Isosorbide plasticizer and preparation method thereof

Abstract

The invention relates to an isosorbide plasticizer and a preparation method thereof, which are characterized in that sorbitol and a first ester reagent are mixed, preheated liquid is continuously input from the upper part of a reaction zone of a device, a solid catalyst and a rectification filler are mixed in the reaction zone, and a second ester reagent is sent to the lower part of the reaction zone in the form of gas; and carrying out countercurrent contact with a liquid flow in a reaction zone, collecting a product at the bottom of the device after the reaction, and purifying to obtain the isosorbide plasticizer. The one-step efficient preparation of the isosorbide plasticizer is realized in one reaction device, the mass transfer and heat transfer effects are good, and the yield of the isosorbide is improved; the catalyst is easy to recycle and separate and low in loss, and the preparation process is shortened.

Description

An isosorbide plasticizer and its preparation method Technical Field

[0001] This invention belongs to the field of chemical preparation technology, specifically relating to an isosorbide plasticizer and its preparation method. Background Technology

[0002] Isosorbide plasticizers are a newly emerging class of plasticizers, exhibiting effects comparable to phthalate and terephthalate derivatives. Isosorbide dihexanoate, produced by the esterification reaction of isosorbide and hexanoic acid, is a high-performance, environmentally friendly plasticizer that complies with the EU RoHS directive and is considered a good alternative to phthalate plasticizers, attracting significant attention and possessing strong competitiveness. However, isosorbide plasticizers are generally prepared using isosorbide as a raw material, and the current high market price of isosorbide significantly limits its application.

[0003] In recent years, research on renewable resources—biomass and its derivatives—has received increasing attention. Sorbitol, in particular, a hydrogenation product of glucose, has become an important platform compound for biomass conversion. As an important chemical product, sorbitol is widely found in nature and can be easily prepared from readily available renewable biomass resources such as starch, sucrose, or glucose. Isosorbitol is mainly prepared from sorbitol through two catalytic dehydration processes. The first dehydration yields 1,4-dehydrated sorbitol, followed by a second dehydration to obtain isosorbitol. The byproducts from the first dehydration step condense in the second dehydration step to form high-polymer byproducts, which adversely affect the reaction process. Currently, sulfuric acid is used industrially as a catalyst in a one-pot dehydration reaction to prepare isosorbitol. However, liquid acid is highly damaging to equipment, produces numerous byproducts, and requires complex post-processing, resulting in high costs for isosorbitol production. Moreover, the process of first dehydrating and purifying isosorbide to prepare isosorbide from sorbitol, and then esterifying it with ester to prepare isosorbide ester is long and economically unsound, which limits the promotion and application of isosorbide ester.

[0004] CN106632369A discloses a method for preparing isosorbide dicarboxylate. Using sorbitol as a raw material, a dehydration reaction is carried out at 100-180℃ under a N2 atmosphere with the aid of a dehydration catalyst for 0.5-48 h. Then, a monobasic acid and an esterification catalyst are added, and the reaction temperature is increased to 185-250℃ for esterification for 0.5-48 h. The product is obtained by vacuum distillation. The dehydration catalyst used is one or more composite components selected from HY, NaY, NaX, NaA, HMOR, NaMOR, HZSM-5, NaZSM-5, HUSY, NaUSY, and Hβ. The esterification catalyst is one or more composite components selected from NaOH, Na2CO3, NaHCO3, KOH, K2CO3, and KHCO3. Isosorbide dicarboxylate is a novel biomass-based plasticizer that can replace phthalates in the production of polyvinyl chloride products such as agricultural mulch films.

[0005] CN108658998A discloses an isosorbide ester plasticizer, its preparation method, and its application. The method involves dehydrating sorbitol at 60-180°C under an acidic catalyst to obtain dehydrated sorbitol; then mixing the obtained dehydrated sorbitol with fatty acids and subjecting the mixture to esterification at 100-180°C under an acidic catalyst, followed by neutralization to obtain the isosorbide ester plasticizer. The acidic catalyst is independently sulfuric acid, phosphoric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, aminosulfonic acid, or p-toluenesulfonic acid. The fatty acid is one or more selected from hexanoic acid, octanoic acid, capric acid, lauric acid, and oleic acid.

[0006] In the above method, the preparation of sorbitol to isosorbide is carried out in two steps. On the one hand, the reaction process is long and the preparation cost is high. On the other hand, the dehydration temperature of sorbitol and the esterification temperature of isosorbitol are high, and the viscosity of sorbitol and isosorbitol is high and the flowability is poor, resulting in low mass and heat transfer efficiency, easy occurrence of local overheating, and easy condensation to generate other by-products.

