JP3421900B2 - Dimethyl ether production equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an apparatus and method for producing dimethyl ether using carbon monoxide and hydrogen as main raw materials.

[0002]

2. Description of the Related Art As a technique for directly synthesizing dimethyl ether from a synthesis gas containing carbon monoxide and hydrogen as main raw materials, a technique has been developed in which a raw material gas is passed through a fixed bed catalyst layer to cause a reaction (Japanese Patent Laid-Open No. Hei 2 -280836, JP-A-3-8446, etc.).

However, since the dimethyl ether synthesis reaction is a strong exothermic reaction, in order to avoid deactivation of the catalyst due to local heating of the catalyst layer, a slurry bed reactor in which catalyst fine particles are suspended in high boiling point medium oil is used. A technique for synthesizing dimethyl ether in a high yield by passing a raw material gas through it has been developed.

For example, Japanese Patent Laid-Open No. 2-9833 discloses that
In a process for the direct synthesis of dimethyl ether from said synthesis gas, in which a synthesis gas consisting of hydrogen, carbon monoxide and carbon dioxide is contacted with and reacted in the presence of a solid catalyst, said synthesis gas is contacted in the presence of a solid catalyst system. Wherein the solid catalyst is a single catalyst or a mixture of catalysts suspended in a liquid medium in a three phase (liquid phase, solid phase, gas phase) reactor system,
There, a method for the direct synthesis of dimethyl ether from synthesis gas is disclosed, wherein said three-phase reactor system consists of at least one three-phase reactor.

JP-A-3-52835 discloses that synthesis gas is reacted in the presence of a solid methanol synthesis catalyst to produce methanol, and the produced methanol is reacted in the presence of a solid dehydration catalyst to produce dimethyl ether. In the method for synthesizing dimethyl ether from a synthesis gas consisting of hydrogen, carbon monoxide and carbon dioxide, the synthesis gas is contacted and reacted in the presence of a solid catalyst system consisting of a methanol synthesis component and a dehydration (ether formation) component, A solid catalyst or a mixture of catalysts in a liquid medium in the solid catalyst system three-phase (liquid phase, solid phase, gas phase) reactor system, wherein the reactor system is operated to obtain the minimum available methanol. The speed is at least 1.
A dimethyl ether synthesis method is disclosed which is characterized by maintaining 0 gmole of methanol.

Japanese Patent Laid-Open No. 3-181453 discloses a method for producing dimethyl ether from a mixed gas of carbon monoxide and hydrogen, or a mixed gas containing carbon dioxide and / or steam, in which a catalyst is suspended in a solvent. A method for use in a turbid, slurried state is disclosed.

Japanese Patent Laid-Open No. 264046/1992 discloses a method for producing dimethyl ether from a synthesis gas containing hydrogen, carbon monoxide and carbon dioxide, the synthesis gas being in an inert liquid in a liquid phase reactor. Contacting with a slurried powder catalyst and then removing the dimethyl ether containing product, the powder catalyst comprising about 70 to 99.9% by weight of a methanol synthesis catalyst, A method for producing dimethyl ether is disclosed, wherein the residual amount of the powder catalyst consists essentially of a methanol dehydration catalyst.

In addition, Japanese Patent Publication No. 5-810069 (WO 93
/ 10069), in a method for producing dimethyl ether from a mixed gas containing carbon monoxide and one or both of hydrogen and steam, or a mixed gas further containing carbon dioxide, a methanol synthesis catalyst, There is disclosed a method in which a methanol dehydration catalyst and a water gas shift catalyst are co-pulverized, then brought into close contact with pressure, and then the pulverized catalyst is suspended in a solvent and used in a slurry state.

[0009]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention had a problem that the deactivation of the catalyst progressed in a relatively short period of time while continuing the dimethyl ether synthesis experiment using the slurry bed catalyst as described above. I encountered.

An object of the present invention is to provide an apparatus and a method for producing dimethyl ether, which can maintain the activity of the catalyst for a long period in the production of dimethyl ether using a slurry bed catalyst.

