JPS6124526A - Preraration of lower olefin - Google Patents

Abstract

PURPOSE:To obtain the titled compound advantageously from methanol and/or dimethyl ether, by using a specific zeolite catalyst under specific conditions, accompanied with recycling to the reaction system part of or whole fraction remaning after elimination of the titled compound from the reaction product. CONSTITUTION:Methanol or dimethyl ether or both in the gas form are contacted with one or more catalysts selected from alkaline earth metal-containing zeolite, alkaline earth metal-containing zeolite modified with the alkaline earth metal and ZSM based zeolite modified with an alkaline earth metal at a weight hourly space velocity of 0.1-20hr<-1> at 300-650 deg.C reaction temperature under 0.1-100atm total pressure and converted into a hydrocarbon, followed by eliminating 2-3C olefin from the resultant reaction product, preferably further eliminating an aromatic component, and recycling the remaining fraction to the above-mentioned reaction system to obtain the aimed lower olefin, especially 2- 3C olefin in high yield with a long catalyst life and a long stability period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for producing lower olefins, in particular ethylene and propylene, from methanol and/or dimethyl ether, and more particularly relates to the patented alkaline earth metal-containing and/or When producing lower olefins, especially ethylene and propylene, from methanol and/or dimethyl ether using an alkaline earth metal-modified zeolite catalyst, all or part of the fraction remaining after removing ethylene and propylene from the reaction product is reacted. A process for the production of lower olefins, in particular ethylene and propylene, characterized in that they are recycled into the system.

While it is possible to obtain ethylene and propylene with high selectivities, lower reaction temperatures can be employed compared to those traditionally required to obtain ethylene and propylene with this selectivity, which naturally leads to longer reaction times. Benefits 1: Longer catalyst life is obtained, and furthermore, the reaction in the catalyst bed is diffused and the heat of reaction is diluted, preventing local overheating of the catalyst bed! ! : It is something that one has.

In recent years, there has been concern about the stable supply of crude oil, and especially given that our country's dependence on foreign sources exceeds 99%, the effective use of coal, natural gas, etc. has become an important issue.
Olefin from methanol obtained from methane, CO, etc.
,paraffin.

There is a need to establish an industrial synthesis method for aromatic and other organic compounds.

The present invention meets this need.

(Prior Art) It is well known in the art that silica/alumina, crystalline aluminosilicate, etc. have been used as catalysts in hydrocarbon conversion processes.

Now, in the 1970s, Mopil Oil Co., Ltd. developed ZSM- as a shape-selective catalyst for producing carbon 1% arsenic from methanol and dimethyl ether using high-quality gasoline as its main component.
We have developed a type 5 zeolite catalyst. Unlike conventional zeolites, this zeolite has excellent properties such as the ability to freely control the composition SiOν'Al2O3 ratio and extremely high heat resistance. It is also possible to use lower olefins.

However, in order to obtain ethylene and propylene with high selectivity, a high reaction temperature is required, and even the 28M5 type zeolite catalyst does not have a sufficient duration of activity and is deactivated in a short period of time.

As a result of research and development of a catalyst with a longer activity duration than that of the ZSM-5 type catalyst, the present inventors have developed an alkaline earth metal-containing zeolite catalyst (patent application No. 57-205839) and an alkaline earth metal-containing zeolite catalyst (patent application No. 57-205839). Succeeded in developing a zeolite catalyst containing alkaline earth metals (Japanese Patent Application No. 105530/1982).

Although these catalysts have a longer catalyst life than the ZSM-5 type catalyst at high temperatures, there has been a need to develop a method to further extend the catalyst life and enable safe operation over a long period of time.

(Purpose, Structure, and Effects of the Invention) Therefore, in addition to improving the catalyst, the present inventors investigated the process conditions of a method for producing lower olefins, particularly ethylene and propylene, from methanol and/or dimethyl ether.

゛ As feared, it is advantageous to raise the reaction temperature as high as possible in order to produce hydrocarbons mainly composed of lower olefins from methanol or dimethyl ether, but increasing the reaction temperature leads to a rapid reduction in catalyst life. .

For example, at the temperatures normally used when producing olefins from methanol and/or dimethyl ether, raising the reaction temperature by about 50°C will shorten the catalyst life by half, which is useful for maintaining stable operation for a long period of time. It will be contrary. If the operation is continued forcibly, the catalyst activity will be extremely reduced, and a catalyst whose activity has been extremely reduced will no longer be able to sufficiently restore its activity even if it is regenerated.

