Liquid catalyst, preparation method and method for producing second-generation biodiesel

Abstract

The invention relates to the technical field of catalysts, and particularly discloses a liquid catalyst, a preparation method and a method for producing second-generation biodiesel, the liquid catalyst comprises a transition metal component, a functional element auxiliary agent and a compound surfactant; wherein transition metal in the transition metal component is at least two of iron, nickel, cobalt and molybdenum, and the concentration of the transition metal is 0.5-5 wt%; functional elements in the functional element additive comprise lanthanum and ruthenium, and the concentration of the functional elements is 0.1-5 wt%; the molar ratio of lanthanum to ruthenium is (1.5-2): 1; the concentration of the compound surfactant is 0.05 to 0.5 weight percent; the liquid catalyst is used for biodiesel production in a continuous suspended bed reactor. The catalytic activity and stability of the liquid catalyst in the second-generation biodiesel preparation can be improved, and the problem that the liquid catalyst is difficult to recover can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, more particularly, it relates to a liquid catalyst, a preparation method thereof and a method for producing second-generation biodiesel. BACKGROUND

[0002] With the increasing depletion of fossil fuel resources and the increasing environmental protection requirements, biodiesel as a renewable clean energy has attracted widespread attention. The first-generation biodiesel technology is mature but has low energy density and poor low-temperature performance, while the second-generation biodiesel is a clean fuel prepared by hydrogenation deoxygenation process using waste oil and other biomass as raw materials, which has similar chemical structure and performance to petrochemical diesel, higher cetane number, high energy density and excellent low-temperature fluidity, and is a high-end product of current biodiesel technology.

[0003] In the preparation process of the second-generation biodiesel, the solid catalyst used in the traditional fixed-bed hydrogenation process is prone to mechanical wear or breakage due to long-term bearing of bed pressure, fluid scouring and temperature fluctuation, and the generated carbon (especially soft carbon) in the reaction process will cover the active sites on the catalyst surface or block the pores, resulting in rapid decrease of activity, and there may be problems such as easy breakage, rapid deactivation and poor adaptability to raw materials. If a liquid catalyst is used, it can be in the same phase state as the reactants, the intermolecular contact is more sufficient, the mass transfer resistance is significantly reduced, and the active sites of the liquid catalyst can be uniformly dispersed in the reaction system, avoiding the "waste" of active sites caused by particle accumulation or pore restriction of the fixed-bed catalyst, and the liquid catalyst has the advantages of high mass transfer efficiency and high utilization rate of active sites, and has high potential in biodiesel hydrogenation and other reactions.

[0004] In view of the above related technologies, the inventors believe that although the liquid catalyst has the advantages of high mass transfer efficiency and high utilization rate of active sites, its intrinsic activity is often insufficient in actual application, and it is prone to component segregation or surface oxidation under reaction conditions, resulting in attenuation of catalytic activity, and it is also difficult to recover the catalyst, which comprehensively has the problems of low catalytic activity, poor stability and difficult recovery.

[0005] Therefore, there is an urgent need to propose a solution to solve the above technical problems. SUMMARY

[0006] In order to improve the catalytic activity and stability of the liquid catalyst in the preparation of the second-generation biodiesel, and to solve the problem of difficult recovery of the liquid catalyst, the present application provides a liquid catalyst, a preparation method thereof and a method for producing second-generation biodiesel.

[0007] In a first aspect, the present application provides a liquid catalyst, which adopts the following technical scheme: A liquid catalyst, comprising a transition metal component, a functional element assistant and a complex surfactant; wherein the transition metal in the transition metal component is at least two of iron, nickel, cobalt and molybdenum, and the transition metal concentration is 0.5-5wt%; the functional element in the functional element assistant comprises lanthanum and ruthenium, and the functional element concentration is 0.1-5wt%; the molar ratio of the lanthanum and ruthenium is (1.5-2):1; the concentration of the complex surfactant is 0.05-0.5wt%; the liquid catalyst is used for biodiesel production in a continuous suspension bed reactor.