[0011]

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that the deactivation of the catalyst is a sulfur compound, a metal carbonyl (iron carbonyl, Ni carbonyl, etc.) (hereinafter referred to as "catalyst depletion"). Active ingredient ”). That is, as the medium oil for suspending the catalyst fine particles in the slurry bed reactor, high boiling point edible oil, deep desulfurized gas oil, Fischer-Tropsch synthetic oil (FT oil) or high boiling point oil such as n-cetane is used. However, the catalyst used in the synthesis of dimethyl ether has low resistance to the catalyst deactivating component, and for example, the sulfur component in the medium oil is several hundreds of p.
When pm is present, the yield of dimethyl ether is 1/3 to 1 /
It will be greatly reduced to 7. Raw material gas such as coal gasification gas is desulfurized in a desulfurization reactor before being used for the reaction, but the sulfur component is not completely removed, and this is gradually accumulated in the medium oil to form a catalyst. I found that it was a poison. It was also found that similar catalytic activity deactivation occurs even with the same level of metal carbonyl.

That is, the present invention relates to a slurry bed reactor filled with a dimethyl ether synthesis catalyst and its medium oil, a condenser for condensing the gasified medium oil discharged from the reactor, and the condenser. Adsorption tank for adsorbing and removing the catalyst deactivating component from the medium oil condensed in the vessel, a dimethyl ether producing apparatus characterized by having a circulation line for connecting these and circulating the medium oil, and at least carbon monoxide A raw material gas containing hydrogen is brought into contact with a slurry in which a dimethyl ether synthesis catalyst is dispersed in the medium oil, and the reaction product gas generated by the catalytic reaction is cooled to condense and separate the gasified medium oil. Then, dimethyl ether is obtained from the gas of this reaction product, while the condensed medium oil is used to remove the catalyst deactivating components contained therein and then the slurry is removed. A process for producing dimethyl ether, characterized by circulating the.

[0013]

Any reactor can be used as long as it is a slurry bed type.

As the dimethyl ether synthesis catalyst, a methanol synthesis catalyst and a methanol dehydration catalyst are mixed and used, and a water gas shift catalyst is further added depending on the case. In addition to being used in a mixed state, the water gas shift catalyst can be cut off to perform a two-step reaction. The present invention can be applied to any of these catalysts.

As the methanol synthesis catalyst, there are copper oxide-zinc oxide, zinc oxide-chromium oxide, copper oxide-zinc oxide / chromium oxide, copper oxide-zinc oxide / alumina and the like which are usually industrially used for methanol synthesis. Examples of methanol dehydration catalysts include acid-base catalysts γ-alumina, silica, silica-alumina, and zeolite. Examples of the metal oxide component of zeolite include oxides of alkali metals such as sodium and potassium, oxides of alkaline earth metals such as calcium and magnesium, and the like. As the water gas shift catalyst, copper oxide-zinc oxide, copper oxide-chromium oxide-zinc oxide,
Examples include iron oxide-chromium oxide. Since the methanol synthesis catalyst has a strong shift catalytic activity, it can also serve as a water gas shift catalyst. An alumina-supported copper oxide catalyst can be used as both a methanol dehydration catalyst and a water gas shift catalyst.

The mixing ratio of the above-mentioned methanol synthesis catalyst, methanol dehydration catalyst and water gas shift catalyst is not particularly limited and may be appropriately selected according to the type of each component, reaction conditions and the like, but is usually a weight ratio. The methanol dehydration catalyst is about 0.1 to 5, preferably about 0.2 to 2 with respect to the methanol synthesis catalyst 1, and the water gas shift catalyst is about 0.2 to 5, preferably about 0.5 to 3. Often the range is appropriate. When the methanol synthesis catalyst also serves as the water gas shift catalyst, the amount of the above water gas shift catalyst is added to the amount of the methanol synthesis catalyst.

The above catalyst is used in a powder state and has an average particle size of 300 μm or less, preferably about 1 to 200 μm.
Particularly preferably, about 10 to 150 μm is suitable. Therefore, it can be further crushed if necessary.

