JPS6111216B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a process for producing ethylamines, particularly triethylamine, from acetaldehyde with high selectivity. There are three types of ethylamine: monoethylamine (MEA), diethylamine (DEA), and triethylamine (TEA), and they are used in a wide variety of fields including agricultural chemicals and paints, but the demand for them varies depending on the field of use. Varies depending on Therefore, there is a need for a technology that can produce different amounts of the three types of ethylamine depending on industrial demands. A method for producing ethylamine by reacting acetaldehyde with ammonia and hydrogen in the gas phase in the presence of a nickel-based hydrogenation catalyst is known. In this method, a mixture of three types of ethylamine is generally obtained as a reaction product, and an example of the ratio thereof is MEA:DEA:TEA=50:35:15.
(German organic synthesis technology PB report included, page 53,
1955 Maruzen) Demand is high in the field of paints, etc.
In order to increase TEA production, the generated MEA, DEA
However, this not only has the disadvantage of increasing production costs, but also
The conversion effect to TEA is insufficient, and the purpose of producing TEA with high selectivity cannot be achieved. Reducing the ratio of ammonia to acetaldehyde in the feed composition also helps increase selectivity to TEA.
For example, according to JP-A No. 49-36608, in Example 4 in which the molar ratio of charged ammonia/acetaldehyde was lowered to 0.5, TEA was 30.5 mol% (an atomic group having two carbon atoms, hereinafter abbreviated as _C2) . The selection rate for TEA is 42.8%), which is relatively high. However, if only the molar ratio of ammonia was reduced, TEA
cannot be produced selectively enough, and this method also has disadvantages such as an increase in by-product ethanol. Although inventions have been made to increase the selectivity between DEA and TEA by improving catalysts (Japanese Patent Publication No. 45-32408, Japanese Patent Application Laid-Open No. 47-25111), these methods
Although the selection rate of DEA + TEA increases, it is not possible to decrease DEA and increase TEA. Furthermore, once the catalyst is placed in the reactor, it is used for a long period of time, so the solution based on the type of catalyst is not suitable for precisely changing the production ratio of the three types of ethylamine in response to changes in demand. Based on the above circumstances, the inventors of the present invention can increase production of TEA for a desired period according to changes in demand.
As a result of intensive studies aimed at providing a method for producing ethylamine, it was discovered that TEA could be produced with high selectivity by selecting a specific value for the reactant gas linear velocity, which no one had paid attention to until now, and the present invention was completed. did. That is, the present invention provides a method for producing ethylamine by a gas phase reaction of acetaldehyde, ammonia, and hydrogen in the presence of a nickel-based hydrogenation catalyst, in which the linear velocity of the reaction gas passing through the catalyst layer is preferably 0.5 m to 3 m/s. is a method for producing ethylamine to increase the selectivity of triethylamine, characterized in that the length is 0.8 m to 1.5 m. A reaction to which the present invention can be applied is a gas phase reductive amination reaction of acetaldehyde using a nickel-based catalyst, which is generally used in hydrogenation reactions. produced in the gas phase reductive amination reaction of acetaldehyde.
In some cases, MEA and DEA are subjected to reactions in the form of gas circulation or a two-step reaction. In this case, the raw material molar ratio conditions are that 1 mol of DEA is evaluated as 1 N (nitrogen) atom corresponding to 1 mol of ammonia and 2 C ₂ atomic groups corresponding to 2 mol of acetaldehyde. In the case of MEA, there is one N atom and one _C2 atomic group. In this way, the raw material molar ratio is N/, which corresponds to the reaction of ammonia and acetaldehyde.
It can be converted and displayed as a ratio of C ₂ . As a catalyst, a nickel-based fixed bed hydrogenation catalyst known in the prior art can be used.
Nickel-based catalysts containing other promoter metals such as copper and chromium may also be used. One preferred form is a reduced nickel catalyst supported on a support such as diatomaceous earth, often in pellet form. As long as the reactor can achieve the specified gas linear velocity,
A known suitable type reactor such as a tube reactor or a Fischer furnace reactor can be used. The reaction gas passing through the catalyst bed comprises a feed gas consisting of hydrogen, ammonia, acetaldehyde or a conversion gas derived therefrom, or additionally a predetermined amount of recycle gas added thereto. Other gases that do not interfere with the reaction may also be included. The gas linear velocity is determined by dividing the volume velocity of these gases entering the reactor (0°C, 1 atm standard) by the cross-sectional area of the catalyst layer, and in the present invention, the value is 0.5 m/sec.
