JPS5857470B2 - Olefuin Oyobi Tankanhou Kouzokutankasuisono Seizouhou - Google Patents

Description

[Detailed description of the invention] [I] Background of the invention The present invention relates to a method for pyrolysis of heavy hydrocarbon oils.

More specifically, the present invention involves hydrogenation (hereinafter simply referred to as "hydrogenation") of a relatively heavier hydrocarbon oil than a kerosene fraction among various fractions obtained by fractional distillation of crude oil.

), and a method for producing olefins and monocyclic aromatic hydrocarbons useful as chemical raw materials in high yield through thermal decomposition.

Various distillate oils obtained by applying crude oil to an atmospheric distillation column and/or a vacuum distillation column are pyrolyzed in the presence of steam in a tubular pyrolysis furnace to produce lower unsaturated hydrocarbons (olefins) such as ethylene and propylene. ) and monocyclic aromatic hydrocarbons such as benzene, toluene, and xylene are widely practiced industrially.

In addition, there are various methods for producing olefins using crude oil, atmospheric residue oil, vacuum residue oil, etc. as pyrolysis raw materials, such as fluidized bed pyrolysis, regenerator pyrolysis, and high-temperature steam pyrolysis. Proposed.

However, compared to conventionally widely used olefin production methods that use natural gas or naphtha as raw materials for thermal cracking, olefin production methods that use heavy hydrocarbon oils heavier than kerosene and gas oil as raw materials generally have lower olefin yields and 180% ℃
A large amount of by-product heavy oil with a boiling point range above is produced.

Therefore, in the production of olefins using heavy oil as a raw material, it is necessary to reduce the amount of by-product heavy oil produced in the pyrolysis process by subjecting the feed oil to hydrogenation treatment in advance, or to effectively utilize this by-product oil. is becoming one of the major issues that will affect economic efficiency.

It is generally known that this thermal decomposition by-product oil contains three to four times or more the sulfur content of the thermal decomposition raw material oil, and contains a large amount of polycyclic aromatics because it has been subjected to high-temperature treatment.

Therefore, recycling by-product heavy oil as it is as pyrolysis feedstock will only accelerate the coking rate change in the furnace, and no substantial increase in olefin yield can be expected at all.

Furthermore, when heavy oil with a high sulfur content is used as a fuel, large amounts of sulfur oxides are generated, causing air pollution.Also, when used as a raw material for petroleum coke, heavy oil with a high sulfur content is generated. You can only get quality coke.

The present invention aims to provide an economical method for producing olefins and monocyclic aromatics using such heavy oil as a raw material, including hydrogenation and thermal cracking steps, and an economical method for producing olefins and monocyclic aromatics including thermal cracking steps. It is something to do.

On the other hand, when naphtha and kerosene are used as pyrolysis raw materials, it has already been proposed to hydrogenate them in advance to increase the yield of useful light olefins and monocyclic aromatics ( JP 45-22522, JP 49-90303, JP 47-27903,
JP-A No. 48-52702).

However, these proposals are aimed at hydrogenating hydrocarbon oils that are relatively light, have low sulfur content, and have low aromaticity, such as naphtha and kerosene oil. It is extremely difficult to effectively apply the proposed catalysts, reaction conditions, reaction methods, etc. to the hydrogenation treatment of heavy oils, especially highly aromatic hydrocarbon oils.

Furthermore, the various ion-exchanged zeolites or solid acid carriers such as silica-alumina that have been proposed as hydrogen cracking catalysts increase hydrogen consumption due to decomposition of non-aromatic hydrocarbons during the hydrogenation process. , and a decrease in liquid yield, and in addition, it cannot necessarily be expected to improve the yield of olefins in the thermal decomposition process, and therefore does not meet the object of the present invention.

Therefore, the reality is that there has been no satisfactory technology for the purpose of the present invention, which is to provide an economical method for producing olefins and monocyclic aromatics using heavy oil as a raw material. .

In order to achieve the above objectives, the present inventors (1) increased olefin yield and decreased by-product heavy oil by hydrogenating pyrolysis feedstock oil, and (2) hydrogenating by-product heavy oil. With a focus on reusing raw materials as feedstock, we conducted a detailed study of hydrogenation catalysts and hydrogenation treatment conditions.

As a result of such studies, the findings obtained by the present inventors will be described below.

In general, even if polycyclic aromatics (typical compounds include naphthalenes, anthracenes, benzothiophenes, etc.) are simply introduced into a thermal decomposition furnace, gases such as hydrogen and methane are not generated and polycondensation occurs. It merely causes a reaction and produces coke.

