KR101754833B1 - Catalyst For Preparing Secondary Dialkylamines and Use Thereof - Google Patents

Abstract

The present invention relates to a metal complex oxide catalyst for the production of a secondary dialkylamine represented by the following general formula (1) and its use. The present invention relates to a catalyst for the production of a secondary alkylamine having a high yield, Effect.
[Chemical Formula 1]
NiO (a) · MgO (b ) · M (c) · Al 2 O 3 (d)
M is a complex oxide of at least one metal element selected from the group consisting of cobalt (Co), copper (Cu), iron (Fe), and zinc (Zn).

Description

Catalyst For Preparing Secondary Dialkylamines and Use Thereof < RTI ID = 0.0 >

The present invention relates to a metal complex oxide catalyst for the production of a secondary alkylamine; And a process for preparing a secondary dialkylamine using the catalyst.

Secondary dialkylamine is a high-performance additive for automobile fuel economy improvement and engine life improvement because it is a raw material of molybdenum lubricant additive used as engine oil and grease additive, and has excellent abrasion resistance compared to conventional engine oil and grease additive. However, since the production technology of the secondary dialkylamine is monopolized in advanced countries such as the USA, Japan, and Germany, all of the high-grade lubricant additives are being imported.

Amine compounds are useful compounds for use as medicinal intermediates, pesticide intermediates, dye intermediates, rubber chemicals, surfactants, water treatment agents, urethane raw materials, epoxy hardeners, emulsifiers and solvents. Among them, the commercial application range of the secondary amine derivative compounds, especially the secondary amine compounds, belongs to a unique region which is different from the general class 1 and tertiary alkylamine derivative compounds, such as corrosion inhibitors, emulsifiers, urethane raw materials, pesticide and dye intermediates. The main applications of the secondary dialkylamines are the addition of molybdenum oils and greases as antioxidants, antiwear agents, extreme pressure additives and friction modifiers. As a result, Is known to exhibit excellent performance. In particular, the molybdenum-based engine oil additive synthesized using secondary amine as a raw material is a method for improving the fuel efficiency of a vehicle for reduction of CO _2, which is a main cause of global warming gas, It is known that it has the excellent effect of reducing energy by reducing wear, improving the machine efficiency and reducing fuel consumption, and the demand is increasing all over the world.

As a method for producing a secondary amine, there is a method in which fatty nitrile is synthesized from a fatty acid, a fatty nitrile is hydrogenated to produce a primary amine and then reacted with an alcohol to produce a secondary alkylamine in three steps A two-step preparation method in which a fatty alcohol is aminated with ammonia to produce a primary amine in one step, and a secondary alkyl alcohol is produced by reacting the fatty alcohol with an alcohol, There is a one-step preparation method for producing a lower alkyl alcohol. Among these processes, the conventional processes are mainly 2 to 3 steps of complicated processes from fatty acids to produce secondary alkylamines. However, recently, due to the development of amination technique, a 1-step fatty alcohol amination catalyst and a secondary alkyl Amine production processes are being actively researched and developed.

According to recent manufacturing alkylamine using a catalyst development process, the carbon number of 4 or butyl alcohol at 180 ℃ 30 atm to buy the German BASF using a NiO-CuO-CoO-ZrO ₂ catalyst in a tubular reactor in U.S. Patent 5,530,127 No. The yield of primary amine and primary amine was 51% and 43%, respectively, by reacting with ammonia. When the tridecanol alcohol having 13 carbon atoms was reacted with ammonia at 200 ° C and 200 atm using NiO-CuO-MoO ₃ -ZrO ₃ catalyst, the primary amine yield was 74% and the secondary amine yield was 25%. In U.S. Patent No. 4,415,755, Texaco of the United States had a primary amine yield of 80% and a secondary amine yield of 15% using a CuO-CrO catalyst in a tubular reactor at 282 ° C and normal pressure when octyl alcohol was reacted with ammonia , The yield of primary amine was 58% and the yield of secondary amine was 33% under the conditions of 275 ° C and 5 atm.

However, when the amination reaction is carried out in a tubular reactor, BASF and Texaco have a problem that the reaction is carried out at a high pressure and a severe reaction condition, and the yield of the secondary amine is less than 50%.

