Mo-pr liquid catalyst for hydroconversion of biomass feedstock and preparation method and application thereof

Abstract

The application relates to a Mo-Pr liquid catalyst for hydrogen conversion of a biomass raw material, which comprises the following raw materials: a molybdate, praseodymium nitrate and an organic ligand, wherein the molar ratio of Mo in the molybdate to Pr in the praseodymium nitrate is (5-15):1. The conversion rate of the catalyst for hydrogen conversion of the biomass raw material is greater than 92%, the cetane number is greater than 65, the condensation point is less than -22 DEG C, the sulfur content is less than 10 ppm, and the cycle number of the catalyst is greater than 20 times.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biofuels, and particularly relates to a Mo-Pr liquid catalyst for hydrogenation conversion of biomass raw materials and a preparation method and application thereof. BACKGROUND

[0002] The second generation of biodiesel (i.e. hydrogenated vegetable oil, HVO) has become an important direction for replacing fossil fuels due to its excellent blending property with petroleum diesel and more excellent environmental performance. Existing industrial production mainly relies on hydrogenation treatment of a supported solid catalyst (such as Ni-Mo / Al2O3, Co-Mo / Al2O3) in a fixed bed reactor. This technical route has inherent defects: first, the internal surface utilization rate of the solid catalyst is low, especially for macromolecular oil and fat raw materials, the mass transfer resistance is large; second, the catalyst is easy to be deactivated due to coking and metal deposition, has a short service life, is frequently replaced, has high cost and produces solid waste; third, the fixed bed reactor is prone to pressure drop and bed plugging problems when processing high-viscosity raw materials.

[0003] In order to overcome the limitations of solid catalysts, liquid catalyst systems have begun to attract attention. Liquid catalysts can theoretically achieve molecular-level contact with reactants, eliminate internal diffusion limitations, and improve atomic economy. However, existing liquid catalyst systems (such as homogeneous acid and base catalysts) face two major challenges: first, the balance between catalytic activity and stability is difficult to achieve, and second, the separation and recovery of catalysts and products after the reaction are extremely difficult, resulting in high cost and environmental pollution, making it difficult to achieve industrial application.

[0004] Therefore, there is an urgent need in the art for a catalyst system that has high catalytic activity, excellent stability and can be recovered simply and efficiently, and a matching reaction process, to break through the technical and economic bottlenecks of the production of the second generation of biodiesel. SUMMARY

[0005] The purpose of the present application is to overcome the inherent defects of existing solid catalysts and traditional homogeneous catalysts, and to provide a new second generation of biodiesel production solution that integrates high-performance liquid catalysts with special reaction and separation technologies.

[0006] In the first aspect of the present application, the present application provides a Mo-Pr liquid catalyst for hydrogenation conversion of biomass raw materials, comprising the following raw materials: molybdate, praseodymium nitrate and organic ligand, the molar ratio of Mo in the molybdate to Pr in the praseodymium nitrate being (5-15): 1.

[0007] By adopting the technical scheme, the application provides a Mo-Pr liquid catalyst for hydrogenation conversion of biomass raw materials, the conversion rate of the catalyst for hydrogenation conversion of biomass raw materials is greater than 92%, the cetane number is greater than 65, the condensation point is less than -22 DEG C, the sulfur content is less than 10 ppm, and the cycle number of the catalyst is greater than 20 times. This may be because, on the one hand, Mo 4+ / Mo 6+ and Pr 3+ / Pr 4+ form a heteronuclear electron transition channel, significantly reduce the C-O bond dissociation energy barrier, and the oxygen vacancy induced by Pr can timely remove CO / CO2, and inhibit carbon deposition; on the other hand, the liquid catalyst eliminates the internal diffusion resistance, so that the reaction can be completed at a lower temperature and a shorter residence time.

[0008] Optionally, the organic ligand is at least one of citric acid, oxalic acid or tartaric acid, and the ratio of the molar amount of the organic ligand to the total molar amount of Mo and Pr is (1.5-2.5):1.

[0009] By adopting the technical scheme, the catalyst is formed by selecting a specific organic ligand (such as citric acid) and reacting with a molybdenum source under weak acidic conditions to form a liquid complex stable in water. The catalyst has strong homogeneity, and the active sites are highly dispersed, and there is no internal diffusion problem.