Therefore, the present inventors conducted intensive research on a method to increase the selectivity to ethylene and propylene while keeping the reaction temperature constant. It has been found that the yields of ethylene and propylene can be increased by recycling them into the reactor. Even by recycling this product, the conversion reaction of the raw materials methanol and/or dimethyl ether to lower olefins is hardly inhibited, and as a result, it is possible to obtain ethylene and propylene with high selectivity at low reaction temperatures, and the catalyst life span. I learned that it will be extended. It has also been found that recycling this reaction product gives very good results in avoiding local overheating of the catalyst bed. In other words, the reaction from methanol to dimethyl ether is a significantly exothermic reaction, and the conversion reaction from dimethyl ether to olefins such as propylene is also an exothermic reaction, so the removal of the reaction heat is an important issue and cannot be removed adequately. This causes the catalyst bed to overheat and shorten the catalyst life.

On the other hand, since the production of lower olefins by decomposition of hydrocarbons is a strongly endothermic reaction, the strong exothermic heat generated during the production of olefins from methanol is recycled, which partially cancels out the endothermic reaction of the hydrocarbon decomposition reaction, resulting in the temperature of the catalyst bed. The present invention was completed after discovering that the advantage of easy control can be obtained.

Therefore, the present invention provides a method for increasing the yield of ethylene and propylene in methanol and/or dimethyl ether conversion reactions by recycling all or part of the residue after removing ethylene and propylene from the reaction product. High yield.

Furthermore, it relates to a method for diluting the heat of reaction.

The zeolite catalyst used in this reaction is B.

Aromatic compounds such as T, X are considered coke precursors,
B, T, as it causes a decrease in catalyst life.
A catalyst that produces 10% or less of X is desirable. Further, a catalyst in which the production ratio of C2 to C5 lower olefins is 50% or more is desirable.

Specific examples of zeolite catalysts that satisfy these conditions include the above-mentioned alkaline earth metal-containing zeolite and alkaline earth metal-modified alkaline earth metal-containing zeolite, as well as alkaline earth metal precipitated modified ZSM thread zeolite catalysts ( Examples include Japanese Patent Application No. 58-234747) and an alkaline earth metal-modified ZSM zeolite catalyst obtained by simply mixing a ZSM catalyst and an alkaline earth metal-containing compound in a solid state. Here, as the 7.8M zeolite catalyst, ZSM-5, 78M-1i, Z
SM-12, ZSM-23, 78M 35, 78
M'38 Oyohi78 M-48 can be mentioned, and Z SM-5 is particularly preferred.

Recirculating the reaction product as described above not only helps improve the yield of ethylene and propylene, but also has an excellent effect on removing the heat of reaction and diluting the reaction product. Generally, in the presence of a zeolite catalyst, the conversion reaction of methanol and/or dimethyl ether generates an extremely large amount of heat and rapidly occurs, so many methods have been proposed to control the reaction temperature by removing or diluting the reaction heat. There is. The use of water or nitrogen gas is usually proposed to dilute the heat of reaction, and this is effective to some extent.

Flue gas can also be used as a diluent gas after removing residual oxygen and impurities such as sulfur dioxide, and carbon dioxide can also be used for the same purpose. However, the use of these substances merely dilutes the heat of reaction.

It goes without saying that if a part of the reaction product is recycled for dilution according to the present invention, a dilution effect can be obtained, and in addition to improving the yield of ethylene and pyrene, extremely strong reaction heat can be removed or alleviated. The difficulty of driving, which has hitherto been recognized, is significantly eliminated.

As a component used for recycling, all or part of the fraction obtained by removing ethylene and propylene from the reaction product is used. Aromatic compounds such as BT and X cause coking of the catalyst and have excellent value as raw materials for chemical industries, so it is preferable to remove them from the recycled fraction. Hydrocarbons with a large number of carbon atoms, even aliphatic hydrocarbons, tend to cause coking or produce tar-like substances in reactions, so it is preferable that the number of carbon atoms in the recirculated hydrocarbons is 8 or less. Hydrocarbons higher than C6 cannot be converted into ethylene and propylene unless they are highly decomposed, which places a burden on the catalyst and tends to cause cyclization and aromatization, increasing the yield of ethylene and propylene. It is particularly suitable for the recycled hydrocarbons to have a carbon number of less than 6. Butylene is itself a lower olefin, 8BA, 'M
Various solvents such as EK, butipy cellosolve, antioxidants, and pesticides.

There is no need to recycle it because it is used as a synthetic raw material for various uses such as surfactants.

In addition, the components of 04 and above removed from the recycled fraction are:
In some cases, lower olefins can be produced by further thermal decomposition or steam decomposition after hydrogenation.

The reaction can be carried out under a wide range of conditions. For example, the reaction temperature is 300 to 650°C, the weight hourly space velocity of the new raw material is 0.1 to 20 hr, preferably 1 to 10 hr, and the total pressure is 0.
．． It can be carried out under conditions of 1 to 100 atm, preferably 0.5 to 10 atm. In the method of the present invention, high ethylene and propylene yields can be obtained without particularly harsh conditions, so the degree of one reaction source is 600°C or less.

