Organic N-P polymer and preparation method thereof, heterogeneous catalyst and application thereof

Abstract

The invention provides an organic N-P polymer, a preparation method of the organic N-P polymer, a heterogeneous catalyst and application of the heterogeneous catalyst. The organic N-P polymer can form coordination with rhodium, a resin solid heterogeneous catalyst with monatomic catalysis is obtained, the catalytic activity of homogeneous catalysis is reserved, the heterogeneous catalyst is used for olefin hydroformylation reaction, simple solid-liquid separation of the catalyst after the reaction can be realized, the loss of the catalyst is reduced, and the yield of olefin hydroformylation reaction is improved. The problems that a homogeneous catalyst is high in separation cost and high in precious metal rhodium loss are effectively solved, high selectivity and conversion rate are achieved, and the problems that other heterogeneous catalysts adopted in the existing preparation process are low in conversion rate and poor in selectivity are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to an organic NP polymer and a preparation method thereof, a heterogeneous catalyst and application thereof. Background Art

[0002] Olefin hydroformylation is a homogeneous catalytic reaction that is crucial in industrial production. It has always been limited by problems such as catalyst separation and recovery difficulties. For olefin hydroformylation, multiphase catalysts are easy to separate, but have relatively low activity and poor regioselectivity. The original separation difficulty of homogeneous catalysts will cause the loss of active precious metals and expensive phosphine ligands, hindering their large-scale industrial application. Based on this, single-atom catalysts (abbreviated as: SACs) have the advantages of high atom utilization, stable active sites, easy separation and recovery, etc. They play a bridging role between homogeneous catalysts and heterogeneous catalysts and are expected to be widely used in the field of hydroformylation. Summary of the invention

[0003] In view of this, the object of the present invention is to provide an organic NP polymer and a preparation method thereof, a heterogeneous catalyst and its application. The catalyst has the advantages of high atomic utilization, stable active sites, easy separation and recovery, etc.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides an organic NP polymer as shown in Formula I:

[0006] Formula I;

[0007] The value of n is any integer between 1 and 500.

[0008] In a second aspect, the present invention provides a method for preparing the above-mentioned organic NP polymer, comprising the following steps:

[0009] Under an inert atmosphere, melamine formaldehyde condensate is reacted with diphenylphosphine chloride in the presence of a solvent and an alkaline substance to obtain an organic NP polymer.

[0010] Preferably, the molar ratio of diphenylphosphine chloride to melamine formaldehyde condensate is (3-5):1.

[0011] Preferably, the reaction temperature is room temperature and the reaction time is 8 to 20 h.

[0012] Preferably, the solvent is selected from toluene and / or xylene.

[0013] Preferably, the alkaline substance is an organic base, and the organic base is selected from triethylamine and / or diphenylamine.

[0014] Preferably, after the reaction is completed, a purification step of filtration and recrystallization is further included.

[0015] Preferably, the recrystallization comprises a first recrystallization and an optional second recrystallization.

[0016] Preferably, the solvent for the first recrystallization is selected from alkanes.

[0017] Preferably, the solvent for the second recrystallization is selected from acetonitrile.

[0018] Preferably, the recrystallization temperature is 2-8°C.

[0019] In a second aspect, the present invention provides a heterogeneous catalyst, comprising a carrier and metal rhodium loaded on the carrier; the molar ratio of the carrier to the metal rhodium is (1~20):1.

[0020] The carrier is the organic NP polymer involved in the above technical solution.

[0021] In a third aspect, the present invention provides a use of the above heterogeneous catalyst in the synthesis of aldehydes by hydroformylation.

[0022] In a fourth aspect, the present invention provides a method for producing normal aldehydes by hydroformylation, comprising the following steps:

[0023] Under the conditions of hydrogen and carbon monoxide, the organic NP polymer, rhodium salt and terminal olefin are reacted to obtain normal aldehyde;

[0024] The organic NP polymer is the organic NP polymer involved in the above technical solution.

