Process for producing amines

Abstract

The invention discloses a method for producing alkylamines on a solid catalyst by utilizing synthesis gas reaction and nitrogen-containing compounds in a single reaction stage. The process has high alkylamine selectivity, low carbon dioxide and non-nitrogen hydrocarbon yields. The invention also discloses a method, wherein the produced alkylamine is mainly an aliphatic amine of which the hydrocarbon chain contains 7 to 30 carbon atoms. A solid catalyst for use in the process is also disclosed.

Description

Technical Field

[0001] The present invention relates to a process for producing alkylamines (including fatty amines) by reacting synthesis gas and nitrogen-containing compounds over a solid catalyst. Background Art

[0002] Alkylamine is a compound having the following general molecular formula (ie, RN-[B1, B2])

[0003]

[0004] The lengths of the carbon-based substituents R, B1 and B2 connected to the central N atom determine their technical characteristics and application areas. In a common class of alkylamines, the longest substituent R is an alkyl group, which is usually composed of 4 or more carbon atoms, defining the molecular skeleton of the alkylamine compound, while the substituents B1 and B2 are H atoms, shorter alkyl substituents containing 1 to 3 carbon atoms, or the two ends of a cycloalkyl group. Therefore, alkylamines are divided into primary amines, secondary amines and tertiary amines according to whether the substituents B1 and B2 are both H atoms, only one is an H atom, or neither is an H atom.

[0005] Fatty amine (where R is C n Alkyl substituents, typically n is 7 to 30 carbon atoms) and their derivatives (e.g. quaternary ammonium compounds) are used as surfactants, emulsifiers, flotation agents and anti-caking agents in different industries, such as paints and coatings, textiles, personal care, mining and oil and gas industries. Tertiary fatty amines, where R is C n Alkyl substituent, n=7-30, B1 and B2 are C m Alkyl substituents, usually m≤3, such as methyl (C1), ethyl (C2), isopropyl (C3), etc., are of interest as preservative components, fuel oil additives, fungicides, rare metal extractants, cosmetics, active ingredients in polymer manufacturing, accelerators and solidifying agents for foams and resins, and precursors for cationic, nonionic and amphoteric surfactants. Short-chain alkylamines, where R is C n Alkyl substituents, n=4-6, can be used as precursors for drugs, pesticides, dyes, solvents, chromatographic reagents in life sciences, rubber vulcanization accelerators and plasticizers, etc.

[0006] Alkylamines are usually produced by amination or reductive amination of a pre-existing alkyl compound (such as an aldehyde, alcohol, olefin or aliphatic organic halide) with a nitrogen-containing compound (N-compound, such as an amine or ammonia). Alternatively, alkylamines can also be produced by hydrogenation of aliphatic nitriles. The document Catalytic Synthesis of Higher Aliphatic Amines from the Corresponding Alcohols by A. Baiker and J. Kijenski (Catal. Rev.-Sci. Eng. 27 (4), 653-697 (1985)) provides an overview of existing methods for producing alkylamines.

[0007] Alternatively, the alkylamines can be produced by hydroamination, ie the catalytic addition of NH bonds to unsaturated CC bonds of pre-existing aliphatic olefins, as described in US Pat. No. 7,642,383 B2, US Pat. No. 4,138,437, US Pat. No. 5,043,453 A.

[0008] Another method for synthesizing alkylamines is the so-called hydrogen-aminomethylation of olefins, in which aliphatic olefins are reacted with carbon monoxide, hydrogen and a nitrogen-containing compound (such as an amine or ammonia) to produce an alkylamine whose hydrocarbon chain length is extended by one carbon atom relative to the starting olefin. This reaction was first reported by Reppe and Vetter, who used a molecular cobalt carbonyl catalyst (Reppe, W., & Vetter, H. (1953), "Carbonylierung VI. Synthesen mit Metallcarbonylwasserstoffen", Justus Liebigs Annalen der Chemie, 582, 133-161). Document US4250115A relates to a method for preparing tertiary amines, comprising the reaction of an olefin compound, carbon monoxide, hydrogen and a nitrogen-containing compound of the general formula HN-R2 (wherein R is selected from hydrogen radicals, alkyl radicals, aryl radicals, cycloalkyl radicals, aralkyl radicals and alkyl radicals) in the presence of a rhodium catalyst. Document US4543411A relates to a method for preparing secondary and tertiary amines, which comprises reacting olefins, nitrogen-containing compounds and synthesis gas in the presence of a catalyst, wherein the catalyst comprises a ruthenium-containing compound combined with an organic ligand composed of a quaternary ammonium salt. Document US4096150A relates to a method for preparing highly selective substituted amines by reacting an olefin reagent, hydrogen, CO and a secondary amine in the presence of a coordination complex catalyst of a Group VIII metal and a ligand. Documents WO2005077884A2 and DE10321421A1 also disclose methods for synthesizing alkylamines by hydroaminomethylation of olefins.

[0009] The common point of the above-mentioned methods for preparing alkylamines is that the alkyl hydrocarbon substituent (R = C n ) needs to be provided in the form of a component (synthon) of a reactant compound, such as an aldehyde, alcohol, olefin or alkyl halide. In the case of the hydrogen-aminomethylation process of olefins, C n-1 The alkyl chain of the olefin reactant is extended by one carbon atom to form the substituent R(C n In the method for producing fatty amines, the reactant providing the alkyl substituent (R) can be a natural fatty acid or a derivative thereof. Although these methods in the art can effectively and selectively produce alkylamines, they require the provision of a preformed C n or C n-1 The present invention relates to a process for selectively producing alkylamines, wherein a more versatile and cost-effective single-carbon compound (C1) is used as the sole precursor of the hydrocarbon backbone in the alkylamine product.

[0010] Synthesis gas, often abbreviated as "syngas", is a mixture consisting of carbon monoxide (CO), hydrogen (H2) and, in some cases, carbon dioxide (CO2) as the main components. The synthesis gas stream may also include other gases, such as nitrogen (N2), helium (He), argon (Ar), water vapor (H2O) or light hydrocarbons such as methane (CH4), ethane (C2H6), propane (C3H8), which do not significantly change the reactivity of the main components. Synthesis gas can be obtained from a variety of carbonaceous sources, such as by steam reforming or partial oxidation of natural gas or shale gas, gasification of coal, gasification and / or reforming of biomass, hydrogenation of carbon dioxide or co-electrolysis of CO2 and water, etc., so it is considered to be a very versatile C1 feedstock for the production of chemical products from a variety of carbonaceous feedstocks that replace petroleum.

