CN116265088A - Preparation of magnetic bifunctional catalyst NiCoAl and research method for hydrodeoxygenation of lignin phenol derivatives - Google Patents

Abstract

The invention discloses a preparation of a magnetic bifunctional catalyst NiCoAl and a research method for hydrogenation and deoxygenation of lignin phenolic derivatives. The preparation method of the bifunctional catalyst is to introduce Ni and Co with metal active components on the basis of Al ₂ O ₃ as the acidic site, through hydrothermal synthesis, and calcining and reducing to synthesize a magnetic NiCoAl catalyst, and then the bifunctional The functional catalyst is applied in the reaction of hydrodeoxygenation of lignin phenolic derivatives. The invention utilizes acidic sites and introduces bimetallic active sites on this basis, which can not only improve the hydrogenation activity but also effectively improve the selectivity of target products, and realize the hydrodeoxygenation of lignin phenolic derivatives. The catalyst is simple to prepare, economical, has high catalytic activity, and metal sites are not easily lost, and can realize efficient conversion of lignin phenol derivatives in the green solvent dioxane (Dio). Lignin phenolic derivatives are important components in bio-oil, and their high-value conversion has a good application prospect.

Description

Preparation of a magnetic bifunctional catalyst NiCoAl and its application in lignin phenolic derivatives Research methods of hydrodeoxygenation

technical field

The invention belongs to the technical field of preparation of catalytic upgrading of lignin phenol derivatives, and relates to the preparation of a magnetic bifunctional catalyst NiCoAl and a research method for hydrogenation and deoxygenation of lignin phenol derivatives.

Background technique

The gradual depletion of petroleum-based fuels has led to a global energy crisis. Greenhouse gas emissions introduced by burning fossil fuels have made global warming one of the greatest environmental challenges in human history. Biomass, as one of the most important renewable resources on earth and the only renewable resource that can be converted into liquid fuels, has received considerable attention in recent years when people are looking for alternatives to fossil fuels. The main components of biomass are cellulose, hemicellulose and lignin. Cellulose and hemicellulose are composed of complex polysaccharides. The unique aromatic structure of lignin makes it a viable chemical feedstock for the production of value-added chemicals and fuels, which can alleviate various problems caused by increasing energy demand. In the conversion route, fast pyrolysis is an efficient and promising method, because high yield and quality liquid fuels can be obtained, and most of the energy in lignin can be preserved in liquid products, but lignin-derived bio Oil is poor quality fuel, unstable and has suboptimal physical properties, so it needs to be upgraded.

Bio-oil itself has some non-ideal properties, including low calorific value, high viscosity, incomplete volatility and chemical instability due to the high oxygen content (35-40 wt%) in the liquid. Upgrading bio-oils to conventional transportation fuels requires extensive deoxygenation, which can be accomplished through two main routes: hydrodeoxygenation and zeolite upgrading. Especially hydrodeoxygenation is considered as an effective method for bio-oil upgrading. There are mainly two types of CO bonds (hydroxyl (C _sp2 -OH) and methoxyl (C _sp2 -OCH ₃ )) in lignophenolic derivatives. Bifunctional catalysts contain metal sites and acidic sites and are commonly used in HDO reactions. Acidic catalysts mainly include solid acids, metal oxides, phosphides, and Lewis acids. It was found that Al ₂ O ₃ was more suitable as a suitable acid site due to its higher total acidity, which is more conducive to the transfer of lignin macromolecules. Noble metals have good activity in HDO of bio-oils, however, their high cost hinders their application in commercial operations. Nickel metal is relatively cheap and also shows high hydrogenation activity, but due to the disadvantages of easy passivation, sintering, carbon deposition, etc., it is difficult to obtain ideal products. On the contrary, cobalt metal has higher selectivity to products, but Co Hydrogenation activity is average.

Aiming at the deficiencies of the prior art, the present invention provides a new reaction method for hydrodeoxygenation of lignin phenolic derivatives. The catalyst can effectively complete the hydrodeoxygenation of lignin phenolic derivatives, wherein the conversion The efficiency can reach 100%, and the selectivity of the corresponding alcohol can reach 80-91%.