[0025] Preferably, the terminal olefin is selected from 1-octene.

[0026] Preferably, the rhodium salt is selected from any one or more of rhodium trichloride, tetrarhodium dodecacarbonyl or rhodium dicarbonyl acetylacetonate.

[0027] Preferably, the reaction temperature is 70-130° C. and the reaction time is 3-8 h.

[0028] Preferably, the reaction pressure is 1-5 MPa.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention provides an organic NP polymer synthesized from melamine formaldehyde condensate and diphenylphosphonium chloride. The NP polymer belongs to a ligand containing N and P and having a resin polycondensation structure, can form coordination with rhodium, and obtain a resin solid heterogeneous catalyst with single-atom catalysis, retains the catalytic activity of homogeneous catalysis, and is used in olefin hydroformylation reaction. The heterogeneous catalyst can realize simple solid-liquid separation of the catalyst after the reaction, reduces the loss of the catalyst, and effectively solves the problems of high separation cost of homogeneous catalysts and large loss of precious metal rhodium, and has high selectivity and conversion rate, and solves the problems of low conversion rate and poor selectivity in other heterogeneous catalysts used in the existing preparation process.

[0031] After testing, using the heterogeneous catalyst and the method for hydroformylation of 1-octene provided by the present invention, after 60 hours of continuous cycle evaluation, the catalytic activity of the heterogeneous catalyst for 1-octene did not decrease, and the conversion rate of 1-octene was still maintained at 95.2% after 60 hours, and the selectivity of n-nonanal was 98.1%.

[0032] Affected by the electronic and steric effects of nitrogen-phosphine ligands, the catalytic activity and regioselectivity of SACs are improved. The synergistic effect of single-atom Rh and the synchronous coordination of ligands enable highly dispersed Rh to form multiple coordination bonds with P atoms in phosphine ligands. Rh SACs have superb activity and stability, and the TOF value for various long-chain olefins reaches 300~500 h -1 The continuous catalytic time for 1-octene is up to 400 h. Affected by the steric hindrance of the phosphine ligand, the aldehyde selectivity is about 90% (l / b≈90:10). DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0035] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials of conventional purity used in the field of producing n-nonanal by hydroformylation.

[0036] All noun expressions, abbreviations and trademarks in the present invention are conventional noun expressions, abbreviations and trademarks in the field. Each noun expression, abbreviation and trademark is clear and unambiguous in its relevant application field, and those skilled in the art can clearly, accurately and uniquely understand it based on the noun expressions, abbreviations and trademarks.

[0037] In view of the problems of difficulty in separation and loss of active precious metals in homogeneous catalysts in olefin hydroformylation reactions in the prior art, the present invention provides an organic NP polymer as shown in Formula I:

[0038] Formula I;

[0039] The value of n is any integer between 1 and 500, such as 1, 10, 50, 100, 200, 300, 400 or 500.

[0040] In the present invention, the organic NP polymer is a porous phosphine polymer containing N, P ligands with a resin polycondensation structure, which can form coordination with rhodium to obtain a resin solid heterogeneous catalyst with single-atom catalysis.

[0041] The present invention also provides a method for preparing the above-mentioned organic NP polymer, comprising the following steps:

[0042] Under an inert atmosphere, melamine formaldehyde condensate is reacted with diphenylphosphine chloride in the presence of a solvent and an alkaline substance to obtain an organic NP polymer.

[0043] The present invention has no particular limitation on the inert atmosphere, and the inert atmosphere may be any atmosphere well known to those skilled in the art, such as nitrogen.

[0044] In the present invention, the molar ratio of diphenylphosphonium chloride to melamine formaldehyde condensate is (3-5):1, preferably (3-4.5):1.