[0007] CN112724154A discloses an isosorbide ester plasticizer and its preparation method. The method involves dissolving isosorbide in an ionic liquid, adding a monocarboxylic acid and a catalyst, stirring while purging with nitrogen, and reacting under microwave conditions at 40-95°C. After the reaction is complete, the mixture is cooled and the isosorbide ester plasticizer is obtained by vacuum distillation. The ionic liquid is selected from those with [BF4] as the anion. -The ionic liquid is specifically at least one of [Bmim][BF4], [C4mim][BF4], [C8mim][BF4], and [Rpy][BF4]. The monocarboxylic acid is a C5-C10 monocarboxylic acid, such as at least one of valeric acid, isovaleric acid, hexanoic acid, 2-ethylbutyric acid, heptanoic acid, 2-ethylvaleric acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, 2-propylheptanoic acid, decanoic acid, and isodecanic acid. The catalyst is at least one of sulfuric acid, hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, permanganic acid, trifluoroacetic acid, and trichloroacetic acid, preferably at least one of p-toluenesulfonic acid and permanganic acid. This method avoids the high-temperature dehydration and carbonization of isosorbide by introducing an ionic liquid to dissolve isosorbide and carrying out the esterification reaction in the presence of microwaves. However, the introduction of an ionic liquid makes the subsequent extraction and separation of the product more difficult, and the cost of the ionic liquid is also higher. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an isosorbide plasticizer and its preparation method. This invention achieves efficient one-step preparation of isosorbide plasticizer in a single reaction apparatus, exhibiting good mass and heat transfer effects, thus improving the isosorbide yield; moreover, the catalyst is easily recovered and separated, resulting in low loss and a shortened preparation process.

[0009] The present invention provides a method for preparing isosorbide plasticizer, comprising the following steps:

[0010] Sorbitol is mixed with a first ester reagent. The preheated liquid is continuously fed into the upper part of the reaction zone of the device. The reaction zone is filled with a solid catalyst and distillation packing. At the same time, a second ester reagent is sent to the lower part of the reaction zone in gaseous form and comes into countercurrent contact with the liquid flow in the reaction zone. After the reaction, the product is collected at the bottom of the device and purified to obtain isosorbide plasticizer.

[0011] In this invention, the sorbitol is a solid with a purity of not less than 98%.

[0012] In this invention, the ester reagent is a monocarboxylic acid methyl ester or a monocarboxylic acid ethyl ester, wherein the monocarboxylic acid can have 2-9 carbon atoms, preferably one or more of the following: n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, n-heptanoic acid, 2-ethylvaleric acid, n-octanoic acid, and 2-ethylhexanoic acid.

[0013] In this invention, sorbitol and the first ester reagent are mixed at a mass ratio of 1:0.5-2. The preheating temperature is 55-65℃, and the preheated liquid is continuously fed into the upper part of the reaction zone of the device, generally at a feed rate of 0.5-3.0 kg / h.

[0014] In this invention, the distillation packing is the packing used in conventional distillation reactions, such as at least one of stainless steel θ mesh rings, stainless steel Pall rings, and stainless steel stepped rings.

[0015] In this invention, the solid catalyst is a zeolite molecular sieve, a sulfonic acid resin catalyst, a WO3 / ZrO2 solid acid catalyst, an AlPO4 / BPO4 phosphate, or an H3PW catalyst. 12 O 40 / H4SiW 12 O 40 One or more of the following: heteropoly acids.

[0016] A fluorine-modified solid catalyst is further preferred, prepared by the following method, the preparation of which specifically includes the following steps:

[0017] (a) Mix beta molecular sieve with a fluoride ion solution, heat to 60-100℃ to react, separate the solid after reaction, wash and dry to obtain solid product;

[0018] (b) The solid was mixed with SnF4 in a certain proportion, ball-milled under an inert atmosphere, and then calcined to obtain the catalyst.

[0019] In the above catalyst preparation method, the beta molecular sieve mentioned in step (a) is preferably an H-beta molecular sieve, and the silicon-to-aluminum ratio of the molecular sieve, calculated as SiO2 / Al2O3, is 20-80, preferably 20-40. The solute in the fluoride-containing solution is at least one of hydrofluoric acid, ammonium fluoride, etc., and the mass fraction of the solute in the solution is 5%-30%. The solid-liquid ratio of the beta molecular sieve to the fluoride-containing solution is 1g:15-30mL.

