as a useful raw material for synthetic rubber
It is preferable to provide a device Rt for separating cyclopentadiene in order to suppress deterioration of the catalyst over time.

The reaction conditions of the catalytic cyclization reactor 2 are normal pressure to 60 kp/cr.
IG, preferably at a pressure of normal pressure to 10 ky/crlG.

The temperature is 300 to 600C, preferably 450 to 600C. mi Nitrogen velocity IJ [(W)TSV) is 0.1 He1
0 Hr-', preferably 0.1 h2. OHr-',
More preferably, it is 0.1 to 0.8) (r-1).

Furthermore, as the catalyst used in the catalytic cyclization, aluminosilicate zeolite having a function as a solid acid catalyst can be widely used. Preferably, ZSM-5 type zeolite, for example, a method of converting a liquid hydrocarbon having 5 or more carbon atoms in which the 111 aromatic component is 15% by weight or less into an aromatic compound (Japanese Patent Publication No. 56-42639), or 12:
It is preferable to use a zeolite catalyst used in a method for converting hydrocarbons having a boiling point of 204 C or less into aromatic compounds (JP-A-5O-4029).

The ZSM-5 series zeolite mentioned here is one whose X@ diffraction pattern is the same as or similar to ZSM-5, and may contain other metals instead of aluminum, and It may also contain other elements along with aluminum.

More preferably, the catalyst used in the present invention is ZSM-5 type zeolite containing zinc, and the 28
The M-5 type zeolite satisfies the following (1) to Tiii).

(1) The atomic ratio of silicon/aluminum is 10.75, preferably 12S50. (11) The atomic ratio of zinc/silicon is o, o o a to 0.
03, preferably has a χ1 component of 0.01 to 0.02 +
il) Equivalence at 500 to 900C by temperature-programmed desorption method using pyridine and heating rate of 15C/min.
z The amount of pyridine desorbed per 1f of SM-5 type zeolite is 40 to 120 μmol/f.The range of the amount of pyridine desorbed in (iii) above is the same as that of ZSM-5 type zeolite f.
600,800 CO temperature, water pressure of 0.1 to 1 atm, 0
．． It is obtained by heating the catalyst in the coexistence of water vapor under conditions of a treatment time of 20 hours to suppress a decrease in the activity of the catalyst and stabilize it.

Furthermore, in the above catalyst, it is preferable that the ZSM-5 type zeolite is hydrothermally synthesized in the coexistence of one or more compounds selected from lower alkyl urea compounds and lower alkyl thiourea compounds. .

In the present invention, the type of the catalytic cyclization reactor is as follows:
It has the advantage that not only a fluidized bed but also a fixed bed reactor can be used.

In this catalytic cyclization reactor 2, the supplied carbon number fraction 1
3 and a carbon number fraction 19 to be described later are converted into a high-yield, highly selective KBTX component by the action of a catalyst, producing a reaction fluid 14 rich in the BTX component.

The catalytic cyclization reactor 2ft Izumo reaction fluid 14 is transferred to the heat exchanger 1
After the input heat is recovered in step 5, it joins with the reaction fluid 6 again and is supplied to the pyrolysis gasoline separator 7.

As a result, the BTX component contained in the reaction fluid 16 is separated as pyrolyzed gasoline 8, and hydrogen and hydrocarbons having 1 to 4 carbon atoms are separated as cracked gas 17. That is,
By carrying out the BTX separation from the reaction fluid 16 using the same pyrolysis gasoline separator 7 as the reaction fluid 6 produced from the freshly fed feedstock hydrocarbon 3 and containing 1 BTX fraction, the catalytic cyclization reactor 2y&: There is no need to provide an independent separation and recovery device for the discharged reaction fluid 14, and equipment investment and energy usage for separation and recovery can be greatly reduced.

On the other hand, the reaction fluid 17 leaving the pyrolysis gasoline separator 7 is
The 4-carbon fraction separator 18 is supplied with a 4-carbon fraction 19.
and hydrogen, and a reaction fluid 20 consisting of light hydrocarbons having 1 to 3 carbon atoms. The reaction fluid 20 is transferred to a separation and purification device 21
and separated into hydrogen and methane 22, light olefins such as ethylene and propylene 23, and light paraffins such as ethane and propane 24 - The 4-carbon fraction 19 is directly combined with the 5-carbon fraction 13 and subjected to a catalytic ring process. Preferably, F12 or one of Poutadier/Imbutylene, which is useful as a raw material for petrochemical products contained in the C4 fraction, may be supplied to the chemical reaction reactor 2.
It is advisable to provide a device for species separation. When the 4-carbon fraction 19 is also supplied to the catalytic cyclization reactor 2, it is produced through the same reaction and the same route as the 5-carbon fraction 13.
:BTX component is recovered as pyrolyzed Ganlin 8.

