A Ce-based rare earth composite solid strong acid catalyst for biodiesel and its preparation process

Abstract

The present application relates to the technical field of solid acid catalysts, and specifically discloses a Ce-based rare earth composite solid strong acid catalyst for biodiesel and a preparation process thereof. The catalyst comprises a catalytic component and an active component loaded on the catalytic component; the catalytic component is mesoporous zirconium phosphate; the active component comprises cerium trichloride and cerium oxide; the catalyst of the present application has high catalytic activity, can be automatically separated from a liquid product after the esterification reaction is completed, has simple post-treatment, can be reused after simple activation treatment, has good reuse performance, can achieve a biodiesel yield of up to 100% in the first catalysis, and can still achieve a biodiesel yield of more than 90% after repeated use for 20 times; the preparation process of the catalyst comprises the steps of dissolving the active component in a mixed acid solution and then adding the catalytic component to mix to obtain a suspension; drying the suspension, activating it, and grinding it to obtain the catalyst; the above-mentioned preparation process is simple, the preparation conditions are mild, and the obtained catalyst has strong catalytic activity and good reusability.

Description

Technical Field

[0001] The present application relates to the technical field of solid acid catalysts, and more specifically, to a Ce-based rare earth composite solid strong acid catalyst for biodiesel and a preparation process thereof. Background Art

[0002] Biodiesel is an alkane monoester compound produced by transesterification and esterification of animal and plant fats, restaurant waste oil or microbial fats with alcohols under the action of a catalyst. Compared with traditional petrochemical diesel, biodiesel has a wide range of sources, is clean and environmentally friendly, renewable, and biodegradable. It has the advantages of good ignition performance, more complete combustion, safety and reliability, good versatility, and wide applicability.

[0003] The traditional methods for preparing biodiesel are mainly divided into acid catalysis and base catalysis. Among them, the acid catalysis method for preparing biodiesel can be further divided into liquid acid catalysis and solid acid catalysis. Liquid acid (such as concentrated sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, toluenesulfonic acid, etc.) is a commonly used catalyst with the characteristics of high catalytic efficiency, but liquid acid catalysts have the problems of transportation danger, strong corrosion to equipment, difficulty in post-processing separation and purification, and easy to cause environmental pollution, which limits its industrial application. Compared with liquid acid catalysts, solid acid catalysts are easy to store and transport, have low corrosion to equipment, and the post-processing of the products prepared by catalysis is simple. However, in the prior art, the solid acid catalyst for preparing biodiesel has poor reusability, short catalyst life, large catalyst addition amount, resulting in increased production cost, and poor adaptability to raw materials, and is not suitable for preparing raw oils and fats with complex components such as kitchen waste oil into biodiesel. Based on the above statement, the present application provides a Ce-based rare earth composite solid strong acid catalyst for biodiesel and a preparation process thereof. Summary of the invention

[0004] In order to solve the problems of poor reusability of solid acid catalysts for biodiesel, short catalyst life, large catalyst addition amount, and poor adaptability to raw materials, the present application provides a Ce-based rare earth composite solid strong acid catalyst for biodiesel and its preparation process.

[0005] In the first aspect, the present application provides a Ce-based rare earth composite solid strong acid catalyst for biodiesel, which adopts the following technical solution:

[0006] A Ce-based rare earth composite solid strong acid catalyst for biodiesel, comprising a catalytic component and an active component supported on the catalytic component;

[0007] The catalytic component is mesoporous zirconium phosphate;

[0008] The Dv of the mesoporous zirconium phosphate 50 Particle size is 100-120nm;

[0009] The active components include cerium trichloride and cerium oxide;

[0010] The mass ratio of the cerium trichloride to cerium oxide is 7.5-9.5:1.

