Cesium chloride molecular sieve catalyst and application thereof in preparation of bio-based polyether polyol

Abstract

In order to solve problems with current liquid acid catalysis processes, such as equipment corrosion, product separation difficulty and recycling challenges, the present invention provides a cesium chloride molecular sieve catalyst and an application thereof in the preparation of a bio-based polyether polyol. The present invention first uses formic acid to perform pore enlargement on a beta molecular sieve, and then grafts cesium chloride to a framework of the beta molecular sieve by means of ion exchange to form a Cs-Si structure, which enhances acid strength and forms a cesium chloride molecular sieve catalyst. Then, using corn starch as a raw material, and a mixture of polyethylene glycol 200 and glycerol as a liquefying agent, the cesium chloride molecular sieve catalyst is used to prepare a bio-based polyether polyol, allowing starch to be converted into a polyol at a conversion rate greater than 99.5%.

Description

Cesium chloride molecular sieve catalyst and application thereof in preparation of bio-based polyether polyol TECHNICAL FIELD

[0001] The present application belongs to the field of fine chemical technology, and particularly relates to a cesium chloride molecular sieve catalyst and application thereof in preparation of bio-based polyether polyol. BACKGROUND

[0002] Due to the increasing scarcity of petrochemical resources, high prices and the increasingly serious environmental problems, the use of bio-based products to replace petroleum raw materials to produce polyurethane has become an important direction of the development of polyurethane materials. Biomass polyols have 23% lower energy consumption, 61% lower non-renewable resource consumption and 36% lower greenhouse gas emissions than petroleum polyols, which have outstanding advantages.

[0003] Corn starch not only has the characteristics of renewable resources possessed by other biomass raw materials, but also has relatively simple composition and contains a large number of hydroxyl groups in the molecular chain, which is suitable for use as a raw material for producing polyols. Starch liquefaction is an important way to convert starch into liquid polyol. At present, catalytic liquefaction method is mainly used, and mineral liquid acid catalysts such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid and p-toluene sulfonic acid are mainly used. For example, Huang Yuanbo et al. confirmed by single factor experiment method that sulfuric acid is an effective catalyst for corn starch polyol liquefaction, and the optimal liquefaction process of corn starch is that the mass ratio of corn starch to liquefying agent is 1:6, the amount of sulfuric acid is 3% of the mass of the liquefying agent, the mass ratio of PEG 400 to glycerol in the liquefying agent is 7:3, the liquefaction time is 25 min, and the liquefaction temperature is 150℃. Under the above conditions, the residue rate of the liquefied product is 2.0%, and the hydroxyl value of the prepared corn starch liquefied product is 447.0 mgKOH / g (Huang Yuanbo, Zheng Yunwu, Zheng Zhifeng, et al. Study on the liquefaction process of corn starch polyol [J]. Journal of Southwest Forestry University, 2011, 31(01)). CN103193974A discloses a method for preparing polyether polyol by starch liquefaction. The method uses starch as raw material, mixed polyol as liquefying agent, and methanesulfonic acid as catalyst to prepare polyether polyol. The above liquid acid catalysts have the problems of corroding equipment, being difficult to separate and recycle. SUMMARY

[0004] In order to solve the problems of corroding equipment, difficult product separation and difficult recycling in the existing liquid acid catalytic process, the application provides a cesium chloride molecular sieve catalyst and application thereof in preparation of bio-based polyether polyol. The application firstly adopts formic acid to expand the hole of the Beta molecular sieve, then ion exchange is adopted to graft the cesium chloride to the skeleton of the Beta molecular sieve to form Cs-Si structure, the acid strength is enhanced, a cesium chloride molecular sieve catalyst is formed, then the corn starch is used as raw material, the mixture of polyethylene glycol 200 and glycerol is used as liquefying agent, the cesium chloride molecular sieve catalyst is adopted to prepare the bio-based polyether polyol, and the conversion rate of starch to polyol can reach more than 99.5%.

[0005] The technical scheme of the application is as follows: a preparation method of a cesium chloride molecular sieve catalyst, firstly, formic acid is adopted to expand the hole of the Beta molecular sieve, then ion exchange is adopted to graft the cesium chloride to the skeleton of the Beta molecular sieve to form Cs-Si structure, and the cesium chloride molecular sieve catalyst is obtained.

[0006] Further, the specific steps of the preparation method of the cesium chloride molecular sieve catalyst are as follows:

[0007] (1) formic acid is dissolved in distilled water, the Beta molecular sieve is added and heated to reflux for expansion hole treatment, filtration, water washing until neutral, drying, crushing, and then calcination at 500-600 DEG C, and the expanded hole Beta molecular sieve is obtained;

[0008] (2) the cesium chloride is dissolved in distilled water, then the expanded hole Beta molecular sieve is added, the cesium chloride is grafted to the skeleton of the Beta molecular sieve by heating to reflux, then filtration, water washing, drying, and then calcination at 500-600 DEG C, grinding and sieving, and the cesium chloride molecular sieve catalyst is obtained by selecting the particles with a particle size of 60-80 mesh.