The present inventors investigated the thermal decomposition behavior of intermediate products in the hydrogenation reaction of these polycyclic aromatics using naphthalene as a model raw material.

When naphthalene is used as a model raw material, the following reaction routes can be considered as the main hydrogenation reaction routes.

A comparison of the thermal decomposition behavior of these naphthalenes and their hydrogenated products revealed that the reaction temperature was 750°C and the contact time was 0.
The results shown in Table 1 were obtained under the conditions of 6 seconds and a steam/oil ratio (weight) of 1.0.

As shown in Table 1, when polycyclic aromatic hydrocarbons are completely hydrogenated to cycloparaffins, they exhibit favorable behavior as thermal decomposition raw materials. We found that almost no effect was observed.

Similarly, the thermal decomposition behavior when anthracene is used as a hydrogenation model raw material shows that as long as polycyclic aromatic hydrocarbons are not completely hydrogenated, in other words, even a partial aromatic ring remains in the polycyclic naphthene ring. It was confirmed that the hydrogenation effect cannot be expected much with such hydrogenation.

It is possible to use the distribution of hydrogen contained in hydrocarbon oil (which can be measured by NMR) as an indicator of the aromatic content in hydrocarbon oil, and the degree of hydrogenation of various hydrogenated oils can be indicated by hydrogen distribution. The figure below shows the correlation between this hydrogen distribution and the thermal decomposition products of the hydrogenated oil.

The drawing is based on the aforementioned knowledge that polycyclic cycloparaffins have favorable properties as a pyrolysis raw material and that partially hydrogenated products have almost no hydrogenation effect. Polycyclic aromatic-containing hydrocarbons were subjected to relatively high-level hydrogenation using various catalysts and various hydrogenation conditions, and then subjected to tubular pyrolysis in the presence of steam (temperature 750°C, residence time 1.0 seconds, Steam/raw oil ratio =
1 (weight ratio).

That is, the hydrogen distribution in the hydrogenated oil was measured by NMR,
When we plotted the yields of pyrolysis products ethylene, propylene, and BTX against the percentage of aromatic nucleation hydrogen (hereinafter abbreviated as HAROM) to the total hydrogen in hydrocarbon oil, there was a good correlation. HARO in hydrogenated oil
This shows that as the value of M decreases, there is a range in which the yields of olefins and monocyclic aromatic hydrocarbons increase significantly.

This indicates that complete hydrogenation of aromatic nuclei during the hydrogenation treatment of polycyclic aromatic hydrocarbons is preferable for subsequent thermal decomposition, rather than only partial hydrogenation.

Prior to such thermal decomposition, the heavy oil is hydrogenated to reduce the HA[OM of the heavy oil. As a catalyst, nickel oxide and tungsten oxide, or sulfurized titanium oxide and silicon oxide mixed oxide are used. Catalysts containing nickel and tungsten sulfide are most suitable.

[■] Summary of the Invention Therefore, the method for producing olefins and single aromatic hydrocarbons of the present invention based on the above knowledge is characterized by including the following steps and B).

Button Contains polycyclic aromatic hydrocarbons and has a temperature of 180 to 600℃
A step of hydrogenating heavy hydrocarbon oil within the distillation range of in the presence of a catalyst in which nickel oxide and tungsten oxide, or nickel sulfide and tungsten sulfide are supported on a titanium oxide-silicon oxide mixed oxide; and B) pyrolyzing the liquid product from;

The production method of the present invention configured as described above is characterized in that, in particular, in the first step, hydrogenation step, polycyclic aromatic hydrocarbon oil is highly hydrogenated to substantially convert it into polycyclic cycloparaffin. One of its greatest features is that it converts polycyclic aromatic-containing hydrocarbons into hydrocarbon oils that are preferable as thermal cracking raw materials, specifically by reducing the HAROM value.

Furthermore, the present invention consists of this highly characteristic and effective hydrogenation step and the subsequent thermal decomposition step, and by this combination, polycyclic aromatic-containing hydrocarbon oil, which has not been considered as a raw material for thermal decomposition, can be used as a raw material. Naethylene, propylene, 1,3 useful as petrochemical raw materials when used in oil
The greatest effect is that light olefins such as butadiene and monocyclic aromatic hydrocarbons such as benzene, toluene, and xylene can be produced in good yields.

In addition, the catalyst used in the first step of the production method of the present invention has extremely high poison resistance against sulfur compounds and nitrogen compounds, and
Therefore, it is expected to maintain good hydrogenation activity over a long period of time even for heavy oils containing relatively large amounts of these toxic components, such as asphalt decomposition by-product oils.