[0010] In the second aspect of the application, the application provides a preparation method of the Mo-Pr liquid catalyst for hydrogenation conversion of biomass raw materials in the first aspect, comprising the following steps:

[0011] a1: preparing a mixed solution of molybdate and praseodymium nitrate;

[0012] a2: adding an organic ligand to the mixed solution of molybdate and praseodymium nitrate prepared in step a1, stirring, adjusting pH, and reacting to obtain a Mo-Pr-organic ligand solution;

[0013] a3: cooling, constant volume, aging, and obtaining a Mo-Pr liquid catalyst.

[0014] In the third aspect of the application, the application provides a method for producing second-generation biodiesel by using the Mo-Pr liquid catalyst for hydrogenation conversion of biomass raw materials in the first aspect of the application, comprising the following steps:

[0015] S1: enzymatically hydrolyzing biomass raw materials to obtain pretreated biomass raw materials;

[0016] S2: adding the Mo-Pr liquid catalyst for the hydrogenation conversion of the biomass raw material into the pretreated biomass raw material obtained in step S1, and reacting in a fixed bed reactor and a suspension bed reactor, and separating and recovering the Mo-Pr liquid catalyst to obtain the second-generation biodiesel.

[0017] By adopting the technical scheme, in the fixed bed reaction zone, the system provides a necessary high-pressure and high-temperature environment, so that the active species in the liquid catalyst are activated in situ or converted into high-activity intermediate states, and meanwhile, the deep hydrogenation and saturation reactions of the biomass raw material are completed; when the reaction material enters the suspension bed reaction zone, the moderate reduction of the pressure and the change of the flow state promote the active species and the reaction intermediates to perform sufficient mass transfer and subsequent conversion reactions, and meanwhile, the excessive cracking and carbon deposition are effectively inhibited.

[0018] Optionally, in step S2, the volume ratio of the fixed bed reactor reaction zone to the suspension bed reactor reaction zone is 1:2.

[0019] Optionally, in step S2, the operation conditions of the fixed bed reactor reaction zone are as follows: the pressure is 12-18 MPa, the temperature is 330-370 ℃, the hydrogen / oil volume ratio is 800-1000:1, and the liquid hourly space velocity is 1.0-2.0 h -1 ;

[0020] In step S2, the operation pressure of the suspension bed reactor reaction zone is 0-0.1 MPa, the temperature is 330-370 ℃, the hydrogen / oil volume ratio is 400-600:1, and the liquid hourly space velocity is 0.8-1.0 h -1 .

[0021] Optionally, the biomass raw material in step S1 is catering waste oil.

[0022] Optionally, in step S1, the biomass raw material is subjected to enzymatic hydrolysis by using lipase PS-IM.

[0023] The addition amount of the lipase PS-IM is 0.5-1.5% of the weight of the biomass raw material, the enzymatic hydrolysis temperature is 45-55 ℃, and the enzymatic hydrolysis time is 4-8 h.

[0024] Optionally, in step S2, the separation and recovery of the Mo-Pr liquid catalyst comprises the following steps:

[0025] a: liquid-liquid separation: separating the reaction product to obtain an oil phase rich in biodiesel and a water phase containing the liquid catalyst;

[0026] b: catalyst concentration: concentrating the separated water phase to obtain concentrated catalyst;

[0027] c: recycling: recycling the concentrated catalyst solution by adding water.

[0028] Optionally, the catalyst in step b is concentrated by dehydrating and concentrating the separated water phase through a nanofiltration membrane system.

[0029] The nanofiltration membrane has a molecular weight cut-off of 200-500 Dalton, an operating pressure of 1.0-3.0 MPa, and a temperature of 50-70℃.

[0030] In the fourth aspect of the present application, the present application provides a second-generation biodiesel produced by the method for producing second-generation biodiesel using the Mo-Pr liquid catalyst for the hydrogenation conversion of biomass raw materials according to the first aspect of the present application.