[0011] Fischer-Tropsch synthesis is a catalytic reaction by which synthesis gas is directly converted into a mixture of synthetic aliphatic hydrocarbons, primarily n-alkanes (Fischer-Tropsch Synthesis, Catalysts, and Catalysis: Advances and Applications; BH Davis, ML Occelli (eds.), CRC Press (2016), ISBN 978-1466555297). Early work known to those skilled in the art mixed the synthesis gas feed with a gaseous nitrogen source (such as ammonia) under standard conditions for Fischer-Tropsch synthesis and contacted the gas mixture with a catalyst to promote the formation of N-compounds. Typically, a complex mixture of N-compounds is produced together with non-nitrogenated hydrocarbons.

[0012] Document US2,518,754 discloses a method for synthesizing fatty amines, which comprises contacting a gas mixture containing synthesis gas and ammonia with an iron-containing hydrogenation catalyst and recovering the fatty amine from the product of the reaction. The condensation reaction product consists of a mixture of aliphatic primary amines, nitrogen-free hydrocarbons and ammonium carbonate salts.

[0013] Document US2,821,537 discloses a method for catalytic hydrogenation of carbon monoxide, which produces a primary synthesis product containing nitrogenous compounds in addition to relatively high content of oxygenates (preferably alcohols). Synthesis gas mixture is fed with 0.5 volume % to 2 volume % of nitrogenous compounds (selected from ammonia and methylamine), and the mixture is reacted on a precipitated iron catalyst. The reaction product contains N-compounds (including amines), but in addition, also contains more than 20% of oxygenates and a high content of non-nitrogenated olefins.

[0014] US Pat. No. 3,726,926 discloses a method for preparing n-alkylamines, wherein a gaseous feed consisting of a mixture of synthesis gas and ammonia is contacted with an iron-based catalyst and n-alkylamines are recovered from the reaction products. Under the conditions of the method, the organic products include non-nitrogenated hydrocarbons and hydrocarbons having C3 to C 22 A mixture of fatty amines with alkyl chains. Due to the non-nitrogenated hydrocarbon by-products, the highest selectivity to amines reported in the literature is 35%.

[0015] Document WO 2009 / 127942 A2 discloses a method for producing at least one nitrogen- or phosphorus-containing compound from synthesis gas, the nitrogen- or phosphorus-containing compound being selected from linear nitriles, amides, formamides and phosphorus-containing compounds, wherein the synthesis gas is fed into a reactor together with the at least one nitrogen- or phosphorus-containing compound and reacted over a catalyst, which preferably consists of unsupported and promoted iron. The method is carried out at a temperature of 433 K to 673 K and a pressure of 1 bar to 50 bar. Ammonia, nitrogen oxides NO x(N2O, NO, NO2) and mixtures thereof are disclosed in the document as nitrogen-containing compounds which can be fed as nitrogen sources and reacted with the synthesis gas. Therefore, under the conditions of the process, the synthesis gas components and the nitrogen source compounds are both gaseous. The organic products include a mixture of non-nitrogenated hydrocarbons (chain alkanes, olefins and oxygenates) and nitrogenated organic compounds. In addition to producing linear nitriles, amides or amide-formamide compounds, the process also produces amines. However, due to the concomitant production of oxygenates and nitrogen-free hydrocarbons, the selectivity of amines is limited to ≤6.6% under the conditions disclosed in the document. As disclosed by the same author in T. Sango et al., Applied Catalysis A: General 502 (2015) 150-156, the amine compounds produced are primary n-alkylamines, and the length of the R alkyl substituent chain is mostly between 2 and 13 carbon atoms. It should be noted that a large amount of CO2 is also produced under the conditions of the process, and the CO2 selectivity varies between 35% and 40% (based on carbon).

[0016] Document WO225870 A1 discloses a hydrogenation process for producing N-compounds, which comprises contacting a gaseous feed stream consisting of a mixture of synthesis gas and ammonia with a solid catalyst preferably comprising cobalt and manganese to form at least one fatty amine and / or nitrile compound. Under preferred process conditions, the maximum selectivity of the fatty amine disclosed in the document is 25%.

[0017] A method for producing alkylamines directly from synthesis gas and nitrogen source compounds with higher selectivity (i.e., by minimizing or directly avoiding the co-production of low-value by-products) is needed. A major limitation of methods known in the art is the co-production of non-nitrogenated compounds (i.e., paraffins, olefins, and oxygenates). Without wishing to be bound by theory, the inventors believe that this is due to insufficient rate of amination reaction on the catalyst surface. Higher selectivity for alkylamines will translate into lower product separation and purification costs, as well as reduced by-products of waste or low value-added products, thereby improving process efficiency and economy.

[0018] Therefore, an object of the present invention is to provide a method for producing alkylamines, which achieves high selectivity for alkylamines by using synthesis gas as the sole carbon source of R alkyl chains in the amine product and a nitrogen source reactant as the sole nitrogen source in the amine product, and minimizes nitrogen-free hydrocarbons and CO2 by-products by reacting on a solid catalyst in a single reaction step. Another object of the present invention is to provide a method, wherein the alkylamine product is a fatty amine. Still another object of the present invention is to provide a solid catalyst for the method. Summary of the invention

[0019] It has been found that the method can be implemented by at least the following steps:

[0020] i) Provide the reactor

[0021] a. Synthesis gas feed, and

[0022] b. a liquid feed, the liquid feed comprising a nitrogen source reactant, the nitrogen source reactant being selected from primary amine compounds, secondary amines, acyclic secondary amines, cyclic secondary amines (including non-N-substituted compounds such as piperidine, morpholine, pyrrolidine, pyrrole, imidazole), N,N-dialkylformamide compounds, N,N-cycloalkylformamide compounds and any combination thereof, the nitrogen source reactant being in pure form or dissolved in a suitable solvent that does not react under the conditions of the method;

[0023] ii) reacting the feed provided in i) over a solid catalyst comprising at least ruthenium, cobalt or any combination thereof, preferably ruthenium, in unsupported form or dispersed on a support material at a reaction temperature of 373 degrees Kelvin (K) to 523 K and a total pressure of 1 bar to 300 bar; and

[0024] iii) recovering the alkylamine compound from the product of the reaction.

[0025] As mentioned above, the first aspect of the present invention relates to a process for producing alkylamines. The second aspect of the present invention relates to a process wherein the alkylamine product is a fatty amine. The third aspect of the present invention relates to a solid catalyst for use in said process.

[0026] The term "nitrogen source reactant" as used in the context of the present invention is understood to mean a nitrogen-containing compound which participates in and is consumed in the process and which provides the reactive nitrogen species.

[0027] The term "conversion rate" as used in the context of the present invention is expressed as a percentage and is understood to be the amount of CO in the syngas feed that is converted into other carbon-containing compounds in the reactor. x (x=1 or 2).

[0028] The term "selectivity" as used in the context of the present invention is defined on a carbon basis and is therefore understood to refer to the ratio of the total molar amount of carbon in the target product (eg, alkylamine) to the total molar amount of carbon in all reaction products.