[0011] By adopting the above technical scheme, the present application selects mesoporous zirconium phosphate with uniform pore size, orderly arrangement and high porosity as the catalyst catalytic component, which is convenient for heavy oil components and macromolecules to enter for catalytic reaction, has good applicability to catalytic raw materials, has a large specific surface area, and is easy to functionalize the surface. When used for active component loading, the active components can be highly dispersed, so that the active components are evenly distributed on the surface of the catalytic component, the loading amount is high, the loading stability is good, and sufficient active sites are provided for the catalytic reaction; cerium trichloride and cerium oxide are selected as the active components in combination, which further improves the catalytic activity and selectivity of the solid strong acid catalyst, and the obtained catalyst has high catalytic activity and is used for biodiesel preparation, and the first catalytic yield of biodiesel can reach up to 100%.

[0012] After the esterification reaction is completed, the catalyst of the present application can be automatically separated from the liquid product, and the post-processing is simple. The separated catalyst can be reused after a simple activation treatment, and has good reuse performance. It can be reused 20 times and still achieve a biodiesel yield of more than 90%.

[0013] Preferably, the mesoporous zirconium phosphate is prepared by the following method: adding zirconium phosphate to an aluminum salt solution, stirring and mixing, adding a silane coupling agent and continuing to mix, drying, calcining, and grinding to obtain the desired mesoporous zirconium phosphate.

[0014] Preferably, the aluminum salt solution is a polyaluminum chloride solution with a mass concentration of 8-15%.

[0015] Preferably, the silane coupling agent is at least one of coupling agent KH550, coupling agent KH560, and coupling agent KH570.

[0016] By adopting the above technical scheme, a polyaluminium chloride solution is selected to disperse and adsorb zirconium phosphate, and by adding a silane coupling agent, the compatibility and dispersion stability of zirconium phosphate and the polyaluminium chloride solution can be effectively improved. The mesoporous zirconium phosphate obtained in the present application is used to load active components, and has the characteristics of high loading amount and good loading stability. The obtained catalyst can be used to catalyze the esterification reaction of animal and plant oils and alcohols, and can also be used to catalyze the preparation of raw oils with complex components such as waste cooking oils into biodiesel, with high catalytic activity and high biodiesel yield.

[0017] Preferably, the silane coupling agent is a compound of coupling agent KH550 and coupling agent KH570 in a mass ratio of 1:3.5.

[0018] By adopting the above technical solution and selecting coupling agent KH550 and coupling agent KH570 with a mass ratio of 1:3.5 to jointly modify zirconium phosphate, the surface properties of zirconium phosphate can be significantly improved and the catalytic activity can be further enhanced.

[0019] Preferably, the mass ratio of the aluminum salt solution, zirconium phosphate and silane coupling agent is 10:5-6:0.1-0.3.

[0020] Preferably, the mixing and stirring temperature is 60-70° C., the mixing and stirring speed is 300-500 r / min, the first stirring time is 10-20 min, and the second stirring time is 40-60 min.

[0021] Preferably, the drying temperature is 110-120° C., and the drying time is 1-2 hours.

[0022] Preferably, the calcination temperature is 520-580° C., and the calcination time is 1-4 hours.

[0023] By adopting the above technical solution and controlling the raw material ratio and processing condition parameters within the above range, the loading performance and catalytic performance of the obtained mesoporous zirconium phosphate can be further improved.

[0024] In the second aspect, the present application provides a preparation process of a Ce-based rare earth composite solid strong acid catalyst for biodiesel, which adopts the following technical solution:

[0025] A preparation process of a Ce-based rare earth composite solid strong acid catalyst for biodiesel, comprising the following preparation steps:

[0026] S1. After the active component is added with acid solution and stirred to dissolve, the catalytic component is added and ultrasonically stirred and mixed, and the mixture is allowed to stand for aging to obtain a suspension. S2. After the suspension is dried, it is activated and ground to obtain the desired Ce-based rare earth composite solid strong acid catalyst for biodiesel.

[0027] By adopting the above technical scheme, the active components are dissolved in the mixed acid solution, the catalytic components are dispersed and impregnated, and the desired catalyst is obtained by drying and activation. The preparation process of the present application is simple, the preparation conditions are mild, the loading stability of the active components of the obtained catalyst is good, and during the reaction, the loaded Ce-based rare earth will not fall off and be lost, the catalytic activity is strong, and the reusability is good.