[0031] In summary, the present application has at least one of the following beneficial technical effects:

[0032] 1. The present application provides a Mo-Pr liquid catalyst for the hydrogenation conversion of biomass raw materials, which has a conversion rate greater than 92%, a cetane number greater than 65, a freezing point less than -22℃, a sulfur content less than 10 ppm, and a catalyst cycle number greater than 20 times. In one aspect, the Mo 4+ / Mo 6+ and Pr 3+ / Pr 4+ form a heteronuclear electron transition channel, significantly reducing the C-O bond dissociation energy barrier, while the Pr-induced oxygen vacancies can timely remove CO / CO2, inhibiting carbon deposition; on the other hand, the liquid catalyst eliminates internal diffusion resistance, allowing the reaction to be completed at a lower temperature and shorter residence time.

[0033] 2. The present application provides a method for producing second-generation biodiesel using the Mo-Pr liquid catalyst for the hydrogenation conversion of biomass raw materials. In the fixed bed reaction zone, the system provides the necessary high pressure and high temperature environment, so that the active species in the liquid catalyst are activated or converted into highly active intermediate states in situ, while completing the deep hydrogenation and saturation reactions of the biomass raw materials; when the reaction material enters the suspension bed reaction zone, the moderate reduction of pressure and the change of flow state promote the active species and reaction intermediates to undergo sufficient mass transfer and subsequent conversion reactions, while effectively inhibiting excessive cracking and carbon deposition. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. The specific conditions not mentioned in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer, and the reagents or instruments not mentioned by the manufacturer are conventional products that can be purchased on the market.

[0035] Lipase PS-IM was purchased from Shanghai Macklin Biochemical Technology Co., Ltd. (P953726), and free lipase NS81006 was purchased from Novozymes.

[0036] Preparation Example 1

[0037] Preparation of Mo-Pr liquid catalyst

[0038] a1: 13.24 g (NH4)6Mo7O 24 ·4H2O was dissolved in 60 mL of deionized water, and stirred at 70°C until completely transparent to obtain a (NH4)6Mo7O 24 solution;

[0039] a2: 3.26 g Pr(NO3)3·6H2O was weighed according to Mo / Pr=10 (molar ratio), and the (NH4)6Mo7O 24 solution prepared in step a1 was added, and stirring was continued at 70°C for 10 min to obtain a mixed solution of (NH4)6Mo7O 24 and Pr(NO3)3;

[0040] a3: 31.70 g of citric acid (Cit) was added to the mixed solution of (NH4)6Mo7O 24 and Pr(NO3)3 prepared in step a2, and stirring was continued at 70°C; the pH was adjusted to 4.0, and the reaction was kept for 3 h to obtain a Mo-Pr-Cit solution, wherein the molar ratio of citric acid to the total molar amount of Mo and Pr was 2.0:1;

[0041] a4: After stopping heating and cooling to room temperature, it was transferred into a 200 mL volumetric flask, water was added to constant volume, and it was sealed and placed in a 60°C oven for aging for 18 h to obtain a Mo-Pr liquid catalyst.

[0042] Preparation Example 2

[0043] Preparation Example 2 is different from Preparation Example 1 in that Mo / Pr=5 (molar ratio).

[0044] Specifically, the preparation of step a2 is different, specifically: 6.52 g Pr(NO3)3·6H2O was weighed according to Mo / Pr=5 (molar ratio), and the (NH4)6Mo7O 24 solution prepared in step a1 was added at 70°C, and stirring was continued for 10 min to obtain a mixed solution of (NH4)6Mo7O 24 and Pr(NO3)3;

[0045] Specifically, the preparation of step a3 is different, and 31.70 g of citric acid (Cit) was added to the mixed solution of (NH4)6Mo7O 2434.58 g of citric acid (Cit) was added to a mixed solution of Mo and Pr(NO3)3, and the mixture was stirred at 70 °C. The pH was adjusted to 4.0, and the reaction was maintained at this temperature for 3 h to obtain a Mo-Pr-Cit solution, wherein the molar ratio of citric acid to the total molar ratio of Mo and Pr was 2.0:1.

[0046] Preparation Example 3

[0047] The difference between Preparation Example 3 and Preparation Example 1 is that Mo / Pr = 15 (molar ratio).