Above, the drawings show that the 4-carbon and 5-carbon fractions produced by thermal decomposition of feedstock hydrocarbons, which are normally evaluated only as fuel, are subjected to a catalytic cyclization reaction, in which BTXt is selectively and in high yield. - The case where the generated pyrolysis gasoline is separated and recovered as pyrolysis gasoline by sharing an existing pyrolysis gasoline separation device without using an independent separation port collection f is shown.

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

(1) Capital investment for the separation, purification, and recovery of BTX, the light gas produced by the catalytic cyclization reaction, by organically combining conventional thermal decomposition of petroleum hydrocarbons and catalytic cyclization technology. , energy usage can be significantly reduced.

(21) The effective product yield from petroleum hydrocarbons, which is a raw material, was around 60% by weight in conventional thermal cracking, but by selective aromatization of C4, °C, and fractions, which are by-products, Approximately 65
The weight can be increased to a degree K.

(3) The organic combination of the pyrolysis process and the catalytic cyclization process allows for maintaining or exceeding effective product yields that are unattainable by each process alone;
It becomes possible to have a flexible yield structure depending on the demand for petrochemical products.

That is, for example, lowering the pyrolysis temperature to increase the propylene yield usually results in a significant decrease in the effective product yield due to a decrease in the yield of ethylene, BTX;
4. Since it is possible to selectively convert the C5 fraction to the BTX component, the total effective product yield including the catalytic cyclization process can be the same as or even higher than that of conventional thermal cracking. Moreover, it becomes possible to selectively increase the production of propylene and BTX.

,(Example) Next, the present invention will be explained in more detail with reference to Examples.

Examples 1 and 2, Comparative Examples 1 and 2 (11 Preparation of catalyst (a) Sodium silicate (water glass No. 3) 290/-I Dissolved in 230f of distilled water 7'CA solution, - Separately aluminum sulfate hexahydrate 11.4j' and tetrapropylammonium bromide 502, sulfuric acid 13? in distilled water 300f
Solution B '5I dissolved in: Preparation (7 times. Next, using a homogenizer, add Solution B to Solution A under strong stirring to form a homogeneous mixed gel. This gel f 1 was charged into an autoclave and heated at 160C 11000 rpm. After the reaction, the solid substance was filtered, washed with water, dehydrated, dried, and calcined in air at 550C for 13 hours.The resulting white powder was confirmed by X-ray diffraction, and was found to be ZSM. -5 type diffraction pattern.Fluorescent X-ray analysis showed a psi/A diffraction pattern.
The t ratio was found to be 25. This zeolite.

Ion conversion was performed using a 10% ammonium chloride aqueous solution in a conventional manner to obtain H-type zeolite. Then 5% zinc nitrate
Impregnated with water solution-i' and evaporated to dryness 1. Drying, firing (50
(0° C., 3 hours) and zinc-containing zeolite. next,
After compression molding and sizing into 9 to 20 meshes, they were filled into a quartz reaction tube for the purpose of activity control, and treated in 80 volumes of steam (primary dilution, atmospheric pressure) at 650°C for 1 hour (catalyst A).

(b) Steaming conditions for activity control are 6
507::, prepared in the same manner as Catalyst A, except for 5 hours (Catalyst B).

(c) In the preparation of catalyst A, instead of using tetrapropylammonium bromide, 1,5-dimethylurea 23.4'? It was prepared in the same manner except that . fc'x L, steaming for activity control was carried out at 650C for 15 hours, the same as for catalyst B (catalyst C).

(21 Conversion Reaction In the conversion reaction example, Middle Eastern naphtha (boiling point 4
0 to 180C), first to the front type pyrolysis equipment, normal pressure,
The C4 fraction obtained was supplied and thermally decomposed at a steam dilution ratio of 0.5 and each predetermined temperature.

After the Cs fractions are separated by total distillation of butadiene, imbutylene, isoprene, and cyclopentadiene, respectively, they are supplied to a fixed bed reactor packed with the above-mentioned catalyst, and after catalytic cyclization, the reaction fluid is separated into pyrolysis gasoline. It was supplied to the tower and recycled.