[0028] Preferably, the mixed acid solution in step S1 is a mixture of 18-25 g / L citric acid aqueous solution and 4-dodecylbenzenesulfonic acid; the mass ratio of the citric acid aqueous solution to 4-dodecylbenzenesulfonic acid is 4-6:1.

[0029] Preferably, in step S1, the mass ratio of the active component, the mixed acid solution and the catalytic component is 0.05-0.1:1:1.

[0030] By adopting the above technical scheme, controlling the principle ratio, dissolving the active components in a mixed acid solution and then dispersing and impregnating the catalytic components to obtain a catalyst, the obtained catalyst can accelerate the catalytic ester exchange reaction and esterification reaction at the same time under mild reaction conditions, and can also prevent the generation of foam during the reaction process, thereby further improving the yield of biodiesel.

[0031] Preferably, in step S1, the ultrasonic stirring temperature is 55-65° C., the ultrasonic frequency is 22-28 KHz, the stirring speed is 300-500 r / min, the stirring time is 20-40 min, and the aging time is 2-4 h.

[0032] By adopting the above technical scheme and controlling the ultrasonic stirring and static aging conditions, it is possible to further promote the efficient dispersion of active components and load them inside the pores of the catalytic components, with high loading capacity and good loading stability, thus providing sufficient active sites for the catalytic reaction.

[0033] Preferably, the drying in step S2 specifically refers to: drying the suspension at a temperature of 110-120° C. for 1-2 hours.

[0034] Preferably, the activation in step S2 specifically refers to: in a nitrogen atmosphere, controlling the heating rate to 5-12°C / min, gradually heating from room temperature to 420-460°C, keeping the temperature for activation for 3-5h, cooling to room temperature, and grinding to obtain the desired Ce-based rare earth composite solid strong acid catalyst for biodiesel.

[0035] By adopting the above technical solution and controlling the activation condition parameters within the above range, the catalytic activity and use stability of the catalyst finally obtained can be further improved and the service life can be extended.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. The present application uses mesoporous zirconium phosphate with uniform pore size, orderly arrangement and high porosity as the catalyst catalytic component, which is convenient for heavy oil components and macromolecules to enter for catalytic reaction, has good applicability to catalytic raw materials, has a large specific surface area, and is easy to functionalize the surface. It can be used for active component loading, and can highly disperse the active components so that the active components are evenly distributed on the surface of the catalytic component, with a high loading amount and good loading stability, providing sufficient active sites for the catalytic reaction; a compound of cerium trichloride and cerium oxide is used as the active component, which further improves the catalytic activity and selectivity of the solid strong acid catalyst. The obtained catalyst has high catalytic activity and is used for biodiesel preparation. The first catalytic yield of biodiesel can reach up to 100%.

[0038] 2. After the esterification reaction is completed, the catalyst of the present application can be automatically separated from the liquid product, and the post-processing is simple. The separated catalyst can be reused after a simple activation treatment, and has good reuse performance. After being reused 20 times, it can still achieve a biodiesel yield of more than 90%.

[0039] 3. In the present application, the active components are dissolved in a mixed acid solution, and then the catalytic components are dispersed and impregnated, and the desired catalyst is obtained by drying and activation. The preparation process is simple, the preparation conditions are mild, the loading stability of the active components of the obtained catalyst is good, and during the reaction, the loaded Ce-based rare earth will not fall off and be lost, the catalytic activity is strong, and the reusability is good. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the embodiments.

[0041] Preparation Examples 1-5 and Comparative Preparation Examples 1-2 provide methods for preparing mesoporous zirconium phosphate, which are described below using Preparation Example 1 as an example.

[0042] Preparation Example 1

[0043] Mesoporous zirconium phosphate is prepared by the following method:

[0044] Add zirconium phosphate with a particle size of 30 μm to a polyaluminium chloride solution with a mass concentration of 8%, control the mixing and stirring temperature to 60°C, the mixing and stirring speed to 500 r / min, stir and mix for 10 minutes, add coupling agent KH550 and continue mixing for 60 minutes, mix evenly and place at 110°C, dry for 5 hours, place at 520°C, calcinate for 4 hours, cool and grind to obtain the required mesoporous zirconium phosphate with a Dv50 particle size of 100 nm;

[0045] Wherein, the aluminum oxide content of the polyaluminum chloride in the polyaluminum chloride solution is 28wt%;

[0046] The mass ratio of polyaluminium chloride solution, zirconium phosphate and coupling agent KH550 is 10:5:0.1.