Any medium oil can be used as long as it exhibits a liquid state under the reaction conditions. For example, aliphatic, aromatic and alicyclic hydrocarbons, alcohols, ethers, esters, ketones and halides,
A mixture of these compounds can be used. Further, gas oil from which sulfur has been removed, vacuum gas oil, hydrolyzed coal tar high boiling point fraction, Fischer-Tropsch synthetic oil, high boiling point edible oil and the like can also be used. The amount of catalyst to be present in the solvent is appropriately determined depending on the type of solvent, reaction conditions, etc.
Usually, it is 1 to 50% by weight, preferably about 2 to 30% by weight, based on the solvent.

The condenser may be any condenser as long as it condenses the medium oil vaporized in the reactor, and the name thereof such as a heat exchanger does not matter.

The catalyst deactivating component is preferably removed using an adsorbent. This adsorbent may be a commonly used adsorbent such as gamma-alumina, activated carbon, or adsorbed zeolite, and the optimum amount of adsorbent is determined by the adsorbability of these adsorbents. It is preferable to provide a plurality of adsorption tanks so that adsorption and removal can be continued in another tank even during regeneration.

The circulation line connects the slurry bed reactor, the condenser and the adsorption tank in sequence to form a circulation path. A backflow prevention mechanism is installed in the middle of the line. This backflow prevention mechanism may be a simple backflow prevention valve or the like, and it is possible to perform forced circulation with a pump.

The apparatus of the present invention further includes a storage tank, an intermediate tank,
Valves, measuring instruments, etc. are provided as appropriate.

The mixing ratio of hydrogen and carbon monoxide is H ₂ / CO
A molar ratio of 0.5 to 3.0, preferably 0.8 to 2.0 can be used. On the other hand, in the case of a mixed gas in which the ratio of hydrogen and carbon monoxide (H ₂ / CO ratio) is extremely small (for example, 0.5 or less) or carbon monoxide containing no hydrogen, steam is separately supplied to the reactor. Among them, it is necessary to convert a part of carbon monoxide into hydrogen and carbon dioxide by steam. The amount of water vapor is equimolar to the amount of carbon monoxide to be converted (equal to the lacking amount of hydrogen). The amount of carbon dioxide is the same as the number of moles of converted carbon monoxide. Examples of such raw material gas include coal gasification gas, synthesis gas from natural gas, coalbed methane, and the like. When the raw material gas contains a sulfur compound in order to prevent catalyst poisoning, it is necessary to perform desulfurization treatment in advance. Due to this desulfurization, the concentration of sulfur compounds is several hundred ppm
It is about 50 to 200 ppm or less. The types of sulfur compounds include SOx, H ₂ S, and COS.

As the reaction conditions in the slurry bed reactor, the reaction temperature is preferably 150 to 400 ° C., particularly 25
The range of 0 to 350 ° C. is preferable. When the reaction temperature is lower than 150 ° C or higher than 400 ° C, the conversion rate of carbon monoxide is low. Reaction pressure is 10 to 300 kg / c
m ² is suitable, more preferably 15 to 150 kg / cm ² , and particularly preferably 20 to 70 kg / cm ² . If the reaction pressure is lower than 10 kg / cm ^2, the conversion rate of carbon monoxide is low, and if it is higher than 300 kg / cm ² , the reactor becomes special, and a large amount of energy is required for pressurization, which is economical. Not. The space velocity (the supply rate of the mixed gas in the standard state per 1 kg of the catalyst) is 100 to
50,000 l / kg · h is preferable, especially 500 to 30
It is 000 l / kg · h. Space velocity is 50000l /
If it is larger than kg · h, the conversion rate of carbon monoxide will decrease,
If it is less than 100 l / kg · h, the reactor becomes extremely large, which is not economical.

As a condition for removing the catalyst deactivating component, it is necessary that the concentration of the catalyst deactivating component in the medium oil from which the catalyst deactivating component is adsorbed and removed is 100 ppm or less, preferably 50.
It may be ppm or less.