[0008] By adopting the above technical solution, the transition metal acts as an active center, and its d electron orbit can participate in the adsorption and activation of reactant molecules; the complex of multiple transition metals can optimize the electronic structure of the active site through electronic effect and improve the catalytic efficiency. The functional element assistant is used, the introduction of lanthanum can enhance the metal dispersion, inhibit the sintering of the active site, adjust the electron density of ruthenium, optimize the adsorption strength of the reaction intermediate, and avoid the substantial decay of the catalytic activity; the combination of lanthanum and ruthenium can play a complex synergistic effect, and can further balance the activity and durability in the application process of the liquid catalyst and bring corresponding improvement effect. The complex surfactant forms a micelle structure in the reaction system, ensures the uniform distribution of the liquid catalyst in the continuous flow reactor, reduces the interfacial tension between the catalyst and the biomass raw material, promotes the mass transfer efficiency, reduces the adsorption of the catalyst on the reactor wall surface through electrostatic repulsion, and maintains the suspended state of the catalyst, thereby improving the recovery effect. In this way, the functional element assistant and the complex surfactant can fully interact with the transition metal component, which can not only improve the catalytic activity and stability of the liquid catalyst in the second generation of biodiesel production, but also improve the recovery difficulty of the liquid catalyst, realizes efficient, stable and easy-to-recover biodiesel production.

[0009] Preferably, the transition metal in the transition metal component is a combination of nickel and molybdenum, and the molar ratio of nickel and molybdenum is (2-5):1.

[0010] By adopting the technical scheme, the synergistic effect of nickel and molybdenum can significantly regulate the electronic structure of the active site, and the molar ratio of nickel to molybdenum is (2-5):1, which can balance the electronic effect of the two metals and avoid the limitation of a single metal; at the same time, in the nickel-molybdenum system, nickel may be responsible for activating the reactants, while molybdenum promotes the conversion of intermediates, and the two work together to improve the reaction selectivity and efficiency; therefore, under the above combination and corresponding molar ratio, excellent activity and stability can be achieved, and excellent synergistic effect with functional element additives and complex surfactants can be achieved, thereby bringing outstanding performance of the corresponding effect.

[0011] Preferably, the complex surfactant is composed of sodium dodecyl sulfate and Tween 80, and the weight ratio of sodium dodecyl sulfate to Tween 80 is 1:(1-3).

[0012] By adopting the technical scheme, the combination of sodium dodecyl sulfate and Tween 80 can play an excellent synergistic effect, which can improve the interfacial activity of the liquid catalyst and accelerate the mass transfer efficiency, thereby improving the reaction rate, and the mixed micelles formed by the combination of the two can effectively alleviate the catalytic activity decay of the liquid catalyst during application, and make the liquid catalyst uniformly dispersed, thereby significantly enhancing the application stability; at the same time, the use of the above complex surfactant also helps to improve the recovery rate of the liquid catalyst during separation.

[0013] Preferably, the liquid catalyst further comprises a complex adjusting additive, the concentration of the complex adjusting additive is 0.5-3wt%, and the complex adjusting additive is composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol in a weight ratio of (3-5):1:(10-16).

[0014] By adopting the technical scheme, polyvinylpyrrolidone can stabilize the dispersion state of the liquid catalyst, which is beneficial to a certain extent for the liquid catalyst to maintain stable active sites; ethylenediaminetetraacetic acid can selectively bind metal ions, regulate the electronic structure of the active center, promote substrate adsorption and conversion, and improve catalytic activity; polyethylene glycol can optimize the contact efficiency of reactants and catalysts by regulating the solvation environment, thereby improving the catalytic efficiency; when polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol are combined as a complex adjusting additive, the three can play an excellent synergistic effect, not only can form a steric hindrance effect to improve the stability of the liquid catalyst during application, but also can bring an excellent interface regulation effect to improve the catalytic activity of the liquid catalyst during application, and at the same time, it is also beneficial to the separation and recovery of the liquid catalyst; therefore, the catalytic activity and stability of the liquid catalyst in the preparation of the second generation of biodiesel can be further improved, and the problem of difficult recovery of the liquid catalyst can also be improved.

[0015] Preferably, the weight ratio of the polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol is 4:1:13.

[0016] By adopting the above technical solution, the polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol with the above weight ratio have better synergistic effect when applied, and have better adaptability with other component raw materials in the liquid catalyst, thereby facilitating the production of the liquid catalyst with better application quality.