[0009] Further, in step (1), the mass ratio of the formic acid to the Beta molecular sieve is 1:4-6, and the mass ratio of the formic acid to the distilled water is 2-4:100.

[0010] Further, in step (2), the mass ratio of the cesium chloride to the expanded hole Beta molecular sieve is 1:5-6, and the mass ratio of the cesium chloride to the distilled water is 2-4:100.

[0011] Further, in steps (1) and (2), the heating reflux temperature is 75-85 DEG C.

[0012] The application further provides application of the cesium chloride molecular sieve catalyst in preparation of bio-based polyether polyol.

[0013] The application further provides a method for preparing a bio-based polyether polyol by using the cesium chloride molecular sieve catalyst, which comprises the following steps: taking corn starch as a raw material, taking a polyethylene glycol 200 and glycerol mixture as a liquefying agent, adding the cesium chloride molecular sieve catalyst, and performing liquefaction at 120-150 DEG C for 2-5 h; filtering the liquefied product after the liquefaction is completed, wherein the solid after the filtration is the cesium chloride molecular sieve catalyst after the reaction (which can be recycled and reused after activation), and then performing vacuum distillation on the filtered liquefied product to remove water, so as to obtain the bio-based polyether polyol.

[0014] Further, the mass ratio of the corn starch to the liquefying agent is 1:2-7, the mass ratio of the polyethylene glycol 200 to the glycerol in the liquefying agent is (6.5-7.5):(2.5-3.5), and preferably 7:3; and the addition amount of the cesium chloride molecular sieve catalyst is 5-10% of the mass of the liquefying agent.

[0015] Further, the method further comprises recycling and activating the cesium chloride molecular sieve catalyst after the reaction, specifically by calcining the cesium chloride molecular sieve catalyst after the reaction at 500-700 DEG C for 5-8 h, and then crushing and reusing the catalyst.

[0016] The technical principle of the application is that the Beta molecular sieve is composed of SiO2-Al2O3, SiO2-Al2O3 has strong acidity, the acid strength of which is equivalent to that of a 90% or above concentrated sulfuric acid aqueous solution, and is a solid acid that can hydrolyze starch into polyhydric alcohol. In addition to the acid function of the surface, the influence of the pore structure on the diffusion of reactants and the heat transfer process must also be considered. The Beta molecular sieve is a truncated cubic octahedron composed of 12 tetrahedra, 8 hexahedra and 6 octahedra, and has a total of 26 faces and 48 corner tops. This structure is beneficial to the diffusion of reactants and the heat transfer process. Because the molecular weight of starch is relatively large, it is not conducive to entering the pore channel of the Beta molecular sieve, so formic acid is used to expand the pore of the Beta molecular sieve to facilitate the entry of starch into the Beta molecular sieve for acid hydrolysis reaction. In order to enhance the strength of the acid, cesium chloride is grafted onto the framework of the Beta molecular sieve to form a Cs-Si structure through ion exchange. Cesium chloride is also a Lewis acid, has good catalytic activity, can be reused, further enhances the strength of the acid, and forms a cesium chloride molecular sieve composite catalyst, so that the conversion rate of starch into polyhydric alcohol reaches 99.5% or above.

[0017] The beneficial effects of the present application are as follows: the use of the cesium chloride molecular sieve catalyst solves the problems of corrosion of equipment, difficulty in product separation, and difficulty in recycling and reuse of liquid acid catalysts, and the conversion rate of starch to polyol is more than 99.5%. The cesium chloride molecular sieve catalyst can be recycled, activated and reused, saving costs. The use of the catalyst for preparing bio-based polyether polyol has mild reaction conditions, simple preparation method, low cost, high liquefaction rate, can completely replace petroleum resources, and also reduces the emission of carbon dioxide, is a green process route, and is beneficial to industrial production. DETAILED DESCRIPTION

[0018] The present application is further described below in conjunction with examples.

[0019] Example 1: Preparation of cesium chloride molecular sieve catalyst

[0020] (1) 6g of formic acid was dissolved in 200g of distilled water, 24g of Beta molecular sieve was added for pore expansion treatment, heated to reflux at 80℃ for 4h, filtered, washed with water until neutral, dried at 100℃ for 12h, crushed, and then calcined at 550℃ for 5h to obtain the pore-expanded Beta molecular sieve;

[0021] (2) 3g of cesium chloride was dissolved in 100g of distilled water, then 15g of the pore-expanded Beta molecular sieve was added, heated to reflux at 80℃ for 8h, filtered, washed with water until no white color was detected by silver nitrate test, dried in an oven at 100℃ for 12h, calcined at 550℃ for 5h, ground and sieved, and particles with a particle size of 60-80 mesh were selected to obtain the cesium chloride molecular sieve catalyst.

