Preparation of titanium aluminum oxide loaded NiCo catalyst and method for preparing cyclohexanol by hydrodeoxygenation of guaiacol

Abstract

The invention discloses preparation of a titanium aluminum oxide loaded NiCo catalyst and a research method for applying the catalyst to hydrodeoxygenation of lignin-derived phenolic compounds. The preparation method of the catalyst comprises the following steps: preparing two composite metal oxides of gamma-Al2O3 and TiO2 as a carrier by a gel-sol method, loading two active components nickel and cobalt on the carrier by an impregnation method, synthesizing the NiCo / gamma-Al2O3-TiO2 catalyst by calcination reduction, and then applying the catalyst to the hydrodeoxygenation process of guaiacol. According to the present invention, the acidic site of the carrier is utilized, and the active metal component is introduced, such that the good hydrodeoxygenation activity and the target product selectivity of the catalyst during the reaction process can be achieved, and the hydrodeoxygenation of the lignin-derived phenolic compound is achieved; the prepared catalyst has the characteristics of simple preparation process, low cost, mild reaction conditions, high catalytic activity and the like. The lignin-derived phenolic compound is an important component of the bio-oil, the components of the bio-oil are effectively upgraded through catalytic hydrogenation upgrading treatment, and the lignin-derived phenolic compound has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic quality improvement of lignin-derived phenolic compounds and relates to a preparation method of a composite metal oxide-supported NiCo catalyst and a research method for the hydrodeoxygenation of lignin-derived phenolic compounds. Background Art

[0002] With the development of society and industry, people's demand for fuels and chemicals is gradually increasing. The over-exploitation and use of non-renewable fossil resources will lead to many social problems, such as energy security and environmental problems. In order to achieve green and sustainable development, the use of widely available and renewable wood fiber biomass for the production of fuels and high value-added chemicals is expected to solve the problems caused by the use of fossil resources. The main components of wood fiber are cellulose, hemicellulose and lignin, of which the lignin content is 25%-35%. Lignin is the most important source of aromatic structural compounds in nature and can be used as a starting material for the production of aromatic compounds. Its carbon-hydrogen ratio is close to that of natural petroleum. Therefore, it is expected to replace petroleum to prepare various high value-added chemicals and liquid fuels.

[0003] Lignin pyrolysis oil is considered a potential substitute for non-renewable fossil fuels, but the high acidity, richness of oxygen-containing compounds, low calorific value and high viscosity of lignin oil limit its wide application. It needs to be hydrogenated, deoxygenated and desulfurized to improve the quality of phenolic compounds and other components before it can be used as a high-value-added liquid fuel. At present, many methods for improving the quality of lignin oil are mainly focused on the development of catalysts used in the quality improvement process. A variety of functionalized supported catalysts have been developed, including hydrogenation catalysts prepared by loading metals on molecular sieves, metal organic frameworks, mesoporous silica, metal oxides loaded with metals and carbon materials. These heterogeneous catalysts have a variety of specific characteristics, such as certain acidity (helping to break CC and CO bonds in phenolic compounds) and rich hydrogenation active sites (hydrogenation conversion of unsaturated aromatic rings).

[0004] In view of the deficiencies of the prior art, the present invention provides a new method for the hydrodeoxygenation of lignin-derived phenolic compounds. The catalyst can effectively realize the efficient and directional preparation of cyclohexanol from guaiacol, wherein the guaiacol conversion rate can reach 100%, and the selectivity of the target product cyclohexanol can reach 85-94%. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 Catalyst X-ray diffraction pattern (XRD)

[0006] Figure 2 Catalyst infrared spectrum (FTIR) Summary of the invention

[0007] The present invention discloses a method for preparing a titanium aluminum oxide supported NiCo catalyst and a method for studying the hydrogenation and deoxygenation of lignin phenolic derivatives. The purpose of the present invention is to address the problems existing in the prior art and to prepare a catalyst that can provide strong hydrogenation activity and obtain ideal products. The catalyst preparation process is simple, the cost is low, the stability is high, and the catalyst can be recycled.

[0008] The technical solution of the present invention is a method for preparing a titanium aluminum oxide supported NiCo catalyst and using it for preparing cyclohexanol by hydrodeoxygenation of guaiacol, which is characterized by comprising the following steps:

[0009] 1) Take a certain amount of isopropyl titanate and add it to 15 mL of anhydrous ethanol for ultrasonic dispersion (10 min). 2 O 3 The powder was added in a certain proportion and magnetically stirred in a 30°C water bath for 30 min.

[0010] 2) The mixture in step 1 was added dropwise to a mixed solution of ethanol, acetic acid and water in appropriate proportions, magnetically stirred in a water bath at 30° C. for 6 h, and then aged at room temperature for 12 h.

[0011] 3) After the aging in step 2 is completed, the supernatant is discarded, and the gel is centrifuged and washed 2 to 6 times. After washing, the water is removed in an 80° C. forced air drying oven.

[0012] 4) Grind the solid obtained in step 3 and place it in a crucible, and calcine it at high temperature for a certain period of time to finally obtain a catalyst carrier.