[0047] Preparation Example 2-3 is the same as Preparation Example 1, except that the preparation process parameters are different, as shown in Table 1.

[0048]

[0049]

[0050] Preparation Example 4

[0051] Preparation Example 4 is the same as Preparation Example 1, except that the coupling agent KH550 is replaced by coupling agent KH570.

[0052] Preparation Example 5

[0053] Preparation Example 5 is the same as Preparation Example 1, except that the mass of coupling agent KH550 is replaced by a compound of coupling agent KH550 and coupling agent KH570 in a mass ratio of 1:3.5.

[0054] Comparative Preparation Example 1

[0055] Comparative Preparation Example 1 is the same as Preparation Example 1, except that the mass of the 8% polyaluminium chloride solution is replaced by an 8% aluminium chloride solution.

[0056] Comparative Preparation Example 2

[0057] Comparative Preparation Example 2 is the same as Preparation Example 1, except that the mass of the 8% polyaluminium chloride solution is replaced by water.

[0058] Embodiments 1-9 provide a Ce-based rare earth composite solid strong acid catalyst for biodiesel and a preparation process thereof, which will be described below using Embodiment 1 as an example.

[0059] Example 1

[0060] A Ce-based rare earth composite solid strong acid catalyst for biodiesel, comprising a catalytic component and an active component supported on the catalytic component;

[0061] Wherein, the catalytic component is the mesoporous zirconium phosphate prepared in Preparation Example 1;

[0062] The active components include cerium trichloride and cerium oxide, and the mass ratio of cerium trichloride to cerium oxide is 7.5:1.

[0063] A preparation process of a Ce-based rare earth composite solid strong acid catalyst for biodiesel, comprising the following preparation steps:

[0064] S1. Mix 18 g / L citric acid aqueous solution and 4-dodecylbenzenesulfonic acid in a mass ratio of 4:1 to obtain an acid solution; after the active component is added to the acid solution and stirred to dissolve, the catalytic component is continued to be added and ultrasonically stirred and mixed, the mass ratio of the active component, the mixed acid solution and the catalytic component is 0.05:1:1, the ultrasonic stirring temperature is controlled to be 65°C, the ultrasonic frequency is 22KHz, the stirring speed is 500r / min, and the mixture is stirred and mixed for 20 minutes and then allowed to stand for 4 hours to obtain a suspension;

[0065] S2. Dry the suspension at 120°C for 1 h, then gradually increase the temperature from room temperature to 420°C under a nitrogen atmosphere at a heating rate of 5°C / min, keep the temperature for 5 h, cool to room temperature, and grind to obtain a Ce-based rare earth composite solid strong acid catalyst for biodiesel with a particle size of 60 nm.

[0066] Example 2-3 is the same as Example 1, except that the preparation process parameters are different, as shown in Table 2.

[0067] Table 2:

[0068]

[0069] Example 4

[0070] Example 4 is the same as Example 1, except that an equal amount of the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Preparation Example 2.

[0071] Example 5

[0072] Example 5 is the same as Example 1, except that the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Preparation Example 3.

[0073] Example 6

[0074] Example 6 is the same as Example 1, except that the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Preparation Example 4.

[0075] Example 7

[0076] Example 7 is the same as Example 1, except that the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Preparation Example 5.

[0077] Example 8

[0078] Example 8 is the same as Example 1, except that the active components include cerium trichloride and cerium oxide, and the mass ratio of cerium trichloride to cerium oxide is 8.5:1.

[0079] Example 9

[0080] Example 9 is the same as Example 1, except that the active components include cerium trichloride and cerium oxide, and the mass ratio of cerium trichloride to cerium oxide is 9.5:1.

