Multifunctional catalyst for preparing bio-jet fuel by hydrogenation isomerization of oil and fat and preparation method thereof

Abstract

The application discloses a multifunctional catalyst for preparing bio-jet fuel by oil hydrogenation isomerization and a preparation method thereof, and belongs to the field of bio-oil and biomass hydrogenation for preparing bio-diesel or bio-jet fuel. The catalyst is a non-supported Mo2NiP x W y M z , wherein 0.6<=x<=1.2, 0 The preparation method comprises the following steps: mixing a solid compound containing Mo and Ni with phosphoric acid, adding deionized water and heating and stirring to form a green transparent solution; adding an aqueous solution of a soluble solid compound containing W, Nb and other metals; after cooling, adding a hole expanding agent and a binder, continuously stirring to form a paste, and then drying, extruding into a strip, drying and calcining to obtain the multifunctional non-supported oil hydrogenation isomerization catalyst. The method has the advantages of simple preparation process, environmental protection, no pollution, mild preparation conditions, good hydrogenation deoxidization activity of the obtained catalyst, strong acidity, high isomerized alkane selectivity, low price, no need of noble metal, and the ability to meet the production requirements of bio-jet fuel and bio-diesel with low condensation points.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bio-oil and biomass hydrogenation to produce biodiesel or bio-jet fuel, and particularly relates to a multifunctional non-supported catalyst with hydrogenation deoxygenation, isomerization and aromatization functions and a method for preparing bio-jet fuel by hydrogenation isomerization of oil. BACKGROUND

[0002] With the global oil reserves drying up in recent years, we are in urgent need of a substitute for fossil fuels. Bio-oil has been considered as an environmentally friendly renewable resource, which has low nitrogen, sulfur and aromatic content, and high fuel performance, and is an ideal substitute for oil. However, due to the high oxygen content and unsaturation of oil, it needs to be hydrogenated to improve the oxidative stability and oil quality. Isomeric alkanes are products obtained by isomerization of n-alkanes, and are important components of gasoline, diesel or aviation kerosene, which can greatly reduce the low-temperature fluidity of the three, and can be mixed with oil-based oil in any proportion in low-temperature environment, and is the key to producing low-condensation-point oil. When the catalyst has strong acidity, the chain alkanes may undergo cyclization and aromatization reactions on the acid sites to generate naphthenes and aromatics, and the aromatics are one of the substances necessary to increase the lubricity of oil, so the production of high-stability bio-oil with high content of isomeric alkanes and aromatics has become a research hotspot.

[0003] There are many types of catalysts for hydrogenation deoxygenation and isomerization of bio-oil, so our catalysts are required to have excellent hydrogenation activity and sufficient strong acid sites to ensure the isomerization reaction. Although noble metal catalysts have high hydrogenation activity, their high price and scarcity limit their wide application and hinder their industrialization process. The deoxygenation activity of sulfide catalysts is excellent, but the activity of the catalysts will gradually decrease during the reaction, and additional sulfurizing agent needs to be added to maintain the activity of the catalysts, which inevitably causes sulfur pollution to bio-oil. The synthesis cost of metal carbide or nitride catalysts is high, the active sites are easy to lose, the pore structure has many defects, and the deoxygenation activity is insufficient, which hinders the industrial application. Some catalysts have good catalytic activity at higher than 500℃, but high temperature consumes a lot of energy, and the catalyst surface is easy to sinter, which covers the active sites, reduces the catalytic activity, and leads to a decrease in hydrogenation deoxygenation and isomerization rate.