[0045] In the present invention, the solvent is used to provide a liquid environment, and can be specifically selected from toluene and xylene; the alkaline substance is used to remove hydrogen chloride generated after the reaction of diphenylphosphonium chloride and melamine formaldehyde condensate, thereby promoting the reaction. In the present invention, the alkaline substance is preferably an organic base, and the organic base is selected from triethylamine and / or diphenylamine, and more preferably triethylamine.

[0046] It should be noted that the reaction between the melamine formaldehyde condensate and diphenylphosphonium chloride is an exothermic reaction. Therefore, in the present invention, diphenylphosphonium chloride is preferably slowly added to the solution of the melamine formaldehyde condensate at a temperature below 0°C. The addition time is preferably 50 to 70 min, more preferably 55 to 60 min. After the addition is completed, the reaction is carried out at room temperature. After the reaction is completed, the solvent is evaporated to obtain an organic NP polymer.

[0047] In some specific embodiments of the present invention, the method for preparing the organic NP polymer comprises the following steps:

[0048] Weigh the melamine formaldehyde condensate and the solvent in a three-necked flask, add an alkaline substance, pass nitrogen, cool the prepared solution to below 0°C, and slowly drop diphenylphosphonium chloride. After the addition of diphenylphosphonium chloride is completed, return to room temperature and react for 8 to 20 hours, preferably 12 to 15 hours; after the reaction is completed, evaporate the solvent to obtain an organic NP polymer.

[0049] The room temperature is 10 to 30°C, preferably 15 to 25°C.

[0050] In some preferred embodiments of the present invention, after the reaction is completed, further purification steps of filtration and recrystallization are included. The recrystallization includes a first recrystallization and an optional second recrystallization; the solvent of the first recrystallization is selected from alkanes, preferably cyclohexane; the solvent of the second recrystallization is selected from acetonitrile, or a solvent with a polarity similar to acetonitrile, such as tetrahydrofuran; the temperature of the recrystallization is 2-8°C, preferably 3-5°C.

[0051] In some preferred embodiments of the present invention, the purification step is specifically:

[0052] (1) filtering the obtained reaction solution to remove impurities, mixing the filtrate with n-hexane, recrystallizing the mixture at 2-8° C., filtering, and obtaining a filtrate;

[0053] (2) The filtrate is rotary evaporated, the concentrate is recrystallized using acetonitrile, filtered, and the filtrate is concentrated to obtain a purified organic NP polymer.

[0054] The present invention provides a method for preparing the above-mentioned organic NP polymer (also called: organic phosphine polymer), wherein melamine formaldehyde condensate is used as a synthetic monomer to prepare a high-melting-point organic phosphine polymer ligand, which is a ligand containing N and P and having a resin condensation structure. It forms a coordination with metal rhodium to form a resin solid catalyst with single-atom catalysis, which not only retains the catalytic activity of homogeneous catalysis, but also can achieve simple solid-liquid separation of the catalyst after the reaction, thereby reducing the loss of the catalyst.

[0055] In addition, the preparation method has simple steps, is easy to implement, and is conducive to large-scale production.

[0056] The present invention is to complete and refine the overall technical solution, better ensure the composition and structure of the catalyst, and further improve the catalytic effect of the catalyst in the process of producing aldehydes by hydroformylation. The present invention also provides a heterogeneous catalyst, including a carrier and a metal rhodium loaded on the carrier. Among them, the carrier is the organic NP polymer involved in the above technical solution, which exists in a solid form in the solution, and the metal rhodium is combined with the organic NP polymer through a coordination bond. Therefore, the heterogeneous catalyst belongs to a coordination complex catalyst.

[0057] In the present invention, the heterogeneous catalyst is preferably present in a solid form in the solution of the reaction system for hydroformylation to synthesize aldehyde.

[0058] In the present invention, the molar ratio of the metal rhodium to the carrier is 1:(1-25), more preferably 1:(10-20).

[0059] The present invention also provides an application of the heterogeneous catalyst in synthesizing aldehydes by hydroformylation.