[0029] method

[0030] According to the process of the invention, the catalyst is contacted with at least one liquid phase which remains liquid under the process conditions. Therefore, suitable reactor types for carrying out the process of the invention are those capable of contacting gaseous and liquid phases with a solid catalyst.

[0031] In one embodiment of the present invention, the reactor is operated in a continuous mode, wherein at least one gas feed stream and one liquid feed stream are continuously provided to the inlet of the reactor (e.g., a bubble column reactor or a trickle bed reactor), and the product stream is continuously removed at the outlet of the reactor.

[0032] In another embodiment of the present invention, the reactor is operated in a discontinuous mode (batch mode), wherein gaseous and liquid feeds and catalyst are provided to the reactor before the reactor temperature is adjusted to the reaction temperature, and no additional stream is provided at the reactor inlet during the reaction. After a certain reaction time, the reaction is terminated by lowering the reactor temperature below the temperature range of the process of the present invention, and at least one product stream is recovered from the reactor.

[0033] In another embodiment of the present invention, the reactor is operated in a semi-continuous mode, wherein gaseous and liquid feeds and a catalyst are provided to the reactor before the reactor temperature is adjusted to the reaction temperature, the reaction is carried out with a continuous supply of a synthesis gas feed stream at the reactor inlet, and after a certain reaction time, the reaction is terminated by reducing the reactor temperature to below the temperature range of the process of the present invention, and at least one product stream is recovered from the reactor.

[0034] According to the present invention, the H2 / CO molar ratio in the synthesis gas feed may be from 0.1 to 10, preferably, the H2 / CO molar ratio in the synthesis gas is from 0.3 to 5, more preferably from 0.5 to 2.

[0035] According to the present invention, the CO2 / CO molar ratio in the feed syngas may be from 0 to 2. In a preferred embodiment of the present invention, the CO2 / CO molar ratio in the syngas is from 0 to 0.5. More preferably, the CO2 / CO molar ratio in the syngas is from 0 to 0.1.

[0036] The syngas feed may also include other compounds that do not interfere with the conversion of the syngas, such as nitrogen, helium, argon, water, C1 to C4 alkanes, or combinations thereof.

[0037] The liquid feed in the method of the present invention comprises a nitrogen source reactant. Without wishing to be bound by theory, the inventors believe that a compound suitable as a nitrogen source reactant is a nitrogen compound having at least one NH bond that can participate in a hydroamination or reductive amination reaction. Alternatively, a compound suitable as a nitrogen source reactant is a compound that can react under the conditions of the method of the present invention to form a compound having at least one NH bond. According to one embodiment of the present invention, the nitrogen source reactant can be selected from primary amine compounds, such as methylamine, ethylamine, propylamine, isopropylamine; acyclic secondary amines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-ethylmethylamine, N-methylpropylamine, etc.; cyclic secondary amines, including non-N-substituted compounds, such as piperidine, morpholine, pyrrolidine, pyrrole, imidazole; N,N-dialkylformamide compounds, such as N,N-dimethylformamide, N,N-diethylformamide, N-methyl-N-ethylformamide, N,N-diisopropylformamide, etc.; N,N-cycloalkylformamide compounds, such as piperidinecarboxamide (piperidine-1-carboxaldehyde), prolinal (pyrrolidine-1-carboxaldehyde); non-N-substituted piperidine, morpholine, pyrrolidine, pyrrole, imidazole compounds; and any combination thereof.

[0038] According to a preferred embodiment of the present invention, the nitrogen source reactant is N,N-dialkylformamide, more preferably N,N-dimethylformamide.

[0039] According to one embodiment of the present invention, the nitrogen source reactant may be provided in the form of a pure compound, or as part of a solution, i.e., dissolved in a suitable solvent that is non-reactive and stable under the conditions of the method. The solvent used in the method of the present invention is not particularly limited, as long as the nitrogen source reactant is at least partially dissolved in the solvent and the solvent remains at least partially liquid under the conditions of the method of the present invention. The solvent may be selected from aliphatic hydrocarbons, such as n-alkanes, selected from non-limiting n-hexane, n-heptane, n-octane, n-decane, n-dodecane, n-hexadecane, wax, or a combination thereof; or isoalkanes, selected from non-limiting isohexane, isooctane, isohexadecane, or a combination thereof; or cycloalkanes, such as cyclohexane; aromatic hydrocarbons, selected from non-limiting benzene, toluene, xylene, ethylbenzene, dimethylbenzene, trimethylbenzene, and a combination thereof; diesel; oxygen-containing compounds, selected from non-limiting n-butanol, isobutanol, cyclohexadecane, or a combination thereof. Hexanol, tetrahydrofuran, methyl isobutyl ketone, ethylene glycol, propylene glycol, glycerol and combinations thereof; water; nitrogen compounds selected from non-limiting aliphatic tertiary amines, N-methylmorpholine, N-methylpiperidine, N-methylpyrrole, aromatic amines and combinations thereof; halogenated organic compounds selected from non-limiting chlorobenzene, bromobenzene, hexachlorocyclopentadiene, perfluorodecalin and combinations thereof; liquid organic salts selected from non-limiting imidazolium, pyridinium, 1,2,3-triazolium, piperidinium, phosphonium and combinations thereof; and combinations thereof.

[0040] According to another embodiment of the present invention, a single N-compound is fed into the reactor, both as a nitrogen source reactant and as a solvent, and a liquid medium is provided under the method conditions. Without wishing to be bound by theory, the inventor believes that a nitrogen source reactant with a high molar content in contact with a solid catalyst can provide an excess of active nitrogen species on the catalyst surface, and therefore, compared with the competitive hydrogenation reaction that produces non-nitrogenated paraffins, it is helpful to increase the reaction rate of the amination reaction of aliphatic Fischer-Tropsch intermediates. When the catalyst contacts a liquid solution of the nitrogen source reactant, or directly contacts the nitrogen source reactant in pure form, this high molar content of the nitrogen source reactant can be achieved. In addition, the use of a single compound as both a nitrogen source reactant and a solvent is conducive to method design and product recovery, because the reaction product can be separated from the solvent, and the solvent can be recycled to the reactor, and only a small amount of supplementation is required to compensate for its consumption in the reaction. In a preferred embodiment of the present invention, N, N-dimethylformamide is fed into the reactor, both as a nitrogen source reactant and as a solvent.

[0041] According to the present invention, the process is carried out at a reaction temperature of 373 degrees Kelvin (K) to 523 K. As used in the context of the present invention, the reaction temperature is understood to mean the maximum temperature in the reactor measured by a K-type thermocouple located in a stainless steel jacket and in contact with the liquid phase. In a preferred embodiment of the present invention, the process can be carried out at a reaction temperature of 393 K to 453 K, more preferably 413 K to 443 K.