[0004] CN109833906B discloses a kind of Pd-Ni2P hydrogenation isomerization bifunctional catalyst with multistage hole nano SAPO-31 molecular sieve as carrier to plant oil hydrogenation deoxidization oil carries out hydrogenation isomerization to prepare low freezing point biodiesel, catalyst reaction activity and isomerization selectivity are high, and biodiesel yield is better, but the introduction of noble metal Pd will limit industrial application, and the loading of the supported catalyst is not good control, and the loading is limited.CN116328830A discloses a sulfidized hydrogenation isomerization catalyst, which is prepared by in-situ sulfidation of molybdenum source and molecular sieve, and is used for hydrogenation deoxidization isomerization of fatty acid and fatty acid methyl ester oil product.The catalyst prepared by the method has mild acidity and low cracking rate, but the catalyst has high selectivity for linear alkanes and low selectivity for isomeric alkanes, which is about 30% at most, and needs to be improved;In addition, the catalyst needs to continuously add sulfur powder to maintain the sulfur environment and catalyst activity during the reaction, which will cause different degrees of sulfur pollution to the obtained oil product.CN110871083A discloses a non-supported Ni x Nb y O z as catalyst for hydrogenation deoxidization of oleic acid and stearic acid and shows good catalytic performance.This reflects that it is feasible to use non-supported catalyst for hydrogenation deoxidization of oil and fat, and avoids the limitation of support on active component, and is simple to operate.Therefore, it is very important to develop a sulfur-free catalyst with simple preparation method, low price, green and pollution-free, good hydrogenation activity and high selectivity of isomeric alkanes. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of multifunctional catalyst for preparing bio-jet fuel by hydrogenation isomerization of oil and fat, which has good hydrogenation deoxidization activity, high selectivity of isomeric alkanes, strong acidity, low price, no need for noble metal, simple preparation process, green and pollution-free, mild preparation conditions, and can meet the production requirements of low freezing point oil product.

[0006] The technical scheme of the catalyst according to the present application is as follows:

[0007] (1) Mix molybdenum trioxide (ammonium molybdate or phosphomolybdic acid), basic nickel carbonate (nickel acetate or nickel nitrate) and phosphoric acid in a high-pressure kettle according to the molar ratio of MoNiP of 2:1:0.6-1.2, add deionized water in the ratio of m 含钼化合物 :m 去离子水 =0.3:1, and continuously stir at a temperature of 60-150℃ for 1.5-2.5h to obtain a green transparent MoNiP solution;

[0008] (2) In the green transparent solution obtained in step (1), add the aqueous solution of ammonium metatungstate (ammonium tungstate or phosphotungstic acid) and niobium oxalate hydrate (ammonium niobate oxalate hydrate) or lanthanum acetate (lanthanum chloride or lanthanum nitrate) or cerium acetate (cerium nitrate or cerium ammonium nitrate) in the order of Mo:Ni:PW:M:W:M' = 2:1:0.6-1.2:0-2.0:0-1.0 (molar ratio) with an interval of 0.5-1 h, and continue stirring at 60-150 °C for 0.5-1 h to obtain a MoNiPWM mixed solution;

[0009] (3) Cool the mixed solution obtained in step (2) to room temperature, and add 1-5 wt% of methyl cellulose and 0-30 wt% of pseudoboehmite in the order with an interval of 0.5-1 h, and then continue stirring at room temperature for 0.5-1 h to obtain a MoNiPWM paste;

[0010] (4) Extrude the paste into a strip after slight drying, transfer it to an oven at 80-120 °C for drying for 8-12 h, and then transfer it to a muffle furnace for calcination at 450-550 °C for 2-6 h, and obtain a multifunctional non-supported oil hydroisomerization catalyst after cooling.

[0011] (5) Before use, activate the multifunctional non-supported oil hydroisomerization catalyst at a temperature of 400-500 °C and a hydrogen pressure of 1-4 MPa for 8-12 h. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 Fig. a and b are the liquid chromatograms of the partial products of the hydrogenation isomerization reaction of methyl stearate catalyzed by the Mo2NiP 0.8 catalyst of Example 4. 0.8 W 0.5 Nb 0.5 Fig. c is the liquid chromatogram of the partial products of the hydrogenation isomerization reaction of methyl stearate catalyzed by the Mo2NiP

[0013] The method of the present application is further illustrated in detail by the following examples:

[0014] Comparative Example

[0015] Mix 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate and 3.14 g of phosphoric acid in an autoclave, add 38 mL of deionized water and continuously stir at 90 °C for 2 h to obtain a green transparent MoNiP solution; cool the obtained green transparent solution to room temperature, and then add 0.74 g of methyl cellulose and 10.31 g of pseudoboehmite in the order with an interval of 30 min under stirring; continue stirring at room temperature for 30 min to obtain a paste. Extrude the paste into a strip after slight drying, transfer it to an oven at 80 °C for drying for 12 h; then transfer it to a muffle furnace for calcination at 500 °C for 4 h, and obtain the catalyst Mo2NiP 0.8which is denoted as Cat-0.