[0022] Example 2: Preparation of cesium chloride molecular sieve catalyst

[0023] (1) 9g of formic acid was dissolved in 300g of distilled water, 45g of Beta molecular sieve was added for pore expansion treatment, heated to reflux at 80℃ for 4h, filtered, washed with water until neutral, dried at 100℃ for 12h, crushed, and then calcined at 550℃ for 5h to obtain the pore-expanded Beta molecular sieve;

[0024] (2) 3g of cesium chloride was dissolved in 100g of distilled water, then 18g of the pore-expanded Beta molecular sieve was added, heated to reflux at 80℃ for 8h, filtered, washed with water until no white color was detected by silver nitrate test, dried in an oven at 100℃ for 12h, calcined at 550℃ for 5h, ground and sieved, and particles with a particle size of 60-80 mesh were selected to obtain the cesium chloride molecular sieve catalyst.

[0025] Example 3: Preparation of cesium chloride molecular sieve catalyst

[0026] (1) 6 g of formic acid was dissolved in 200 g of distilled water, 36 g of Beta molecular sieve was added for pore expansion treatment, heated to reflux at 80°C for 4 h, filtered, washed with water until neutral, dried at 100°C for 12 h, crushed, and then calcined at 550°C for 5 h to obtain the pore-expanded Beta molecular sieve;

[0027] (2) 3 g of cesium chloride was dissolved in 100 g of distilled water, then 16.5 g of the pore-expanded Beta molecular sieve was added, heated to reflux at 80°C for 8 h, filtered, washed with water until no white color was detected by silver nitrate test, dried in an oven at 100°C for 12 h, calcined at 550°C for 5 h, ground and sieved, and then particles with a particle size of 60-80 mesh were selected to obtain the cesium chloride molecular sieve catalyst.

[0028] Example 4: Preparation of biomass polyether polyol

[0029] 10 g of corn starch was added to a mixture of 49 g of polyethylene glycol 200 and 21 g of glycerol as a liquefaction agent, and then 7 g of the cesium chloride molecular sieve catalyst prepared in Example 1 was added, and the mixture was reacted at 140°C for 3 h to perform liquefaction. After the completion of liquefaction, the liquefied product was filtered, and the solid after filtration was the cesium chloride molecular sieve catalyst after reaction, which was recovered, activated and reused. The filtered liquefied product was subjected to vacuum distillation to remove water, and a bio-based polyether polyol was obtained.

[0030] Example 5: Preparation of biomass polyether polyol

[0031] 65 g of corn starch was added to a mixture of 126 g of polyethylene glycol 200 and 54 g of glycerol as a liquefaction agent, and then 10.8 g of the cesium chloride molecular sieve catalyst prepared in Example 2 was added, and the mixture was reacted at 140°C for 3 h to perform liquefaction. After the completion of liquefaction, the liquefied product was filtered, and the solid after filtration was the cesium chloride molecular sieve catalyst after reaction, which was recovered, activated and reused. The filtered liquefied product was subjected to vacuum distillation to remove water, and a bio-based polyether polyol was obtained.

[0032] Example 6: Preparation of biomass polyether polyol

[0033] 50 g of corn starch was added to a mixture of 175 g of polyethylene glycol 200 and 75 g of glycerol as a liquefaction agent, and then 12.5 g of the cesium chloride molecular sieve catalyst prepared in Example 3 was added, and the mixture was reacted at 140°C for 3 h to perform liquefaction. After the completion of liquefaction, the liquefied product was filtered, and the solid after filtration was the cesium chloride molecular sieve catalyst after reaction, which was recovered, activated and reused. The filtered liquefied product was subjected to vacuum distillation to remove water, and a bio-based polyether polyol was obtained.

[0034] The bio-based polyether polyols prepared in Examples 4 to 6 were detected, and the detection results are shown in Table 1. Among them, the determination of hydroxyl value is carried out according to GB / T 12008 "Plastic polyether polyol" Part 3 method, the determination of acid value is carried out according to GB / T 12008 "Plastic polyether polyol" Part 5 method, the determination of viscosity is carried out according to GB / T 12008 "Plastic polyether polyol" Part 7 method, and the determination of moisture is carried out according to the method specified in GB / T 22313-2008.