[0042] The suitable reaction pressure of the inventive method is about 1 bar to about 300 bar.As used in the context of the present invention, operating pressure is understood to refer to the absolute pressure in the reactor head space occupied by gas phase measured by digital pressure sensor under the method condition.In the case of batch reactor operation, wherein pressure reduces in synthesis gas conversion process, as used in the context of the present invention, reaction pressure is understood to refer to the pressure measured when the reaction starts.In a preferred embodiment, the method can be carried out at 10 bar to 300 bar, more preferably at 40 bar to 200 bar reaction pressure.

[0043] The nature of the nitrogen source reactant fed to the process of the present invention primarily determines the type of alkylamine product. Thus, if the nitrogen source reactant is a primary amine of formula B1-N-H2, wherein B1 is an alkyl substituent, the amine product is primarily composed of a secondary alkylamine of formula [R, B1]-NH, wherein R is an alkyl substituent having n (n=4-60) carbon atoms. In addition, if the nitrogen source reactant is a secondary amine of formula [B1, B2]-NH or an N,N-dialkylformamide of formula [B1, B2]-NCHO, wherein B1 and B2 are alkyl or cycloalkyl substituents on the N atom, the amine product is composed of a tertiary alkylamine of formula RN-[B1, B2], wherein R is an alkyl substituent having n (n=4-60) carbon atoms. In a preferred embodiment of the present invention, the primary product is a tertiary alkylamine of formula RN-[B1, B2], wherein R is an alkyl substituent having n (n=4-60) carbon atoms.

[0044] According to a specific embodiment, the alkylamine product is a tertiary fatty amine of the molecular formula RN-(B1, B2), wherein the substituent R is a normal alkyl group having 7 to 30 carbon atoms, wherein the substituents B1 and B2 are selected from methyl, ethyl, propyl or isopropyl, and more preferably, the substituents B1 and B2 are methyl.

[0045] According to another specific embodiment, the alkylamine product is a tertiary fatty amine of the molecular formula RN-(B1, B2), wherein the substituent R is a normal alkyl group having 7 to 30 carbon atoms, wherein the substituents B1 and B2 are both ends of a ring having four carbon atoms or a ring having five carbon atoms.

[0046] In the process of the present invention, the distribution of the alkylamine products generally follows an Anderson-Schulz-Flory (ASF) type chain length distribution, which is typically observed in reactions conducted via a chain growth polymerization mechanism. This product distribution is mathematically described by the following relationship (Equation 1):

[0047] W n =n·(1-α) 2 α n-1 (Equation 1)

[0048] Where W n is the mass fraction of alkylamine, the longest C bond to the nitrogen atom n The alkyl substituent contains n carbon atoms, and α (alpha) is the chain growth probability parameter, which indicates that under the reaction conditions, C n The probability of a hydrocarbon chain undergoing the addition of a monomeric species and thereby growing by one carbon atom, on a 0 to 1 basis. Figure 1 The product distribution predicted by Eq. 1 is shown as C 7-30Evolution of the relative abundance of products with alkyl chain lengths (i.e. corresponding to the fatty alkyl amine range). As observed, the relative contribution of products with alkyl chain lengths in the fatty amine range is greatest for values ​​of α between 0.80 and 0.90. Experimentally, the chain growth probability parameter (α) can be determined according to Equation 2:

[0049] α=e m (Equation 2)

[0050] Where e is Euler's number, m represents the experimental data of the reaction product in Ln(W n The slope of the linear regression function is obtained by performing a mathematical linear regression function on a graph of ( / n) versus n, where Ln represents the natural logarithmic function.

[0051] Typically, the product mixture of the process of the present invention is fractionated to recover the amine product. In one embodiment of the present invention, after recovering the alkylamine from the reaction product, compounds present in the reactor effluent stream, such as unconverted reagents, solvent, reaction products or a combination thereof, are recovered and recycled back to the reactor.

[0052] catalyst

[0053] According to the present invention, the catalyst used in the method of step ii) is solid, comprising at least ruthenium (Ru), cobalt (Co) or any combination thereof, preferably ruthenium as the active metal, which may be in unsupported form or dispersed on a support material.

[0054] In one embodiment of the present invention, the catalyst is an unsupported metal catalyst (bulk type), such as finely divided metal powder (metal black), metal mesh or metal foam.

[0055] In another specific embodiment of the present invention, the catalyst is a supported metal catalyst. The concept of "supported metal catalyst" is understood in the art as a composition comprising an active metal portion and a catalytically inactive portion, wherein the active metal portion is generally dispersed in the form of particles with an average diameter of less than 100 nm, and is therefore active or can be converted into an active phase in situ before or during use of the catalyst, wherein the catalytically inactive portion is called a carrier or carrier material, which is generally porous and constitutes the majority of the catalyst in terms of mass.

[0056] In a specific embodiment of the present invention, the active metal further comprises other elements together with Ru, Co or a combination thereof, the other elements being selected from rhodium (Rh), iridium (Ir) or any combination thereof. According to a preferred embodiment of the present invention, Ru accounts for more than 25 wt % of the active metal. More preferably, Ru accounts for more than 50 wt % of the active metal.

[0057] In the prior art, several methods are known for binding active metal moieties to support materials. These methods include preparation techniques such as impregnation, deposition-precipitation, ion exchange, electro-deposition, electrostatic adsorption, melt infiltration, co-precipitation, which are methods known in the art. The literature "Handbook of Heterogeneous Catalysis" (edited by G. Ertl, H. F. Schüth, J. Weitkamp; Volume 1, Wiley-VCH Verlag GmbH & Co. Weinheim, 2008) and "Synthesis of solid catalysts" (edited by K.P. de Jong; Wiley-VCH Verlag GmbH & Co. Weinheim, 2009) provide references on the existing methods for binding active metal moieties to support materials.

[0058] The porous support material should be chemically stable under the typical reaction conditions of the syngas conversion process. The porous support can be an oxide of those porous oxide supports selected as support materials for supported metal catalysts in the art, and can include but are not limited to SiO2, transitional form of Al2O3, α-Al2O3, TiO2, or a combination thereof. Alternatively, the support material can be a carbide or carbon oxide material, such as SiC, SiO x C y , where x is in the range of 0 < x < 2 and y is in the range of 0 < y < 1. Alternatively, the support material can be carbon. Alternatively, the support material can be a composite material including a combination of the above materials.

[0059] According to a preferred embodiment, the porous support is Al2O3.

[0060] The metal is bound to the support material using a metal precursor compound such as metal inorganic salts selected from the non-limiting group of nitrates, halides, carbonates, sulfates, and combinations thereof; organic salts selected from the non-limiting group of acetates, acetylacetonates, oxalates, ethoxylates, and combinations thereof; metal clusters, and organometallic complexes.