[0020] In the above catalyst preparation method, step (a) involves heating to 60-100℃, preferably 70-90℃, for a reaction time of 4-8 hours. Solid-liquid separation is performed by filtration, centrifugation, etc. The solid is washed with water until neutral and then dried at 100-120℃ for 10-24 hours.

[0021] In the above catalyst preparation method, SnF4 in step (b) is mixed with the solid from step (1) at a mass ratio of 1:8-15. The inert atmosphere is any one of nitrogen, helium, or argon. The ball milling speed is 35-45 r / min, and the milling time is 6-10 h. The calcination temperature is 500-600℃, and the calcination time is 6-12 h.

[0022] In this invention, the volume ratio of distillation packing to solid catalyst is 1:0.5-2.

[0023] In this invention, the second ester reagent is introduced at a mass ratio of 1:1-3 to sorbitol. Preferably, it is introduced into the apparatus as follows: preheating at 90-210°C, and then introducing it into the reaction apparatus at a feed rate of 0.5-3 kg / h.

[0024] In this invention, the pressure of the reaction apparatus is -0.09 to 0.7 MPa, the temperature of the reaction zone is controlled at 130 to 170°C, the temperature at the top of the apparatus is 80 to 150°C, and the temperature at the bottom of the apparatus is 160 to 240°C. The apparatus is generally in the form of a vertical reaction tower or reactor, such as a distillation tower.

[0025] In this invention, under the action of a catalyst and distillation packing, water and excess ester reagents removed during the reaction are discharged from the top of the reaction apparatus, and isosorbide and other byproducts are discharged from the bottom of the apparatus. The substances at the bottom of the apparatus are purified to obtain isosorbide plasticizer, and the purification can be carried out by distillation or other methods.

[0026] The isosorbide plasticizer described in this invention is prepared using the method described above.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The process of catalytic dehydration of sorbitol to prepare isosorbide and the process of isosorbide esterification to prepare plasticizer are coupled. Under the combined action of solid catalyst, distillation packing and reagent, the one-step efficient preparation of isosorbide plasticizer is achieved. The mass and heat transfer effect is good, which improves the product yield. Moreover, the catalyst is easy to recover and separate, with low loss, which shortens the preparation process.

[0029] (2) Adding ester reagents to the system in two different forms avoids uneven dispersion and coking in the reaction due to the high viscosity of the system, while improving the utilization rate of ester reagents and avoiding loss.

[0030] (3) Combining the reaction process with the distillation process can quickly remove water, organic matter and other substances generated during the reaction process from the reaction system, promote the reaction process, and improve the conversion rate of sorbitol and the yield of isosorbide.

[0031] (4) The use of the fluorine-modified solid catalyst of the present invention can reduce the generation of byproducts caused by excessive dehydration condensation, avoid catalyst blockage, and extend the service life of the catalyst. Detailed Implementation

[0032] The technical solution and its effects of the present invention will be described in detail below with reference to specific embodiments. The embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0034] This invention uses an Agilent 1260 liquid chromatograph with a BIO-RAD HPX-87H column for quantitative analysis of sorbitol and isosorbide.

[0035] Sorbitol conversion rate = (1 - mass of sorbitol after reaction / initial mass of sorbitol) × 100%.

[0036] Isosorbide yield = (Isosorbide mass / Initial sorbitol mass) × 100%.

[0037] Example 1

[0038] Sorbitol (99.3% purity) and ethyl valerate (1:1 by mass) were mixed and preheated at 60°C. The resulting liquid was continuously fed into the upper part of the reaction zone of the 2L reaction tower at a feed rate of 1.5 kg / h. The reaction zone of the tower was packed with stainless steel θ-ring packing and zeolite molecular sieve at a volume ratio of 1:1. Simultaneously, a second ester reagent was fed into the lower part of the reaction zone at a feed rate of 1.12 kg / h, preheated at 150°C. The two reagents reacted countercurrently in the reaction zone. The reaction pressure was set to -0.05 MPa, the reaction zone temperature to 150°C, the top temperature to 130°C, and the bottom temperature to 180°C. The product was collected from the bottom of the tower and purified to obtain isosorbide plasticizer. The experimental results are shown in Table 1.

[0039] Example 2

[0040] Sorbitol (99.3% purity) and the first stream of ethyl acetate were mixed at a mass ratio of 1:2. The preheated liquid, heated to 55°C, was continuously fed into the upper part of the reaction zone of the reaction tower at a feed rate of 1.2 kg / h. The reaction tower had a capacity of 2 L and was packed with stainless steel Pall ring packing and H3PW. 12 O 40 / H4SiW 12 O 40 A commercially available heteropolyacid catalyst was used, with a volume ratio of 1:1.5. Simultaneously, a second ester reagent was fed at a rate of 1.5 kg / h, preheated at 120°C, to the lower part of the reaction zone, where the two reacted countercurrently. The reaction pressure was set at 0.6 MPa, the reaction zone temperature at 130°C, the top temperature at 110°C, and the bottom temperature at 160°C. The product was collected from the bottom of the column and purified to obtain isosorbide plasticizer. The experimental results are shown in Table 1.