In U.S. Patent Nos. 5,266,730 and 4,792,622, and Japanese Patent Laid-Open Nos. 1990-202854 and 1989-102045, Kao, Japan, discloses lauryl alcohol as a catalyst for Cu-Zn-Pd / Zeolite and Cu-Co-Pd / Zeolite catalyst At a reaction temperature of 180 ° C, a catalyst of 0.25 wt%, a reaction time of 5 hr, and an ammonia flow rate of 30 L / hr in a batch reactor. As a result, a secondary amine yield of 94% was obtained. Laurylamine, a primary amine, was reacted with stearyl alcohol at a temperature of 180 ° C, a catalyst of 1%, a reaction time of 5 hours and a primary amine flow rate of 25 L / hr under Cu-Pd / Zeolite and Cu-Ni-Ru / To give a secondary amine in a yield of 97%.

However, since the above-mentioned results have the problems of using expensive noble metal catalysts and reacting primary amines with various alcohols, various secondary amines can be synthesized with higher yields, but the process is complicated due to the two-step reaction .

Accordingly, the present inventors have synthesized and reacted various nickel and transition metal composite oxide catalysts in order to solve the problems of the prior art. As a result, they found that the reaction yield is high, the process is simple, the catalyst can be reused repeatedly five times or more, And a quaternary metal complex oxide catalyst for the production of a secondary alkylamine capable of obtaining a secondary amine having excellent quality.

A first aspect of the present invention provides a metal complex oxide catalyst for producing a secondary dialkylamine represented by the following general formula (1).

[Chemical Formula 1]

NiO (a) · MgO (b ) · M (c) · Al 2 O 3 (d)

Wherein a, b, c and d represent the content based on the total weight of the catalyst, a is 40 to 80 wt%, b is 1 to 15 wt%, c is 0.5 to 10 wt% d is 10 to 40 wt%, and M is a complex oxide of at least one metal element selected from cobalt (Co), copper (Cu), iron (Fe) and zinc (Zn).

A second aspect of the present invention provides a process for producing a secondary dialkylamine comprising the step of reacting an alcohol and ammonia in the presence of a metal complex oxide catalyst for producing a secondary dialkylamine according to the first aspect.

Hereinafter, the present invention will be described in detail.

The present invention is characterized by using a catalyst represented by the following formula (1) in the production of a secondary alkylamine by reacting an alcohol and ammonia.

[Chemical Formula 1]

NiO (a) · MgO (b ) · M (c) · Al 2 O 3 (d)

M is a complex oxide of at least one metal element selected from the group consisting of cobalt (Co), copper (Cu), iron (Fe), and zinc (Zn).

In the metal composite oxide catalyst of the present invention, M is a cocatalyst component of NiO, which is the main active component of the catalyst, and increases the activity and selectivity of the transition metal, which is in the oxidized state. Since they are similar in size, they improve the structural and electronic stability of the NiO component, so that the activity is maintained even after repeated use of the catalyst, and the reaction stability of the catalyst can be improved.

For example, in the above formula (1), M is at least one metal selected from the group consisting of Mo, W, Mn, and Sn, unlike the case where M is selected from cobalt (Co), copper (Cu), iron In the case of an element, a large amount of catalyst should be used, and since the activity of the catalyst is not stable, there is a problem that it is difficult to repeatedly reuse the catalyst three times or more.

The catalyst according to the present invention can be used as a catalyst for dialkylamination of alcohol. An example of the dialkylamination reaction of the alcohol may be represented by the following reaction formula (1).

[Reaction Scheme 1]

The alkyl group (R-) may be one or two kinds, and the alkyl group (R-) preferably has 6 to 20 carbon atoms.

The alcohols may also be linear, branched or cyclic and may be primary or secondary alcohols. Preferably, the alcohol may be a linear or branched primary alcohol, in which case the yield of the dialkylamination reaction is high.

The catalyst according to the present invention is a four-component metal composite oxide, wherein the nickel oxide (NiO) (a) is 40 to 80 wt% and the magnesium oxide (MgO) (b) is 1 to 15 wt% It is preferable that the M oxide (c) is 0.5 to 10 wt%, and the aluminum oxide (Al ₂ O ₃ ) (d) is 10 to 40 wt%.

More preferably, the nickel oxide is 50 to 75 wt%, the magnesium oxide is 3 to 12 wt%, the M oxide is 1 to 7 wt%, and the aluminum oxide is 15 to 35 wt%.

