JPH07102265A - Process for hydrogenating unsaturated hydrocarbon and organic sulfide in hydrocarbon - Google Patents

Abstract

PURPOSE:To obtain a longer operating cycle by performing in two-step vapor- phase reaction regions the complete hydrogenation of unsaturated hydrocarbons and organic sulfides in the raw material for production of aromatics. CONSTITUTION:A process for hydrogenating unsaturated hydrocarbons and organic sulfides in hydrocarbons by mixing them with a hydrogen containing gas in the presence of a sulfur-containing catalyst having cobalt and molybdenum supported on alumina, wherein vapor-phase reaction regions are established in two steps in series, with the first region having an inlet temperature of 150-350 deg.C and a pressure of 10-100 kg/cm<2>.G and the second region having an inlet temperature at least equal to the outlet temperature of the first region and a pressure of 10-100 kg/cm<2>.G.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hydrogenating unsaturated hydrocarbons and organic sulfides in pyrolysis gasoline and crude benzene which are hydrocarbons as a raw material for aromatic production.

[0002]

2. Description of the Related Art Pyrolysis gasoline, which is a so-called general aromatic raw material for producing benzene, toluene, xylene, etc.,
Crude benzene contains unsaturated hydrocarbons such as olefins and organic sulfides, but these impurities are generally hydrogenated for reasons of product purity maintenance and manufacturing processes. One of the general two-step hydrogenation methods is the two-step unifining method presented by Universal Oil Products Co. in Japanese Patent Publication No. 35-2937. This method uses a first-stage reactor packed with a cobalt-molybdenum catalyst for 15
Olefins are selectively hydrogenated at 0 to 232 ° C, and organic sulfides and the like are hydrogenated at about 288 to 427 ° C in a second-stage reactor filled with a catalyst such as cobalt and molybdenum.

Further, a method in which a cobalt molybdenum catalyst is filled in a reactor in both of the two steps and both of the two steps are operated in a gas phase is disclosed in Japanese Examined Patent Publication No. Sho 49-39482 (Air Products.
And Chemicals Incorporated), it is presented as a hydrogenation method of doriporene. Further, Japanese Patent Publication No. 48-7242 discloses a method of filling the first-stage reactor with a palladium catalyst and hydrogenating it in a liquid phase or a gas-liquid mixed phase.

However, in the two-stage unifining method, the concentration of olefins at the inlet of the first-stage reactor is high, so that a polymerized product is produced by the dimerization of olefins, resulting in an increase in pressure loss in the reactor or a catalyst activity. Therefore, there was a problem that the operating cycle of the reactor was extremely shortened due to the decrease of the temperature. Therefore, in these methods, in order to suppress the generation of polymerized products, operation is carried out at the lowest possible temperature within the range where hydrogenation is not affected, but the production of polymerized products is still unavoidable and the reaction is continued for several weeks of continuous operation. It was necessary to stop the cleaning process to clean the reaction system or to carry out a process for reactivating the catalyst.

In addition, in the hydrogenation method of doriporene, although a method of selectively hydrogenating olefinic hydrocarbons present in drypolene completely with a catalyst and operating for a long period of 6 months or more is proposed, Since the target of hydrogenation is limited to olefins and the hydrogenation of organic sulfides has a concomitant effect, it is unclear how to make the hydrogenation rate of organic sulfides 100%. There is a problem that the operating cycle becomes short when the hydrogenation rate of both organic sulfides is 100%. Also, the second
Although the raw material that flows into the reaction zone of the stage is used after being cooled, it cannot be denied that it is disadvantageous in terms of energy recovery.

Further, in the method of hydrogenating in a liquid phase or a gas-liquid mixed phase using a catalyst such as palladium, since it is vulnerable to poisoning by arsenic or heavy metals, pretreatment equipment for raw materials such as equipment for removing arsenic and heavy metals in raw materials. is necessary. Further, in this method, when the concentration of olefins is high, the production of the polymer is severe even if it is operated at a low temperature. Therefore, the outlet gas of the first-stage or second-stage reactor is liquefied again and the inlet of the first-stage reactor is liquefied. It is necessary to take measures to reduce the concentration of olefin by recycling it to. That is, for example, in order to obtain benzene by a dealkylation reaction, since the reactor outlet gas is introduced into the dealkylation reactor in a gas state, the reactor outlet gas must be cooled again to obtain a recycled liquid. However, there is a new problem that a large energy loss occurs.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the conventional hydrogenation method, and enables continuous operation for a long time without pressure loss and deterioration of catalyst activity, and also energy loss. It is an object of the present invention to provide a stable hydrogenation method for unsaturated hydrocarbons and organic sulfides in raw material hydrocarbons.