[0016] Example 1

[0017] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate and 3.14 g of phosphoric acid were mixed, 38 mL of deionized water was added and stirred at 90°C for 2 h to obtain a green transparent MoNiP solution; 0.99 g of ammonium metatungstate was dissolved in water and added to the obtained MoNiP solution and stirred at 90°C for 30 min to obtain a MoNiPW mixed solution; after the mixed solution was cooled to room temperature, 0.79 g of methyl cellulose and 10.88 g of pseudoboehmite were added in turn under stirring, with an interval of 30 min; after continuous stirring at room temperature for 30 min, a paste was obtained. The paste was slightly dried and extruded into strips, transferred to an oven at 80°C and dried for 12 h; then it was transferred to a muffle furnace and calcined at 500°C for 4 h, and after cooling, the catalyst Mo2NiP 0.8 W 0.1 which is denoted as Cat-1.

[0018] Example 2

[0019] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate and 3.14 g of phosphoric acid were mixed, 38 mL of deionized water was added and stirred at 90°C for 2 h to obtain a green transparent MoNiP solution; 0.99 g of ammonium metatungstate was dissolved in water and added to the obtained MoNiP solution and stirred at 90°C for 30 min to obtain a MoNiPW mixed solution; after the mixed solution was cooled to room temperature, 0.79 g of methyl cellulose and 10.88 g of pseudoboehmite were added in turn under stirring, with an interval of 30 min; after continuous stirring at room temperature for 30 min, a paste was obtained. The paste was slightly dried and extruded into strips, transferred to an oven at 80°C and dried for 12 h; then it was transferred to a muffle furnace and calcined at 500°C for 4 h, and after cooling, the catalyst Mo2NiP 0.8 W 0.5 which is denoted as Cat-2.

[0020] Example 3

[0021] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate, and 3.14 g of phosphoric acid were mixed, and 38 mL of deionized water was added. The mixture was stirred continuously at 90 °C for 2 h to obtain a green transparent MoNiP solution. 9.85 g of ammonium metatungstate was dissolved to prepare an aqueous solution, which was then added to the obtained MoNiP solution and stirred at 90 °C for 30 min to obtain a MoNiPW mixed solution. After cooling the mixed solution to room temperature, 1.15 g of methylcellulose and 15.99 g of boehmite were added sequentially under stirring, with a 30 min interval between additions. Stirring was continued at room temperature for another 30 min to obtain a paste. The paste was slightly dried, extruded into strips, and dried in an 80 °C oven for 12 h. Subsequently, it was transferred to a muffle furnace and calcined at 500 °C for 4 h. After cooling, the catalyst Mo2NiP was obtained. 0.8 W 1.0 It is denoted as Cat-3.

[0022] Example 4

[0023] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate, and 3.14 g of phosphoric acid were mixed, and 38 mL of deionized water was added. The mixture was stirred continuously at 90 °C for 2 h to obtain a green transparent MoNiP solution. 4.93 g of ammonium metatungstate and 10.76 g of niobium oxalate hydrate were dissolved separately to prepare aqueous solutions, which were then added sequentially to the obtained MoNiP solution while stirring continuously at 90 °C, with a 30 min interval between each addition. After reacting for 1 h, a MoNiPWNb mixed solution was obtained. The obtained mixed solution was cooled to room temperature, and 1.07 g of methylcellulose and 14.78 g of boehmite were added sequentially under stirring, with a 30 min interval between each addition. Stirring was continued at room temperature for another 30 min to obtain a paste. The paste was slightly dried, extruded into strips, and dried in an 80 °C oven for 12 h. Subsequently, it was transferred to a muffle furnace and calcined at 500 °C for 4 h. After cooling, the catalyst Mo2NiP was obtained. 0.8 W 0.5 Nb 0.5 It is denoted as Cat-4.