When the nickel oxide content exceeds 80 wt%, the size of the nickel crystal increases and the reaction activity decreases. When the nickel oxide content is less than 40 wt%, the nickel crystal size is small, but the amination activity is low and the conversion is reduced.

When the content of magnesium oxide is less than 1 wt% or the content of aluminum oxide is more than 10 wt%, the high dispersion and uniformity of the nickel oxide (NiO) crystal are decreased, and the amination reaction activity is low, Is more than 15% by weight, or when the content of aluminum oxide is more than 40% by weight, the acidity and the basicity of the catalyst are greatly increased, and the aldol condensation and the side reaction of the amine are increased, , Tertiary amine by-products are increased.

If the content of M oxide is less than 0.5 wt%, the amination reaction activity is increased, or the stabilization which suppresses the sintering of the nickel oxide (NiO) crystal does not have an effect of increasing the service life by repeated use of the catalyst. , Rather, it inhibits the formation of nickel oxide (NiO) crystals, resulting in reduced catalytic activity and lower conversion.

Non-limiting examples of alcohols having 6 to 20 carbon atoms include 2-Ethylhexanol, n-Octanol, or Isotridecanol. Preferably, the alcohol may have 6 to 18 carbon atoms.

When an alcohol having a carbon number of 5 or less or 20 or more is used, the activity, selectivity, etc. of the catalyst of the present invention may be reduced and a separate and improved catalyst may be required.

On the other hand, the dialkylamination reaction of alcohol may be carried out by introducing the catalyst according to the present invention into the reactor after introducing alcohol as a starting material into the reactor.

In the synthesis of the secondary alkylamine, the amount of the catalyst according to the present invention is 1 to 18% by weight, preferably 3 to 15% by weight, based on 100% by weight of the alcohol. The reaction temperature for the synthesis is 120 to 220 캜, preferably 140 to 200 캜, and the reaction pressure is 0.2 to 3 atm, preferably 0.3 to 2.5 atm. When the amount of the catalyst is 18% by weight or more, the reaction temperature is 220 ° C or higher, and the reaction pressure is 0.2 atm or lower, the activity of the catalyst is excessively increased and the amination reaction is further advanced to convert the secondary amine to tertiary amine The yield of the primary amine is reduced.

When the amount of the catalyst is 1 wt% or less, the reaction temperature is 120 ° C or lower, and the reaction pressure is 3 atm or higher, the conversion rate is lowered and the reaction time is greatly increased. The yield of the secondary amine is also reduced.

When the four-component metal complex oxide catalyst according to the present invention is used, it is possible to obtain a final product having a high reaction yield in the production of a secondary alkylamine, a simple process in a one-step reaction, and excellent purity and quality.

In addition, since the catalyst of the present invention has a large specific gravity, the volume of the catalyst for the reactant is small and the precipitate filtration separability is good, so that it is simple and easy to recover and reuse.

Furthermore, the catalyst of the present invention has high structural and electronic stability, and maintains the activity and the reaction stability of the catalyst even in repeated use of the catalyst.

Fig. 1 shows the results of XRD analysis of the amination catalyst according to Example 1. Fig.

The present invention will be further illustrated by the following examples and the following examples are only illustrative examples of the present invention and are not intended to limit or limit the scope of protection of the present invention.

Example  One

(1-1) Amination catalysts NiO (64), MgO (10), CoO (6), Al ₂ O ₃ (20)

640 g (2.2 mol) of nickel nitrate [Ni (NO ₃ ) ₂ .6H ₂ O], 154 g (0.6 mol) of magnesium nitrate [Mg (NO ₃ ) ₂ .6H ₂ O], and cobalt [Co (NO ₃ ) ₂ 58 g (0.2 mol) of 6H ₂ O and 375 g (1.0 mol) of aluminum aluminum nitrate [Al (NO ₃ ) ₃ .9H ₂ O] were dissolved in deionized water to prepare a 3 L solution (solution A). 320 g (8.0 mol) of sodium hydroxide [NaOH] was dissolved in deionized water to prepare a 3 L solution (solution B). 53 g (0.5 mol) of sodium carbonate [Na ₂ CO ₃ ] was dissolved in deionized water to prepare a 1 L solution (solution C).

The solution C was added to a 20 L reactor equipped with a pH electrode and stirred. A solution B and a solution B were added at the same flow rate for 3 hours to a solution C at pH 9 and adjusted to a solution B so that the final pH of the dispersion was 9. The mixture was stirred at 80 DEG C for 12 hours and filtered. 7 L of deionized water was added, followed by dispersion and stirring, and filtration was repeated three times. The filtered hydroxides were dried at 100 < 0 > C for 10 hours.