[0008]

The inventors of the present invention have conducted extensive studies to solve the drawbacks of the conventional method, and as a result, the polymer produced by the polymerization of unsaturated hydrocarbons such as olefins is produced in the reactor. It has been found that the temperature loss increases when operated at a high temperature, which causes an increase in pressure loss in the reactor, but the higher the temperature, the more the polymer decomposes and the pressure loss in the reactor decreases. It was also found that when the concentration of olefins etc. is low, the amount of polymer produced is significantly reduced, and there is no production of polymer to the extent that continuous operation is impaired. Based on these findings, The inventors invented a method of reacting both the reaction zone and the second reaction zone in the gas phase.

That is, according to the present invention, unsaturated hydrocarbons and organic sulfides in hydrocarbons used as a raw material for producing aromatics are mixed with hydrogen-containing gas in the presence of a sulfur-containing catalyst having cobalt and molybdenum supported on alumina. In the method of mixing with and hydrogenating, the reaction zone is installed in two stages in series, the reaction conditions in the reaction zone are both gas phase reactions, and one or more reaction zones of the first stage are installed. The inlet temperature of the first-stage reaction zone is 150 to 350 ° C, and the pressure is 10 to 100 Kg /
cm ² · G, the inlet temperature of the reaction zone of the second stage is at least the outlet temperature of the reaction zone of the first stage, and the pressure is 10 to
A method for hydrogenating unsaturated hydrocarbons and organic sulfides in hydrocarbons, characterized in that the content is 100 Kg / cm ² · G, and unsaturated hydrocarbons in hydrocarbons used as a raw material for aromatic production, and In a method of hydrogenating an organic sulfide by mixing it with a hydrogen-containing gas in the presence of a sulfur-containing catalyst in which cobalt and molybdenum are supported on alumina, reaction zones are installed in two stages in series and reaction conditions in the reaction zone are set. Is a gas-phase reaction in both stages, one or more first-stage reaction zones are installed, the hydrogenation rate of unsaturated hydrocarbons in the first-stage reaction zone is 50% or more, and hydrogenation of organic sulfides is performed. The rate is 70% or more,
A method for hydrogenating unsaturated hydrocarbons and organic sulfides in hydrocarbons, characterized in that all unsaturated hydrocarbons and organic sulfides remaining in the second reaction zone are hydrogenated Is.

The aromatic raw material used in the present invention is pyrolysis gasoline, crude benzene and the like. The present invention is directed to the aromatic raw material containing pentene, hexene, heptene, octene,
Pentadiene, hexadiene, heptadiene, octadiene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclopentadiene, cyclohexadiene, cycloheptadiene, cyclooctadiene
Unsaturated hydrocarbons such as styrene and thiophene / methylthiophene / ethylthiophene / propylthiophene /
Organic sulfides such as methyl mercaptan, ethyl mercaptan, propyl mercaptan, allyl mercaptan, dimethyl sulfide and dimethyl disulfide are hydrogenated in the presence of a catalyst.

In the hydrogenation, the reaction zone is divided into two stages, and a desulfurization catalyst using ordinary cobalt, molybdenum, etc. is used in the first and second stage reaction zones, and the raw material is the first stage reaction zone. 70 to 90 mol%, preferably 75 to 8
Hydrogen-containing gas containing 5 mol% of hydrogen is mixed with 1.4 to 2.0 normal cubic meters, preferably 1.6 to 1.8 normal cubic meters per 1 Kg of raw material.

In the first stage reaction zone, 50% or more, preferably 70% or more, of unsaturated hydrocarbons contained in the hydrocarbons flowing in, and 70% or more, preferably 90% of organic sulfides are contained.
% As the temperature of the catalyst layer inlet under gas phase conditions of 150 to
350 ° C, preferably 200-300 ° C, pressure 10-10
0 Kg / cm ² · G, preferably 50 to 70 Kg / cm ²
-Hydrogen treatment under the conditions of G, and then in the second-stage reaction zone, at least the catalyst layer inlet temperature above the outlet temperature of the first-stage reaction zone, preferably 300-330 ° C and a pressure equivalent to the first-stage. All unsaturated hydrocarbons and organic sulfides that remain under the conditions are hydrogenated under gas phase conditions.