[0026]

【Example】

(Example 1) FIG. 1 shows an apparatus for producing dimethyl ether, which is an example of the present invention. This apparatus comprises a slurry reactor 1, a condenser 2, a gas-liquid separator 3, an adsorption tank 4 and a pump 5, which are sequentially connected by piping to form a circulation line 6. The raw material gas is supplied from the raw material gas supply pipe 7 to the slurry reactor 1 from the bottom thereof. Slurry reactor 1
The medium oil that has been evaporated from or has been carried out with the high-temperature reaction gas and flowed out is cooled to a temperature below which it is heat-exchanged and condensed in the condenser 2, and then separated from the reaction products and unreacted gas in the gas-liquid separator 3. It The separated and recovered medium oil is sent to the adsorption tank 4, and the catalyst deactivating component in the medium oil is adsorbed and removed. The purified medium oil is recirculated to the reactor 1 by the pump 5,
The catalyst deactivating component concentration in the medium oil inside the reactor 1 is maintained at a low concentration. The desulfurization operation of the adsorptive desulfurization tank 4 may be carried out under the same high pressure condition as the reaction conditions of the reactor or under the normal pressure condition once depressurized. Two or more adsorption tanks 4 may be installed and used alternately.

Using a gas flow type autoclave as a slurry bed type reactor, pressure 30 kg / cm ² G, temperature 2
Carbon monoxide and hydrogen were supplied at a ratio of 1: 1 as the raw material gas at 80 ° C., and the catalyst weight ratio W / F to the carbon monoxide molar flow rate was set.
= 4.0 g-cat · h / CO-mol, a reaction experiment was conducted using medium oils having different dissolved sulfur component concentrations. A copper-zinc-alumina catalyst as a methanol synthesis catalyst and a powder catalyst of a copper-alumina catalyst as a methanol dehydration catalyst were mixed at a weight ratio of 2: 1 and used as a reaction catalyst.

As the medium oil, n-cetane containing no sulfur component, industrial light oil 1 having a sulfur component refined to 250 ppm, industrial light oil 2 having a sulfur component refined to 100 ppm, and industrial light oil 3 having a sulfur component refined to 50 ppm have been used. Was used.

The carbon monoxide conversion rate, which was 50.5% in the medium oil of n-cetane, was 8.1% in the industrial light oil having a sulfur content of 250 ppm and 3% in the industrial light oil having a sulfur content of 100 ppm.
5.2%, 45.6% for industrial light oil with 50 ppm sulfur
Met. Therefore, in the present invention, the concentration of the sulfur component in the medium oil from which the sulfur component has been adsorbed and removed needs to be 100 ppm or less, and preferably 50 ppm or less.

The above results are shown in Table 1. In the table, the reaction rate is shown as the conversion rate per mol of the raw material carbon monoxide.

[0031]

[Table 1]

When n-cetane having a boiling point of 286.8 ° C. and a molecular weight of 226 is used as the medium oil, the internal conditions of the reactor are as follows: pressure 30 kg / cm ² G, temperature 280 ° C., catalyst weight ratio to raw carbon monoxide gas. W / F = 6 kg-cat / C
With O-kg · mol and catalyst slurry concentration of 20% by weight, the outflow amount of the weight of the medium oil flowing out from the reactor based on the gas-liquid equilibrium calculation under the internal conditions of the reactor is first expressed as the weight with respect to the weight of the medium oil inside the reactor. Approximately 50% when calculated as a ratio
/ H.

Actually, the amount of the outflowing medium oil is lower than this estimated value due to the temperature drop or the like in the upper part of the reactor, but under the normal reaction conditions, the adsorbing tank 4 shown in FIG. Medium oil circulates.

Example 2 Using the medium oils shown in Table 2, the same procedure as in Example 1 was carried out to obtain the results shown in Table 2.

[0035]

[Table 2]

Example 3 The effectiveness of the present invention was confirmed by continuously suppressing the concentration of sulfur components in the medium oil using a high pressure reaction gas of continuous flow type.