[0060] Specifically, the present invention also provides a method for producing normal aldehydes by hydroformylation, comprising the following steps:

[0061] Under the conditions of hydrogen and carbon monoxide, the organic NP polymer, rhodium salt and terminal olefin involved in the above technical solution are reacted to obtain normal aldehyde.

[0062] In the present invention, the pressure of the hydrogen and carbon monoxide is 1 to 5 MPa, preferably 1.5 to 4.5 MPa, more preferably 2 to 4 MPa, and further preferably 2.5 to 3.5 MPa.

[0063] In the present invention, the terminal olefin is an α-olefin, preferably 1-octene.

[0064] In the present invention, the rhodium salt is selected from any one or more of rhodium trichloride, tetrarhodium dodecacarbonyl or rhodium dicarbonyl acetylacetonate.

[0065] In the present invention, the reaction temperature is 70-130°C, preferably 80-120°C, and more preferably 90-110°C.

[0066] In the present invention, the reaction time is 3 to 8 h, preferably 4 to 7 h, and more preferably 5 to 6 h.

[0067] Illustratively, in some embodiments of the present invention, the method for producing n-nonanal by hydroformylation comprises the following steps:

[0068] Add metal rhodium catalyst and organic NP polymer into a high-temperature and high-pressure reactor, fill it with synthesis gas at a certain pressure, replace it 3 to 5 times, inject a certain amount of 1-octene through a pressure tank, fill it with synthesis gas, maintain the pressure required for the reaction, and heat the reaction to obtain n-nonanal.

[0069] The invention uses 1-octene as a raw material and a complex heterogeneous catalyst of organic NP polymer coordinated rhodium as a catalyst to carry out a hydroformylation reaction, has high reaction activity, can obtain high conversion rate and activity, and realizes the cyclic evaluation of the catalyst.

[0070] After testing, using the heterogeneous catalyst and the method for hydroformylation of 1-octene provided by the present invention, after 60 hours of continuous cycle evaluation, the catalytic activity of the solid catalyst for 1-octene did not decrease, and the conversion rate of 1-octene was still maintained at 95.2% after 60 hours, and the selectivity of n-nonanal was 98.1%.

[0071] It can be seen that the organic NP polymer provided by the present invention forms a complex with rhodium, which has the advantages of high atomic utilization, stable active sites, easy separation and recovery, etc. At the same time, the separation process reduces the generation of heavy components and increases the stability of rhodium during continuous use.

[0072] In summary, the solid-phase complex catalyst designed by the present invention has a specific structure and composition, uses an organic NP polymer with a resin condensation structure containing N and P as a carrier, and forms a coordination with metal rhodium, can achieve a similar effect to single-atom catalysis, and is used in olefin hydroformylation reaction. The catalyst can achieve simple solid-liquid separation of the catalyst after the reaction, reduce the loss of the catalyst, and effectively solve the problems of high separation cost of homogeneous catalysts and large loss of precious metal rhodium. It also has high selectivity and conversion rate, and solves the problems of low conversion rate and poor selectivity in other heterogeneous catalysts used in the existing preparation process.

[0073] In order to further illustrate the present invention, the following examples are provided for detailed description. The experimental raw materials used in the following examples of the present invention are all common commercially available products.

[0074] Among them, 1-octene conversion rate = 1-octene peak area ratio; aldehyde selectivity = 1-octane peak area ratio.

[0075] Example 1

[0076] S1: Weigh 100 g of melamine formaldehyde polymer (molecular weight 156) and 20 mL of toluene into a 500 mL three-necked flask, and add 51 g of triethylamine, the molar ratio of diphenylphosphine chloride to triethylamine is 1:2, the solution is cooled below 0°C under a nitrogen atmosphere, and 56 g of diphenylphosphine chloride is slowly added dropwise. After the addition of diphenylphosphine chloride is completed, return to room temperature and react for 12 h; after the reaction is completed, distill off the toluene to obtain an organic NP polymer (molecular weight 800).