As the reaction zone in the present invention, a multi-stage adiabatic reactor in which a catalyst layer is divided into two stages and a heat exchanger is installed between the stages to supply heat may be used, but edited by Kenji Hashimoto. It is desirable to use two purely adiabatic one-stage adiabatic reactors described in "Industrial reaction apparatus" (Baifukan, 1984), paragraphs 25-26, in series. As a one-stage adiabatic reactor,
A one-stage adiabatic fixed bed reactor, a one-stage adiabatic moving bed reactor and a one-stage adiabatic fluidized bed reactor can be mentioned, but it is preferable to use the one-stage adiabatic fixed bed reactor.

In the conventional hydrogenation method of doriporene, the operating cycle is set to be 6 months or more, but this is limited to the case where the complete hydrogenation of only olefins is intended. On the other hand, in the case of the present invention, the operating cycle for completely hydrogenating both unsaturated hydrocarbons and organic sulfides is 3 months or longer in the first stage reaction zone and 15 months or longer in the second stage reaction zone. Operation can be continued without regeneration of the catalyst during the period.

In the present invention, the hydrogenation rate of unsaturated hydrocarbons in the first stage reaction zone is 50% or more, preferably 70% or more, and the hydrogenation rate of organic sulfides is 70% or more, preferably 90%.
% Or more, and by limiting the concentration of unsaturated hydrocarbons and organic sulfides flowing into the reaction zone of the second stage to a low level, the activity of the catalyst in the reaction zone of the second stage is maintained and the operating cycle jumps. I was able to extend it.

For this purpose, the operating temperature of the reaction zone of the first stage must be set higher than the temperature in the prior art, and there is concern that the production of polymer in the reaction zone of the first stage will increase. However, surprisingly, the discovery of the decomposition of the polymerized product at higher temperatures made it possible to ensure a commercially satisfactory operating cycle. That is, when the pressure loss increases due to the increased production of the polymer in the reaction zone of the first stage, the produced polymer is decomposed by continuously increasing the inlet temperature stepwise, and the pressure loss of the reaction zone of the first stage increases. By reducing the pressure loss, the operating cycle is extended. It is desirable that the upper limit of the operating temperature of the reactor is 350 ° C., and if the operating temperature is higher than this, operating problems such as increase in pressure loss in the reaction zone may occur.

Unsaturated hydrocarbons in the first stage reaction zone only
It is necessary to divide the reaction zone into two or more stages, because if the organic sulfide is to be completely hydrogenated, the operation cycle of the reaction zone of the first stage becomes short and it becomes commercially unsatisfactory. In addition, since the operation cycle of the reaction zone of the first stage is usually about 3 months, it is desirable to install two or more reaction zones in parallel in the reaction zone of the first stage and adopt a switching system. In this case, there is an advantage that the catalyst in the reaction zone which has been used can be regenerated while the catalyst in one reaction zone is being used, and the stop of the process for regenerating the catalyst in the reaction zone of the first stage can be avoided.

In addition, in the prior art hydrogenation method of doriporene, it was necessary to cool the raw material when flowing it into the reaction zone of the second stage, but in the present invention, the raw material is fed before flowing into the reaction zone of the second stage. Is heating. Therefore, it is also a feature of the present invention that energy reduction can be achieved in a process in which a raw material is heated and used after the hydrogenation reaction zone, such as a process in which benzene is obtained by dealkylation.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a process chart showing an example of the process of the present invention. In FIG. 1, raw materials such as pyrolysis gasoline and crude benzene are evaporated by a direct or indirect evaporator and introduced into a first stage reactor 10 through pipes 1 and 2. A pipe 3 is connected between the pipes 1 and 2, from which a high-temperature hydrogen-containing gas is introduced, and by adjusting the amount or temperature of the hydrogen-containing gas, the inlet of the first-stage reactor 10 Temperature is 150-35
Adjust to the desired temperature of 0 ° C. In particular, when the pressure loss of the first-stage reactor tends to increase, it is effective when the inlet temperature is raised to decompose the produced polymer which causes the increase in pressure loss.

The reaction gas discharged from the first-stage reactor enters the heat exchanger 11 through the pipe 4, and is heated by the heat medium of an appropriate temperature to the second stage.
It is heated to the required inlet temperature in the stage reactor 12 and introduced into the second stage reactor 12 via the pipe 5. As an alternative to indirect heating in the heat exchanger 11, for example, a high-temperature hydrogen-containing gas may be introduced and heated directly. The reaction gas that has left the second-stage reactor is led to the downstream process through the pipe 6.