[0048] Specifically, the preparation of step a2 is different, as follows: 2.17g of Pr(NO3)3·6H2O is weighed according to a Mo / Pr ratio of 15, and (NH4)6Mo7O prepared in step a1 is added at 70℃. 24 The solution was stirred for another 10 minutes to obtain (NH4)6Mo7O. 24 A mixed solution of Pr(NO3)3;

[0049] Specifically, the preparation of step a3 is different, and the (NH4)6Mo7O prepared in step a2 is used instead. 24 Add 30.74 g of citric acid (Cit) to a mixed solution of Mo and Pr(NO3)3, and continue stirring at 70 °C; adjust the pH to 4.0, and keep the reaction at this temperature for 3 h to obtain a Mo-Pr-Cit solution, wherein the molar ratio of citric acid to the total molar ratio of Mo and Pr is 2.0:1.

[0050] Preparation Example 4

[0051] The difference between Preparation Example 4 and Preparation Example 1 is that the molar ratio of citric acid to the total molar ratio of Mo and Pr is 1.5:1.

[0052] Specifically, the preparation of step a3 is different, specifically: (NH4)6Mo7O prepared in step a2 is... 24 23.77 g of citric acid (Cit) was added to a mixed solution of Mo and Pr(NO3)3, and the mixture was stirred at 70 °C. The pH was adjusted to 4.0, and the reaction was maintained at this temperature for 3 h to obtain a Mo-Pr-Cit solution, wherein the molar ratio of citric acid to the total molar ratio of Mo and Pr was 1.5:1.

[0053] Preparation Example 5

[0054] The difference between Preparation Example 5 and Preparation Example 1 is that the molar ratio of citric acid to the total molar ratio of Mo and Pr is 2.5:1.

[0055] Specifically, the preparation of step a3 is different, specifically: (NH4)6Mo7O prepared in step a2 is... 2439.62 g of citric acid (Cit) was added to a mixed solution of Mo and Pr(NO3)3, and the mixture was stirred at 70 °C. The pH was adjusted to 4.0, and the reaction was maintained at this temperature for 3 h to obtain a Mo-Pr-Cit solution, wherein the molar ratio of citric acid to the total molar ratio of Mo and Pr was 2.5:1.

[0056] Preparation Example 6

[0057] The difference between Preparation Example 6 and Preparation Example 1 is that the organic ligand citric acid is replaced with tartaric acid in equimolar amounts.

[0058] Specifically, the preparation of step a3 is different, specifically: (NH4)6Mo7O prepared in step a2 is... 24 Add 24.76 g of tartaric acid (Tart) to a mixed solution of Mo and Pr(NO3)3, and continue stirring at 70 °C; adjust the pH to 4.0, and keep the reaction at this temperature for 3 h to obtain a Mo-Pr-Tart solution, wherein the molar ratio of tartaric acid to the total molar ratio of Mo and Pr is 2.0:1.

[0059] Comparative Preparation Example 1

[0060] The difference between Preparation Example 1 and Preparation Example 2 is that Pr is replaced with Mo in equimolar amounts.

[0061] Specifically, the preparation steps differ, as follows:

[0062] a1: 13.24g of (NH4)6Mo7O 24 • 4H₂O was dissolved in 60 mL of deionized water and stirred at 70 °C until completely transparent to obtain the first (NH₄)₆Mo₇O. 24 Solution;

[0063] a2: Weigh 1.32g (NH4)6Mo7O 24 ·4H2O, add the first (NH4)6Mo7O prepared in step a1 24 The solution was stirred at 70°C for 10 minutes to obtain the second (NH4)6Mo7O. 24 Solution;

[0064] a3: The second (NH4)6Mo7O prepared in step a2 is then... 24 31.70 g of citric acid (Cit) was added to the solution and stirred at 70 °C. The pH was adjusted to 4.0 and the reaction was maintained at this temperature for 3 h to obtain a Mo-Cit solution, wherein the molar ratio of citric acid to Mo was 2.0:1.

[0065] a4: Stop heating, cool to room temperature, transfer to a 200mL volumetric flask, add water to make up to volume, seal and place in a 60℃ oven for aging for 18h to obtain the Mo liquid catalyst.

[0066] Comparative Preparation Example 2

[0067] Comparative Preparation Example 2 differs from Preparation Example 1 in that Mo is replaced by Pr in equimolar amount.