[0017] In a second aspect, the application provides a preparation method of a liquid catalyst, which adopts the following technical solution: A preparation method of a liquid catalyst, comprising the following steps: (1) Dissolve the transition metal component and the functional element additive in deionized water to prepare a mixed solution; (2) Take the mixed solution in step (1) and add a complex surfactant, then stir and mix at 50-70°C, adjust the pH to 6.5-7.5, and then age for 12-24h to obtain the liquid catalyst.

[0018] By adopting the above technical solution, the preparation method is simple in operation, suitable for large-scale industrial production, and can ensure that the component raw materials fully act and cooperate during the process, thereby obtaining the liquid catalyst with excellent and stable quality.

[0019] In a third aspect, the application provides a method for producing second-generation biodiesel by using a liquid catalyst, which adopts the following technical solution: A method for producing second-generation biodiesel by using a liquid catalyst, comprising the following steps: (1) Pretreatment of raw materials, the biomass raw materials are subjected to dehydration and impurity removal treatment; (2) Hydrogenation reaction, the pretreated raw materials obtained in step (1) are introduced into a continuous suspension bed reactor together with the liquid catalyst to perform hydrogenation reaction; (3) Product separation, after the hydrogenation reaction in step (2) is completed, the liquid catalyst is recovered by using centrifugal separation and membrane separation technology, and second-generation biodiesel is obtained.

[0020] By adopting the above technical solution, the pretreatment can remove water and impurities in the biomass raw materials, reduce the generation of by-products in the subsequent reaction, and help to improve the selectivity of the hydrogenation reaction; the continuous suspension bed reactor is used for hydrogenation reaction, which can effectively control the reaction temperature and quickly remove heat, and at the same time, improve the reaction environment of the catalyst and reduce the risk of deactivation; finally, the liquid catalyst is separated and recovered, and second-generation biodiesel is obtained. In the process of producing second-generation biodiesel by using the liquid catalyst, the efficiency, stability and environmental protection can be considered, and the whole process has strong applicability and promotion.

[0021] Preferably, step (1) is specifically provided that the raw material is pretreated, and after the biomass raw material is treated by dehydrating and removing impurities, the raw material is treated by lipase at 45-55°C for 2-4 hours, and the enzyme dosage is 0.5-1.5% of the weight of the raw material.

[0022] By adopting the above technical solution, the lipase can specifically hydrolyze the triglyceride in the biomass raw material to decompose it into free fatty acid and glycerol, providing high-purity substrate for subsequent hydrogenation reaction, reducing reaction energy consumption and improving biodiesel yield. The use of lipase to treat the raw material at 45-55°C for 2-4 hours and the enzyme dosage of 0.5-1.5% of the weight of the raw material can make the enzyme activity higher, accelerate the reaction process, ensure sufficient reaction while avoiding excessive hydrolysis, and thus achieve excellent and stable effect.

[0023] Preferably, the hydrogenation reaction conditions in step (2) are temperature 280-340°C, pressure 8-12 MPa, time 2-6h, and hydrogen oil volume ratio (800-1200):1.

[0024] By adopting the above technical solution, the temperature range can accelerate the hydrogenation deoxidization and cracking reaction rate, and is conducive to improving the equilibrium conversion rate; under the above pressure range, the volume expansion effect of the hydrogenation cracking reaction can be inhibited, the reaction can be promoted in the forward direction, and the alkane yield can be improved; at the same time, the hydrogen oil volume ratio (800-1200):1 can avoid catalyst poisoning and inhibit the generation of carbon deposits, which is conducive to achieving efficient deoxidization and isomerization. Therefore, under the above conditions, the biodiesel produced has high cetane number and high product quality.

[0025] Preferably, in step (3), ceramic ultrafiltration membrane is used to separate the catalyst, the membrane pore size is 10-50nm, the operating pressure is 0.2-0.5MPa, and the temperature is 50-70°C.

[0026] By adopting the above technical solution, the ceramic ultrafiltration membrane, with a pore size of 10-50nm, can effectively retain the transition metal components (such as iron, nickel, cobalt, molybdenum) and functional element additives (such as lanthanum, ruthenium) in the liquid catalyst, while allowing biodiesel (mainly composed of fatty acid methyl ester) to pass through, realizing efficient separation of the catalyst and the product.

