C4 olefin hydroformylation method

Abstract

The invention discloses a method for hydroformylation of C4 olefin. The method comprises the steps that C4 olefin, a rhodium catalyst, ionic liquid and a solvent are mixed to obtain a liquid phase solution, the liquid phase solution makes contact with CO and H2 mixed gas to react to synthesize aldehyde, and the ionic liquid is carbon negative ion phosphonium salt. The method provided by the invention not only can ensure a relatively high conversion rate, but also can improve the selectivity of normal aldehyde.

Description

Technical Field

[0001] This invention belongs to the field of organic compound preparation methods, specifically relating to a method for hydroformylation of C4 olefins. Background Technology

[0002] The hydroformylation of olefins to prepare aldehydes, especially n-aldehydes, has high practical value. As an intermediate in organic synthesis, aldehydes are widely used in fragrances, surfactants, plasticizers, and mineral processing agents. C4 olefin hydroformylation technology plays an important role in the conversion of chemical raw materials and the production of high-value-added chemicals. Its research and industrial applications are constantly making new progress, which is of great significance for promoting the sustainable development of the chemical industry.

[0003] CN102260147B uses ionic liquids as solvents for the hydroformylation of low-carbon olefins, which greatly improves the reaction activity, but the product's N / I ratio is only about 3. CN101348423B uses a composite catalyst system composed of water-soluble phosphine ligands, rhodium complexes, and cationic dual-long-chain cationic surfactants in a water / organic two-phase catalyst system for the hydroformylation of butenes, solving the catalyst separation problem. However, a high CO partial pressure is still required to ensure CO dissolution in order to achieve a high conversion rate, and the N / I ratio is also not high. Therefore, to solve the above problems, there is an urgent need to develop a new method for the hydroformylation of C4 olefins. Summary of the Invention

[0004] One objective of this invention is to overcome the shortcomings of existing olefin hydroformylation reaction technologies and provide a new method for the hydroformylation of C4 olefins, which reduces the partial pressure of CO in the reaction, increases the positive-to-iso ratio of the product aldehyde, and enhances catalytic activity.

[0005] This invention provides a method for the hydroformylation of C4 olefins, the method comprising mixing a C4 olefin, a rhodium catalyst, an ionic liquid, and a solvent to obtain a liquid phase solution, wherein the liquid phase solution is contacted with a mixture of CO and H2 gas to react and synthesize an aldehyde, wherein the ionic liquid is a carbanion phosphonium salt.

[0006] Further, the C4 olefin is one or more of butene-1, butene-2, isobutene, and 2,5-dihydrofuran.

[0007] Furthermore, the solvent is at least one selected from toluene, ethylbenzene, xylene, and n-decane.

[0008] Furthermore, the rhodium catalyst is one or more of rhodium chloride, rhodium acetate, rhodium dicarbonylacetylacetone, and rhodium triphenylphosphine carbonylacetylacetone.

[0009] Further, in the carbanion phosphonium salt, the cation is selected from at least one of dibutyldiphenylphosphonium ion, tetrabutylphosphonium ion, dioctyloxophosphonium ion, tetraphenylphosphonium ion, and triphenylbutylphosphonium ion; and the anion is selected from 2,4-pentanedione ion. 5,5-Dimethylcyclohexanedione ion 1,3-Indanedione ion Diphenylformylmethane ion At least one of them.

[0010] Furthermore, the reaction is carried out in a microreactor, which includes a liquid inlet, a gas inlet, and a product outlet. The interior of the microreactor consists of microchannels, which are circular pores with a diameter of 0.5–2 mm.

[0011] Furthermore, the mixed gas and liquid solution enter the microchannel in a T-shape for mixing.

[0012] Furthermore, the microreactor is made of one of the following materials: iron, copper, stainless steel, titanium alloy, glass, or polytetrafluoroethylene.

[0013] Furthermore, the reaction includes a liquid solution entering the microreactor through a liquid inlet, which is mixed with a CO and H2 mixture entering the microreactor through a gas inlet, flows through a microchannel and reacts, and the resulting aldehyde product flows out of the microreactor through a product outlet.

[0014] Furthermore, the partial pressure ratio of H2 to CO is 4 to 9:1.

[0015] Further, in the liquid solution, the molar concentration of C4 olefin is 0.08–0.35 mol / L, preferably 0.12–0.27 mol / L; the concentration of rhodium catalyst, calculated as rhodium element, is 0.1–1.0 mmol / L, preferably 0.3–0.6 mmol / L; and the molar ratio of rhodium catalyst, calculated as rhodium element, to ionic liquid is 1:10–300, preferably 1:100–300.

[0016] Furthermore, the reaction temperature is 60–130°C, and the reaction pressure is 0.5–3.0 MPa, for example, but not limited to 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, and any value within the range formed by any two of these values.

[0017] Furthermore, the gas-liquid volumetric flow rate ratio is 150–500:1. The gas-liquid volumetric flow rate ratio refers to the ratio of the standard flow rate of the CO and H2 mixture to the volumetric flow rate of the liquid solution.

[0018] Furthermore, the reaction time is 10–200 s.

[0019] Traditional olefin hydroformylation mechanisms suggest that excessively high CO partial pressures reduce the coordination number of phosphine ligands on the catalyst Rh, thereby decreasing the formation of active species, lowering catalytic activity, reducing steric hindrance, and increasing the formation of branched aldehyde products (decreasing the N / I ratio). Conversely, excessively low CO partial pressures reduce the rate of carbonyl insertion reactions in olefins. The ionic liquid of this invention significantly reduces the amount of CO required in the gas phase of the reaction, enabling faster hydroformylation at lower CO partial pressures and improving CO utilization.

[0020] H2 and CO have strong interactions with the cations and anions in conventional ionic liquids, thus enabling them to be physically adsorbed. However, unlike conventional ionic liquids, the ionic liquid used in this invention contains carbanions that can chemically bind to CO. Taking 2,4-pentanedione ions as an example, the reaction formula is shown in formula (1), which greatly increases the solubility of CO in the liquid phase, which is dozens of times that of traditional physical adsorption. The cation contains P, which can complex with the rhodium catalyst. In this way, CO can indirectly coordinate with Rh through the ionic liquid without occupying the coordination number of Rh. This increases the coordination number of phosphine ligands (increasing steric hindrance and improving the positive-to-anisotropic ratio) and ensures the coordination of CO (which determines the reaction rate of subsequent olefin carbonylation).

[0021]

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention is the first to propose using carbanion phosphonium salts as auxiliaries for hydroformylation. This increases the number of active species without reducing CO coordination, resolving the trade-off between these two factors. This increases both activity and the N / A ratio. Simultaneously, the ionic liquid of this invention, acting as a phosphine ligand, possesses suitable steric hindrance, reducing the formation of branched aldehyde products and further improving the N / A ratio.

[0024] 2. The ionic liquid used in this invention can chemically adsorb CO, and its adsorption capacity is dozens of times that of conventional ionic liquids. It can carry out hydroformylation reaction at a lower CO partial pressure, thereby improving CO utilization and saving energy consumption in CO recycling.

[0025] 3. This invention employs a microchannel reactor, which ① enhances gas-liquid mass transfer and accelerates the carbonylation and hydrogenation processes; ② enhances reaction heat transfer, reducing the loss of ionic liquids due to local high-temperature decomposition; ③ shortens the reaction time, reduces side reactions from excessive hydrogenation, and improves the selectivity of aldehydes.

[0026] 4. The C4 olefin hydroformylation method of this invention can significantly improve catalytic activity while maintaining a high aldehyde-to-isocarbon ratio, achieving a TOF of 30,000 h⁻¹. -1 above. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the microreactor structure used in this invention;

[0028] Explanation of key figure labels:

[0029] 1-Liquid inlet, 2-Gas inlet, 3-Product outlet. Detailed Implementation

[0030] The following examples further illustrate the function and effect of the present invention, but the following examples do not constitute a limitation on the method of the present invention.

[0031] The method of the present invention, such as Figure 1 As shown, the process includes: C4 olefin, rhodium catalyst and ionic liquid dissolved in solvent to obtain liquid phase solution, liquid phase solution enters liquid inlet 1 of microreactor, mixed with CO and H2 gas mixture in gas inlet 2, reacts, synthesizes aldehyde product, aldehyde flows out through product outlet 3.

[0032] The microreactor used in this invention is as follows: Figure 1 As shown, the interior of the microreactor is a micro-channel, which is a circular channel with a diameter of 1 mm, and the gas and liquid phases are in T-type contact.

[0033] In the method of this invention, the conversion rate of C4 olefins and the selectivity and normal-to-isorionic ratio of the aldehyde product are determined by gas chromatography, and their definitions are as follows:

[0034] C4 olefin conversion (%) = (moles of reacted C4 olefins / moles of feed C4 olefins) × 100%;

[0035] Aldehyde selectivity (%) = number of moles of aldehydes produced / number of moles of C4 olefins reacted × 100%;

[0036] Catalyst conversion frequency TOF(h) -1 = (Number of moles of reacted C4 olefins) / (Number of moles of rhodium × Reaction time);

[0037] The ratio of normal to isoform aldehydes produced = number of moles of normal aldehydes produced / number of moles of isoform aldehydes produced.

[0038] In this invention, the ionic liquid is prepared according to the method described in the literature (Angew. Chem. Int. Ed., 2017, 56, 6843-6847).

[0039] Example 1

[0040] Butene-1, rhodium dicarbonylacetylacetonate, and the ionic liquid 2,4-pentanedione triphenylbutylphosphonium salt were dissolved in toluene to form a liquid solution. This liquid solution entered the liquid inlet of a microreactor and reacted with a mixture of CO and H2 from the gas inlet to synthesize an aldehyde. In the liquid solution, the concentration of butene-1 was 0.18 mol / L, the concentration of rhodium dicarbonylacetylacetonate (based on rhodium elemental concentration) was 0.3 mmol / L, the molar ratio of rhodium dicarbonylacetylacetonate to the ionic liquid was 1:200, the partial pressure ratio of H2 to CO in the mixed gas was 5:1, the reaction pressure was 0.8 MPa, the reaction temperature was 100 °C, the gas-liquid volumetric flow rate ratio was 200:1, and the reaction time was 60 s.

[0041] In this example, the C4 olefin conversion rate was 97.2%, the aldehyde selectivity was 98.6%, and the TOF was 34992 h. -1 The product has an aldehyde-to-isotropic ratio of 25.8.

[0042] Examples 2-4

[0043] Compared with Example 1, Examples 2-4 differ in the molar ratio of rhodium catalyst and ionic liquid. The final C4 olefin conversion and the ratio of aldehyde to isocyanate are shown in Table 1.

[0044] Table 1. C4 olefin conversion and aldehyde-to-isorhodium ratio at different molar ratios of rhodium catalysts and ionic liquids.

[0045]

[0046]

[0047] Example 5

[0048] Butene-2, rhodium acetate, and the ionic liquid diphenylformylmethane dioctyloxyphosphoric acid salt were dissolved in toluene to form a liquid solution. This liquid solution entered the liquid inlet of a microreactor and reacted with a mixture of CO and H2 at the gas inlet to synthesize an aldehyde. In the liquid solution, the concentration of butene-2 ​​was 0.2 mol / L, the concentration of rhodium acetate (based on rhodium elemental concentration) was 0.45 mmol / L, the molar ratio of rhodium acetate to the ionic liquid (based on rhodium elemental concentration) was 1:180, the partial pressure ratio of H2 to CO in the mixed gas was 6:1, the molar ratio of CO to C4 olefin was 40:1, the reaction pressure was 0.9 MPa, the reaction temperature was 120 °C, the gas-liquid volumetric flow rate ratio was 250:1, and the reaction time was 45 s.

[0049] In this example, the C4 olefin conversion rate was 96.9%, the aldehyde selectivity was 97.8%, and the TOF was 34453 h. -1 The product has an aldehyde-to-isotropic ratio of 26.2.

[0050] Example 6

[0051] Butene-2, acetylacetone triphenylphosphine carbonyl rhodium, and the ionic liquid 1,3-indanedione tetraphenylphosphine salt were dissolved in ethylbenzene to form a liquid solution. This liquid solution entered the liquid inlet of a microreactor and reacted with a mixture of CO and H2 at the gas inlet to synthesize an aldehyde. In the liquid solution, the concentration of butene-2 ​​was 0.27 mol / L, the concentration of acetylacetone triphenylphosphine carbonyl rhodium was 0.6 mmol / L (based on rhodium elemental concentration), the molar ratio of acetylacetone triphenylphosphine carbonyl rhodium to the ionic liquid was 1:280 (based on rhodium elemental concentration), the partial pressure ratio of H2 to CO in the mixed gas was 7:1, the molar ratio of CO to C4 olefin was 40:1, the reaction pressure was 0.9 MPa, the reaction temperature was 120 °C, the gas-liquid volumetric flow rate ratio was 250:1, and the reaction time was 40 s.

[0052] In this example, the C4 olefin conversion rate was 98.5%, the aldehyde selectivity was 98.4%, and the TOF was 35460 h⁻¹. -1 The product has an aldehyde-to-isotropic ratio of 28.1.

[0053] Example 7

[0054] Butene-2, rhodium acetate, and the ionic liquid 5,5-dimethylcyclohexanedione dibutyldiphenylphosphonium salt were dissolved in toluene to form a liquid solution. This liquid solution entered the liquid inlet of a microreactor and reacted with a mixture of CO and H2 gas at the gas inlet to synthesize an aldehyde. In the liquid solution, the concentration of butene-2 ​​was 0.35 mol / L, the concentration of rhodium acetate (based on rhodium elemental concentration) was 0.9 mmol / L, the molar ratio of rhodium acetate to the ionic liquid (based on rhodium elemental concentration) was 1:80, the partial pressure ratio of H2 to CO in the mixed gas was 4:1, the reaction pressure was 0.9 MPa, the reaction temperature was 120 °C, the gas-liquid volumetric flow rate ratio was 300:1, and the reaction time was 60 s.

[0055] In this example, the C4 olefin conversion rate was 94.3%, the aldehyde selectivity was 96.0%, and the TOF was 22003 h⁻¹. -1 The product has an aldehyde-to-isotropic ratio of 23.2.

[0056] Comparative Examples 1-5

[0057] The difference from Example 1 is that in Comparative Examples 1-5, the ionic liquids were replaced sequentially with triphenylbutylphosphine tetrafluoroborate, bis(trifluoromethanesulfonyl)imide triphenylbutylphosphine, 2,4-pentanedione triphenylbutylammonium salt, 2,4-pentanedione tetramethylphosphonium salt, and 2,4-pentanedione dioctyldiphenylphosphine salt, respectively. Other conditions were the same as in Example 1. The C4 olefin conversion rate and the positive-to-negative ratio of the product aldehydes are shown in Table 3.

[0058] Table 3. Conversion rate of C4 olefins and aldehyde ratio under different ionic liquids.

[0059]

[0060] Comparative Examples 6-7

[0061] The difference from Example 1 is that in Comparative Examples 6-7, the phosphine ligands were replaced with triphenylphosphine and bidentate phosphineamide, respectively, while other conditions were the same as in Example 1. The C4 olefin conversion rate and the positive-to-negative ratio of the product aldehyde are shown in Table 4.

[0062] Table 4. Conversion rate of C4 olefins and aldehyde-to-isotropic ratio of products under the action of different phosphine ligands.

[0063]

[0064] Comparative Examples 8-10

[0065] The difference from Example 1 is that the partial pressure ratio of H2 and CO in the mixed gas of Comparative Examples 8-10 is different, while other conditions are the same as in Example 1. The C4 olefin conversion rate and the positive-to-negative ratio of the product aldehyde are shown in Table 4.

[0066] Table 5. Conversion rate of C4 olefins and normal-to-isotropic ratio of aldehydes under different partial pressure ratios.

[0067] Example 1 Comparative Example 8 Comparative Example 9 Comparative Example 10 <![CDATA[Partial pressure ratio of H2 and CO]]> 5：1 1：1 2：1 12：1 TOF / h-1 34922 20808 28224 13608 <![CDATA[C4 olefin conversion rate / %]]> 97.2 57.8 78.4 37.8 Aldehyde selectivity / % 98.6 98.3 97.0 96.7 The product aldehyde positive and negative ratio 25.8 25.6 24.8 3.5

[0068] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for hydroformylation of C4 olefins, characterized in that, The method includes mixing a C4 olefin, a rhodium catalyst, an ionic liquid, and a solvent to obtain a liquid phase solution, which is then reacted with a mixture of CO and H2 gases to synthesize an aldehyde, wherein the ionic liquid is a carbanion phosphonium salt.

2. The method according to claim 1, characterized in that, The C4 olefin is one or more of butene-1, butene-2, isobutene, and 2,5-dihydrofuran; and / or the solvent is at least one of toluene, ethylbenzene, and n-decane.

3. The method according to claim 1, characterized in that, The carbanion phosphonium salt has a cation selected from at least one of dibutyldiphenylphosphonium ion, tetrabutylphosphonium ion, dioctyloxyphosphonium ion, tetraphenylphosphonium ion, and triphenylbutylphosphonium ion; and an anion selected from at least one of 2,4-pentanedione ion, 5,5-dimethylcyclohexanedione ion, 1,3-indenedione ion, and diphenylformylmethane ion.

4. The method according to claim 1, characterized in that, The rhodium catalyst is one or more of rhodium chloride, rhodium acetate, rhodium dicarbonyl acetylacetone, and rhodium triphenylphosphine carbonyl acetylacetone.

5. The method according to claim 1, characterized in that, The reaction is carried out in a microreactor; and / or, the microreactor includes a liquid inlet, a gas inlet, and a product outlet; and / or, the interior of the microreactor is a microchannel, which is a circular channel with a diameter of 0.5 to 2 mm; and / or, the mixed gas and liquid solution enter the microchannel in a T-shape for mixing.

6. The method according to claim 1, characterized in that, In the liquid solution, the molar concentration of C4 olefin is 0.08–0.35 mol / L, preferably 0.12–0.27 mol / L; and / or, the concentration of rhodium catalyst is 0.1–2.0 mmol / L, preferably 0.3–0.6 mmol / L; and / or, the molar ratio of rhodium catalyst to ionic liquid is 1:10–300, preferably 1:100–300.

7. The method according to claim 1 or 5, characterized in that, The reaction temperature is 60–130℃, and the reaction pressure is 0.5–3.0 MPa.

8. The method according to claim 1 or 5, characterized in that, The partial pressure ratio of H2 to CO is 4 to 9:

1.

9. The method according to claim 1 or 5, characterized in that, The gas-liquid volumetric flow rate ratio is 150–500:

1.

10. The method according to claim 1 or 5, characterized in that, The reaction time is 10–200 s.

Images