[0024] Example 5

[0025] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate, and 3.14 g of phosphoric acid were mixed, and 38 mL of deionized water was added. The mixture was stirred continuously at 90 °C for 2 h to obtain a green transparent MoNiP solution. 4.93 g of ammonium metatungstate and 6.32 g of lanthanum acetate were dissolved separately to prepare aqueous solutions, which were then added sequentially to the obtained MoNiP solution while stirring continuously at 90 °C, with a 30-min interval between each addition. After reacting for 1 h, a MoNiPWLa mixed solution was obtained. The obtained mixed solution was cooled to room temperature, and 1.09 g of methylcellulose and 15.15 g of boehmite were added sequentially under stirring, with a 30-min interval between each addition. Stirring was continued at room temperature for another 30 min to obtain a paste. The paste was slightly dried, extruded into strips, and dried in an 80 °C oven for 12 h. Subsequently, it was transferred to a muffle furnace and calcined at 500 °C for 4 h. After cooling, the catalyst Mo2NiP was obtained. 0.8 W 0.5 La 0.5 It is denoted as Cat-5.

[0026] Example 6

[0027] In an autoclave, 11.52 g of molybdenum trioxide, 5.02 g of basic nickel carbonate, and 3.14 g of phosphoric acid were mixed, and 38 mL of deionized water was added. The mixture was stirred continuously at 90 °C for 2 h to obtain a green transparent MoNiP solution. 4.93 g of ammonium metatungstate and 6.35 g of cerium acetate were dissolved separately to prepare aqueous solutions, which were then added sequentially to the obtained MoNiP solution while stirring continuously at 90 °C, with a 30-min interval between each addition. After reacting for 1 h, a MoNiPWCe mixed solution was obtained. The obtained mixed solution was cooled to room temperature, and 1.10 g of methylcellulose and 15.26 g of boehmite were added sequentially under stirring, with a 30-min interval between each addition. Stirring was continued at room temperature for another 30 min to obtain a paste. The paste was slightly dried, extruded into strips, and dried in an 80 °C oven for 12 h. Subsequently, it was transferred to a muffle furnace and calcined at 500 °C for 4 h. After cooling, the catalyst Mo2NiP was obtained. 0.8 W 0.5 Ce 0.5 It is denoted as Cat-6.

[0028] Example 7

[0029] This embodiment describes a method for evaluating catalyst activity.

[0030] 2 mL of catalyst was activated and reduced for 8 h in a fixed-bed apparatus at 380 °C, 3 MPa hydrogen pressure, and 30 mL / min hydrogen flow rate. Subsequently, activation and reduction were carried out at 360 °C, 3 MPa hydrogen pressure, and 3 h⁻¹ liquid hourly space velocity. -1 Under reaction conditions of a hydrogen-to-oil ratio of 300:1, 10 wt% methyl stearate / cyclohexane was used as a raw material for hydroisomerization.

[0031] The table below shows the product distribution of the hydrogenation isomerization reaction of methyl stearate using the catalyst of this invention. Wherein nC 5～18 iC represents the content of n-alkanes with 5 to 18 carbon atoms in the product. 5～18 The content of isoalkanes with 5 to 18 carbon atoms in the product is proportional to iC. 5～18 / nC 5～18 The value of C 9～14 This refers to the content of alkanes (normal and isomers) with 9 to 14 carbon atoms in the product, i.e., the content of alkanes in the jet fuel fraction.

[0032] Table 1. Distribution of products from the hydroisomerization reaction of methyl stearate using the catalyst of the present invention.

[0033]