The dried hydroxide was pulverized in a pulverizer to a size of 10 to 60 micrometers and calcined in air at 600 DEG C for 6 hours. The calcined oxide powder was reduced in a reducing furnace at 500 DEG C for 5 hours under a hydrogen flow.

The calcined catalyst in air was analyzed by XRD. As a result, crystals of nickel oxide were confirmed, and magnesium oxide, cobalt oxide and aluminum oxide were microscopic amorphous (see FIG. 1). The reduced catalyst powder was stabilized by flowing nitrogen gas containing 5% carbon dioxide at 30 ° C. for 6 hours and used as a catalyst.

(1-2) Amination reaction

3.5 kg of isotridecanol was added to a 10 L stainless steel reactor, and 0.3 kg of a NiO (64) MgO (10) CoO (6) Al ₂ O ₃ (20) catalyst was added. Nitrogen gas was then injected into the reactor, and the pressure was repeated to replace the reactor with nitrogen. After replacing the nitrogen, ammonia gas (NH ₃ ) was charged at 1.0 atm while being heated to 90 ° C, and then the temperature was raised to 170 ° C and amination reaction was performed for 10 hours. After the reaction, the mixture was cooled to 60 DEG C, depressurized, purged with nitrogen, and then allowed to stand to precipitate a catalyst layer. The amine layer corresponding to the upper layer was distilled to obtain a 98% purity secondary amine. The secondary amine after separation of the catalyst and the amine sample after distillation were analyzed by GC (gas chromatography). The results of the reaction are shown in Table 1 below.

Examples 2 to 3

NiO (a) · MgO (b ) · CoO (c) · Al 2 O 3 (d) Example 2 NiO (73) in the composition of the catalyst · MgO (5) · CoO ( 2) · Al 2 O 3 ( 20), and Example 3 was changed to a composition of NiO (53) MgO (10) CoO (5) Al ₂ O ₃ (32) And the reaction was carried out in the same manner as in Example (1-2). The results of the reaction are shown in Table 1 below.

Comparative Examples 1 to 4

NiO (a) · MgO (b ) · CoO (c) · Al 2 O 3 (d) a 40 to 80% by weight in the composition of the catalyst, b is 1 to 15 wt%, c is 0.5 to 10% by weight, d was changed from 10 to 40 wt% in the same manner as in the above Example (1-1) except that the catalyst was changed as shown in Table 1, and the reaction was carried out as in the above Example (1-2) . Further, B111W (Raney Nickel) catalyst of Evonik Co. was reacted as in Example (1-2). The results of the reaction are shown in Table 1 below.

Example 4

NiO (64), MgO (10), FeO (6), Al ₂ O ₃ (20) catalysts were synthesized in the same manner as in the above Example (1-1) except that cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O (Fe (NO ₃ ) ₂ .9H ₂ O] was used in place of the iron nitrate [Fe (NO ₃ ) ₂ .9H ₂ O]. The results of the reaction are shown in Table 1 below.

Example 5

Co (NO ₃ ) ₂ .6H ₂ O] was prepared in the same manner as in Example (1-1) except that NiO (64) MgO (10) CuO (6) Al ₂ O ₃ Instead, copper nitrate [Cu (NO ₃ ) ₂ .3H ₂ O] was used and the reaction was carried out in the same manner as in Example (1-2). The results of the reaction are shown in Table 1 below.

Example  6

The catalysts of NiO (64), MgO (10), ZnO (6) and Al ₂ O ₃ (20) were synthesized in the same manner as in Example (1-1), except that cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O (Zn (NO ₃ ) ₂ .6H ₂ O] was used instead of zinc nitrate, and the reaction was carried out in the same manner as in Example (1-2). The results of the reaction are shown in Table 1 below.