That's all. The reactant gas linear velocity in the prior art is
For example, since it is about 0.2 to 0.3 m/sec, it can be said that the present invention is characterized by reaction conditions of relatively high linear gas velocity. The selectivity of ethyl groups in the three types of ethylamines obtained, that is, the ratio of ethyl groups in each obtained ethylamine to the _C2 atomic groups in the raw material, is determined by the fact that TEA increases due to high gas line velocity, whereas DEA is significant. go down to Taking an example where the molar ratio of raw materials is N/C ₂ = 1.3, as the gas linear velocity increases from 0.3 to 0.5 to 0.74 to 0.9 m/s, the selectivity of ethyl groups to TEA increases by 57 m/s.
%, 62%, 67%, and 76%, and the selection rate for DEA decreases to 30%, 30%, 24%, and 2%. The selectivity is affected not only by the linear gas velocity but also by the composition of the charged gas and the amount of circulating gas. If the gas linear velocity is increased by increasing the circulating gas, TEA selectivity will be improved up to a certain point due to the increase in the gas linear velocity, but if the circulating gas is increased too much, the increase in the N/C ₂ ratio will reverse the effect.
TEA selection rate may also decrease. In order to have the effect of improving TEA selectivity and not bring disadvantages in terms of required power, the gas linear velocity must be 0.5 to 3 m/
It should be selected within the range of sec, especially 0.8 to 1.5
A range of m/sec is preferred. In order to obtain a high TEA selectivity immediately after the start of the reaction, it is preferable to treat the catalyst with a high linear velocity gas of hydrogen and ammonia in advance before charging the aldehyde. When performing a gas phase catalytic reaction of acetaldehyde, ammonia, and hydrogen using the gas linear velocity in the above range, the reaction temperature is usually 90 to 200°C, especially 110 to 160°C, and the raw material charging molar ratio of hydrogen: ammonia: acetaldehyde is 5. ~20:0.3 ~ 5:1 can be selected from the usual conditions, but regarding the charged ammonia / acetaldehyde molar ratio
It is preferably 2.5 or less. If this ratio is too large, the result obtained when increasing the gas linear velocity is
TEA selectivity reaches its maximum value at a relatively small value. In addition to fresh feed gas, recycled gas can also be introduced into the catalyst bed. The circulating gas can be used either as the gas emitted from the catalyst bed or in the form of residual gas obtained by condensing or absorbing ethylamine from the reaction outlet gas. The latter often also contains hydrogen, ammonia, and some ethylamine. Of course, it is also possible to use a known technique in which monoacylamine or the like is further added to the circulating gas depending on the balance of demand. 〓〓〓〓
The reaction gas introduced into these catalyst layers has an apparent linear velocity of 0.5 m/sec to 3 m/sec as defined above.
It passes through the catalyst layer in seconds. The contact time at that time is a value determined from the apparent volume of the catalyst and the volume velocity of the charged gas at 0° C. and 1 atm, and is usually 0.1 to 5 seconds. If the contact time is too short, impure compounds will be present in the obtained product, and if the contact time is too long, it will only lower the space-time yield and is useless. A range of 0.4 to 3 seconds is preferably used. The reaction is not particularly limited to pressure. Usually, a so-called normal pressure reaction, that is, a method in which a gas pressurized by the value of the pressure loss accompanying the gas flow is supplied, is suitable, but it can also be carried out under reduced pressure or increased pressure, if necessary. Ethylamine can be separated from the gas reacted as described above by a known separation means such as condensation, absorption, or distillation to obtain TEA and DEA as a by-product. By the method of the present invention, ethylamine can be produced with a particularly high selectivity for TEA compared to conventional techniques in which the reactant gas linear velocity is low. The selectivity of ethyl groups to TEA in the reaction product is determined by the linear velocity of the reaction gas.
58 as increasing from 0.3m/sec to 0.9m/sec
% to 76% (when preparation N/C ₂ = 1.3), 65 to 86
% (when charge N/C ₂ =0.9). At the same time, the ethanol by-product rate has increased from 1.4% to approx.