[0021]

The present invention will be described in more detail with reference to the following examples.

Example 1 An example is shown in which a mixture of cracked gasoline and crude benzene having the following composition and properties was hydrogenated by the method of the present invention. The composition shown in (Table 1) is a value measured by the following equipment.
The table shows the average and maximum / minimum values of the raw material composition during 94 days of operation. Shimadzu Corporation GC-14A (FID) type gas chromatography.

The compositions shown in Table 2 are values measured by the following equipment. In the table, for the organic sulfide, thiophene was measured as a representative composition, and the average value in 94 days of operation is shown. Shimadzu Corporation GC-14A (FPD) type gas chromatography.

The properties shown in (Table 3) are values measured by the following methods. In Table 3, the bromine number is measured as an index showing the concentration of unsaturated hydrocarbons, and the average value in 94 days of operation is shown. JIS K-2605 Coulometric titration method.

The compositions and properties shown in (Table 4) show changes in the concentration of the object to be hydrogenated when continuously operated for 94 days. Organic sulfides in the table indicate organic sulfides (thiophenes). The measuring instruments are (Table 2) and (Table 3).
It is the same equipment as.

Table 5 shows the operating conditions of the reactor at this time. In the description of (Table 5), the reactor is the first
Adiabatic fixed bed reactors were used for both the second and second stages.
In addition, the space velocity depends on the first stage reactor 1.6 to 1.8, the second stage reactor
The conditions of the stage reactor 2.7 to 3.0. The space velocity referred to here is determined based on the liquid material to be supplied, and indicates the amount (liter) of the material supplied per 1 liter of the catalyst per hour. The hydrogen-containing gas contains 78 to 80 mol% of hydrogen, and the hydrogen-containing gas and the amount of the raw material hydrocarbons are in the condition of 6.7 to 7.3 mol ratio. The pressures in the table are gauge pressures.

The catalyst used in this example is generally used for hydrogenation, and its properties and sulfiding conditions are as follows. Further, in the examples, an adiabatic fixed bed type reactor generally used as a reaction zone was used.

The catalyst comprises cobalt molybdenum supported on alumina. Cobalt is 2.9 with respect to the weight of the catalyst.
~ 3.1 wt%, molybdenum 9.7 to 10.3 wt%
It is contained. DMDS (dimethyl disulfide) was circulated through this catalyst so as to contain 3.2 to 4.0% by weight of elemental sulfur based on the weight of the catalyst, and the temperature was 180 to 220 ° C. and the pressure was 59 to 61 Kg. /
Under a condition of cm ² · G, hydrogen gas having a hydrogen purity of 78 to 80 mol% was used as a carrier gas, and sulfurized for 12 hours before use.

As shown in (Table 4), the hydrogenation rate of unsaturated hydrocarbons such as olefins in the first-stage reactor was 82.4% (hydrogenation of organic sulfide) on average for 94 days. Even though the average rate is 92.1%),
No problems in operation such as increase in pressure loss and decrease in catalyst activity occurred for a long period of 4 days, and continuous operation could be carried out in the first stage reactor. At this time, the second-stage reactor had been operated continuously for 15 months, but like the first-stage reactor,
No operational problems or inconveniences such as an increase in pressure loss or a decrease in catalyst activity were observed, and hydrogenation could be carried out so that both unsaturated hydrocarbons and organic sulfides were below the detection limit.

Further, contrary to the prior art, since the fluid is heated to increase the temperature when flowing into the second stage reactor, it is advantageous in energy recovery from the prior art. In addition, since the cobalt-molybdenum catalyst is used as the catalyst in this embodiment, there is an advantage that the raw material pretreatment equipment such as the heavy metal removing equipment necessary when using the palladium catalyst is not used. Thus, the present invention alleviates the problems of the prior art. Incidentally, the reactor of the first stage became inoperable due to the increase in pressure loss after that, so the operation was continued by switching to the standby device.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

Comparative Example 1 An example in which unsaturated hydrocarbons / organic sulfides are hydrogenated using only the first-stage reactor will be shown. In addition to the fact that the second stage reactor was not used, the catalyst used, the sulfidizing conditions, etc. were used in Example 1.
The same operation was performed.

The compositions shown in (Table 6) are values measured by the following equipment. In the table, the average value and the maximum / minimum value of the raw material composition in 42 days of operation are shown. Shimadzu Corporation GC-14A (FID) type gas chromatography. The composition shown in (Table 7) is a value measured by the following equipment. For the organic sulfides in (Table 7), thiophene was measured as a representative composition, and the average value over 42 days of operation is shown. Shimadzu Corporation GC-14A (FPD) type gas chromatography.