[0027] In summary, the present application has the following beneficial effects: 1、In the liquid catalyst, by compounding lanthanum and ruthenium in the functional element additive, and by compounding them with the compounded surfactant, the lanthanum and ruthenium can fully interact with the transition metal components, which can not only improve the catalytic activity and stability of the liquid catalyst in the preparation of the second-generation biodiesel, but also solve the problem of difficult recovery of the liquid catalyst, realizing efficient, stable and easy-to-recover biodiesel production. 2、The application uses sodium dodecyl sulfate and Tween 80 as a complex surfactant, which can effectively improve the interfacial activity of the liquid catalyst and accelerate the mass transfer efficiency, thereby increasing the reaction rate, and effectively alleviate the catalytic activity decay of the liquid catalyst during application, thereby significantly enhancing the application stability. At the same time, the use of the above-mentioned complex surfactant also helps to improve the recovery rate of the liquid catalyst during separation; 3、The application uses a complex adjusting aid composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol. Through the synergistic effect of the three, the catalytic activity and stability of the liquid catalyst in the preparation of the second generation of biodiesel can be further improved, and the recovery difficulty of the liquid catalyst is also improved. DETAILED DESCRIPTION

[0028] The application will be further described in detail below in combination with examples and comparative examples.

[0029] The raw materials used in the examples and comparative examples of the application are commercially available, except as otherwise specified.

[0030] The polyvinylpyrrolidone is purchased from Kunbo Biological Technology Co., Ltd. of Shandong, and the polyvinylpyrrolidone K30 is used. The polyethylene glycol is purchased from Jinan Quanchi New Material Co., Ltd., and PEG6000 is used.

[0031] Example 1 A liquid catalyst comprising a transition metal component, a functional element aid and a complex surfactant; wherein the transition metal in the transition metal component is a combination of nickel and molybdenum, the transition metal concentration is 2.75wt%, and the molar ratio of nickel to molybdenum is 3.5:1; the functional element in the functional element aid is a combination of lanthanum and ruthenium, the functional element concentration is 2.55wt%, and the molar ratio of lanthanum to ruthenium is 1.75:1; the complex surfactant is composed of sodium dodecyl sulfate and Tween 80, the concentration is 0.25wt%, and the weight ratio of sodium dodecyl sulfate to Tween 80 is 1:2; at the same time, the liquid catalyst is prepared by the following steps: (1) Dissolve the transition metal component and the functional element aid in deionized water to prepare a mixed solution; (2) Take the mixed solution in step (1) and add the complex surfactant, then stir and mix at 50-70℃, adjust the pH to 6.5-7.5, and then age for 12-24h to obtain the liquid catalyst.

[0032] Note: In the above step (1), the transition metal component is nickel nitrate and ammonium molybdate, and the functional element aid is lanthanum nitrate and ruthenium chloride; in step (2), the temperature is preferably 60℃, the pH is adjusted to 7, and the aging time is preferably 18h.

[0033] Example 2 A liquid catalyst, different from Example 1 in that the transition metal concentration is 0.5wt%, the functional element concentration is 0.1wt%, and the complex surfactant concentration is 0.05wt%.

[0034] Example 3 A liquid catalyst, different from Example 1 in that the transition metal concentration is 5wt%, the functional element concentration is 5wt%, and the complex surfactant concentration is 0.5wt%.

[0035] Example 4 A liquid catalyst, different from Example 1 in that the molar ratio of nickel to molybdenum is 2:1.

[0036] Example 5 A liquid catalyst, different from Example 1 in that the molar ratio of nickel to molybdenum is 5:1.

[0037] Example 6 A liquid catalyst, different from Example 1 in that the molar ratio of lanthanum to ruthenium is 1.5:1.

[0038] Example 7 A liquid catalyst, different from Example 1 in that the molar ratio of lanthanum to ruthenium is 2:1.

[0039] Example 8 A liquid catalyst, different from Example 1 in that the weight ratio of sodium dodecyl sulfate to Tween 80 is 1:1.

[0040] Example 9 A liquid catalyst, different from Example 1 in that the weight ratio of sodium dodecyl sulfate to Tween 80 is 1:3.