Table 1 shows the yields of mild pyrolysis and severe pyrolysis within the range of realistic pyrolysis conditions as Comparative Example 1 and Comparative Example 2, respectively. It is written as follows. However, as the catalyst for catalytic cyclization used in the examples in Table 8g1, Catalyst A prepared above was used.

Table 1 *I M effect products *11. =BY+PY-+fljix7
+ca~a aromatic *2 EY = ethylene, PY = propylene As is clear from the examples and comparative examples in Table 1, according to the method of the present invention, the C4 fraction excluding butadiene and imbutylene, isopre/ By catalytically cyclizing the C5 fraction excluding cyclopentadiene and recycling it to the pyrolysis gasoline separation tower, C4, which has conventionally only been evaluated as a fuel, is produced.
, C, the fraction disappears, and it can be seen that useful C0 to C8 aromatics are selectively produced. In addition, the effective product yield also increases by about 5 to 8% compared to the case of only thermal decomposition, and the increase is larger when using mild thermal decomposition. The combination shows that any pyrolysis operating conditions can be achieved according to demand without reducing the effective product yield, which is not possible with pyrolysis alone.

Examples 3 and 4 Table 2 shows the reaction products obtained by catalytic cyclization of each of the C4 and C5 fractions using catalyst A and one-pass conversion.

Table 2 × 1 Distillate obtained by removing butadiene and inbutylene from the C1 fraction produced by thermal decomposition of naphtha × 2 Distillation obtained by removing isogrene and cyclopentadiene from the 7tcs fraction produced by thermal decomposition of naphtha *3 °C, ~8 Aromatic selectivity - produced 2c,... Aromatic fraction/conversion rate From Table 2, all fractions have a conversion rate of C6 ~
Both C8 aromatic selectivity is high, and this reaction is selective at 4C6~℃
, which has been shown to be useful for aromatic production.

Examples 5 to 7 Table 5 shows that isoprene and cyclopentadiene were separated by distillation. , shows the catalytic activity half-life of each catalyst determined from the aging deterioration of the catalyst during continuous oil passage.The catalytic activity half-life here refers to the catalytic cyclization reaction as the primary This is the date from which the activity of the catalyst deteriorates over time until it reaches % of the initial reaction rate constant.

Table 3 If the temperature and conversion rate of catalysts A, B, and C are constant, C6
It can be seen that the C1 aromatic yield is also almost constant.

However, it is clear that the deterioration resistance of the catalyst is superior to that of ℃, B, and A.

[Brief explanation of drawings]

The figure is a flow sort showing one embodiment of the present invention.

Claims (3)

[Claims] (1) After pyrolyzing petroleum hydrocarbons using a steam cracking device, the pyrolysis gasoline separated by a pyrolysis gasoline separator is supplied to a 5-carbon fraction separator to separate a 5-carbon fraction; The fraction or one or two of cyclopentadiene and isoprene contained therein is separated at a temperature of 300 to 600°C and a mass of 0 to 60 kg/cm.
It is characterized in that it is supplied to a catalytic cyclization reactor in which it is brought into contact with crystalline aluminosilicate under a pressure condition of ^2G to convert it into an aromatic compound, and the resulting reaction product is recycled to the pyrolysis gasoline separator. A method for producing aromatic hydrocarbons. (2) The method according to claim 1, wherein the thermal decomposition using a steam cracking device is performed at a temperature of 750 to 850°C, a pressure of 0 to 15 kg/cm^2, and a residence time of 0.1 to 0.8 seconds. (3) After pyrolyzing petroleum hydrocarbons using a steam cracking device, the pyrolyzed gasoline separated by a pyrolyzed gasoline separator is supplied to a 5-carbon fraction separator to separate a 5-carbon fraction; The fraction, or one or two of cyclopentadiene and isoprene contained therein, and the remaining pyrolysis product from which the pyrolyzed gasoline has been separated are fed to a 4-carbon fraction separator to obtain 4-carbon fractions. The fraction is separated, and the fraction or one or two of butadiene and isobutylene separated therein is crystallized at a temperature of 300 to 600°C and a pressure of 0 to 60 kg/cm^2G. A method for producing aromatic hydrocarbons, which comprises supplying the aromatic hydrocarbons to a catalytic cyclization reactor in which they are brought into contact with a catalytic aluminosilicate to convert them into aromatic compounds, and recycling the resulting reaction product to the pyrolysis gasoline separator.