[■] Detailed Description of the Invention (1) Hydrogenation Process Feedstock The feedstock that is the object of the present invention has a percentage of aromatic nucleus-forming hydrogen (HAROM) relative to the total hydrogen in the hydrocarbons of 3.
It is a polycyclic aromatic-containing hydrocarbon with a distillation range of 180 to 600°C.

If the number of HAROMs is less than 3, the effect of the hydrogenation treatment will not be sufficient, and therefore the purpose of the present invention will not be met.

Further, the fraction of 180° C. or lower has a small content of polycyclic compounds, and thus cannot effectively enjoy the effects of the present invention.

On the other hand, when a fraction of 600° C. or higher is used as a raw material oil, it is not preferable because coking becomes significant in the hydrogenation treatment and subsequent thermal decomposition reaction.

Examples of such polycyclic aromatic-containing hydrocarbon oils suitable as feedstock oils of the present invention include straight-run oils such as:
Heavy gas oil, vacuum gas oil, tar sand synthetic crude oil, etc. Also, as by-product oils in various processes, pipe distillate oil pyrolysis by-product oil, fluidized bed distillate oil or residual oil pyrolysis by-product oil , cycle oil produced by fluidized bed catalytic cracking, etc.

Catalyst As mentioned above, the filtration hydrogenation treatment in the present invention is capable of highly nuclear hydrogenation or hydrogen decomposition of polycyclic aromatic raw material oil without substantially lightening it by hydrogenolysis. For this purpose, the present inventors supported a hydrogenated metal species such as a combination of nickel oxide and tungsten oxide or nickel sulfide and tungsten sulfide on a titanium oxide-silicon oxide mixed oxide. The catalyst was found to be the most suitable.

In this case, the composition of the catalyst is aNiO-bWO3/
When expressed as a c-support (even when the hydrogenated metal species is in the form of a sulfide, it is converted into an oxide form), it is particularly preferable that a=3 to 10 by weight and b=10 to 25 by weight.

A particularly preferred composition range of the carrier TlO28102 is Ti
e2/Sio, = 1 to 7 (weight ratio).

The preparation of this catalyst can be carried out in a generally known manner, but as a specific method, for example, nickel nitrate and ammonium paratungstate are mixed as aqueous solutions in a titania-silica mixed hydrogel or slurry, respectively. Particularly preferred is a method in which the mixture is kneaded, evaporated to dryness, and then fired.

In the hydrogenation process of the present invention, it is possible to use the thus obtained oxide form as it is as a catalyst, but even better results can be obtained by further converting it to the sulfide form. .

In this case, the conversion to the sulfide catalyst can be carried out by a commonly known method, but it is more preferably carried out at a high temperature range of 350 to 600°C, for example in a hydrogen-hydrogen sulfide mixed gas flow. By carrying out sulfurization of the catalytic hydrogenation metal species, a catalyst can be obtained which is highly suitable for the purpose of the present invention.

Furthermore, this conversion to the sulfide form can also proceed automatically during the hydrogenation reaction of heavy oil containing sulfur compounds.

In this case, in the initial stage of using the catalyst, it is desirable to promote the conversion to a sulfide form without actively removing sulfur compounds from the recycled gas, which will be described later.

For more details on the preparation of a catalyst in which nickel oxide-tungsten oxide or nickel sulfide-tungsten sulfide is supported on a titanium oxide-silicon oxide mixed oxide support suitable for the purpose of the present invention, and the hydrogenation effect, please refer to JP-A-51
- It can be obtained from Japanese Patent Publication No. 121495, published in Japanese Unexamined Patent Publication No. 1983
The contents of Japanese Patent No. 121495 are hereby incorporated by reference (however, as mentioned above, the present invention also includes hydrogenation using an oxide catalyst).

Reaction Conditions As the hydrogenation reaction conditions of the present invention, it is possible to adopt the conditions generally used for hydrogenation treatment of straight-run heavy oil, but as mentioned above, HAR of oil
It is particularly preferable to adopt conditions such that OM is greatly reduced, and specifically, for example, the ranges shown below may be mentioned. Although it can be carried out according to the generally widely practiced catalytic reaction method using reaction conditions, more specifically, the feed oil and hydrogen can be mixed, preheated, and this feed mixture can be catalyzed. Hydrogenation is carried out by passing it through a packed bed,
It consists of separating the effluent from the catalyst packed bed into a liquid effluent and a gaseous effluent, the gaseous effluent being recycled to the catalyst packed bed and the liquid effluent being fed to the next pyrolysis step.