In particular, it is preferable to keep the temperature at 550° C. or lower to maintain the activity of the catalyst for a long period of time. Furthermore, the space velocities mentioned above are for new raw materials, ie methanol and/or dimethyl ether, and the space velocities considering recycled hydrocarbons are naturally higher than that, usually about 1.
It becomes 2 to 1.8 times.

In the process of the present invention, the heat of reaction is reduced and diluted by recycling a portion of the reaction product, but, of course, as in the conventional process, the raw material is water vapor or an inert gas, such as nitrogen,
It is also possible and generally preferred to feed it over the catalyst diluted with argon, carbon dioxide, flue gas, etc.

In the process of the present invention, the product stream consists of steam, hydrocarbons, and unreacted raw materials, and by appropriately setting the reaction conditions, the proportion of lower olefins such as ethylene and propylene in the hydrocarbons can be increased. The steam and hydrocarbon products are separated and purified from each other by known methods.

In the method for producing lower olefins of the present invention, both methanol and dimethyl ether are starting materials, so when calculating selectivity, dimethyl ether produced from methanol may be regarded as an unreacted material.

(Examples, etc.) The present invention will be described below with reference to Examples, etc., but the present invention is not limited thereto unless it exceeds the gist thereof.

Reference Example 1 Aluminum nitrate nonahydrate 1.14.9 and calcium acetate monohydrate 1.34Q - dissolved in water 901) to make solution A,
Cataloid 5I-30 water glass (Catalyst Chemical ■, 8i
02 30.5%t Na2O0.42%) 601) Dissolved in 40I of water and used as solution B. The KB solution in the A solution was added while stirring vigorously, and then a solution of 2ONK sodium hydroxide in water and 1.26.9% was added. 30 more water
JI with tetrapropylammonium bromide 8.1)
．． 9' was added and stirring continued for about 10 minutes to obtain an aqueous gel mixture. This preparation ratio is 3i
Q2/At203=200.

This aqueous gel mixture was charged into an autoclave with an internal volume of 300 ml, and hydrothermally treated at 160'C under autogenous pressure for 18 hours with stirring (500 r, p, m2). The reaction product is separated into a solid component and a solution part using a centrifuge.
The solid components were thoroughly washed with water and further dried at 120°C for 5 hours. Then, treated in air at 520°C for 5 to 10 hours,
Add 0.6N hydrochloric acid to this calcined zeolite (IJI) for 15 minutes.
- and stirred at room temperature for 24 hours. After that, it was thoroughly washed with water at room temperature, dried at 120"C, and then
Calcination was performed in air at 20° C. for 5 hours to convert it into a hydrogen type. (8i=43.2%, Aj=0.42%, Ca-0,
70%) 5 g of the Ca-containing zeolite thus obtained was added to 10 parts of water with Ca (CH3COO)2- H2O3,14
, S'. About 8Q' of this mixture
After keeping for 20 hours at C, the mixture was heated to 100-1)
Evaporate to dryness at 0°C. After that, in air at 200℃
The zeolite was calcined at 500° C. for 18 hours to obtain a Ca-modified Ca-containing zeolite.

Comparative Example 1 The zeolite powder obtained in Reference Example 1 was heated to a pressure of 400KII/-
The tablets were then crushed into 10 to 20 meshes, and 2 ml of the tablets were filled into a reaction tube with an inner diameter of 1°.

Liquid methanol was mixed with argon gas at 41 rL and 1 ml, and sent to the reaction tube at approximately normal pressure, and the reaction was carried out at 500'C, and the product was analyzed using a gas chromatograph. The experiment using only methanol as a reaction raw material, which serves as a standard for evaluating the effectiveness of the method of the present invention, was repeated under the same reaction conditions, and the average value and minimum and maximum values of the results were also recorded to show fluctuations. They are also shown in Table 1.

Example 1 Due to constraints on the reactor, instead of recycling a part of the reaction product to the reactor, 1-butene gas was added to the raw material of Comparative Example 1 with 4-
Using the material added at 3 vJ/min as a raw material, the reaction was carried out using the same equipment and under the same conditions as in Comparative Example 1, and the product was analyzed in the same manner.

The results are shown in Table 1. This experiment corresponds to a raw material feed rate 1.4048 times that of Comparative Example IK on a carbon basis.

This value is almost the same on a carbon basis as in the case where the C4-C6 aliphatic hydrocarbon obtained in Comparative Example 1 was recycled and supplied to the reactor together with the new raw material.Ethylene (C2')+ in the reaction product The carbon-based proportion of propylene (C3') has decreased from 45.75% in Comparative Example 1 to 41.90%, but the carbon-based supply rate is 1.40%.
Considering that the increase is 48 times, the yield of C2'103' is that of Comparative Example 1. This is an increase of 1.29 times compared to . Assuming that a portion of the added l-butene reaction product is recycled, the selectivity of the carbon base to 02+03 is determined to be 58.86.