[0061] Some specific examples of ruthenium precursors are ruthenium acetylacetonate, ruthenium chloride, ruthenium nitrate, triruthenium dodecacarbonyl, bis(cyclopentadienyl)ruthenium (II), etc. Ruthenium precursors can provide ruthenium in zero oxidation state, oxidation state II, oxidation state III, or a combination thereof. According to a preferred embodiment of the present invention, ruthenium nitrate is used as a ruthenium precursor to prepare the catalyst. Some specific examples of cobalt precursors are cobalt nitrate, cobalt acetylacetonate, cobalt acetate, cobalt oxalate, cobalt chloride, dicobalt octacarbonyl, etc. Cobalt precursors can provide cobalt in zero oxidation state, oxidation state II, oxidation state III, or a combination thereof. According to a preferred embodiment of the present invention, cobalt nitrate is used as a cobalt precursor to prepare the catalyst.

[0062] Typically, after combining the metal precursor, a heat treatment is performed in a static gas atmosphere or under flowing air, steam, inert gas (such as nitrogen, helium, argon) or a combination thereof to decompose the metal precursor to an oxide or suboxide form on the surface of the support material.

[0063] Preferably, the weight loading of the active metal, ie the weight fraction of the total catalyst corresponding to the active metal in the catalyst, is 0.5 wt % to 50 wt %, more preferably 3 wt % to 20 wt %.

[0064] In the art, supported metal catalysts, in addition to the main active metal part and the support material, generally include a so-called promoter. Generally, a promoter is a substance that can improve the performance of the catalyst in terms of activity, selectivity to a given product or product fraction, stability under operating conditions, or a combination thereof. In one embodiment of the invention, the catalyst includes at least one promoter. Under the conditions of the inventive method, the promoter can help to improve the selectivity of the alkylamine product. Without wishing to be bound by theory, the inventors believe that a suitable promoter can promote the activation of the nitrogen source reactant so that it participates in the amination reaction of the intermediate converted with synthesis gas on the catalyst surface.

[0065] According to a specific embodiment, the promoter can be selected from the 3rd, 4th, 5th, 6th, 7th, 12th, 13th, 14th, 15th group elements and lanthanides in the periodic table and any combination thereof. In a preferred embodiment of the present invention, the promoter is selected from Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Zn, Ga, In, P, lanthanides and any combination thereof. Based on the total mass of the catalyst, the mass content of the promoter is greater than 0 weight % and less than 50 weight %. Preferably, the mass content of the promoter is greater than 0 weight % and less than 25 weight %. Preferably, in the catalyst, the promoter element is in ionic form, such as an oxide or a subvalent oxide.

[0066] According to a preferred embodiment, the promoter is an oxide selected from the stable oxides of elements of Groups 3, 4, 5, 6, 7, 12, 13, 14, 15 and lanthanides of the periodic table and any combination thereof.

[0067] Suitable methods for incorporating other active metals other than ruthenium, cobalt or a combination thereof (preferably ruthenium) and promoter elements include techniques known in the art, such as impregnation, precipitation-deposition, ion exchange, electrochemical deposition, electrostatic adsorption, melt infiltration or co-precipitation with suitable precursors, such as metal inorganic salts selected from non-limiting nitrates, halides, carbonates, sulfates and combinations thereof; organic salts selected from non-limiting acetates, acetylacetonates, oxalates, ethoxylates and combinations thereof; metal clusters and organometallic complexes.

[0068] Preferably, the weight loading of the active metal, ie, the weight fraction of the active metal in the catalyst corresponding to the total catalyst, is 0.5 wt % to 50 wt %, more preferably 3 wt % to 20 wt %.

[0069] Prior to application in the process of the invention, the catalyst (whether unsupported or supported) is generally subjected to a heat treatment in the presence of hydrogen or other reducing agent to convert part or all of the active metals into their metallic state, i.e., zero-valent state. In a preferred embodiment, the reduction treatment is carried out in a temperature range of 373 K to 873 K, more preferably in a temperature range of 373 K to 773 K and in a flowing stream comprising hydrogen, either pure or in combination with an inert gas (selected from nitrogen, helium, argon, or a combination thereof). The heat treatment may be omitted if the conditions of exposure to the reaction process (i.e., in the presence of synthesis gas as a reducing atmosphere) are sufficient to convert part or all of the active metals into their metallic state in situ in the reactor of the process of the invention.

[0070] The present invention will now be described in more detail by means of the following figures and experimental examples.

[0071] Throughout the specification and claims, the word "comprise" and its variants are not intended to exclude other technical features, additives, components or steps. For those skilled in the art, other objects, advantages and features of the present invention can be derived in part from the specification and embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 : Figure 1 Shows C 7-30The relative abundance of products with alkyl chain lengths (i.e. corresponding to the fatty alkylamine range) as a function of the chain growth probability parameter (dimensionless) of the Anderson-Schulze-Flory distribution, in arbitrary units, increasing from bottom to top along the Y-axis and from left to right along the X-axis. The lines connecting the scattered data points correspond to the interpolating spline functions. Example

[0073] The following examples are given by way of illustration and are not intended to limit the scope of the present invention.

[0074] The following methods were used to determine the properties of the materials prepared and used in the examples:

[0075] (i) The specific surface area and pore volume of the support material used for the catalyst synthesis were determined by nitrogen adsorption. The nitrogen adsorption isotherms were recorded at -196 °C (77 K) using an ASAP 2420 instrument (Micromeritics). Prior to the analysis, about 200 mg of sample (0.2 mm to 0.4 mm sieve) was heated at 673 K and about 5 × 10 -6 bar overnight. 0 ) using the Brunauer-Emmett-Teller (BET) equation to determine the specific surface area. The pore volume is given by the relative pressure P / P 0 = 0.95 when the nitrogen adsorption was determined.

[0076] (ii) The elemental composition of the catalyst was determined by energy dispersive X-ray spectroscopy (EDS) in a ZEISS ULTRA-55 field emission scanning electron microscope (FE-SEM) equipped with an X-Max 80-Oxford Instruments EDS detector. The powder sample was spread on a section of a metal sheet coated with a double-sided bonded carbon film. Then, at least 5*10 4 μm 2 The elemental composition is determined by integrating the K series of lines of the X-ray emission spectrum for elements with atomic numbers Z equal to or less than 30 and integrating the L series of lines for elements with atomic numbers Z greater than 30.