Description of drawings

Figure 1 Catalyst X-ray Diffraction Pattern (XRD)

Figure 2 Catalyst transmission electron microscope (SEM&TEM) distribution map

Fig.3 Cycle diagram of catalyst Ni ₁ Co ₃ Al ₂ -600

Figure 4 Separation diagram of catalyst and reaction product

Table 1 Catalyst performance in guaiacol hydrodeoxygenation reaction

Contents of the invention

The present invention is a preparation of a magnetic bifunctional catalyst NiCoAl and a research method on hydrodeoxygenation of lignin phenolic derivatives. The hydrogen activity can also obtain the catalyst of the ideal product, and the product and the catalyst are easy to separate, have high stability, and can be recycled.

Technical solution of the present invention: a preparation of a magnetic bifunctional catalyst NiCoAl and a research method for hydrodeoxygenation of lignin phenolic derivatives, which are characterized by the following steps:

1) Take a certain amount of Al(NO ₃ ) ₃ 9H ₂ O, Co(NO ₃ ) ₂ 6H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O and urea in the PTFE lining, Then add deionized water, and stir magnetically for 10-20 minutes at room temperature;

2) Place the polytetrafluoroethylene lining in step 1 into a hydrothermal reaction kettle, and age it in an oven at a certain temperature for a period of time.

3) After the reaction in step 2 is completed, pour off the supernatant, and wash the solid by centrifugation for 2 to 6 times. After the washing is completed, remove the water in a vacuum drying oven to obtain a solid;

4) putting the solid obtained in step 3 into a crucible, and calcining at high temperature for a certain period of time to finally obtain a catalyst precursor.

5) The catalyst precursor obtained in step 4 is reduced at high temperature for a certain period of time to obtain the final catalyst.

6) Adding lignin phenol derivatives, solvent and catalyst into the autoclave to form a reaction system, the amount of lignin phenol derivatives added is 1-5 mmol, and the amount of catalyst is 0.05 g-0.1 g.

2. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: the bifunctional catalyst, the acidic component of the catalyst is an aluminum compound, and the metal active component is Ni and Co metal.

3. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: the molar ratio of the metal active component to the acidic component is 2-5.

4. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 1), the stirring speed is 600-800rpm.

5. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 2), the temperature of the oven is 100-150°C, and the reaction time is 24-30h.

6. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 3), the vacuum drying time is 6-12 hours, the drying temperature is 50-80° C., and the obtained solid is light red powder.

7. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 3), the solid is calcined under air conditions at 450-600°C for 2-6 hours to obtain a precursor named Ni _x Co _y Al _z -C (x, y, z are the corresponding mole numbers, C is the calcination temperature).

8. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 4), the catalyst precursor is calcined at 450-700° C. under anaerobic conditions for 2-6 hours to obtain the catalyst.

9. The bifunctional NiCoAl catalyst prepared as claimed in claim 1 is used in the experiment of preparing cyclohexanol by hydrodeoxygenation of guaiacol, which is characterized in that it comprises the following steps.

10. The bifunctional NiCoAl catalyst according to claim 1, lignin phenolic derivatives, solvent is added in the autoclave to form a reaction system, the added amount of lignin phenolic derivatives is 1 ~ 5mmol, and the consumption of catalyst is 0.05g～0.1g.

11. At a temperature of 150-250°C, under a hydrogen atmosphere, carry out the reaction for 0.01-8h, and then separate from the catalyst after the reaction to obtain the target product.

12. The solvent is dioxane (Dio), isopropanol (IPA), ethanol (EtOH), methanol (MeOH) and the like.

13. The molar numbers of Ni, Co, and Al contained in the catalyst are 0-5mmol, 0-10mmol, and 2-10mmol respectively, and different metal salts are added according to the preparation of the catalyst, and the catalyst is named Ni _x Co _y Al _z - T (T is the reduction temperature).