Example 2 In place of 4.3 ml/min of 1-butene in Example 1, i-
An experiment was conducted in the same manner as in Example 1 for the case where butene gas was added at a rate of 4.8 ml/min. The results are shown in Table 1. The results of this experiment can be interpreted in the same manner as described in Example 1.

In Examples 1 and 2, the reaction product was recycled in an amount equivalent to about 40 to 45% on a carbon basis with respect to the new raw material, but in this case, C4 to C4 in the reaction product was recycled.
As the C6 component carbon increases, the C4 to C6 components circulate.
It is shown that the amount of I is further increased.

Example 3 Supply amount k of i-butene gas 1). 4 WLl/mi
The operation was carried out in exactly the same manner as in Example 2 except that n was increased. The results are shown in Table 1.

Example 4 The operation was carried out in the same manner as in Example 2 except that the amount of 1-butene gas supplied was increased to 16.5 mJ/min. The results are shown in Table 1.

In Example 3, the amount of i-butene added was 107.254% on a carbon basis with respect to the new raw material. and! l! 1 in Example 4
This corresponds to 54.71%. In this case, the amount of C4 to C6 components in the reaction product on a carbon basis is determined by the amount of i-
This is lower than the amount of butene on a carbon basis. The results of Examples 1 to 4 show that the amount of hydrocarbon recirculation during the implementation of the process of the invention automatically settles to a certain value as operation continues. However, it is of course possible to set the operating conditions so that the recirculation amount is a value different from this automatically determined value.

Example 5 Instead of adding 1-butene gas at a rate of 4.3 mJ/min in Example 1, 1-hexene was calculated as a liquid at 2@j/h.
The operation was carried out in exactly the same manner as in Example 1, except that the addition was carried out at a ratio of r. The results are shown in Table 1.

Example 6 Addition of 2 ml/hr of 1-hexene in Example 5 instead of 1
-Octene was operated in exactly the same manner as in Example 5, except that octene was added at a rate of 21 nl/hr calculated as a liquid. The results are shown in Table 1.

1-hexene from Example 5 in liquid form at 2 TrLl/h
The addition at a rate of r corresponds to a recycle of 90.25% on a carbon basis for the fresh feedstock, and the addition of 2 ml/hr of 1-octene in Example 6 is also 1) 0.96%.
corresponds to the recirculation of Example 3 The percentage of carbon base in the product of ethylene and propylene and the selectivity at a hypothetical carbon pace considering this addition as recycle are the amount of recycle at the same level of carbon pace.
When compared with , the ratio decreases in the order of Examples 5.3 and 6, and the selectivity decreases in the order of Examples 3, 5.6. However, the variation among these three is not that great, and compared to the selectivity of Comparative Example 1, all of them show a significantly higher value. The production rate of high-boiling hydrocarbons of unknown structure increases in the order of Examples 3, 5, and 6, indicating that as the number of carbon atoms in the recirculated hydrocarbon increases, the production of heavy substances increases and the risk of catalyst fouling and coking increases. It shows.

Pot I C, total Qin 2 of olefin and 06 paraffin
Dimethyl ether *3 High boiling point hydrocarbon with unknown structure The sum of the selectivities to ethylene and propylene (
AxB)

Claims (6)

[Claims] (1) Methanol and/or dimethyl ether in the gas phase, weight hourly space velocity of 0.1 to 20 hr^-^1, reaction temperature of 300 to 650°C, and total pressure of 0.1 to 100 atm, containing alkaline earth metals. The reaction product is brought into contact with at least one catalyst selected from the group consisting of zeolite, alkaline earth metal-modified alkaline earth metal-containing zeolite, and alkaline earth metal-modified ZSM-based zeolite to carry out a conversion reaction to hydrocarbons. A method for producing lower olefins, which comprises recycling all or a portion of the remaining fraction after removing C_2 and C_3 olefins from C_2 and C_3 olefins to the reaction system. (2) The production method according to claim 1, wherein the recycled fraction is the remaining fraction after aromatic components have been removed from the remaining fraction. (3) The production method according to claim 2, wherein the recycled fraction is C_4 to C_8 hydrocarbons. (4) The production method according to claim 3, wherein the recycled fraction is C_4 to C_6 hydrocarbons. (5) The production method according to claim 4, wherein the recycled fraction is C_5 and/or C_6 hydrocarbons. (6) The manufacturing method according to any one of claims 1 to 5, wherein the reaction temperature is 300 to 600°C.