[0077] S2: 3 g of organic NP polymer, 50 mg of dicarbonyl acetylacetonate rhodium (the molar ratio of the organic NP polymer to the rhodium in dicarbonyl acetylacetonate rhodium is 21:1), and 20 g of 1-octene are added into a 100 mL reactor, and the air in the reactor is replaced by synthesis gas (a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of 1:1). The temperature of the reactor is set at 100°C, and after the temperature of the reaction system is stable, CO / H2 (volume ratio of 1:1) is introduced until the pressure reaches 3 MPa, and the reaction is carried out for 3 h: after the reaction is completed, the temperature is cooled to room temperature, the catalyst is filtered out, and the obtained sample is analyzed by gas chromatography. The conversion rate of 1-octene is 93.5%, and the selectivity of n-nonanal is 95.6%.

[0078] Example 2

[0079] S1: Weigh 120 g of melamine formaldehyde polymer (molecular weight 156) and 20 mL of toluene into a 500 mL three-necked flask, and add 61.2 g of triethylamine, the molar ratio of diphenylphosphine chloride to triethylamine is 1:2, the solution is cooled below 0°C under a nitrogen atmosphere, and 67.2 g of diphenylphosphine chloride is slowly added dropwise. After the addition of diphenylphosphine chloride is completed, the room temperature is restored and the reaction is carried out for 12 hours; after the reaction is completed, the toluene is evaporated to obtain an organic NP polymer (molecular weight 1600).

[0080] S2: 3 g of organic NP polymer, 50 mg of dicarbonyl acetylacetonate rhodium (the molar ratio of the organic NP polymer to the rhodium in dicarbonyl acetylacetonate rhodium is 10.5:1), and 20 g of 1-octene are added into a 100 mL reactor, and the air in the reactor is replaced by synthesis gas (a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of 1:1). The temperature of the reactor is set at 110°C, and after the temperature of the reaction system is stable, CO / H2 (volume ratio of 1:1) is introduced until the pressure reaches 3 MPa, and the reaction is carried out for 3 h: after the reaction is completed, the temperature is cooled to room temperature, the catalyst is filtered out, and the obtained sample is analyzed by gas chromatography. The conversion rate of 1-octene is 97.4%, and the selectivity of n-nonanal is 92.5%.

[0081] Example 3

[0082] S1: Weigh 100 g of melamine formaldehyde polymer (molecular weight 156) and 20 mL of toluene into a 500 mL three-necked flask, and add 86 g of diphenylamine, the molar ratio of diphenylphosphine chloride to diphenylamine is 1:2, and the solution is cooled below 0°C under a nitrogen atmosphere, and 56 g of diphenylphosphine chloride is slowly added dropwise. After the addition of diphenylphosphine chloride is completed, return to room temperature and react for 12 hours; after the reaction is completed, distill off the toluene to obtain an organic NP polymer (molecular weight 800).

[0083] S2: 3 g of organic NP polymer, 50 mg of dicarbonyl acetylacetonate rhodium (the molar ratio of the organic NP polymer to the rhodium in dicarbonyl acetylacetonate rhodium is 21:1), and 20 g of 1-octene are added into a 100 mL reactor, and the air in the reactor is replaced by synthesis gas (a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of 1:1). The temperature of the reactor is set at 100°C, and after the temperature of the reaction system is stable, CO / H2 (volume ratio of 1:1) is introduced until the pressure reaches 3 MPa, and the reaction is carried out for 4 h: after the reaction is completed, the temperature is cooled to room temperature, the catalyst is filtered out, and the obtained sample is analyzed by gas chromatography. The conversion rate of 1-octene is 95.5%, and the selectivity of n-nonanal is 96.7%.

[0084] Example 4

[0085] With reference to Example 1, the reaction temperature and pressure of the above step S2 were adjusted according to Table 1 below, and parallel experiments were conducted, wherein the 1-octene conversion rate and the aldehyde selectivity are shown in Table 1 below.