The apparatus shown in FIG. 2 was used. In this device, a second condenser 8 and a second gas-liquid separator 9 are attached to the gas discharge side of the gas-liquid separator 3 of the device shown in FIG.

The reaction refined gas from which the medium oil has been separated in the gas-liquid separator 3 is further cooled in the second condenser 8 and then in the second gas-liquid separator 9 dimethyl ether, methanol, water, unreacted gas and dioxide. Separated into carbon and liquid components in line 10
Therefore, the gas component is recovered from the line 11.

The reaction was carried out under the same conditions as in Example 1, and a gas containing hydrogen sulfide at a concentration of 600 ppm as an impurity, carbon monoxide and hydrogen at a ratio of 1: 1 was fed to the reactor. Supplied. N-Cetane containing no sulfur component was used as the medium oil. As the adsorbent, granular gamma-alumina was used, and the adsorbent 4 was charged with an amount of adsorbent sufficient to adsorb and desulfurize hydrogen sulfide dissolved in the medium oil.

The obtained results are shown in FIGS. 3 and 4.

FIG. 3 shows the changes in the sulfur component concentration in the medium oil when the adsorbent 4 was or was not charged with the adsorbent. With desulfurization operation, the sulfur component concentration in the circulating medium oil is maintained at almost zero, but without desulfurization operation, the sulfur component concentration in the circulating medium oil is over time. Is increasing with.

FIG. 4 shows changes in the reaction conversion rate of the raw material carbon monoxide gas corresponding to the changes with time of the sulfur component shown in FIG. When the desulfurization operation is performed, the reaction conversion rate of the raw material carbon monoxide gas maintains almost the initial value, but when the desulfurization operation is not performed, the reaction conversion rate of the raw material carbon monoxide gas increases to the sulfur component concentration. Correspondingly, it decreases sharply over time, showing the effectiveness of the present invention.

[0043]

INDUSTRIAL APPLICABILITY The present invention is a slurry prepared by suspending a reaction catalyst in a medium oil of a raw material gas mainly composed of carbon monoxide gas such as coal gasification gas and synthesis gas from natural gas and hydrogen gas. In the reaction process of synthesizing dimethyl ether by supplying to the reactor, by continuously removing the trace amount catalyst deactivating component contained in the raw material gas and maintaining the concentration of the catalyst deactivating component in the medium oil at a low concentration. The high catalytic reaction activity can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is a flow sheet of an apparatus used in an example of the present invention.

FIG. 2 is a flow sheet of an apparatus used in an example of the present invention.

FIG. 3 is a graph of the results obtained in the examples of the present invention.

FIG. 4 is a graph of the results obtained in the examples of the present invention.

[Explanation of symbols]

1 ... Slurry reactor (slurry floor type reactor) 2 ... condenser 3 ... Gas-liquid separator 4 ... adsorption tank 5 ... Pump 6 ... Circulation line 7 ... Raw material gas supply pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tsutomu Shikata Tsutomu Shibata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) Reference JP-A-3-181435 (JP, A) International Publication 93 / 010069 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 41/01 C07C 41/09 C07C 43/04

Claims (2)

(57) [Claims] 1. A slurry bed reactor filled with a dimethyl ether synthesis catalyst and a medium oil thereof, a condenser for condensing the gasified medium oil discharged from the reactor, and a condenser condensed by the condenser. A device for producing dimethyl ether, comprising: an adsorption tank for adsorbing and removing the catalyst deactivating component from the medium oil, and a circulation line for connecting these to circulate the medium oil. 2. A raw material gas containing at least carbon monoxide and hydrogen is brought into contact with a slurry in which a dimethyl ether synthesis catalyst is dispersed in a medium oil, and a reaction product gas generated by the catalytic reaction is cooled and entrained. The gasified medium oil is condensed and separated, and then dimethyl ether is obtained from the reaction product gas, while the condensed medium oil removes the catalyst deactivating component contained therein, and then the slurry is obtained. Method for producing dimethyl ether, characterized in that