[0068] Specifically, the preparation steps are different, specifically:

[0069] a1: 32.6g Pr(NO3)3·6H2O was dissolved in 60mL deionized water, stirred at 70℃ until completely transparent to obtain a first Pr(NO3)3solution;

[0070] a2: 3.26g Pr(NO3)3·6H2O was weighed and added to the first Pr(NO3)3solution prepared in step a1, and continued to be stirred at 70℃ for 10min to obtain a second Pr(NO3)3solution;

[0071] a3: 31.70g citric acid (Cit) was added to the second Pr(NO3)3solution prepared in step a2, and continued to be stirred at 70℃; the pH was adjusted to 4.0, and the reaction was kept for 3h to obtain a Pr-Cit solution, wherein the ratio of the molar amount of citric acid to the molar amount of Pr was 2.0:1;

[0072] a4: stop heating, cool to room temperature, transfer to a 200mL volumetric flask, add water to constant volume, seal and mature in a 60℃ oven for 18h to obtain a Pr liquid catalyst.

[0073] Example 1

[0074] Example 1 provides a method for producing second-generation biodiesel using a liquid catalyst, which specifically comprises the following steps:

[0075] S1: Take 100g of catering waste oil, stir and heat to 50℃, then slowly add 1M 2-amino-2-methyl-1-propanol to pH=8.0, and then add 1.0g of lipase PS-IM, and enzymatically hydrolyze at 50℃ for 6h to obtain a reaction mixture;

[0076] S2: Separate the lipase PS-IM from the above reaction mixture by a plate and frame filter, collect the liquid phase and heat to 85℃, and heat for 15min to obtain a pretreated biomass raw material;

[0077] S3: The pretreated biomass raw material obtained in step S2 is pumped into a fixed bed-suspension bed combined reactor (volume ratio of fixed bed reaction zone to suspension bed reaction zone is 1:2) together with 5.0g of Mo-Pr liquid catalyst prepared in Preparation Example 1, and the reaction and catalyst recovery are completed according to the following procedure:

[0078] (1) Fixed bed section: pressure 15 MPa, temperature 350°C, hydrogen to oil volume ratio 900:1, liquid hourly space velocity 1.5 h -1 , deep hydrodeoxygenation;

[0079] (2) Suspended bed section: pressure reduced to 0.05 MPa, temperature 350°C, hydrogen to oil volume ratio 500:1, liquid hourly space velocity 1.0 h -1 , continued reaction and inhibition of cracking and carbon deposition;

[0080] (3) The reaction product is separated to recover the catalyst to obtain the second generation biodiesel, and the separation and recovery of the catalyst uses the following steps:

[0081] (a) Liquid-liquid separation: the reaction product is first separated by centrifugation to obtain an oil phase rich in biodiesel and an aqueous phase containing liquid catalyst;

[0082] (b) Catalyst concentration: the separated aqueous phase is concentrated by dehydrating through a nanofiltration membrane system, the nanofiltration membrane has a molecular weight cut-off of 350 daltons, the operating pressure is 2.0 MPa, and the temperature is 60°C;

[0083] (c) Recycling: the concentrated catalyst solution is supplemented with deionized water to a weight of 5.0 g and returned to step S3 for recycling.

[0084] Example 2

[0085] Example 2 provides a method for producing second generation biodiesel using a liquid catalyst, which is different from Example 1 in that the liquid catalyst used in step S3 is the Mo-Pr liquid catalyst prepared in Preparation Example 2.

[0086] Example 3

[0087] Example 3 provides a method for producing second generation biodiesel using a liquid catalyst, which is different from Example 1 in that the liquid catalyst used in step S3 is the Mo-Pr liquid catalyst prepared in Preparation Example 3.

[0088] Example 4

[0089] Example 4 provides a method for producing second generation biodiesel using a liquid catalyst, which is different from Example 1 in that the liquid catalyst used in step S3 is the Mo-Pr liquid catalyst prepared in Preparation Example 4.

[0090] Example 5

[0091] Example 5 provides a method for producing second generation biodiesel using a liquid catalyst, which is different from Example 1 in that the liquid catalyst used in step S3 is the Mo-Pr liquid catalyst prepared in Preparation Example 5.

[0092] Example 6

[0093] Example 6 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the liquid catalyst used in step S3 is the Mo-Pr liquid catalyst prepared in preparation example 6.