[0041] Example 10 A liquid catalyst, different from Example 1 in that sodium dodecyl sulfate is not used.

[0042] Example 11 A liquid catalyst, different from Example 1 in that Tween 80 is not used.

[0043] Example 12 A liquid catalyst, different from Example 1 in that the liquid catalyst further comprises a complex adjusting auxiliary, the concentration of the complex adjusting auxiliary is 2.25wt%, and the complex adjusting auxiliary is composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid, and polyethylene glycol in a weight ratio of 4:1:13, which is used together with the complex surfactant.

[0044] Example 13 A liquid catalyst, different from example 12 is that the concentration of the complexing agent is 0.5wt%.

[0045] Example 14 A liquid catalyst, different from example 12 is that the concentration of the complexing agent is 3wt%.

[0046] Example 15 A liquid catalyst, different from example 12 is that the complexing agent is composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol in the weight ratio of 3:1:10.

[0047] Example 16 A liquid catalyst, different from example 12 is that the complexing agent is composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol in the weight ratio of 5:1:16.

[0048] Example 17 A liquid catalyst, different from example 12 is that polyvinylpyrrolidone and ethylenediaminetetraacetic acid are not used in the complexing agent.

[0049] Example 18 A liquid catalyst, different from example 12 is that polyvinylpyrrolidone and polyethylene glycol are not used in the complexing agent.

[0050] Example 19 A liquid catalyst, different from example 12 is that ethylenediaminetetraacetic acid and polyethylene glycol are not used in the complexing agent.

[0051] Example 20 A liquid catalyst, different from example 12 is that polyvinylpyrrolidone is not used in the complexing agent.

[0052] Example 21 A liquid catalyst, different from example 12 is that ethylenediaminetetraacetic acid is not used in the complexing agent.

[0053] Example 22 A liquid catalyst, different from example 12 is that polyethylene glycol is not used in the complexing agent.

[0054] Example 23 A method for producing second generation biodiesel by using a liquid catalyst, comprising the following steps: (1) Pretreatment of raw materials, the biomass raw material is treated by dehydration and impurity removal, and the water content is controlled below 0.5%. (2) hydrogenation reaction, the pretreated raw material obtained in step (1) is introduced into a continuous suspension bed reactor with liquid catalyst to perform hydrogenation reaction; (3) product separation, after the hydrogenation reaction in step (2) is completed, liquid catalyst is recovered by using centrifugal separation and membrane separation technology, and the second generation biodiesel is obtained.

[0055] Note: in the above operation, the hydrogenation reaction conditions in step (2) are temperature 310℃, pressure 10MPa, time 4h, and hydrogen / oil volume ratio 1000:1. In step (3), ceramic ultrafiltration membrane is used to separate the catalyst, the membrane pore size is 30nm, the operating pressure is 0.35MPa, and the temperature is 60℃.

[0056] Example 24 A method for producing the second generation biodiesel by liquid catalyst, which is different from example 23 in that the hydrogenation reaction conditions in step (2) are temperature 280℃, pressure 12MPa, time 2h, and hydrogen / oil volume ratio 800:1.

[0057] Example 25 A method for producing the second generation biodiesel by liquid catalyst, which is different from example 23 in that the hydrogenation reaction conditions in step (2) are temperature 340℃, pressure 8MPa, time 6h, and hydrogen / oil volume ratio 1200:1.

[0058] Example 26 A method for producing the second generation biodiesel by liquid catalyst, which is different from example 23 in that in step (3), ceramic ultrafiltration membrane is used to separate the catalyst, the membrane pore size is 10nm, the operating pressure is 0.2MPa, and the temperature is 50℃.

[0059] Example 27 A method for producing the second generation biodiesel by liquid catalyst, which is different from example 23 in that in step (3), ceramic ultrafiltration membrane is used to separate the catalyst, the membrane pore size is 50nm, the operating pressure is 0.5MPa, and the temperature is 70℃.

[0060] Example 28 A method for producing the second generation biodiesel by liquid catalyst, which is different from example 23 in that step (1) is specifically set as raw material pretreatment, after the biomass raw material is treated by dehydration and impurity removal, the raw material is treated by lipase at 50℃ for 3 hours, and the enzyme dosage is 1% of the weight of the raw material.