Example Catalyst composition (wt%) Alcohol Conversion Rate (%) Primary amine
yield(%) Secondary amine yield (%) Tertiary amine yield (%) Example 1 NiO (64) MgO (10) CoO (6) Al ₂ O ₃ (20) 96 5 85 6 Example 2 NiO (73) MgO (5) CoO (2) Al ₂ O ₃ (20) 98 4 88 6 Example 3 NiO (53) MgO (10) CoO (5) Al ₂ O ₃ (32) 94 7 84 3 Comparative Example 1 NiO (60) MgO (7) CoO (11) Al ₂ O ₃ (22) 93 22 48 23 Comparative Example 2 NiO (38) MgO (7) CoO (5) Al ₂ O ₃ (50) 54 19 34 One Comparative Example 3 NiO (63) MgO (1) CoO (0.4) Al ₂ O ₃ (35.6) 69 30 37 2 Comparative Example 4 Raney Ni, Evonik B111W 86 26 52 8 Example 4 NiO (64) MgO (10) FeO (6) Al ₂ O ₃ (20) 96 9 82 5 Example 5 NiO (64) MgO (10) CuO (6) Al ₂ O ₃ (20) 94 9 82 3 Example 6 NiO (64) MgO (10) ZnO (6) Al ₂ O ₃ (20) 96 8 83 5

A is from 40 to 80% by weight, b is from 1 to 15% by weight in the composition of NiO (a) MgO (b) CoO c Al ₂ O ₃ (d) , a conversion of 94% or more, a yield of primary amine of 9% or less and a yield of secondary amine of 82% or more within a range of 0.5 to 10 wt% and 10 to 40 wt% of c, respectively , And a high quality secondary amine having a purity of 98% or more upon distillation was obtained. However, as in Comparative Examples 1 to 4, a catalyst in a range of 40 to 80 wt%, b in 1 to 15 wt%, c in 0.5 to 10 wt%, and d in 10 to 40 wt% The yield of the primary amine was 30% or the yield of the tertiary amine was 20% or more, and the yield of the secondary amine was very low. Also, when iron, copper, or zinc oxide was added instead of cobalt oxide, the yield of the secondary amine was 82% or more, which is a good catalyst having a high yield.

Example 7

The NiO (64), MgO (10), CoO (6), Al ₂ O ₃ (20) catalyst of Example (1-1) was used, ).

Comparative Example 5

NiO (63) MgO (7) MoO ₃ (5) Al ₂ O ₃ (25) catalyst was prepared as follows. Nickel nitrate _{[Ni (NO 3) 2 ·} 6H 2 O] 209g, magnesium nitrate _{[Mg (NO 3) 2 ·} 6H 2 O] 38.5g of aluminum nitrate _{[Al (NO 3) 3 ·} 9H 2 O] ride 158g Dissolved in ionized water to prepare 700 ml of a solution (solution A). 112 g of sodium hydroxide [NaOH] was dissolved in deionized water to prepare 700 ml of a solution (solution B). 21.2 g of sodium carbonate [Na ₂ CO ₃ ] was dissolved in deionized water to prepare a 200 ml solution (solution C). C solution was added to a 3L reactor equipped with a pH electrode and stirred. Solution A and solution B were added at the same flow rate for 5 hours at pH 9 of solution C and adjusted to solution B so that the final pH of the dispersion was pH 9. C slurry was added 7.3 g of Na ₂ MoO ₄ · 2H ₂ O and the mixture was stirred for 1 hour.

Then, the mixture was stirred at 80 DEG C for 12 hours and filtered. Next, 15 L of deionized water was added, dispersed and stirred, and filtration was repeated three times. The filtered hydroxide was dried at 100 DEG C for 10 hours. The dried hydroxide was pulverized in a pulverizer to a size of 10 to 60 micrometers and calcined in air at 600 DEG C for 6 hours. The calcined oxide powder was reduced in a reducing furnace under a hydrogen flow at 500 ° C for 5 hours. The reduced catalyst powders were stabilized by flowing nitrogen gas containing 5% carbon dioxide at 30 ° C for 6 hours to synthesize a catalyst. The synthesized catalyst was used to carry out the reaction as in Example (1-2).

Experimental Example 1

The catalysts synthesized in Example 7, Comparative Examples 4 and 5 were repeatedly used under the same reaction conditions as in the above Example (1-2) to carry out the reaction seven times. The yield of the secondary amine after each reaction is shown in Table 2.