[0041] Example 3

[0042] Sorbitol (99.3% purity) and ethyl octanoate (n-octanoate) were mixed at a mass ratio of 1:0.6. The preheated liquid was continuously fed into the upper part of the reaction zone of the 2L reaction tower at a feed rate of 2.0 kg / h. The reaction zone of the tower was packed with stainless steel stepped ring packing and commercially available WO3 / ZrO2 solid acid catalyst at a volume ratio of 1:1.2. Simultaneously, a second ester reagent was fed into the lower part of the reaction zone at a feed rate of 1.8 kg / h, preheated at 200℃. The two reactants underwent a countercurrent reaction in the reaction zone. The reaction pressure was set to -0.03 MPa, the reaction zone temperature to 160℃, the top temperature to 145℃, and the bottom temperature to 200℃. The product was collected from the bottom of the tower and purified to obtain isosorbide plasticizer. The experimental results are shown in Table 1.

[0043] Example 4

[0044] Similar to Example 1, except that 2-ethylhexanoate was used as the ester reagent, and the final product, isosorbide plasticizer, was obtained. The experimental results are shown in Table 1.

[0045] Example 5

[0046] Similar to Example 1, except that: Amberlyst-15 sulfonic acid resin catalyst (commercially available) was used as the solid catalyst, and isosorbide plasticizer was finally obtained. The experimental results are shown in Table 1.

[0047] Example 6

[0048] Same as Example 1, except that: the solid catalyst in step (3) was prepared by the following method: (a) 6g of microporous H-Beta molecular sieve (SiO2 / Al2O3 ratio of 40) was added to the reaction vessel, 120mL of hydrofluoric acid solution (hydrofluoric acid mass content of 15%) was added, and the reaction was carried out at 80℃ for 6h. The solid was obtained by centrifugation, washed multiple times until neutral, and dried at 100℃ for 12h to obtain the solid product; (b) SnF4 powder and the solid product were mixed at a mass ratio of 1:10, and ball milled in a ball mill reactor under a nitrogen atmosphere at a speed of 40r / min for 6h. Then, the mixture was calcined at 550℃ for 8h to finally obtain the catalyst. The experimental results are shown in Table 1.

[0049] Example 7

[0050] Same as Example 1, except that: the solid catalyst in step (3) was prepared by the following method: (a) 6g of hierarchical H-Beta molecular sieve, of which the mesoporous ratio was 30% (SiO2 / Al2O3 was 40), was added to a reaction vessel, and 120mL of ammonium fluoride solution (ammonium fluoride mass content was 15%) was added. The reaction was carried out at 80℃ for 6h, and the solid was obtained by centrifugation. The solid was washed several times until neutral and dried at 100℃ for 12h to obtain the solid product; (b) SnF4 powder and the solid product were mixed at a mass ratio of 1:10 and ball-milled in a ball mill reactor under a nitrogen atmosphere at a speed of 40r / min for 6h. Then, the mixture was calcined at 550℃ for 8h to finally obtain the catalyst. The experimental results are shown in Table 1.

[0051] Comparative Example 1

[0052] Similar to Example 1, except that only a solid catalyst was loaded into the reaction apparatus, and no distillation packing was used, ultimately yielding isosorbide plasticizer. The experimental results are shown in Table 1.

[0053] Comparative Example 2

[0054] Similar to Example 1, except that the reaction apparatus was only filled with packing material, no solid catalyst was used, and sulfuric acid was used as the catalyst. The final product was isosorbide plasticizer. The experimental results are shown in Table 1.

[0055] Comparative Example 3

[0056] Similar to Example 1, except that the ester reagents were added in the first stream during the preparation process, ultimately yielding the isosorbide plasticizer. The experimental results are shown in Table 1.

[0057] Table 1. Analytical data from each embodiment.