[0077] Synthesis of the catalyst according to the invention

[0078] Ru / SiO2 catalyst

[0079] By mixing ruthenium(III) nitrosyl nitrate (N4O 10Ru, AlfaAesar, Ru content ≥ 31.3%) was dissolved in 0.1M HNO3 deionized water solution to prepare the ruthenium precursor solution. Specifically, 1.0 g of metal precursor was added to 2.0 mL of acid solution. Silica gel powder (S10020M-Silicycle) was used as the catalyst support. The metal was bound by incipient wetness impregnation. The SiO2 support was first dried at 423 K in a glass flask under dynamic vacuum (1.5 mbar) for 10 hours. Then, under magnetic stirring and static vacuum, a pore volume equivalent to the SiO2 support (0.72 cm 3 / g) 90% of the volume of the ruthenium precursor solution is contacted with the dry support. After impregnation, the material is kept under dynamic vacuum (1.5mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 623K for 3 hours (heating from room temperature at a rate of 1K / min) under a N2 / H2 flow (80% N2, 20% H2) to decompose the Ru precursor and convert the metal into its metallic state. After the thermal treatment, the tubular reactor is purged with a N2 gas flow and the activated catalyst is transferred to a N2-filled glove box (O2<1.0ppm, H2O<0.1ppm) for storage. The Ru content is 8.0 wt%.

[0080] Ru / Al2O3 catalyst

[0081] Synthesis of the Ru / Al2O3 catalyst was as described above for Ru / SiO2, in this case using γ-Al2O3 as the support material. The γ-Al2O3 support was synthesized by calcining a pseudo-boehmite precursor (DISPERAL 80, Sasol) at 823 K (heating rate of 2 K / min from room temperature) in a muffle furnace in an air atmosphere without forced convection for 5 h. The pore volume of the support was 0.66 cm 3 / g. After incorporation of Ru by incipient wetness impregnation, the solid was dried at room temperature for at least 3 hours under dynamic vacuum (1.5 mbar), transferred to a fixed-bed tubular quartz reactor axially mounted in an oven, and treated at 623 K for 3 hours (heating from room temperature at a rate of 1 K / min) under N2 / H2 flow (80% N2, 20% H2) to decompose the Ru precursor and convert the metal to its metallic state. The Ru content was 7.4 wt%.

[0082] WO3-Ru / SiO2 Catalyst

[0083] The WO3-Ru / SiO2 catalyst was synthesized by combining tungsten oxide as a promoter on the Ru / SiO2 catalyst. 12 O 39The tungsten precursor solution was prepared by dissolving 1.1 g of tungsten salt in 10 mL of acid solution. The catalyst was synthesized as described above for Ru / SiO2. In this case, the pore volume was 0.71 cm 3 / g, using Ru / SiO2 catalyst as support material. Finally, the solid was dried at room temperature under dynamic vacuum (1.5 mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 623K for 3 hours (heating from room temperature at a rate of 1K / min) under N2 / H2 flow (80% N2, 20% H2) to decompose the Ru precursor and convert the metal into its metallic state. The contents of ruthenium and tungsten in the WO3-Ru / SiO2 catalyst were 8.2 wt% and 4.5 wt%, respectively.

[0084] Ru / PrO x -Al2O3 catalyst

[0085] Synthesis of Ru / PrO by incorporating praseodymium oxide as a promoter x -Al2O3 catalyst. First, praseodymium oxide was deposited on the γ-Al2O3 support material. A praseodymium solution was prepared by dissolving praseodymium (III) nitrate hexahydrate (Pr(NO3)3-6H2O, AlfaAesar, 99.99%) in deionized water. Specifically, 1.42 g of the metal precursor was added to 2 mL of deionized water. In addition, a γ-Al2O3 support was synthesized by calcining a pseudoboehmite precursor (DISPERAL HP-14, Sasol) in a muffle furnace at 823 K (heating at a rate of 2 K / min from room temperature) in an air atmosphere without forced convection for 5 hours. The Pr solution was bonded to the γ-Al2O3 support by incipient wetness impregnation. The γ-Al2O3 support was first dried in a glass flask at 423 K under dynamic vacuum (1.5 mbar) overnight. Next, a pore volume equivalent to the support pore volume (0.74 cm 3 / g) 90% of the volume of the praseodymium precursor solution was contacted with the dry support. After impregnation, the material was kept under dynamic vacuum (1.5 mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 823 K for 4 hours (heating from room temperature at a rate of 3 K / min) under a synthetic air flow (200 mL / min) to decompose the Pr precursor into supported oxides. The Pr content was 15.3 wt%, corresponding to 5.5 Pr atoms / nm 2 The specific surface area of ​​alumina.

[0086] Next, ruthenium was incorporated into PrO by impregnation x-Al2O3 carrier. In a 100 mL glass flask, 0.61 g of the carrier was added to 40 mL of deionized water and kept under vigorous magnetic stirring for 10 minutes. Next, 0.17 g of ruthenium (III) nitrosyl nitrate (N4O 10 Ru, AlfaAesar, Ru content ≥ 31.3%) as a metal precursor, suspended in an aqueous solution, and kept under vigorous stirring for 30 minutes. Then, the solvent was evaporated to dryness in a rotary evaporator under vacuum (200 mbar) at 333K, and the recovered solid was dried at 373K for 2 hours. Finally, the solid was dried at room temperature under dynamic vacuum (1.5 mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 623K (heating at a rate of 1K / min from room temperature) under a N2 / H2 flow (80% N2, 20% H2) for 3 hours to decompose the Ru precursor and convert the metal into its metallic state. The contents of Ru and Pr were 10.7 wt% and 14.1 wt%, respectively.

[0087] Ru / ZrO2-Al2O3 Catalyst

[0088] The Ru / ZrO2-Al2O3 catalyst was synthesized by incorporating zirconium oxide as a promoter. First, zirconium oxide was deposited on the γ-Al2O3 support material. The zirconium solution was prepared by dissolving zirconium (IV) isopropoxide complex (Zr(OCH(CH3)2)4-(CH3)2CHOH, SigmaAldrich, 99.9% trace metal basis) in isopropanol (Scharlab, EssentQ, ≥99.5%). Specifically, 1.07 g of metal precursor was added to 2 mL of isopropanol. In addition, the γ-Al2O3 support was synthesized by calcining a pseudoboehmite precursor (DISPERAL HP-14, Sasol) in a muffle furnace at 823 K (heating rate of 2 K / min from room temperature) for 5 hours in an air atmosphere without forced convection. As described above for PrO x As described in detail in the γ-Al2O3 material, the Zr precursor was incorporated into the γ-Al2O3 support to obtain the ZrO2-Al2O3 material. The Zr content was 13.7 wt%, corresponding to 5.7 Zr atoms / nm 2 Next, as described above for Ru / Al2O3, given the pore volume of 0.81 cm 3 / g, ruthenium was bound to the ZrO2-Al2O3 support by impregnation. Finally, the solid was dried at room temperature under dynamic vacuum (1.5 mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 623K (heating from room temperature at a rate of 1K / min) for 3 hours under N2 / H2 flow (80% N2, 20% H2) to decompose the Ru precursor and convert the metal into its metallic state. The contents of Ru and Zr were 9.6 wt% and 8.3 wt%, respectively.