[0081] In order to verify the efficacy of the Ce-based rare earth composite solid strong acid catalyst for biodiesel prepared in Examples 1-9 of the present application, the applicant set up Comparative Examples 1-8, which are as follows:

[0082] Comparative Example 1

[0083] Comparative Example 1 is the same as Example 1, except that an equal amount of the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Comparative Preparation Example 1.

[0084] Comparative Example 2

[0085] Comparative Example 2 is the same as Example 1, except that an equal amount of the mesoporous zirconium phosphate prepared in Preparation Example 1 is replaced by the mesoporous zirconium phosphate prepared in Comparative Preparation Example 2.

[0086] Comparative Example 3

[0087] Comparative Example 3 is the same as Example 1, except that the active components include cerium trichloride and cerium oxide, and the mass ratio of cerium trichloride to cerium oxide is 1:1.

[0088] Comparative Example 4

[0089] Comparative Example 4 is the same as Example 1, except that the active component is cerium trichloride.

[0090] Comparative Example 5

[0091] Comparative Example 5 is the same as Example 1, except that the active component is cerium oxide.

[0092] Comparative Example 6

[0093] Comparative Example 6 is the same as Example 1, except that an aqueous solution of citric acid having a concentration of 18 g / L and 4-dodecylbenzenesulfonic acid are mixed at a mass ratio of 1:1 to obtain an acid solution.

[0094] Comparative Example 7

[0095] Comparative Example 7 is the same as Example 1, except that the acid solution is a citric acid aqueous solution with a concentration of 18 g / L.

[0096] Comparative Example 8

[0097] Comparative Example 8 is the same as Example 1, except that the acid solution is 4-dodecylbenzenesulfonic acid.

[0098] Performance Verification

[0099] Method for preparing biodiesel from soybean oil using the Ce-based rare earth composite solid strong acid catalyst for biodiesel prepared in Examples 1-9 and Comparative Examples 1-8 of the present application:

[0100] The mass ratio of methanol to soybean oil was controlled to be 10:1, the amount of catalyst added was 2% of the soybean oil, the reaction temperature was controlled to be 80°C, the reaction time was 5h, biodiesel was obtained after the reaction was completed, and the catalyst was recovered by standing separation.

[0101] The yields of the biodiesel obtained are respectively determined by gas chromatography;

[0102] The separated catalyst was placed in a muffle furnace and reactivated at 440°C for 1 hour. After cooling, it was ground into a particle size of 60 nm and then reused. The biodiesel yields after 10 and 20 reuses were measured respectively.

[0103] The specific measurement results are shown in Table 3.

[0104] Table 3:

[0105] Biodiesel yield / % First catalytic yield Catalytic yield after 10 times reuse Catalytic yield after 20 times reuse Example 1 99.78 98.73 92.21 Example 2 99.97 99.07 92.53 Example 3 99.82 98.80 92.15 Example 4 100 99.13 92.79 Example 5 99.86 98.85 92.30 Example 6 99.89 98.86 92.33 Example 7 100 99.29 93.02 Example 8 100 99.35 93.27 Example 9 99.94 98.90 92.45 Comparative Example 1 96.71 94.16 85.73 Comparative Example 2 90.02 86.11 75.42 Comparative Example 3 98.24 97.10 90.06 Comparative Example 4 97.13 96.81 88.74 Comparative Example 5 95.97 94.58 85.35 Comparative Example 6 99.15 98.03 91.05 Comparative Example 7 97.94 96.19 89.11 Comparative Example 8 98.38 96.50 90.77

[0106] Combined with the data shown in Table 3 above, we can see that:

[0107] Examples 1-7 of the present application provide a Ce-based rare earth composite solid strong acid catalyst for biodiesel, which has high catalytic activity and good reusability. Among them, Examples 4 and 7-8 can achieve a biodiesel yield of 100% in the first catalysis, and after being reused 10 times, they can still achieve a biodiesel yield of more than 99%. After being reused 20 times, Examples 7-8 can still achieve a biodiesel yield of more than 93%.

[0108] By comparing Example 1 and Comparative Examples 1-2, it can be seen that the present application uses polyaluminum chloride solution to disperse and adsorb zirconium phosphate. Compared with Comparative Example 1 using aluminum chloride solution and Comparative Example 2 using water, the catalytic activity and reusability of Example 1 of the present application are significantly better.