[0058] Serial Number | Sorbitol Conversion Rate | Isosorbide Yield | Isosorbide Yield after 1000h | Example 1 | 99.6% | 60.5% | 55.4% | Example 2 | 99.3% | 62.3% | 58.3% | Example 3 | 98.9% | 59.2% | 54.9% | Example 4 | 98.7% | 58.9% | 54.7% | Example 5 | 99.0% | 59.5% | 55.2% | Example 6 | 99.5% | 62.0% | 60.1% | Example 7 | 99.6% | 62.2% | 61.0% | Comparative Example 1 | 77.8% | 43.6% | 34.6% | Comparative Example 2 | 99.1% | 52.4% | 28.8% | Comparative Example 3 | 82.5% | 45.3% | 43.1% surface

Claims

1. A method for preparing an isosorbide plasticizer, characterized in that... The process includes the following steps: Sorbitol is mixed with a first ester reagent. The preheated liquid is continuously fed into the upper part of the reaction zone of the device. The reaction zone is filled with a solid catalyst and distillation packing. At the same time, a second ester reagent is sent to the lower part of the reaction zone in gaseous form and comes into countercurrent contact with the liquid flow in the reaction zone. After the reaction, the product is collected at the bottom of the device and purified to obtain isosorbide plasticizer.

2. The preparation method according to claim 1, characterized in that: The ester reagent is a monocarboxylic acid methyl ester or a monocarboxylic acid ethyl ester, wherein the monocarboxylic acid has 2-9 carbon atoms, preferably one or more of the following: valeric acid, isovaleric acid, hexanoic acid, 2-ethylbutyric acid, heptanoic acid, 2-ethylvaleric acid, octanoic acid, and 2-ethylhexanoic acid.

3. The preparation method according to claim 1, characterized in that: Sorbitol and the first ester reagent are mixed at a mass ratio of 1:0.5-2, and the preheating temperature is 55-65℃.

4. The preparation method according to claim 1 or 3, characterized in that: The preheated liquid is continuously fed into the upper part of the reaction zone of the device at a feed rate of 0.5-3.0 kg / h.

5. The preparation method according to claim 1, characterized in that: The distillation packing is at least one of stainless steel θ mesh rings, stainless steel Pall rings, and stainless steel stepped rings.

6. The preparation method according to claim 1, characterized in that: The solid catalyst is a zeolite molecular sieve, a sulfonic acid resin catalyst, a WO3 / ZrO2 solid acid catalyst, an AlPO4 / BPO4 phosphate, or an H3PW catalyst. 12 O 40 / H4SiW 12 O 40 One or more of the heteropoly acids.

7. The preparation method according to claim 1, characterized in that: The solid catalyst is a fluorine-modified solid catalyst prepared by the following method, which specifically includes the following steps: (a) mixing beta molecular sieve with a fluorine ion solution, heating to 60-100℃ for reaction, separating the solid after reaction, washing and drying to obtain the solid product; (b) mixing the solid product with SnF4 in a certain proportion, ball milling reaction under an inert atmosphere, and then calcining to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that: The beta molecular sieve mentioned in step (a) is an H-beta molecular sieve, and the silicon-to-aluminum ratio of the molecular sieve, calculated as SiO2 / Al2O3, is 20-80, preferably 20-40.

9. The method according to claim 7, characterized in that: The solute in the fluoride-containing solution mentioned in step (a) is at least one of hydrofluoric acid and ammonium fluoride, and the mass fraction of the solute in the solution is 5%-30%.

10. The method according to claim 7, 8 or 9, characterized in that: The solid-liquid ratio of the beta molecular sieve to the fluoride ion solution in step (a) is 1g:15-30mL; the temperature is raised to 60-100℃, preferably 70-90℃, for a reaction time of 4-8h.

11. The method according to claim 7, characterized in that: In step (b), SnF4 is mixed with the solid from step (1) at a mass ratio of 1:8-15; the inert atmosphere is any one of nitrogen, helium, or argon; the ball milling speed is 35-45 r / min, and the ball milling time is 6-10 h; the calcination temperature is 500-600℃, and the calcination time is 6-12 h.

12. The method according to claim 1, 5, 6 or 7, characterized in that: The volume ratio of distillation packing material to solid catalyst is 1:0.5-2.

13. The method according to claim 1, characterized in that: The second ester reagent is introduced at a mass ratio of 1:1-3 with sorbitol.

14. The method according to claim 1 or 13, characterized in that: The second ester reagent is preheated at 90-210℃ and then introduced into the reaction apparatus at a feed rate of 0.5-3 kg / h.

15. The method according to claim 1, characterized in that: The pressure of the reaction apparatus is -0.09-0.7 MPa, the temperature of the reaction zone is controlled at 130-170℃, the temperature of the top of the apparatus is 80-150℃, and the temperature of the bottom of the apparatus is 160-240℃.

16. An isosorbide plasticizer, characterized in that... It is prepared by the method described in any one of claims 1-15.