[0089] RuRh / Al2O3 catalyst

[0090] By using ruthenium(III) nitrosyl nitrate (N4O 10 Ru, AlfaAesar, Ru content ≥ 31.3%) and rhodium nitrate (III) as a Rh precursor (N3O9Rh-xH2O, Sigma Aldrich, Rh content 36%) were dissolved in a 0.1M HNO3 deionized water solution to prepare a mixed ruthenium / rhodium precursor solution. Specifically, 0.94g of Ru metal precursor and 0.092g of Rh metal precursor were added to 2.0mL of acid solution to obtain a Ru:Rh molar ratio of 90:10. In addition, a γ-Al2O3 carrier was synthesized by calcining a pseudoboehmite precursor (DISPERAL 80, Sasol) at 823K (heating at a rate of 2K / min from room temperature) in a muffle furnace for 5 hours. The pore volume of the carrier material is 0.66cm 3 / g. The mixed metal precursor solution was combined by incipient wetness impregnation and thermally decomposed as detailed above for Ru / SiO2. The contents of Ru and Rh were 6.7 wt% and 0.6 wt%, respectively.

[0091] RuCo / Al2O3 Catalyst

[0092] By using ruthenium(III) nitrosyl nitrate (N4O 10 Ru, Alfa Aesar, Ru content ≥ 31.3%) and cobalt (II) nitrate hexahydrate (Co(NO3)2·6H2O, Sigma Aldrich, ACS reagent, 98%) as a Co precursor were dissolved in deionized water to prepare a mixed ruthenium / cobalt precursor solution. Specifically, 0.23 g of Ru metal precursor and 0.025 g of Co metal precursor were added to 40 mL of deionized water to obtain a Ru:Co molar ratio of 90:10. In addition, a γ-Al2O3 support was synthesized by calcining a pseudo-boehmite precursor (DISPERAL 80, Sasol) at 823 K (heating at a rate of 2 K / min from room temperature) in a muffle furnace for 5 h. Next, the Ru / PrO x-Al2O3, the metals were bound to the γ-Al2O3 support by impregnation as detailed in the . Finally, the solid was dried at room temperature under dynamic vacuum (1.5 mbar) for at least 3 hours, transferred to a fixed bed tubular quartz reactor axially mounted in an oven, and treated at 623 K (heating from room temperature at a rate of 1 K / min) for 3 hours under a N2 / H2 flow (80% N2, 20% H2) to decompose the Ru precursor and convert the metal to its metallic state. The contents of Ru and Co were 6.9 wt% and 0.4 wt%, respectively.

[0093] General method for testing catalysts according to the invention

[0094] In the general experimental method, the conversion process was carried out in a 316L stainless steel, magnetically stirred batch reactor (ILSHIN) with an internal volume of 28 mL. The temperature was read by a K-type thermocouple with a 316L stainless steel sheath inserted into the liquid reaction medium, while the pressure of the gas phase in the head space was read by a digital pressure sensor (Sensys). Before the reaction test, activated molecular sieves ( 3.2mm mesh, SigmaAldrich) all liquid reagents were dried for 12 hours and then stored in a N2 filled glove box (O2<1.0ppm, H2O<0.1ppm). Also under the exclusion of air, fine powder catalyst, nitrogen source reactant, solvent (when the solvent is different from the nitrogen source reactant) and PTFE coated magnetic stirring bar (length × diameter of 9mm × 20mm) were added to the PTFE lined container, the container was capped and placed in the autoclave body. Next, the autoclave was sealed and purged three times with a synthetic synthesis gas mixture containing a preset volume ratio of CO / H2 / Ar (Ar was used as an internal standard for headspace gas chromatography), and then filled with the same synthesis gas mixture until the preset total pressure at room temperature was P (bar). The reactor was placed in a custom aluminum block mounted on a stirring / heating plate (Heidolph), the stirring rate was set to 800rpm, and the temperature in the autoclave liner was raised to the preset reaction temperature at a heating rate of 3K / min. After the selected reaction time, the reactor was cooled to room temperature. The gas phase in the head space is injected into an Agilent 7890 gas chromatograph equipped with two analysis channels and using He as a carrier gas. The first analysis channel is equipped with a packed column HP-PLOT-Q (30m, inner diameter 0.32mm, film thickness 20.0μm) and a packed column molecular sieve HP-MOLSIEVE (30m, inner diameter 0.32mm, film thickness 12.0μm) and a TCD detector using argon as an internal standard to analyze permanent gas and carbon dioxide. The second analysis channel is equipped with a DB 1 capillary column (60m, inner diameter 0.32mm, film thickness 3μm) and a FID detector for analyzing hydrocarbons and nitrogen compounds. The liquid phase of the reaction product is reclaimed from the reactor, and solid catalyst particles are removed by filtration before analysis. Gas chromatography analysis was performed on a Shimadzu GC-2010Plus gas chromatograph equipped with a HP 5 capillary column (30 m, inner diameter 0.25 mm, film thickness 0.25 μm) and a FID detector using H2 as carrier gas and tetrahydrofuran (THF) as external standard. The reaction products were identified by mass spectrometry using a Shimadzu GCMS-QP2010Ultra instrument.

[0095] Embodiment 1

[0096] In the example according to the present invention, 152 mg of Ru / Al2O3 was used as a catalyst, 0.71 mL of dipropylamine (SigmaAldrich, 99%) was added as a nitrogen source reactant, and dissolved in 12 mL of 2,2,4-trimethylpentane (SigmaAldrich, 99%) as a solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0097] Example II

[0098] In the embodiment according to the present invention, 150 mg of Ru / Al2O3 was used as a catalyst, 0.60 mL of piperidine (Sigma Aldrich, 99%) was added as a nitrogen source reactant, and dissolved in 12 mL of 2,2,4-trimethylpentane (Sigma Aldrich, 99%) as a solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0099] Example III

[0100] In the example according to the present invention, 81 mg of Ru / Al2O3 was used as a catalyst, and 5 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was conducted according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0101] Example IV

[0102] In the example according to the present invention, 103 mg of Ru / Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0103] Example V

[0104] In the example according to the present invention, 151 mg of Ru / Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0105] Example VI

[0106] In the embodiment according to the present invention, 152 mg of Ru / SiO2 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction temperature was 473K and the reaction time was 24 h.

[0107] Example VII

[0108] In the example according to the present invention, 151 mg of WO3-Ru / SiO2 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0109] Example VIII

[0110] In the embodiment according to the present invention, 150 mg of Ru / PrO x -Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added into the reactor as a nitrogen source reactant and solvent. The experiment was conducted according to the above general catalytic test method. The reaction time was 24 h.