[0034] Table 1 above lists the product distribution of the hydroisomerization reaction of methyl stearate under different catalysts. The data shows that the content of isoalkanes was significantly increased under the catalytic action of the oil hydroisomerization catalyst prepared by the method of this invention. In Example 4, Mo2NiP... 0.8 W 0.5 Nb 0.5 C in the reaction products of the catalyst 5～18 The highest content of isoalkanes was observed, reaching 66.76%, with an iso-to-normal ratio of 3.60. The isoalkanes content in the products of other catalysts was also no less than 60%, indicating that the catalyst prepared by this method has high isoalkanes selectivity, which can increase the low-temperature fluidity of oil products and meet the production requirements of low-pour-point aviation kerosene. Furthermore, the content of aromatic hydrocarbons and cycloalkanes in the reaction products of the catalyst prepared using this invention method also increased to varying degrees. In Example 4, the content of these two hydrocarbons in Mo2NiP... 0.8 W 0.5 Nb 0.5 The catalyst's reaction products contained the highest amounts of aromatic hydrocarbons (9.57%) and cycloalkanes (4.41%), indicating that the catalyst prepared by this method had improved acidity, leading to aromatization and cycloalkylation of some alkanes. Aromatic hydrocarbons are essential for increasing the lubricity of aviation kerosene. Finally, the table also shows a significant increase in the alkane content within the aviation kerosene fraction of the prepared catalyst, particularly in Example 4 where Mo2NiP... 0.8 W 0.5 Nb 0.5 The catalyst exhibits the highest alkane content in the jet fuel fraction, reaching 54.03%. In summary, the catalyst prepared by this invention demonstrates high hydrodeoxygenation and isomerization activity, good selectivity for alkane components in jet fuel, and fully meets the production requirements for jet fuel with low pour point and high oxidation stability.

[0035] Figure 1 Figures a and b show the Mo2NiP in Comparative Example 1, respectively. 0.8 Catalyst and Mo2NiP in Example 4 0.8 W 0.5 Nb 0.5 The gas chromatogram of some liquid products from the hydroisomerization reaction of methyl stearate under the catalysis of the catalyst shows that the content of isoalkanes increases significantly and the selectivity of isoalkanes increases under the catalysis of the catalyst prepared by the method of this invention, that is, the catalyst has excellent hydroisomerization performance.

[0036] The above description represents the preferred embodiment of the present invention, but is not limited to certain specific details. Some simple improvements and modifications can be made to the technical solution without departing from the technical concept of the present invention, but such improvements and modifications are all within the protection scope of the present invention.

Claims

1. The application of a multifunctional catalyst in the hydroisomerization of oils to prepare biojet fuel, characterized in that, The molar composition of the active component in the bulk phase of the catalyst is Mo2NiP x W y M z Where 0.6≤x≤1.2, 0<y≤2.0, 0<z≤1.0, and y+z≥0.1, and metal M is Nb, the preparation of this catalyst includes the following steps: (1) In a high-pressure reactor, solid molybdenum-containing compounds, nickel-containing compounds, and phosphoric acid are mixed in a molar ratio of 2:1:0.6 to 1.2 (MoNiP), with mass m 含钼化合物 :m 去离子水 Add deionized water at a ratio of 0.3:1 and stir continuously at 60–150°C for 1.5–2.5 h to obtain a green transparent solution; (2) Add soluble tungsten salt and soluble niobium salt aqueous solutions sequentially to the green transparent solution obtained in step (1) in the proportion of MoNiPWM molar ratio of 2:1:0.6~1.2:0~2.0:0~1.0, with an interval of 0.5~1h between the two additions, and then continue stirring at 60~150℃ for 0.5~1h to obtain a MoNiPWM mixed solution; (3) Cool the mixed solution obtained in step (2) to room temperature, add 1-5 wt% methylcellulose and 0-30 wt% boehmite in sequence, with an interval of 0.5-1 h between the two additions, and then continue stirring at room temperature for 0.5-1 h to obtain MoNiPWM paste; (4) After slightly drying the paste, it is extruded into strips and transferred to an oven at 80-120°C for 8-12 hours. Then it is transferred to a muffle furnace and calcined at 450-550°C for 2-6 hours. After cooling, it becomes a multifunctional unsupported oil hydroisomerization catalyst. (5) Before using the multifunctional unsupported oil hydroisomerization catalyst, activate it at a temperature of 400-500℃ and a hydrogen pressure of 1-4MPa for 8-12 hours.

2. The application according to claim 1, characterized in that: Solid molybdenum-containing compounds are molybdenum trioxide, ammonium molybdate, or phosphomolybdic acid.

3. The application according to claim 1, characterized in that: The nickel-containing compounds are basic nickel carbonate, nickel acetate, or nickel nitrate.

4. The application according to claim 1, characterized in that: Soluble tungsten salts are ammonium metatungstate, phosphotungstic acid, or ammonium tungstate.

5. The application according to claim 1, characterized in that: The soluble niobium salt is niobium oxalate hydrate or ammonium oxalate hydrate.

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