Since the hydrogenation catalyst used in the present invention has high toxicity resistance against sulfur compounds, the inclusion of light sulfur compounds, such as hydrogen sulfide, in the recycled gaseous product does not pose any problem in itself. In order to maintain high recycling efficiency, it is desirable to continuously or intermittently separate sulfur compounds from recycled gas.

Separation can be easily carried out, for example, by passing the recycled gas through an alkali washing tower or further through a sulfuric acid washing tower.

(2) Pyrolysis process Pyrolysis treatment methods for obtaining light olefins and monocyclic aromatic hydrocarbons are known for various feedstock oils.

In the thermal decomposition step, which is the second step of the present invention, in addition to such known thermal decomposition means, any various thermal decomposition means,
For example, a tube heating furnace method, a regenerative furnace method, a partial combustion method, a moving bed method, a fluidized bed method, etc. can be adopted, but the present invention applies to a fluidized bed pyrolysis furnace and a tube pyrolysis furnace. , particularly excellent effects can be obtained.

In particular, in the present invention, as a result of the advanced hydrogenation treatment in the first step, the liquid product sent to the thermal decomposition process contains polycyclic aromatic components that cause coking and sulfur compounds as poisonous components. has been significantly reduced.

Therefore, a wider range of reaction conditions can be selected for thermal decomposition than in the case of thermal decomposition of straight-run naphtha.

An example of the treatment conditions in the pyrolysis step of the present invention is as follows:
Reaction layer average temperature 700~850℃, reaction layer outlet pressure 0~
10 Ky/cr/IQ, reaction layer residence time 0.01-2
Seconds.

During such thermal decomposition, it is possible to use water vapor, hydrogen, lower saturated hydrocarbons (methane, ethane, etc.) or a mixture thereof as a diluent.
(hydrogenated oil) in a ratio of 0.1 to 5 (weight ratio).

The gist of the present invention will be explained in more detail below using Examples and Comparative Examples.

(IV) Experimental Examples Example 1 Hydrogenation Treatment Hydrogenation is carried out using a high sulfur-containing gas oil fraction (boiling point range 270 to 350°C) obtained by thermally decomposing vacuum distillation residue oil in the presence of steam as feedstock oil. In this process, an aqueous solution of nickel nitrate and ammonium paratungstate was added to the titania and silica mixed hydrogel, and by evaporating to dryness while mixing and kneading, and baking at 500°C, nickel oxide and tungsten oxide were calculated as oxides, respectively. Swt
N1O-WO3/Ti02Si containing 20 wt%
02 catalyst was manufactured, and this N i 0-WO3/T i
02.SiO2 catalyst at 450°C, 1. Ohr N2:
A hydrogenated catalyst was obtained by presulfiding in a H2S (90:10) mixed gas flow.

This catalyst was filled into a stainless steel reaction tube for 15 minutes, and the raw material oil was hydrogenated.

Table 2 shows the hydrogenation treatment conditions and hydrogenation treatment results.

Through the hydrogenation treatment in this example, the HAROM in the raw oil was reduced from 49.8% to 9.4%, and by further lowering the liquid time-space velocity, it was reduced to 4.7%, and at the same time an extremely high rate of desulfurization was carried out. It was done.

Thermal decomposition The hydrogenated oil and the fertilized oil obtained by the above hydrogenation treatment were subjected to tubular pyrolysis in the presence of steam, and the results and pyrolysis conditions are shown in Table 3.

Because the treated oil contains extremely large amounts of polycyclic aromatics, the yields of ethylene and propylene are only 0.5 and 0.13 wt%, respectively, even if thermal decomposition is carried out in the presence of steam, whereas the yield of the present invention is Hydrogenated oil obtained by this method has a yield of ethylene and propylene of 10 to 15 when thermally cracked.
It increased significantly to w1 weight and 4 to 6wt.

Example 2 The hydrogenation process of naphtha pyrolysis by-product oil was carried out using the same catalyst as in Example 1, N i OWOs / T + 02.5in.
2 catalyst and for comparison N i OWO3/A 72
0 s, using N1O-WO3/5i02・Al2O3 catalyst, pressure 100 Ky/at/l, temperature 400°C,
Liquid hourly space velocity 1 [1-o iA / lj -cat
/hr].

Each catalyst was pre-sulfurized at 450°C for 1 hour prior to the hydrogenation reaction.