[0094] Example 7

[0095] Example 7 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the mass of lipase PS-IM used in step S1 for enzymatic pretreatment of biomass raw material is different.

[0096] Specifically, step S1 is different, specifically: take 100 g of catering waste oil, stir and heat to 50℃, then slowly add 1M 2-amino-2-methyl-1-propanol to pH=8.0, then add 0.5 g of lipase PS-IM, and enzymatically hydrolyze at 50℃ for 6 h to obtain a reaction mixture.

[0097] Example 8

[0098] Example 8 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the mass of lipase PS-IM used in step S1 for enzymatic pretreatment of biomass raw material is different.

[0099] Specifically, step S1 is different, specifically: take 100 g of catering waste oil, stir and heat to 50℃, then slowly add 1M 2-amino-2-methyl-1-propanol to pH=8.0, then add 1.5 g of lipase PS-IM, and enzymatically hydrolyze at 50℃ for 6 h to obtain a reaction mixture.

[0100] Example 9

[0101] Example 9 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the lipase PS-IM used in step S1 for enzymatic pretreatment of biomass raw material is replaced by free lipase NS81006.

[0102] Comparative Example 1

[0103] Comparative Example 1 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the liquid catalyst used in step S3 is the Mo liquid catalyst prepared in comparative preparation example 1.

[0104] Comparative Example 2

[0105] Comparative Example 2 provides a method for producing second generation biodiesel by using liquid catalyst, which is different from example 1 in that the liquid catalyst used in step S3 is the Pr liquid catalyst prepared in comparative preparation example 2.

[0106] Comparative Example 3

[0107] Comparative Example 3 provides a method for producing second generation biodiesel using liquid catalyst, which is different from Example 1 in that the catering waste oil is not pretreated by enzymatic hydrolysis.

[0108] Comparative Example 4

[0109] Comparative Example 4 provides a method for producing second generation biodiesel using liquid catalyst, which is different from Example 1 in that the liquid catalyst used in step S3 is a commercially available conventional solid Mo / Al2O3 catalyst.

[0110] Comparative Example 5

[0111] Comparative Example 5 provides a method for producing second generation biodiesel using liquid catalyst, which is different from Example 1 in that the reaction is not carried out using a suspended bed.

[0112] Specifically, step S3 is different, specifically: the pretreated biomass raw material obtained in step S2 is pumped into a fixed bed reactor together with 5.0 g of Mo-Pr liquid catalyst prepared in Preparation Example 1, and the reaction and catalyst recovery are completed according to the following procedure:

[0113] (1) Fixed bed section: pressure 15 MPa, temperature 350 ℃, hydrogen / oil volume ratio 900:1, liquid hourly space velocity 1.5 h -1 , deep hydrodeoxygenation;

[0114] (2) The reaction product is separated to recover the catalyst to obtain second generation biodiesel, and the recovery of the catalyst uses the following steps:

[0115] (a) Liquid-liquid separation: the reaction product is first centrifuged to obtain an oil phase rich in biodiesel and an aqueous phase containing liquid catalyst;

[0116] (b) Catalyst concentration: the separated aqueous phase is concentrated by a nanofiltration membrane system, the molecular weight cut-off of the nanofiltration membrane is 350 daltons, the operating pressure is 2.0 MPa, and the temperature is 60 ℃;

[0117] (c) Recycling: the concentrated catalyst solution is supplemented with deionized water to a weight of 5.0 g and returned to step S3 for recycling.

[0118] Performance test

[0119] Product analysis:

[0120] Cetane number: ASTM D613;

[0121] Pour point: ASTM D2500;

[0122] Sulfur content: ASTM D5453;

[0123] Process evaluation:

[0124] Conversion rate calculation: gravimetric method, calculation formula as follows:

[0125] Conversion rate = m1 / (m0-m1) x 100%;

[0126] In the formula, m0 is the mass (g) of pretreated biomass raw material, and m1 is the mass (g) of biodiesel.

[0127] Catalyst stability: when the conversion rate is < 50%, it is judged that the catalyst is deactivated, which is counted by the number of recycling of the catalyst.

[0128] Energy consumption analysis: online monitoring system, i.e. energy consumption analysis using energy management software (EMS).