[0061] Example 29 A method for producing second generation biodiesel by using liquid catalyst, which is different from example 23 in that step (1) is specifically set as follows: pretreatment of raw material, after the biomass raw material is treated by dehydration and impurity removal, the raw material is treated by lipase at 45℃ for 4 hours, and the enzyme dosage is 0.5% of the weight of the raw material.

[0062] Example 30 A method for producing second generation biodiesel by using liquid catalyst, which is different from example 23 in that step (1) is specifically set as follows: pretreatment of raw material, after the biomass raw material is treated by dehydration and impurity removal, the raw material is treated by lipase at 55℃ for 2 hours, and the enzyme dosage is 1.5% of the weight of the raw material.

[0063] Comparative example 1 A liquid catalyst, which is different from example 1 in that no functional element additive is used.

[0064] Comparative example 2 A liquid catalyst, which is different from example 1 in that no complex surfactant is used.

[0065] Comparative example 3 A liquid catalyst, which is different from example 1 in that no functional element additive and no complex surfactant are used.

[0066] Comparative example 4 A liquid catalyst, which is different from example 1 in that the functional element in the functional element additive does not contain lanthanum.

[0067] Comparative example 5 A liquid catalyst, which is different from example 1 in that the functional element in the functional element additive does not contain ruthenium.

[0068] Performance detection test Test samples: the liquid catalysts prepared by using examples 1-22 are selected as test samples 1-22, and the liquid catalysts prepared by using comparative examples 1-5 are selected as control samples 1-5.

[0069] Test method: test sample 1 is selected, and the method for producing second generation biodiesel by using liquid catalyst in examples 23-30 is used for application, and the biomass raw material is catering waste oil (acid value 25 mg KOH / g); Test samples 1-22 and control samples 14-5 are selected, and the method for producing second generation biodiesel by using liquid catalyst in example 23 is used for application, and the biomass raw material is refined soybean oil (acid value 0.2 mg KOH / g); The above applications were respectively tested for conversion rate (%), cetane number, acid value (mgKOH / g), condensation point (°C), sulfur content (ppm), catalyst recovery rate (%) and catalyst life (times), and the test results were recorded in Table 1 and Table 2, respectively.

[0070] Table 1 Application test results of examples 23-30

[0071] Table 2 Application test results of test samples 1-22 and control samples 1-5

[0072] In combination with examples 23-30 and in combination with Table 1, it can be seen that the application provides a method for producing second-generation biodiesel with liquid catalyst, which can exhibit excellent and stable application effects, and after the biomass raw material is treated by dehydration and impurity removal, the use of lipase can further improve the quality of the final product, and the overall application is better.

[0073] In combination with examples 1 and comparative examples 1-3 and in combination with Table 2, it can be seen that in the liquid catalyst of the application, the combined action of the functional element additive and the complex surfactant can improve the catalytic activity and stability of the liquid catalyst in the preparation of second-generation biodiesel, and can also improve the problem of difficult recovery of the liquid catalyst. After the above tests, the performance of conversion rate (%), cetane number, acid value (mgKOH / g), condensation point (°C), sulfur content (ppm), catalyst recovery rate (%) and catalyst life (times) are obviously improved. In combination with comparative examples 4-5 and in combination with Table 2, it can be seen that if lanthanum or ruthenium is used alone, even if it is used together with the complex surfactant, the corresponding effect will be obviously lost, and compared with the case where no functional element additive is used, the sum of the improvement effect brought by the single action of lanthanum or ruthenium is also far less than the excellent combination of the two. Therefore, it can be seen that the lanthanum and ruthenium in the functional element additive can realize synergistic effect in the application process, thereby ensuring efficient, stable and easy-to-recover biodiesel production.

[0074] In combination with examples 1 and examples 8-11 and in combination with Table 2, it can be seen that the combination of sodium dodecyl sulfate and Tween 80 can exhibit excellent synergistic effect, which can significantly enhance the application stability of the liquid catalyst. If sodium dodecyl sulfate or Tween 80 is used alone, it is found that the application effect of the liquid catalyst will be obviously lost, which indicates that the synergistic cooperation between the two can form excellent and stable cooperation with other raw materials, thereby playing a better role effect.