[0109] By comparing Example 1 with Comparative Examples 3-5, it can be seen that the present application uses a combination of cerium trichloride and cerium oxide as the active component, which has significantly stronger catalytic activity than using cerium trichloride or cerium oxide alone as the active component, especially when the mass ratio of cerium trichloride to cerium oxide is controlled to 8.5:1, the first catalysis can achieve a biodiesel yield of 100%, and the catalytic performance and reuse performance can be further improved.

[0110] By comparing Example 1 with Comparative Examples 6-8, it can be seen that the catalyst is prepared by dissolving the active component in a mixed acid solution and then dispersing and impregnating the catalytic component. The mixed acid solution is a mixture of citric acid aqueous solution and 4-dodecylbenzenesulfonic acid. Compared with using citric acid aqueous solution or 4-dodecylbenzenesulfonic acid alone as the mixed acid solution, the catalytic activity can be further enhanced and the biodiesel yield can be improved. The catalytic performance can be further improved by controlling the ratio of citric acid aqueous solution to 4-dodecylbenzenesulfonic acid to 4:1.

[0111] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A Ce-based rare earth composite solid strong acid catalyst for biodiesel, characterized in that: It comprises a catalytic component and an active component supported on the catalytic component; The catalytic component is mesoporous zirconium phosphate; The Dv of the mesoporous zirconium phosphate 50 Particle size is 100-120nm; The active components include cerium trichloride and cerium oxide; The mass ratio of cerium trichloride to cerium oxide is 7.5-9.5:1; The mesoporous zirconium phosphate is prepared by the following method: Add zirconium phosphate to the aluminum salt solution, stir and mix, then add a silane coupling agent and continue to mix, dry, calcine and grind to obtain the desired mesoporous zirconium phosphate; The aluminum salt solution is a polyaluminum chloride solution with a mass concentration of 8-15%; The Ce-based rare earth composite solid strong acid catalyst for biodiesel is prepared by a process comprising the following preparation steps: S1. After the active component is added with acid solution and stirred to dissolve, the catalytic component is added and ultrasonically stirred and mixed, and the mixture is allowed to stand for aging to obtain a suspension; S2, drying the suspension, activating it, and grinding it to obtain the desired Ce-based rare earth composite solid strong acid catalyst for biodiesel; The activation in step S2 specifically refers to: in a nitrogen atmosphere, controlling the heating rate to be 5-12°C / min, gradually heating from room temperature to 420-460°C, keeping the temperature for activation for 3-5h, cooling to room temperature, and grinding to obtain the desired Ce-based rare earth composite solid strong acid catalyst for biodiesel.

2. The Ce-based rare earth composite solid strong acid catalyst for biodiesel according to claim 1, characterized in that: The silane coupling agent is at least one of coupling agent KH550, coupling agent KH560, and coupling agent KH570.

3. The Ce-based rare earth composite solid strong acid catalyst for biodiesel according to claim 1, characterized in that: The mass ratio of the aluminum salt solution, zirconium phosphate and silane coupling agent is 10:5-6:0.1-0.

3.

4. The Ce-based rare earth composite solid strong acid catalyst for biodiesel according to claim 1, characterized in that: The mixing and stirring temperature is 60-70°C, the mixing and stirring speed is 300-500r / min, the first stirring time is 10-20min, and the second stirring time is 40-60min; The calcination temperature is 520-580° C., and the calcination time is 1-4 hours.

5. The Ce-based rare earth composite solid strong acid catalyst for biodiesel according to claim 1, characterized in that: The mixed acid solution in step S1 is a mixed solution of 18-25 g / L citric acid aqueous solution and 4-dodecylbenzenesulfonic acid; the mass ratio of the citric acid aqueous solution to 4-dodecylbenzenesulfonic acid is 4-6:

1.

6. The Ce-based rare earth composite solid strong acid catalyst for biodiesel according to claim 1, characterized in that: In step S1, the mass ratio of the active component, the mixed acid solution and the catalytic component is 0.05-0.1:1:1.

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