[0129] Among them, the energy consumption includes: biomass raw material pretreatment energy consumption, catalyst preparation energy consumption, reaction process energy consumption, catalyst separation and recovery energy consumption and equipment operation energy consumption.

[0130] The specific results are shown in Table 1.

[0131] Table 1

[0132]

[0133] It can be seen from Examples 1-3 and Table 1 that in Example 1, when Mo / Pr = 10 (molar ratio), the catalytic activity of the Mo-Pr liquid catalyst, i.e. the conversion rate of catering waste oil to biodiesel, is the highest, and the stability of the catalyst is the best.

[0134] It can be seen from Examples 1, Examples 4-5 and Table 1 that in Example 1, when the molar ratio of citric acid to Mo is 2.0:1, the catalytic activity of the Mo-Pr liquid catalyst, i.e. the conversion rate of catering waste oil to biodiesel, is the highest, and the stability of the catalyst is the best.

[0135] It can be seen from Examples 1, Example 6 and the data in Table 1 that in Example 1, the Mo-Pr liquid catalyst prepared by selecting citric acid as the organic ligand has the optimal conversion rate of catering waste oil to biodiesel compared with the Mo-Pr liquid catalyst prepared by selecting tartaric acid as the organic ligand in Example 6. This may be because citric acid has more coordination teeth, and thus has stronger chelation strength, which is more conducive to enhancing the stability of Mo-Pr bimetallic and further enhancing the synergistic effect of Mo-Pr bimetallic.

[0136] From the combination of Example 1, Example 7-8 and Table 1, it can be seen that the amount of lipase PS-IM used for enzymatic pretreatment of the restaurant waste oil is controlled between 0.5-1.5% by weight of the restaurant waste oil. When the amount of lipase PS-IM used in Example 7 is less, the conversion rate of the restaurant waste oil into biodiesel is reduced, and the stability of the catalyst is also poor.

[0137] From the combination of Example 1, Example 9 and Table 1, it can be seen that the catalytic activity of the Mo-Pr liquid catalyst, i.e. the conversion rate of the restaurant waste oil into biodiesel, is lower than that of Example 1 when the lipase PS-IM is replaced by an equal amount of free lipase NS81006 in Example 9. This may be because the free lipase NS81006 cannot be filtered out from the pretreated biomass raw material, and the enzyme will denature and precipitate in the subsequent high-temperature reaction stage, which may cause blockage, affect the actual pressure during the reaction, and thus affect the catalytic activity of the catalyst.

[0138] From the combination of Example 1, Comparative Examples 1-2 and Table 1, it can be seen that when either of Mo or Pr is missing in the liquid catalyst system, the conversion rate of the restaurant waste oil into biodiesel is reduced, and the service life of the catalyst is shortened due to the destruction of the synergistic effect of Mo and Pr.

[0139] From the combination of Example 1 and Comparative Example 3, it can be seen that when the restaurant waste oil is not subjected to enzymatic pretreatment, the mass transfer and diffusion resistance may increase sharply due to the high molecular weight and high viscosity of the triglyceride, and the decarboxylation / decarbonylation path is inhibited, which may more easily lead to catalyst carbon deposition, and thus significantly reduce the conversion rate and the service life of the catalyst.

[0140] From the combination of Example 1, Comparative Example 4 and Table 1, it can be seen that the conversion rate is reduced, the service life of the catalyst is significantly reduced, and the energy consumption is higher when a conventional solid catalyst is used. This may be because the mass transfer efficiency of the liquid catalyst is better than that of the solid catalyst, and the liquid catalyst has high-dispersed active sites.

[0141] From the combination of Example 1, Comparative Example 5 and Table 1, it can be seen that when the reactor only uses a fixed bed reactor, the conversion rate is reduced, the service life of the catalyst is reduced, and the energy consumption is higher. This may be because the lack of a suspended bed for low-pressure post-treatment results in incomplete reaction, catalyst carbon deposition, and high hydrogen circulation load throughout the high-temperature and high-pressure process.

[0142] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application. Therefore, any equivalent changes made on the basis of the products, methods and principles of the present application should be covered by the protection scope of the present application.