[0086] Table 1

[0087]

[0088] Catalyst cycle evaluation experiment

[0089] 3 g of the organic NP polymer obtained in Example 1, 50 mg of dicarbonyl acetylacetonate rhodium, and 20 g of 1-octene were added to a 100 mL reactor, and the synthesis gas (a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen and carbon monoxide of 1:1) replaced the air in the reactor. The reactor temperature was set at 90°C. After the temperature of the reaction system was stabilized, CO / H2 (volume ratio of 1:1) was introduced until the pressure reached 3 MPa. At the same time, the raw materials were continuously pumped into the reactor at a rate of 32 g / h by a pump, and CO / H2 synthesis gas was continuously introduced into the reactor at a rate of 10 L / h for continuous reaction. At the same time, the reaction mixture was taken out through a filter equipped with a mesh to maintain the volume in the reactor at 50 mL. Samples were taken every hour for chromatographic analysis.

[0090] Meanwhile, referring to Example 1, the reaction temperature and pressure of the above step S2 were adjusted according to Table 2 below, and a parallel experiment was conducted, and the test was performed according to the above experiment. The results are shown in Table 2 below:

[0091] Table 2

[0092]

[0093] It can be seen from the data in Table 2 that after 60 h of continuous cycle evaluation, the catalytic activity of the solid catalyst for 1-octene did not decrease. After 60 h, the conversion of 1-octene was still maintained at 95.2%, and the selectivity of n-nonanal was 98.1%.

[0094] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic NP polymer as shown in Formula I: Formula I; in, The value of n is any integer between 1 and 500.

2. A method for preparing an organic NP polymer as claimed in claim 1, characterized in that: The following steps are involved: Under an inert atmosphere, melamine formaldehyde condensate is reacted with diphenylphosphine chloride in the presence of a solvent and an alkaline substance to obtain an organic NP polymer.

3. The preparation method according to claim 2, characterized in that: The molar ratio of diphenylphosphonium chloride to melamine formaldehyde condensate is (3-5):1; The reaction temperature is room temperature and the reaction time is 8 to 20 h; The solvent is selected from toluene and / or xylene; The alkaline substance is an organic base, and the organic base is selected from triethylamine and / or diphenylamine.

4. The preparation method according to claim 2 or 3, characterized in that: After the reaction is completed, the purification steps of filtration and recrystallization are also included.

5. The preparation method according to claim 4, characterized in that: The recrystallization comprises a first recrystallization and an optional second recrystallization; The solvent of the first recrystallization is selected from alkanes; The solvent of the second recrystallization is selected from acetonitrile; The recrystallization temperature is 2-8°C.

6. A heterogeneous catalyst, characterized in that It comprises a carrier and metal rhodium loaded on the carrier; the molar ratio of the carrier to the metal rhodium is (1-25):1; The carrier is the organic NP polymer as shown in claim 1 or the organic NP polymer prepared by the preparation method according to any one of claims 2 to 5.

7. Use of the heterogeneous catalyst according to claim 6 in the synthesis of aldehydes by hydroformylation.

8. A method for producing normal aldehydes by hydroformylation, characterized in that: The following steps are involved: Under the conditions of hydrogen and carbon monoxide, the organic NP polymer, rhodium salt and terminal olefin are reacted to obtain normal aldehyde; The organic NP polymer is the organic NP polymer as claimed in claim 1 or the organic NP polymer prepared by the preparation method according to any one of claims 2 to 5.

9. The method according to claim 8, characterized in that The terminal olefin is selected from 1-octene; The rhodium salt is selected from any one or more of rhodium trichloride, tetrarhodium dodecacarbonyl or rhodium dicarbonyl acetylacetonate.

10. The method according to claim 8 or 9, characterized in that: The reaction temperature is 70-130°C and the reaction time is 3-8 h; The reaction pressure is 1-5 MPa.

Images