This decreases to 0.8%. Contrary to the increase in TEA, the selection rate for DEA decreases. The present invention can be carried out by manipulating the reaction gas linear velocity, a condition that can be easily changed even during the reaction, without changing the basic reaction conditions such as the type of catalyst. For example, since the reaction gas linear velocity can be changed simply by changing the amount of circulating gas, it is possible to easily increase the production of triethylamine for a desired period of time in response to changes in demand. Thus, according to the present invention, it is possible to flexibly respond to changes in the production plan and increase the production of only triethylamine. Next, the present invention will be explained with reference to examples. Example 1 A stainless steel reactor with an inner diameter of 19 mm was filled with 32 g of a reduced nickel catalyst supported on diatomaceous earth containing 45% nickel and small amounts of copper and chromium as promoters, and acetaldehyde ( A mixed gas consisting of 10 ml/hour (as a liquid), 60 ml/hour of ammonia/hour, and 60/hour of hydrogen was supplied to the catalyst bed, and the reaction gas that had passed through the catalyst bed was circulated to the inlet of the catalyst bed at a flow rate of 720/hour. The linear velocity of the reaction gas in the catalyst layer was 0.9 m/sec, and the contact time based on the charged gas was 1.6 seconds (calculated at 0°C and 1 atm). Calculations were made based on the analysis values of the liquid product obtained by cooling the reaction product gas flowing out from the circulation system, and the conversion rate of acetaldehyde was 99%, the selectivity of triethylamine was 95.3%, and diethylamine, ethanol, and their by-products were 4.7%. It was hot. However, the ethylamine selectivity is the ratio of ethyl atomic groups in the produced ethylamine to the changed acetaldehyde molecules. That is, amine selectivity=number of moles of amine produced×n÷number of moles of changed acetaldehyde, n=3 for TEA, n=2 for DAE, and n=1 for MEA. Comparative Example 1 When the reaction was carried out in the same manner as in Example 1 except that the reaction product gas was not circulated and the linear velocity of the gas passing through the catalyst layer was set to 0.1 m/sec, the acetaldehyde conversion rate was 99. %, diethylamine selectivity was 27%, triethylamine selectivity was 57%, and ethanol selectivity was 1.3%. Example 2 250 g of the same catalyst as in Example 1 was charged into a stainless steel reactor with an inner diameter of 27 mm, and acetaldehyde 65
A mixed gas consisting of 17 g/hour of ammonia and 90 g/hour of hydrogen is supplied to the catalyst bed, and the gas produced by the reaction passes through a cooler to condense and separate most of the amine components, and then as a circulating gas. It was returned to the preparation system at a flow rate of 2000/hour. The reaction temperature was 134°C at the highest point, the linear velocity of the gas passing through the catalyst layer was 1 m/sec, and the contact time was 0.45 sec. As determined from the analytical values of the obtained liquid product, the acetaldehyde conversion rate was 99.5%, the diethylamine selectivity was 15%, the triethylamine selectivity was 84%,
Ethanol and other by-products were 1%. Examples 3 to 11, Comparative Examples 2 to 4 At a reaction temperature of 140°C, the same tests as in Example 1 were conducted by changing the amount of circulating gas and changing the linear velocity within the range of 0.2 to 0.9 m/sec. . The ratio of charged ammonia to acetaldehyde is N/
There were three levels of C ₂ = 1.3, 0.9, and 2.6. 〓〓〓〓
The results are shown in Table 1, and at the gas linear velocity of about 0.2 m/sec used in the prior art, DEA, MEA,
Although the selectivity to ethanol is relatively large, 0.5
It is observed that the selectivity to TEA increases rapidly when the linear velocity is higher than m/sec.

【table】

[Table] Example 12 Nickel catalyst supported on alumina with nickel content of 40%
A test similar to that in Example 1 was conducted using 52 g. Acetaldehyde conversion rate 98.6%, TEA selectivity 54.7%, DEA selectivity 35.4%, MEA selectivity 1.3%
It was hot. When the reaction was carried out at a low linear velocity of approximately 0.1 m/sec without circulation of the reaction gas, the acetaldehyde conversion rate was
99.8%, selectivity to each amine is TEA 46.6%,
DEA was 36.7% and MEA was 13.1%. 〓〓〓〓

Claims (1)

[Claims] 1 In a method for producing ethylamine by a gas phase reaction of acetaldehyde, ammonia, and hydrogen in the presence of a nickel-based hydrogenation catalyst, the linear velocity of the reaction gas passing through the catalyst layer is 0.5 m to 3 m per second.
A method for producing ethylamine for increasing the selectivity of triethylamine, characterized in that: