Oxide / iodine composite particles and dispersion of oxide / iodine composite particles

Abstract

The present invention relates to oxide / iodine composite particles and a dispersion of the oxide / iodine composite particles. The oxide / iodine composite particles of the present invention have a coupling agent grafted onto their outer surfaces. The dispersion of the oxide / iodine composite particles of the present invention comprises the oxide / iodine composite particles and a dispersion medium. The oxide / iodine composite particles of the present invention can prevent iodine loss. Furthermore, the dispersion of the oxide / iodine composite particles exhibits high activity and good stability when used as a catalyst in the cis-trans isomerization reaction of olefins.

Description

Technical Field

[0001] The present invention relates to an olefin cis-trans isomerization catalyst, and in particular to a dispersion of oxide / iodine composite particles, a preparation method and application thereof. Background Art

[0002] Isopentadiene is mainly used to produce C5 aliphatic petroleum resins and methyltetrahydrophthalic anhydride and their rehydrogenation.

[0003] Usually, the isopentadiene product is a mixture of cis-1,3-pentadiene and trans-1,3-pentadiene. The total mass of cis- and trans-pentadiene is generally between 68% and 72%, of which the trans-1,3-pentadiene content is 42% to 46%, the cis-1,3-pentadiene content is 25% to 27%, and the trans-cis mass ratio is 1.67 to 1.74. The other components are cyclopentene and cyclopentane, with the mass contents of the two being 17% to 19% and 5% to 8%, respectively.

[0004] The reaction of piperylene to produce C5 aliphatic petroleum resins is an acid-catalyzed polymerization reaction, in which both cis and trans forms can participate. However, when producing methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride, only trans piperylene can undergo the Diels-Alder reaction with maleic anhydride due to the symmetry mismatch of the cis form. Therefore, the efficient conversion of cis piperylene to trans piperylene is of considerable research significance. According to Gibbs free energy, trans-1,3-pentadiene has a lower energy barrier and higher stability than cis-1,3-pentadiene. Under certain conditions, the cis form can be converted to the trans form, and the equilibrium ratio (trans:cis) decreases with increasing temperature.

[0005] There are two main methods for the isomerization of cis / trans-1,3-pentadiene: photocatalysis and chemical catalysis. FREIDLIN (Bull. Acad. Sci. USSR, Chem. Sci., 1977, 26 (4): 762-767.) used [Co(CN)3EN] -1 Complex catalysts can convert all cis-forms into trans-forms, but the preparation of the catalyst requires highly toxic cyanide, and Co is unstable and easily oxidized. CN103145522A discloses a method for the isomerization of cis-pentadiene, which protects Co from oxidation by adding sodium borohydride, but cannot change the disadvantages of homogeneous catalysis and requires continuous consumption of sodium borohydride. Although photocatalysis (J.Chem.Phys., 1970, 52(6):3277-3282.) is highly efficient, it is very difficult to achieve industrialization. Egger (J.Am.Chem.Soc., 1965, 87(15):3311-3314.)'s research shows that I2 and NO can catalyze the cis-trans isomerization of olefins, and iodine has much higher catalytic activity, but iodine is easily sublimed or lost by addition with olefins, limiting its large-scale use. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides oxide / iodine composite particles and a dispersion of the oxide / iodine composite particles. The oxide / iodine composite particles of the present invention can prevent iodine loss. Furthermore, the dispersion of the oxide / iodine composite particles exhibits high activity and good stability when used as a catalyst in the cis-trans isomerization reaction of olefins.

[0007] A first aspect of the present invention provides an oxide / iodine composite particle, wherein a coupling agent is grafted onto the outer surface of the oxide / iodine composite particle.

[0008] Furthermore, the oxide is at least one of titanium oxide, silicon dioxide, zirconium dioxide and aluminum oxide.

[0009] Furthermore, the coupling agent is a coupling agent containing an electron-withdrawing group, preferably selected from one or more of trimethoxy (3- (4-nitrophenoxy) propyl) silane, trimethoxy (5-methyl-2-nitrobenzyl) silane, 1,3-difluoro-4-nitro-2- (trimethylsilyl) benzene, trimethoxy ((2-nitrophenyl) acetylene) silane, trifluorooctane trimethoxy silane, trimethoxy (pentafluorophenyl) silane, 3-trifluoroacetoxybutyl trimethoxy silane, 3- (trifluoromethyl) phenyl trimethoxy silane, N, N-dimethyl-3- (trimethoxysilyl) propylamine hydrochloride, and trichlorooctane trimethoxy silane.

[0010] Furthermore, based on the weight of the oxide / iodine composite particles, the iodine content is 10wt% to 50wt%, the oxide content is 20wt% to 85wt%, and the coupling agent content is 5wt% to 30wt%; preferably, the iodine content is 10wt% to 30wt%, the oxide content is 30wt% to 75wt%, and the coupling agent content is 12wt% to 25wt%.

[0011] A second aspect of the present invention provides a dispersion of oxide / iodine composite particles, comprising the oxide / iodine composite particles described in the first aspect and a dispersion medium.

[0012] Furthermore, the dispersion medium is selected from at least one of n-pentane, n-hexane, n-heptane, dodecane, cyclohexane, toluene, ethylbenzene, and p-xylene.

[0013] Furthermore, in the dispersion, the average diameter of the oxide / iodine composite particles is 10 to 30 nm.

[0014] Furthermore, the solid content of the dispersion is 1 wt% to 40 wt%, preferably 15 wt% to 35 wt%.

[0015] A third aspect of the present invention provides a method for preparing the oxide / iodine composite particles, comprising:

[0016] (1) mixing an oxide precursor, an iodine element, and a solvent to obtain a mixed solution, and performing a first reaction;

[0017] (2) Adding a coupling agent to step (1) to carry out a second reaction to obtain oxide / iodine composite particles.

[0018] Furthermore, in step (1), the oxide precursor is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, tetraisopropyl titanate, tetrabutyl titanate, zirconium n-propoxide, zirconium isopropoxide, aluminum isopropoxide, and aluminum n-propoxide. The solvent is selected from at least one of ethylene glycol, benzyl alcohol, diethylene glycol, glycerol, n-propanol, isopropanol, 1,3-butanediol, and 1,3-propylene glycol.

[0019] Furthermore, in step (1), the molar ratio of iodine element to oxide precursor is 1:4 to 20, preferably 1:6 to 15. The molar ratio of solvent to oxide precursor is 1:0.2 to 4, preferably 1:0.5 to 3.

[0020] Furthermore, in step (1), the time of the first reaction is 4 to 14 hours, preferably 6 to 12 hours, and the temperature of the first reaction is 10 to 40°C, preferably 15 to 30°C.

[0021] Furthermore, in step (1), the first reaction is carried out under stirring; the environmental humidity of the first reaction is 40% to 80%, preferably 50 to 70%.

[0022] Furthermore, in step (2), the coupling agent is selected from one or more of trimethoxy(3-(4-nitrophenoxy)propyl)silane, trimethoxy(5-methyl-2-nitrobenzyl)silane, 1,3-difluoro-4-nitro-2-(trimethylsilyl)benzene, trimethoxy((2-nitrophenyl)acetylene)silane, trifluorooctanetrimethoxysilane, trimethoxy(pentafluorophenyl)silane, 3-trifluoroacetoxybutyltrimethoxysilane, 3-(trifluoromethyl)phenyltrimethoxysilane, N,N-dimethyl-3-(trimethoxysilyl)propylamine hydrochloride, and trichlorooctanetrimethoxysilane.

[0023] Furthermore, in step (2), the molar ratio of the coupling agent to the oxide precursor is 1:1-5, preferably 1:2-4.

[0024] Furthermore, in step (2), the second reaction is also carried out under stirring, the second reaction time is 8 to 15 hours, preferably 10 to 12 hours, and the second reaction temperature is 10 to 40°C, preferably 15 to 30°C.

[0025] Furthermore, in step (2), after the second reaction, the oxide / iodine composite particles are filtered, washed, and dried. The washing is performed using an alcohol selected from at least one of ethanol, methanol, isopropanol, n-propanol, benzyl alcohol, 1,3-butanediol, and 1,3-propylene glycol. The drying conditions are: a temperature of 80 to 120° C. and a drying time of 4 to 12 hours.

[0026] A fourth aspect of the present invention provides a method for preparing a dispersion of the oxide / iodine composite particles, comprising: dispersing the oxide / iodine composite particles in a dispersion medium to obtain a dispersion of the oxide / iodine composite particles.

[0027] Furthermore, the oxide / iodine composite particles may be dispersed into a dispersion medium using ultrasound to obtain a dispersion of the oxide / iodine composite particles.

[0028] A fifth aspect of the present invention provides an application of a dispersion of oxide / iodine composite particles in cis-trans isomerization of olefins.

[0029] Furthermore, the olefin is a cis-olefin, preferably at least one of cis-2-butene, cis-1,3-pentadiene, cis-2-pentene, and cis-1,4-hexadiene.

[0030] Furthermore, the application is specifically as follows: a cis-olefin raw material reacts under the catalytic action of a dispersion of oxide / iodine composite particles to prepare a corresponding trans-olefin.

[0031] Furthermore, the reaction conditions include: a reaction temperature of 40 to 100° C., preferably 50 to 90° C.; a pressure of 0.2 to 1 MPa, preferably 0.3 to 0.8 MPa; a mass ratio of the dispersion of olefin and oxide / iodine composite particles of 5 to 20:1, preferably 3 to 12:1; a weight space velocity of the olefin of 0.5 to 3 h -1 , preferably 0.8 to 2 hours -1 .

[0032] Furthermore, the olefin is preheated to 30-70°C, fed from the bottom of the bubbling bed, fully contacted and reacted with the dispersion of oxide / iodine composite particles at the bottom of the bed, and the product is directly obtained from the top of the bed. The bed temperature is 20-90°C, preferably 30-60°C.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. In the oxide / iodine composite particles of the present invention, a coupling agent containing an electron-withdrawing group is grafted onto the surface. The coupling agent is covalently bonded to the outer surface of the oxide, thereby reducing the surface energy of the particles so that they can subsequently be highly dispersed in the dispersion medium. The oxide / iodine composite particles composited with the oxide and surface-grafted with the coupling agent can effectively inhibit the loss of iodine.

[0035] 2. The dispersion of the oxide / iodine composite particles of the present invention can retain the dispersibility of the nanoparticles, give full play to the advantage of the high specific surface area of ​​the nanoparticles, and fully utilize the catalytic active sites of iodine to carry out the corresponding catalytic reaction.

[0036] 3. The dispersion of the oxide / iodine composite particles of the present invention is used as a catalyst for the cis-trans isomerization of olefins. The oxide / iodine composite particles after grafting the coupling agent can adsorb olefin double bonds, making the reaction targeted and efficient, and can effectively inhibit the formation of olefin polymers. The catalyst has the advantages of high activity, high selectivity, and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a transmission electron micrograph of the dispersion of silicon dioxide / iodine composite particles obtained in Example 1. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with embodiments and drawings. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0039] In the present invention, a Hitachi HT7700 transmission electron microscope was used to observe the morphology, size, and dispersion of the sample. When observing nanoparticles, a sample of appropriate concentration was dropped onto the carbon film and allowed to air dry before being sampled and observed.

[0040] Example 1

[0041] (1) Preparation of oxide / iodine composite particles and dispersion: 0.8 mol of methyl orthosilicate, 0.1 mol of iodine, and 0.8 mol of ethylene glycol were mixed to obtain a homogeneous solution. The solution was stirred and reacted at 20°C for 8 h in an open atmosphere at a humidity of 70%. 0.8 mol of trimethoxy(3-(4-nitrophenoxy)propyl)silane was added, and the solution was stirred and reacted at 20°C for 12 h. The product was filtered, washed with methanol, and dried at 80°C to obtain silica / iodine composite particles. Based on the mass of the silica / iodine composite particles, the iodine content was 12 wt%, the oxide content was 65 wt%, and the coupling agent content was 23 wt%.

[0042] The obtained silicon dioxide / iodine composite particles were ultrasonically dispersed in n-hexane to obtain a dispersion of silicon dioxide / iodine composite particles with a solid content of 30 wt % and an average particle size of 20 nm.

[0043] (2) Catalyst evaluation: The silica / iodine dispersion prepared in step (1) was diluted to 10 wt %, and 500 g was added to the bottom of a distillation tower. Cis-1,3-pentadiene was preheated to 60° C. and fed from the bottom of the tower in a bubbling manner to fully contact and react with the dispersion of silica / iodine composite particles. The reaction temperature was 60° C., the pressure was 0.5 MPa, and the tower body temperature was 35° C. The mass ratio of cis-1,3-pentadiene to catalyst was 10:1. The weight space velocity of cis-1,3-pentadiene was 0.8 h -1 The reaction produces the corresponding trans-olefin, which is then distilled directly from the top of the tower to obtain a high-purity product. After the unit stabilized, the product analysis results are shown in Table 1.

[0044] Examples 2-4

[0045] Compared with Example 1, the preparation of the catalysts of Examples 2-4 is only based on the use of different oxide precursors (see Table 1 for details).

[0046] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 1.

[0047] Table 1 Catalysts and evaluation results of various examples

[0048]

[0049] Note: The trans-cis molar ratio mentioned in the specification refers to the molar ratio of trans olefins to cis olefins in the product.

[0050] Examples 5-7

[0051] Compared with Example 1, the preparation of the catalysts of Examples 5-7 is only based on the use of different coupling agents (see Table 2 for details).

[0052] The catalyst evaluation method was the same as in Example 1, and the results are shown in Table 2.

[0053] Table 2 Catalysts and evaluation results of various examples

[0054]

[0055] Examples 8-11

[0056] Compared with Example 1, the evaluation method of the catalysts in Examples 8-11 is only to use different temperatures or pressures (see Table 3 for details).

[0057] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 3.

[0058] Table 3 Evaluation results of each case

[0059]

[0060]

[0061] Example 12

[0062] (1) Preparation of oxide / iodine composite particle dispersion: 0.8 mol of methyl orthosilicate, 0.2 mol of iodine, and 0.2 mol of glycerol were mixed to obtain a homogeneous solution. The solution was stirred and reacted at 15°C for 7 h in an open atmosphere at an ambient humidity of 60%. 0.6 mol of trimethoxy(pentafluorophenyl)silane was added, and the solution was stirred and reacted at 15°C for 9 h. The product was filtered, washed with ethanol, and dried at 90°C to obtain silica / iodine composite particles. Based on the mass of the silica / iodine composite particles, the iodine content was 18 wt%, the oxide content was 61 wt%, and the coupling agent content was 21 wt%.

[0063] The obtained silicon dioxide / iodine composite particles were ultrasonically dispersed in toluene to obtain a dispersion of silicon dioxide / iodine composite particles with a solid content of 25 wt % and an average particle size of 21 nm.

[0064] (2) Catalyst evaluation: The silica / iodine dispersion prepared in step (1) was diluted to 10 wt %, and 500 g was added to the bottom of the distillation tower. Cis-2-pentene was preheated to 50° C. and fed from the bottom of the tower in a bubbling manner to fully contact and react with the dispersion of silica / iodine composite particles. The reaction temperature was 50° C., the pressure was 0.6 MPa, and the tower body temperature was 45° C. The mass ratio of the raw material to the catalyst was 9:1. The weight space velocity of cis-2-pentene was 0.9 h / min. -1 The reaction produces the corresponding trans-olefin, which is then distilled directly from the top of the tower to obtain a high-purity product. After the unit stabilized, the product analysis was performed, as shown in Table 4.

[0065] Table 4 Evaluation results of each case

[0066]

[0067] Comparative Example 1-2

[0068] Compared with Example 1, the preparation of the catalyst of Comparative Example 1-2 is only the use of different coupling agents (see Table 5 for details)

[0069] The catalyst evaluation method is the same as in Example 1, and the results are shown in Table 5.

[0070] Table 5 Catalysts and evaluation results for each example

[0071]

[0072] Comparative Examples 3-4

[0073] Compared with Example 1, the catalyst of Comparative Example 3 is prepared by directly dissolving elemental iodine in a dispersion medium.

[0074] The catalyst of Comparative Example 4 directly uses the ungrafted and modified silicon dioxide / iodine composite particles of Example 1 as a catalyst.

[0075] The catalyst evaluation method was the same as in Example 1, and the results are shown in Table 6.

[0076] Table 6 Catalyst evaluation results for each case

[0077]

[0078] The above describes in detail the specific embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present invention and fall within the scope of protection of the present invention.

Claims

1. An oxide / iodine composite particle, characterized in that: The outer surface of the oxide / iodine composite particles is grafted with a coupling agent; The oxide is at least one of titanium oxide, silicon dioxide, zirconium dioxide and aluminum oxide; The coupling agent is selected from one or more of trimethoxy (3- (4-nitrophenoxy) propyl) silane, trimethoxy (5-methyl-2-nitrobenzyl) silane, 1,3-difluoro-4-nitro-2- (trimethylsilyl) benzene, trimethoxy ((2-nitrophenyl) acetylene) silane, trifluorooctane trimethoxy silane, trimethoxy (pentafluorophenyl) silane, 3-trifluoroacetoxybutyl trimethoxy silane, 3- (trifluoromethyl) phenyl trimethoxy silane, N, N-dimethyl-3- (trimethoxysilyl) propylamine hydrochloride, and trichlorooctane trimethoxy silane.

2. The oxide / iodine composite particles according to claim 1, characterized in that: Based on the weight of the oxide / iodine composite particles, the content of iodine is 10wt% to 50wt%, the content of oxide is 20wt% to 85wt%, and the content of coupling agent is 5wt% to 30wt%.

3. The oxide / iodine composite particles according to claim 2, characterized in that: Based on the weight of the oxide / iodine composite particles, the content of iodine is 10wt% to 30wt%, the content of oxide is 30wt% to 75wt%, and the content of coupling agent is 12wt% to 25wt%.

4. A dispersion of oxide / iodine composite particles, characterized in that: The dispersion comprises the oxide / iodine composite particles according to any one of claims 1 to 3 and a dispersion medium.

5. The dispersion according to claim 4, characterized in that: The dispersion medium is selected from at least one of n-pentane, n-hexane, n-heptane, dodecane, cyclohexane, toluene, ethylbenzene, and p-xylene.

6. The dispersion according to claim 4, characterized in that: In the dispersion, the average diameter of the oxide / iodine composite particles is 10 to 30 nm; and / or the solid content of the dispersion is 1 wt % to 40 wt %.

7. The dispersion according to claim 6, characterized in that: The solid content of the dispersion is 15 wt% to 35 wt%.

8. The method for preparing the oxide / iodine composite particles according to any one of claims 1 to 3, comprising: (1) mixing an oxide precursor, an iodine element, and a solvent to obtain a mixed solution, and performing a first reaction; (2) Adding a coupling agent to step (1) to carry out a second reaction to obtain oxide / iodine composite particles.

9. The method according to claim 8, characterized in that: In step (1), the oxide precursor is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, tetraisopropyl titanate, tetrabutyl titanate, zirconium n-propoxide, zirconium isopropoxide, aluminum isopropoxide, and aluminum n-propoxide; and the solvent is selected from at least one of ethylene glycol, benzyl alcohol, diethylene glycol, glycerol, n-propanol, isopropanol, 1,3-butanediol, and 1,3-propylene glycol.

10. The method according to claim 8, characterized in that: In step (1), the molar ratio of iodine element to oxide precursor is 1:4-20; the molar ratio of solvent to oxide precursor is 1:0.2-4; And / or, in step (2), the molar ratio of the coupling agent to the oxide precursor is 1:1-5.

11. The method according to claim 10, characterized in that: In step (1), the molar ratio of iodine element to oxide precursor is 1:6-15; the molar ratio of solvent to oxide precursor is 1:0.5-3; And / or, in step (2), the molar ratio of the coupling agent to the oxide precursor is 1:2-4.

12. The method according to claim 8, characterized in that: In step (1), the time of the first reaction is 4 to 14 hours, the temperature of the first reaction is 10 to 40° C., the first reaction is carried out under stirring, and the environmental humidity of the first reaction is 40% to 80%.

13. The method according to claim 12, characterized in that: In step (1), the time of the first reaction is 6 to 12 hours, the temperature of the first reaction is 15 to 30° C., and the ambient humidity of the first reaction is 50% to 70%.

14. The method according to claim 8, characterized in that: In step (2), the second reaction is carried out under stirring, the second reaction time is 8 to 15 hours, and the second reaction temperature is 10 to 40°C.

15. The method according to claim 14, characterized in that: In step (2), the second reaction time is 10 to 12 hours, and the second reaction temperature is 15 to 30°C.

16. Use of the dispersion of oxide / iodine composite particles according to any one of claims 4 to 7 in cis-trans isomerization of olefins.

17. The use according to claim 13, characterized in that: The olefin is a cis-olefin; the specific application is: the cis-olefin raw material reacts under the catalytic action of a dispersion of oxide / iodine composite particles to prepare the corresponding trans-olefin.

18. The use according to claim 17, characterized in that: The olefin is at least one of cis-2-butene, cis-1,3-pentadiene, cis-2-pentene, and cis-1,4-hexadiene.

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