14. Advantages of the present invention: the catalyst used in the present invention is cheap and easy to obtain, non-toxic, green and environmentally friendly, and can be reused many times. The reaction system is preferably green and reproducible with solvents, non-toxic, and has high selectivity for obtaining products.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the specific implementation of the present invention will be described in detail below in conjunction with specific examples. In the following description, many specific details are set forth in order to fully understand the present invention, and it should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Implementation Case 1

Add 0.05g ~ 0.1g catalyst, 1 ~ 5mmol guaiacol and 20mL solvent into the autoclave, put a certain amount of pressure into the autoclave, and then set the autoclave to a certain reaction temperature. Stir. After the reaction is finished, cool to room temperature, analyze the liquid product by gas phase, and calculate the conversion rate of guaiacol and the selectivity of cyclohexanol through quantitative analysis.

(1) Catalyst performance comparison

Table 1 ^[a]

[a] Reaction conditions: 1-5 mmol guaiacol, 0.05 g-0.1 g catalyst, 20 mL solvent, 180° C., 2 MPaH ₂ . When dioxane (Dio) was used as the reaction solvent, Ni ₁ Co ₃ Al ₂ -600 catalyst exhibited higher catalytic activity in the reaction of catalyzing the hydrodeoxygenation of guaiacol to prepare cyclohexanol. The conversion rate of guaiacol was 100%, and the selectivity of cyclohexanol was 91%. Therefore, in the following tests, we chose to take Ni ₁ Co ₃ Al ₂ -600 catalyst as an example for exploration.

Implementation Case 2

Take 0.05g～0.1g of catalyst, 1～5mmol of guaiacol and 20mL of dioxane as solvent and put them into the reaction kettle, then feed 1～2MPa _H2 into the reaction kettle, and then set the temperature of the reaction kettle to 180°C, keep stirring during the reaction process, after the reaction is finished, react for a certain period of time, cool to room temperature, and analyze the gas phase product, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 90%. ~91%, and repeated 5 times, as shown in Figure 3, the catalyst maintained good stability. It can be seen from Figure 4 that after the reaction is completed, due to the strong magnetism, it can be quickly separated by a magnet, and the operation is simple and convenient.

Implementation Case 3

Take 0.05g～0.1g of catalyst, 1～5mmol of 3-methoxyphenol and 20mL of dioxane as solvent and add it into the reaction kettle, then feed 1～2MPa _H2 into the reaction kettle, and then control the temperature of the reaction kettle Set it to 180°C, keep stirring during the reaction, and react for a certain period of time. After the reaction is over, cool to room temperature, and analyze the gas phase product. The conversion rate of 3-methoxyphenol is 100%, and that of cyclohexanol is 100%. The selectivity was 83%.

Implementation Case 4

Take 0.05g~0.1g catalyst, 1~5mmol 2,6-dimethoxyphenol and 20mL dioxane as solvent and add it into the reaction kettle, then feed 1~2MPa _H2 into the reaction kettle, and then put the reaction Set the temperature of the kettle to 180°C, keep stirring during the reaction, and react for a certain period of time. After the reaction is completed, cool to room temperature, and analyze the gas phase product, and the conversion rate of 2,6-dimethoxyphenol is 100%. %, the selectivity of cyclohexanol is 90%.

Implementation Case 5

Take 0.05g~0.1g catalyst, 1~5mmol 2-methoxy 4-methylphenol and 20mL dioxane as solvent and add it into the reaction kettle, then feed 1~2MPa H ₂ into the reaction kettle, and then put Set the temperature of the reaction kettle to 180°C, keep stirring during the reaction, and react for a certain period of time. After the reaction is completed, cool to room temperature and analyze the gas phase product to obtain the conversion rate of 2-methoxy 4-methylphenol is 100%, and the selectivity of 4-methylcyclohexanol is 85%.

Implementation Case 6

Take 0.05g～0.1g of catalyst, 1～5mmol of eugenol and 20mL of dioxane as solvent and add it into the reaction kettle, then feed 1～2MPa H ₂ into the reaction kettle, and then set the temperature of the reaction kettle to 180 ℃, keep stirring during the reaction, react for a certain period of time, after the reaction is finished, cool to room temperature, and analyze the gas phase product, the conversion rate of eugenol is 100%, and the selectivity of 4-propylcyclohexanol is 100%. 85%.