Example Catalyst composition (wt%) Secondary amine yield (%) One time reaction 2 reactions 3 times reaction 4 times reaction 5 times reaction 6 reactions 7 reactions Example 7 NiO (64) MgO (10) CoO (6) Al ₂ O ₃ (20) 85 84 84 83 83 83 82 Comparative Example 4 Raney Ni, Evonik B111W 52 50 45 41 37 35 33 Comparative Example 5 NiO (63) MgO (7) MoO ₃ (5) Al ₂ O ₃ (25) 84 81 74 69 64 60 56

As in Example 7, the NiO (64), MgO (10), CoO (6), and Al ₂ O ₃ (20) catalysts exhibited a secondary amine yield of 85% to 82% 3%, and the yield was 82% or more. However, as in Comparative Example 5, the NiO (63), MgO (7), MoO ₃ (5), and Al ₂ O ₃ (25) catalysts exhibited a secondary amine yield of 84% %. The Raney Ni and Evonik B111W catalysts of Comparative Example 4 showed a 19% decrease in the secondary amine yield from 52% to 33% when using 7 times repeatedly.

Examples 8 to 12

NiO (64), MgO (10), CoO (6), and Al ₂ O ₃ (20) catalysts of Example (1-1) were used and the reaction conditions were changed as shown in Table 3, (1-2). The results of the reaction are shown in Table 3.

Example Amount of catalyst
(weight%) Reaction temperature (캜) Reaction pressure (atmospheric pressure) Reaction time (hours) Alcohol conversion (%) Primary amine
yield(%) Secondary amine yield (%) Tertiary amine yield (%) Example 8 12 160 0.7 8 96 5 84 7 Example 9 8 150 0.8 14 93 8 82 3 Example 10 8 160 2.0 11 98 13 82 3 Example 11 8 180 0.8 8 97 5 82 10 Example 12 5 160 1.0 11 93 6 84 3

As in Examples 8 to 12, when the amount of the catalyst used was 1 to 18 wt%, the reaction temperature was 120 to 220 DEG C, and the reaction pressure was 0.2 to 3 atm, the yield of the secondary amine was 82% or more As the starting material.

Examples 13 to 14

The reaction was carried out in the same manner as in Example ₁ except that NiO (64), MgO (7), CoO (6), Al ₂ O ₃ (20) And 2-ethylhexanol were reacted in the same manner as in Example (1-2). The results of the reaction are shown in Table 4 below.

Example Reactive alcohol Alcohol Conversion Rate (%) Primary amine
yield(%) Secondary amine yield (%) Tertiary amine yield (%) Example 13 Normal octanol 98 6 86 6 Example 14 2-ethylhexanol 96 10 80 6

As in Examples 13 to 14, the amination reaction was carried out using n-octanols having 8 carbon atoms and 2-ethylhexanol. As a result, it was possible to synthesize secondary amines in a high yield of more than 80%.

 Therefore, when a secondary dialkylamine is produced from an alcohol using a catalyst according to the present invention, it is possible to produce a product having a simple process, an excellent reaction yield, purity and quality, and therefore an engine oil additive and a grease additive There is an advantage that it can be used.

Claims (8)

A composite metal oxide catalyst for producing a secondary dialkylamine represented by the following formula (1)
[Chemical Formula 1]
NiO (a) · MgO (b ) · M (c) · Al 2 O 3 (d)
Wherein a, b, c and d represent the content based on the total weight of the catalyst, a is 40 to 80 wt%, b is 1 to 15 wt%, c is 0.5 to 10 wt% d is 10 to 40% by weight, and M is an oxide of at least one metal element selected from cobalt (Co), copper (Cu), iron (Fe) and zinc (Zn). The method of claim 1, wherein in the formula 1, a is 50 to 75 wt%, b is 3 to 12 wt%, c is 1 to 7 wt%, and d is 15 to 35 wt% Complex metal oxide catalyst for the production of dialkylamines. The composite metal oxide catalyst for producing a secondary dialkylamine according to claim 1, wherein M in the formula (1) is a cobalt (Co) oxide. A process for producing a secondary dialkylamine comprising the step of reacting an alcohol and ammonia in the presence of the composite metal oxide catalyst for producing a secondary dialkylamine according to any one of claims 1 to 3. 5. The method of claim 4, wherein the alcohol has from 6 to 20 carbon atoms. The method of claim 4, wherein the alcohol is 2-ethylhexanol, n-octanol, or isotridecanol. 5. The method of claim 4, wherein the catalyst is used in an amount of 1 to 18% by weight based on 100% by weight of alcohol. The process for producing a secondary alkylamine according to claim 4, wherein the reaction temperature is 120 to 220 ° C and the reaction pressure is 0.2 to 3 atm.

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