Furthermore, the hydrogenated oil and untreated oil treated in the above hydrogenation process were thermally decomposed in the presence of steam using the conditions of reaction salt v775°C, residence time 1 second, and steam to feedstock oil ratio 1.0. did.

Table 4 shows the hydrogenated oil properties and thermal decomposition yield at this time.

As a result, hydrogen decomposition is substantially suppressed and HAROM
Lowering the ratio of N1O-WO leads to an increase in the yield of light olefins during pyrolysis.
It can be seen that the 3/TiO2.S t O2 catalyst is most suitable.

Example 3 Table 5 shows the reaction conditions and reaction results when hydrogenation treatment was carried out in the presence of the same catalyst as in Example 1 using a tar sands synthetic crude oil fraction as a feedstock oil.

Further, Table 6 shows the decomposition conditions and results when the hydrogenated oil and untreated oil shown in Table 5 were thermally decomposed in the presence of steam.

The percentage of HAROM increases from 6.9 to 5.0 by hydrogenation treatment.
0%, and the ethylene yield by thermal decomposition increases by 2 wt% by hydrogenation, indicating that it is possible to increase the yield of light olefins by reducing HAROM.

Example 4 Hydrogenation conditions, feedstock oil, and hydrogenated oil when hydrogenation was carried out using the same catalyst as in Example 1 using normal pressure heavy gas oil and vacuum gasoil obtained from crude oil from the Middle East as feedstock oil. Table 7 shows the properties of
(Feedstock oil/normal pressure heavy gas oil) and Table 9 (Feedstock oil/vacuum gas oil).

For comparison, N 1O-WO3/l'203 and N 1O-WO3/
The hydrogenation results using the S 102A1203 catalyst have been added to Tables 7 and 9.

Furthermore, Tables 8 and 10 show the reaction conditions and yields when the hydrogenated oils and unprocessed oils shown in Tables 7 and 9 were thermally decomposed in the presence of steam.

As a result, substantially suppressing hydrogenolysis and lowering the percentage of HAROM leads to an increase in the yield of light olefins in pyrolysis, and such hydrogenation processes require N t
It is clear that the OWOs/T i 02·S t 02 catalyst is most suitable.

Example 5 N1O-WOs/Tio2S obtained in Example 1
A stainless steel reaction tube was filled with 20 g of iO2 catalyst and this catalyst at a ratio of hydrogen and hydrogen sulfide of about 90/10 [vol/vol:]. After reducing the mixture at 400°C for 3 hours under conditions of 65-661 g/hr at 500°C
, Ni5-WS3/Ti obtained by pre-sulfurization treatment for 30 minutes
α-Methylnaphthalene was hydrogenated as a model raw material for polycyclic aromatic hydrocarbons using two catalysts: O,·S t 02 catalyst.

The reaction conditions were pressure crab 100KP/d・G, reaction temperature: 4
25° C., liquid hourly space velocity: 11 raw oil per 11 catalysts per hour, hydrogen consumption: 800ON7 per 11 raw oil.

The results are shown in Table 11 below.

The above table shows that presulfidation treatment is particularly excellent for nuclear hydrogenation of polycyclic aromatics, but N1O-WO3
A large reduction in HAROM (i.e., from 70% to 13% of α-methylnaphthalene) is also possible with the /TiO2·S t O2 catalyst, and therefore the present method for producing olefins and aromatic hydrocarbons by pyrolysis is suitable. This shows that it is effective as a one-step catalyst.

In particular, since the catalyst is automatically sulfurized under normal hydrogenation conditions for sulfur-containing heavy carbonized oil, the oxide catalyst is effective as the first step catalyst of the present invention without pre-sulfurization.

[Brief explanation of the drawing]

The drawing is a graph showing the correlation between the percentage of aromatic nucleus-forming hydrogen (HAROM) to total hydrogen in various hydrogenated oils and the yield of each thermally decomposed component when the hydrogenated oils are thermally decomposed.

Claims (1)

[Scope of Claims] 1. A method for producing olefins and monocyclic aromatic hydrocarbons from a hydrocarbon oil containing polycyclic aromatic hydrocarbons, which comprises the following steps and (B). (4) Contains a polycyclic aromatic hydrocarbon and has a molecular weight of 180 to 600
Heavy hydrocarbon oil within the distillation range of °C is treated with titanium oxide.
a step of hydrogenating a silicon oxide mixed oxide in the presence of a catalyst comprising nickel oxide and tungsten oxide or nickel sulfide and tungsten sulfide; and B) thermally decomposing the liquid product from the step.