[0075] It can be seen from the combination of Embodiment 1 and Embodiments 12-22 and Table 2 that the application uses the complex adjustment agent composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol, and the complex synergistic effect brought by the three can further improve the catalytic activity and stability of the liquid catalyst in the preparation of the second generation of biodiesel, and the problem of difficult recovery of the liquid catalyst is also enhanced; if any one or two of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol is used, the sum of the improvement effect brought by each of them is far inferior to the excellent improvement effect brought by the synergistic effect of the three, and only simple addition of the effect can be brought between any two, so it can be seen that the action system of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol is indispensable, and is the key to realize the excellent application performance improvement of the liquid catalyst.

[0076] The specific embodiments are only an explanation of the application, and are not a limitation of the application, and those skilled in the art can make modifications to the embodiments without creative contribution according to the needs after reading the specification, but as long as the scope of the claims of the application is within the scope of the patent law.

Claims

1. A liquid catalyst, characterized in that, The liquid catalyst comprises a transition metal component, functional element auxiliaries, and a compound surfactant; The transition metal component comprises at least two of the following: iron, nickel, cobalt, and molybdenum, with a transition metal concentration of 0.5-5 wt%. The functional element additive contains lanthanum and ruthenium, with a concentration of 0.1-5 wt%; the molar ratio of lanthanum to ruthenium is (1.5-2):

1. The concentration of the compound surfactant is 0.05-0.5 wt%; The liquid catalyst is used in a continuous suspended bed reactor for biodiesel production.

2. The liquid catalyst according to claim 1, characterized in that: The transition metal component is a combination of nickel and molybdenum, and the molar ratio of nickel to molybdenum is (2-5):

1.

3. The liquid catalyst according to claim 1, characterized in that: The compound surfactant is composed of sodium dodecyl sulfate and Tween 80, and the weight ratio of sodium dodecyl sulfate to Tween 80 is 1:(1-3).

4. The liquid catalyst according to claim 1, characterized in that: The liquid catalyst further comprises a compound regulating agent, the concentration of which is 0.5-3 wt%, and the compound regulating agent is composed of polyvinylpyrrolidone, ethylenediaminetetraacetic acid and polyethylene glycol in a weight ratio of (3-5):1:(10-16).

5. The liquid catalyst according to claim 4, characterized in that: The weight ratio of polyvinylpyrrolidone, ethylenediaminetetraacetic acid, and polyethylene glycol is 4:1:

13.

6. The method for preparing the liquid catalyst according to claim 1, characterized in that: Includes the following steps: (1) Dissolve the transition metal components and functional element additives in deionized water to prepare a mixed solution; (2) Take the mixture from step (1) and add the compound surfactant, then stir and mix at 50-70℃, adjust the pH to 6.5-7.5, and then mature for 12-24h to obtain the liquid catalyst.

7. A method for producing second-generation biodiesel using the liquid catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Raw material pretreatment: Dehydration and impurity removal of biomass raw materials; (2) Hydrogenation reaction: The pretreated raw material obtained in step (1) and the liquid catalyst are fed into a continuous suspended bed reactor for hydrogenation reaction; (3) Product separation: After the hydrogenation reaction in step (2) is completed, the liquid catalyst is recovered by centrifugal separation and membrane separation technology to obtain second-generation biodiesel.

8. The method for producing second-generation biodiesel according to claim 7, characterized in that: Step (1) is specifically set as follows: raw material pretreatment, after the biomass raw material is dehydrated and impurities are removed, the raw material is treated with lipase at 45-55℃ for 2-4 hours, and the amount of enzyme used is 0.5-1.5% of the weight of the raw material.

9. The method for producing second-generation biodiesel according to claim 7, characterized in that: The hydrogenation reaction conditions in step (2) are: temperature 280-340℃, pressure 8-12MPa, time 2-6h, and hydrogen-oil volume ratio (800-1200):

1.

10. The method for producing second-generation biodiesel according to claim 7, characterized in that: In step (3), a ceramic ultrafiltration membrane is used to separate the catalyst. The membrane pore size is 10-50 nm, the operating pressure is 0.2-0.5 MPa, and the temperature is 50-70 °C.

Images