Claims

1. A Mo-Pr liquid catalyst for hydroconversion of biomass feedstock to produce second generation biodiesel, characterized in that, The liquid catalyst comprises the following raw materials: molybdate, praseodymium nitrate and organic ligand, the molar ratio of Mo in the molybdate to Pr in the praseodymium nitrate is (5-15):1, the organic ligand is at least one of citric acid, oxalic acid or tartaric acid, and the ratio of the molar amount of the organic ligand to the total molar amount of Mo and Pr is (1.5-2.5):

1. The preparation method of the liquid catalyst comprises the following steps: a1: preparing a mixed solution of molybdate and praseodymium nitrate; a2: adding an organic ligand to the mixed solution of molybdate and praseodymium nitrate prepared in step a1, stirring, adjusting pH, and reacting to obtain a Mo-Pr-organic ligand solution; a3: cooling, constant volume, and aging to obtain a Mo-Pr liquid catalyst.

2. A process for the preparation of the Mo-Pr liquid catalyst according to claim 1, characterized in that, The preparation method of the liquid catalyst comprises the following steps: a1: preparing a mixed solution of molybdate and praseodymium nitrate; a2: adding an organic ligand to the mixed solution of molybdate and praseodymium nitrate prepared in step a1, stirring, adjusting pH, and reacting to obtain a Mo-Pr-organic ligand solution; a3: cooling, constant volume, and aging to obtain a Mo-Pr liquid catalyst.

3. A method for producing second generation biodiesel using the Mo-Pr liquid catalyst of claim 1, characterized by, The preparation method of the liquid catalyst comprises the following steps: S1: enzymolysis of a biomass raw material to obtain pretreated biomass raw material; S2: adding the Mo-Pr liquid catalyst of claim 1 to the pretreated biomass raw material obtained in step S1, and performing fixed bed reactor reaction and suspension bed reactor reaction, and separating and recovering the Mo-Pr liquid catalyst to obtain the second generation biodiesel.

4. The process for the production of second generation biodiesel using Mo-Pr liquid catalyst for hydroconversion of biomass feedstock as claimed in claim 3 wherein, In step S2, the volume ratio of the fixed bed reactor reaction zone to the suspension bed reactor reaction zone is 1:

2.

5. The process for the production of second generation biodiesel using Mo-Pr liquid catalyst for hydroconversion of biomass feedstock as claimed in claim 3 wherein, In step S2, the operating conditions of the fixed bed reactor reaction zone are: pressure 12-18 MPa, temperature 330-370℃, hydrogen / oil volume ratio 800-1000:1, and liquid hourly space velocity 1.0-2.0 h-1. In step S2, the operating pressure of the suspension bed reactor reaction zone is 0-0.1 MPa, the temperature is 330-370℃, the hydrogen / oil volume ratio is 400-600:1, and the liquid hourly space velocity is 0.8-1.0 h-1.

6. The process for the production of second generation biodiesel using Mo-Pr liquid catalyst for hydroconversion of biomass feedstock as claimed in claim 3 wherein, In step S1, the enzymolysis of the biomass raw material uses lipase PS-IM. The addition amount of the lipase PS-IM is 0.5-1.5% of the weight of the biomass raw material, the enzymolysis temperature is 45-55℃, and the enzymolysis time is 4-8 h.

7. The process for the production of second generation biodiesel using Mo-Pr liquid catalyst for hydroconversion of biomass feedstock as claimed in claim 3 wherein, In step S2, the separation and recovery of the Mo-Pr liquid catalyst comprises the following steps: a: liquid-liquid separation: separation of the reaction product to obtain an oil phase rich in biodiesel and a water phase containing the liquid catalyst; b: catalyst concentration: concentrating the separated water phase to obtain concentrated catalyst; c: recycling: recycling the concentrated catalyst solution by adding water.

8. The process for the production of second generation biodiesel from Mo-Pr liquid catalyst for hydroconversion of biomass feedstock as claimed in claim 7 wherein, In step b, the catalyst concentration is dehydration concentration of the separated water phase by a nanofiltration membrane system. The nanofiltration membrane has a molecular weight cut-off of 200-500 daltons, an operating pressure of 1.0-3.0 MPa, and a temperature of 50-70℃.

9. A second generation biodiesel characterized in that, The second generation biodiesel is produced by the method of any one of claims 3-8.

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