[0035] In addition, the conversion rate (starch liquefaction rate) of the starch conversion polyol was determined according to the following method: 20 mL of a mixed solution of dioxane and water (volume ratio of dioxane to water is 1:1) and 2.0 g of the liquefaction product were added to a beaker, the beaker was placed in a water bath at 80°C, and after stirring for 20 min, it was cooled to room temperature. Then filter in a Buchner funnel, wash with a mixed solution of dioxane and water until the filtrate is colorless. After suction filtration, the residue was placed in a 105°C oven for drying for 4h, and the mass of the liquefaction product residue was weighed, and the liquefaction rate was calculated according to the following formula: Residue rate (%) = mass of residue / mass of liquefaction product taken × 100% Liquefaction rate (%) = 100% - residue rate (%)

[0036] Table 1: Determination results of bio-based polyether polyol indicators

[0037] As can be seen from the results in Table 1, the bio-based polyether polyol meets the standard of GB / T 12008 "Plastic polyether polyol", and the conversion rate (starch liquefaction rate) of the starch conversion polyol reaches more than 99.5%.

[0038] The cesium chloride molecular sieve catalyst after reaction was activated at 600°C for 6h, and after crushing, it was repeatedly used. Taking the catalyst prepared in Example 1 as an example, after each reaction, it was activated at 600°C for 6h and repeatedly used for 8 times, and the liquefaction rate was still maintained at more than 99.5% (see Table 2).

[0039] Table 2: Repeated use effect of cesium chloride molecular sieve composite catalyst of Example 1

[0040] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a cesium chloride molecular sieve catalyst, characterized in that, First, formic acid is used to expand the pores of Beta molecular sieve. Then, cesium chloride is grafted onto the framework of Beta molecular sieve through ion exchange to form a Cs-Si structure, thus obtaining a cesium chloride molecular sieve catalyst.

2. The method for preparing the cesium chloride molecular sieve catalyst as described in claim 1, characterized in that, Specifically, the following steps are included: (1) Dissolve formic acid in distilled water, add Beta molecular sieve and heat and reflux to expand the pores, filter, wash with water until neutral, dry, pulverize, and then calcine at 500-600℃ to obtain expanded pore Beta molecular sieve. (2) Cesium chloride is dissolved in distilled water, then pore-expanded Beta molecular sieve is added, and the mixture is heated under reflux to graft cesium chloride onto the framework of Beta molecular sieve. The mixture is then filtered, washed with water, dried, calcined at 500-600℃, ground and sieved to obtain cesium chloride molecular sieve catalyst.

3. The method for preparing the cesium chloride molecular sieve catalyst as described in claim 2, characterized in that, In step (1), the mass ratio of formic acid to Beta molecular sieve is 1:4-6; the mass ratio of formic acid to distilled water is 2-4:

100.

4. The method for preparing the cesium chloride molecular sieve catalyst as described in claim 2, characterized in that, In step (2), the mass ratio of cesium chloride to expanded-pore Beta molecular sieve is 1:5-6; the mass ratio of cesium chloride to distilled water is 2-4:100; and the grinding and screening process yields particles with a particle size of 60-80 mesh.

5. The method for preparing the cesium chloride molecular sieve catalyst as described in claim 2, characterized in that, In steps (1) and (2), the temperature of the heating reflux is 75-85℃.

6. A cesium chloride molecular sieve catalyst prepared by the method according to any one of claims 1-5.

7. The application of the cesium chloride molecular sieve catalyst as described in claim 6 in the preparation of bio-based polyether polyols.

8. A method for preparing bio-based polyether polyols using the cesium chloride molecular sieve catalyst as described in claim 6, characterized in that, The method includes: using corn starch as raw material, using a mixture of polyethylene glycol 200 and glycerol as a liquefying agent, adding the cesium chloride molecular sieve catalyst, reacting at 120-150℃ for 2-5 hours to liquefy, filtering the liquefied product after liquefaction, the filtered solid being the reacted cesium chloride molecular sieve catalyst, and then removing water from the filtered liquefied product by vacuum distillation to obtain bio-based polyether polyol.

9. The method for preparing bio-based polyether polyols as described in claim 8, characterized in that, The mass ratio of corn starch to liquefaction agent is 1:2-7, and the mass ratio of polyethylene glycol 200 to glycerol in the liquefaction agent is (6.5-7.5):(2.5-3.5); the amount of cesium chloride molecular sieve catalyst added is 5-10% of the mass of the liquefaction agent.

10. The method for preparing bio-based polyether polyols as described in claim 8, characterized in that, The method further includes: recovering and activating the reacted cesium chloride molecular sieve catalyst, specifically by calcining the reacted cesium chloride molecular sieve catalyst at 500-700℃ for 5-8 hours, pulverizing it, and reusing it.

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