Implementation Case 7

Take 0.05g~0.1g catalyst, 1~5mmol 2-methoxy 4-ethylphenol and 20mL dioxane as solvent and add it into the reaction kettle, then feed 1~2MPa H ₂ into the reaction kettle, and then put Set the temperature of the reaction kettle to 180°C, keep stirring during the reaction, and react for a certain period of time. After the reaction is completed, cool to room temperature and analyze the gas phase product to obtain the conversion rate of 2-methoxy 4-ethylphenol was 100%, and the selectivity of 4-ethylcyclohexanol was 88%.

The bifunctional catalyst is suitable for other similar phenolic derivatives. From the above cases, the catalyst has good catalytic activity for the removal of methoxy functional groups, and the corresponding selectivity is high. It can be considered that this type of catalyst is in the Phenol derivatives containing methoxy groups can show good selectivity, and have good application prospects for high-value lignin-derived bio-oils.

Finally, it should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel points disclosed herein.

Claims (13)

1. The preparation of a kind of magnetic bifunctional catalyst NiCoAl and the research method in hydrodeoxygenation of lignin phenolic derivatives, it is characterized in that: this catalyst is based on Al ₂ O ₃ on the basis of acidic active site, has added both The Ni metal that can contribute to hydrogenation activity and the selective Co metal that can also increase the target product are prepared by hydrothermal, calcination and reduction methods according to a certain ratio. The preparation method is as follows: 1) Take a certain amount of Al(NO ₃ ) ₃ 9H ₂ O, Co(NO ₃ ) ₂ 6H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O and urea in the PTFE lining, Then add deionized water, and stir magnetically for 10-20 minutes at room temperature; 2) Place the polytetrafluoroethylene lining in step 1 into a hydrothermal reaction kettle, and age it in an oven at a certain temperature for a period of time. 3) After the reaction in step 2 is completed, pour off the supernatant, and wash the solid by centrifugation for 2 to 6 times. After the washing is completed, remove the water in a vacuum drying oven to obtain a solid; 4) The solid obtained in step 3 is placed in a crucible, and calcined at a high temperature for a certain period of time to finally obtain a catalyst precursor. 5) The catalyst precursor obtained in step 4 is reduced at high temperature for a certain period of time to obtain the final catalyst. 2. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: for the bifunctional catalyst, the acidic component of the catalyst is an Al ₂ O ₃ compound, and the metal active component is Ni and Co metal. 3. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: the molar ratio of the metal active component to the acidic component is 2-5. 4. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 1), the stirring speed is 600-800rpm. 5. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 2), the temperature of the oven is 100-150°C, and the reaction time is 24-30h. 6. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 3), the vacuum drying time is 6-12 hours, the drying temperature is 50-80° C., and the obtained solid is light pink powder. 7. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 3), the solid is calcined at 450-600° C. under air condition for 2-6 hours to obtain the precursor. 8. The bifunctional NiCoAl catalyst according to claim 1, characterized in that: in step 4), the catalyst precursor is calcined at 450-700° C. under anaerobic conditions for 2-6 hours to obtain the catalyst. 9. The bifunctional NiCoAl catalyst prepared as claimed in claim 1 is used in the experiment of hydrodeoxygenation of lignin phenolic derivatives, which is characterized by the following steps. 10. The bifunctional NiCoAl catalyst according to claim 1, lignin phenolic derivatives, solvent is added in the autoclave to form a reaction system, the added amount of lignin phenolic derivatives is 1 ~ 5mmol, and the consumption of catalyst is 0.05g～0.1g. 11. At a temperature of 150-250°C, under a hydrogen atmosphere, carry out the reaction for 0.01-8h, and then separate from the catalyst after the reaction to obtain the target product. 12. The solvent is dioxane (Dio), isopropanol (IPA), ethanol (EtOH), methanol (MeOH) and the like. 13. The molar numbers of Ni, Co, and Al contained in the catalyst are 0-5 mmol, 0-10 mmol, and 2-10 mmol, respectively.

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