The properties shown in Table 8 are values measured by the following methods. JIS K-2605 Coulometric titration method. In (Table 8), as an index showing the concentration of unsaturated hydrocarbons,
The bromine number was measured and the average value in 42 days of operation is shown. The compositions and properties shown in (Table 9) show changes in the concentration of the object to be hydrogenated and the like after continuous operation for 42 days. Organic sulfides in the table indicate organic sulfides (thiophenes). The measuring instruments are the same as those in (Table 7) and (Table 8).

Table 10 shows the operating conditions of the reactor at this time. In Table 10, the reactor used was an adiabatic fixed bed reactor. The space velocity is a condition of the first stage reactor 1.6 to 1.8. The space velocity here is determined based on the liquid material to be supplied, and indicates the amount (liter) of the material supplied per 1 liter of the catalyst per hour. The hydrogen-containing gas contains 78 to 80 mol% of hydrogen, and the hydrogen-containing gas and the amount of the raw material hydrocarbons are in the condition of 6.7 to 7.3 mol ratio. The pressures in the table are gauge pressures.

In this example, the raw material composition and the bromine number were almost the same as those in Example 1, and the thiophene concentration was much lower than that in Example 1. Further, in the first-stage reactor, complete hydrogenation of both bromine number and thiophene concentration below the detection limits was not achieved. As described above, although the condition is mild compared with the first embodiment, the first
The catalyst activity of the stage reactor decreased after 42 days of operation, making it difficult to continue operation.

[0041]

[Table 6]

[0042]

[Table 7]

[0043]

[Table 8]

[0044]

[Table 9]

[0045]

[Table 10]

[0046]

EFFECTS OF THE INVENTION Pyrolysis gasoline, which is a general raw material for producing so-called aromatic compounds such as benzene, toluene and xylene,
It has become possible to obtain a commercially satisfactory operating cycle for hydrogenating both unsaturated hydrocarbons such as olefins and organic sulfides in crude benzene to below the detection limit of analytical instruments. Further, in the prior art, cooling was required when flowing into the reaction zone of the second stage, and the part which had an energy loss was changed to operate by heating, so that there was no energy loss. .

[Brief description of drawings]

FIG. 1 is a process chart showing an example of a process of the present invention.

[Explanation of symbols]

 1 1st stage reactor inlet pipe 2 1st stage reactor inlet pipe 3 Hydrogen-containing gas introduction pipe 4 1st stage reactor outlet pipe 5 2nd stage reactor inlet pipe 6 2nd stage reactor outlet pipe 10 1st stage Reactor 11 Heat exchanger 12 Second stage reactor

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[Procedure amendment]

[Submission date] November 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

[0031]

[Table 1]

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10G 45/38 2115-4H

Claims (2)

[Claims] 1. Hydrogen is obtained by mixing unsaturated hydrocarbons and organic sulfides in hydrocarbons used as a raw material for producing aromatics with a hydrogen-containing gas in the presence of a sulfur-containing catalyst in which cobalt and molybdenum are supported on alumina. In the method of
The reaction zones are installed in two stages in series, the reaction conditions in the reaction zones are both gas phase reactions, one or more first stage reaction zones are installed, and the inlet temperature of the first stage reaction zone is set. 150-3
50 ° C., a pressure of 10 to 100 Kg / cm ² · G, an inlet temperature of the reaction zone of the second stage is at least an outlet temperature of the reaction zone of the first stage, and a pressure of 10 to 100 Kg / cm ²
A method for hydrogenating unsaturated hydrocarbons and organic sulfides in hydrocarbons, characterized in that G is used. 2. Hydrogen is obtained by mixing unsaturated hydrocarbons and organic sulfides in hydrocarbons used as aromatic raw materials with a hydrogen-containing gas in the presence of a sulfur-containing catalyst in which cobalt and molybdenum are supported on alumina. In the method of
The reaction zones are installed in series in two stages, the reaction conditions in the reaction zones are both gas-phase reactions, and one or more first-stage reaction zones are installed, and the first-stage reaction zone is unsaturated. The hydrogenation rate of hydrocarbons is 50% or more, and the hydrogenation rate of organic sulfides is 70%
The above is a method for hydrogenating unsaturated hydrocarbons and organic sulfides in hydrocarbons, characterized in that all of the unsaturated hydrocarbons and organic sulfides remaining in the second reaction zone are hydrogenated.