[0111] Example IX

[0112] In the example according to the present invention, 152 mg of Ru / ZrO2-Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was conducted according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0113] Example X

[0114] In the example according to the present invention, 152 mg of RuRh / Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was conducted according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0115] Example XI

[0116] In the example according to the present invention, 152 mg of RuCo / Al2O3 was used as a catalyst, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added to the reactor as a nitrogen source reactant and solvent. The experiment was carried out according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0117] Example XII

[0118] This is a comparative example not according to the present invention. In this comparative example, an organic metal ruthenium molecular catalyst is used instead of the solid ruthenium catalyst of the present invention. As described in document US4543411A, the catalyst is obtained by combining a Ru precursor and a quaternary ammonium salt as a ligand in a reaction medium. In the experiment, 25 mg of Ru3(CO)12 (SigmaAldrich, 99%) and 302 mg of tetrabutylphosphonium bromide (SigmaAldrich, 98%) were used as catalysts, 0.62 mL of diethylamine (SigmaAldrich, 99.5%) was added as a nitrogen source reactant, and 12 mL of N,N-dimethylformamide (SigmaAldrich, 99.8%) was added as a solvent. The experiment was performed according to the above-mentioned general catalytic test method. The reaction time was 24 h.

[0119] Table 1: Summary of product conversion, selectivity and yield of experimental examples according to the invention (Examples I-XI) and comparative examples not according to the invention (Example XII)

[0120]

[0121]

[0122] (a) reaction temperature; (b) reaction pressure measured at the reaction temperature; (c) molar ratio between CO in the syngas feed and the active metal of the catalyst; (d) CO conversion; (e) selectivity based on carbon moles; (f) non-nitrogenated hydrocarbons (alkanes, olefins, etc.); (g) based on the total mass of active metals (i.e., Ru and its combination with Co, Rh or Ir); (h) ASF distribution in the chain length range n = 5-21, by analyzing the alkyl chain length (C n ) determined chain growth probability parameters; (h) remaining products include other nitrogen-containing compounds, such as N,N-alkylamides; (i) not detected; (j) not applicable.

[0123] From the results given in Table 1, it can be inferred that the process of the present invention (Examples I-XI) achieves high alkylamine selectivity in a single conversion step. Alkylamine products with a chain growth probability parameter of alkyl groups of 0.80 to 0.90 are particularly suitable for the production of fatty amines. On the contrary, as shown in Comparative Example XII, although molecular ruthenium catalysts have been proven to be effective for the production of alkylamines from fatty olefins according to the method described in document US4543411A, in the process of the present invention, when synthesis gas is used as the only carbon source feed for the formation of alkyl groups, the catalyst is ineffective for the production of alkylamines, especially fatty alkylamines.

[0124] Although the present invention has been described according to preferred embodiments, it should be understood that this description should not be construed as limiting the invention described herein. After reading the specification, it will be apparent to those skilled in the art that various changes and modifications may be made thereto in accordance with the teachings of the present invention. The appended claims should be construed to include all changes and modifications that fall within the spirit and scope of the present invention.

Claims

1. A method for directly synthesizing alkylamines, comprising at least the following steps: i) Provide the reactor a. Synthesis gas feed, and b. a liquid feed, wherein the liquid feed comprises a nitrogen source reactant, wherein the nitrogen source reactant is selected from: a primary amine; an acyclic secondary amine; a cyclic secondary amine, wherein the cyclic secondary amine comprises a non-N-substituted compound such as piperidine, morpholine, pyrrolidine, pyrrole, imidazole; an N,N-dialkylformamide compound; an N,N-cycloalkylformamide compound; and any combination thereof; ii) reacting the feed provided in i) over a solid catalyst comprising at least one active metal selected from ruthenium, cobalt or any combination thereof, in unsupported form or dispersed on a support material at a reaction temperature of 373 degrees Kelvin to 523 degrees Kelvin and a total pressure of 1 bar to 300 bar; and iii) recovering the alkylamine compound from the reaction product of step ii).

2. The method according to claim 1, wherein the nitrogen source reactant is N,N-dialkylformamide.

3. The method according to claim 2, wherein the nitrogen source reactant is N,N-dimethylformamide.

4. The method according to any one of the preceding claims, wherein step b further comprises a solvent selected from aliphatic hydrocarbons, aromatic hydrocarbons, oxygen-containing compounds, water, nitrogen compounds, halogenated organic compounds, liquid organic salts and any combination thereof.

5. The process according to any one of the preceding claims, wherein the solid catalyst further comprises rhodium, iridium or any combination thereof as active metal.

6. The process according to any one of the preceding claims, wherein the solid catalyst is a supported catalyst, wherein the active metal is dispersed on a support material selected from SiO2, Al2O3, TiO2, carbon or any combination thereof.

7. The method according to claim 6, wherein the weight fraction of the active metal corresponding to the total catalyst is 0.5 wt% to 50 wt%.

8. The method according to any one of the preceding claims, wherein the solid catalyst further comprises an oxide selected from the stable oxides of elements of Groups 3, 4, 5, 6, 7, 12, 13, 14, 15 of the Periodic Table and lanthanides and any combination thereof.

9. The process according to any one of the preceding claims, wherein the reaction is carried out in a stirred batch-type reactor.

10. The process according to any one of claims 1 to 8, wherein the reaction is carried out in a continuous type reactor into which both a gas stream and a liquid stream are fed.

11. The method according to any one of the preceding claims, wherein the reaction temperature is from 393K to 453K.

12. The process according to any one of the preceding claims, wherein the reaction pressure is from 10 bar to 300 bar.

13. A process according to any one of the preceding claims, wherein the molar ratio of H2 to CO in the synthesis gas feed is from 0.1 to 10.

14. A process according to any one of the preceding claims, wherein the alkylamine product is a tertiary fatty amine of formula RN-(B1, B2), wherein the substituent R is a normal alkyl group having 7 to 30 carbon atoms, and wherein the substituents B1 and B2 are selected from methyl, ethyl, propyl or isopropyl. The method according to claim 14 , wherein the substituents B1 and B2 are methyl groups.

16. The method according to any one of claims 1 to 13, wherein the alkylamine product is a tertiary fatty amine of the formula RN-(B1, B2), wherein the substituent R is a normal alkyl group having 7 to 30 carbon atoms, and wherein the substituents B1 and B2 are both ends of a ring having four carbon atoms or a ring having five carbon atoms.

17. The method according to any one of claims 1 to 16, wherein the synthesis gas feed further comprises other compounds, such as nitrogen, helium, argon, water, C1 to C4 alkanes or combinations thereof.

18. The process according to any one of the preceding claims, wherein after recovering the alkylamine from the reaction product, a stream containing unconverted reagents, solvent, unrecovered reaction product, or a combination thereof, is recycled to the reactor.

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