[0013] 5) A certain proportion of Ni and Co is impregnated onto the catalyst carrier obtained in step 4 by an impregnation method, and moisture is removed in a forced air drying oven at 105°C.

[0014] 6) Grinding the solid obtained in step 5 and placing it in a crucible, calcining it at high temperature for a certain period of time to obtain a catalyst precursor, and then reducing it at high temperature to obtain the final catalyst.

[0015] 2. NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 The catalyst is characterized in that: the catalyst carrier is prepared by a sol-gel method, and the acidic component of the catalyst is γ-Al 2 O 3 , the metal active components are Ni and Co metals.

[0016] 3. NiCo / γ-Al according to claim 1 2 O 3 -TiO 2Catalyst, characterized in that: γ-Al 2 O 3 With TiO 2 The molar ratio of the metal active component to the oxide carrier is 1:0.5-2, and the mass ratio of the metal active component to the oxide carrier is 0.10-0.15.

[0017] 4. NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 The catalyst is characterized in that: in step 2), the concentration of acetic acid is 99%, the ratio of ethanol, acetic acid and water is 5:2:2, the total volume of the mixed solution is 18-27 mL, the water bath temperature is 20-40° C., the speed of magnetic stirring is 600-800 rpm, and the aging time is 8-12 h.

[0018] 5. NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 The catalyst is characterized in that: in step 4), the powder is calcined in an air atmosphere at 450-600° C. for 3-6 hours to obtain a carrier.

[0019] 6. The NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 The catalyst is characterized in that: in step 5), the metal compound is first dissolved in 10-15 mL of deionized water, a certain amount of carrier is added to the solution, stirred at room temperature for 5-12 hours, and then the mixed solution is transferred to a 80-105° C. air dryer and dried for 3-6 hours to remove moisture.

[0020] 7. The NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 The catalyst is characterized in that: in step 6), the ground powder is calcined at 450-600°C in air atmosphere for 2-6 hours, and then heated at 400-600°C and 10 mol% H 2 / 90mol%N 2 The catalyst was obtained by reducing the catalyst in a tubular furnace under a mixed gas atmosphere for 4-6 hours.

[0021] 8. The NiCo / γ-Al according to claim 1 2 O 3 -TiO 2 Catalyst, guaiacol and solvent are added into a high pressure reactor to form a reaction system. The amount of guaiacol added is 1-5 mmol, the amount of catalyst used is 0.05-0.1 g, and the solvent is isopropyl alcohol (IPA).

[0022] 9. Carry out the reaction at a temperature of 160-240°C in a hydrogen atmosphere for 0.5-4 hours. After the reaction is completed, separate the catalyst to obtain the target product. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used 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 limited by the claims attached to the application.

[0024] Implementation Case 1

[0025] Add 0.05g 10Ni-5Co / γ-Al into the autoclave 2 O 3 -TiO 2 (2:1) catalyst, 1 mmol guaiacol and 20 mL isopropanol, 1 MPa hydrogen is introduced and the reaction is carried out at 200°C for 2 hours, and stirring is continued during the reaction. After the reaction is completed, it is cooled to room temperature, and the liquid product is analyzed by gas phase. The conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 95% calculated by quantitative analysis.

[0026] Implementation Case 2

[0027] The reaction steps are exactly the same as those in Example 1, except that in the catalyst preparation step, 10Ni-5Co / γ-Al 2 O 3 -TiO 2 (1:1). The conversion rate of guaiacol was 100%, and the selectivity of cyclohexanol was 90%.

[0028] Implementation Case 3

[0029] The reaction steps are exactly the same as those in Example 1, except that in the catalyst preparation step, 10Ni-5Co / γ-Al 2 O 3 -TiO 2 (1:2). The conversion rate of guaiacol was 100%, and the selectivity of cyclohexanol was 81%.

[0030] Implementation Case 4

[0031] The reaction steps are exactly the same as those in Example 1, except that the reaction temperature is 160° C., the conversion rate of guaiacol is 41%, and the selectivity of cyclohexanol is 12%.

[0032] Implementation Case 5

[0033] The reaction steps are exactly the same as those in Example 1, except that the reaction temperature is 180° C., the conversion rate of guaiacol is 80%, and the selectivity of cyclohexanol is 48%.

[0034] Implementation Case 6

[0035] The reaction steps are exactly the same as those in Example 1, except that the reaction temperature is 220° C., the conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 81%.

[0036] Implementation Case 7

[0037] The reaction steps are exactly the same as those in Example 1, except that the reaction pressure is 2 MPa, the reaction time is 1 h, the conversion rate of guaiacol is 99%, and the selectivity of cyclohexanol is 90%.

[0038] Implementation Case 8

[0039] The reaction steps are exactly the same as those in Example 1, except that the reaction pressure is 2 MPa, the reaction time is 2 h, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 94%.

[0040] Implementation Case 9

[0041] The reaction steps are exactly the same as those in Example 1, except that the reaction pressure is 2 MPa, the reaction time is 3 h, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 94%.

[0042] Implementation Case 10

[0043] The reaction steps are exactly the same as those in Example 1, except that the reaction pressure is 2 MPa, the reaction time is 4 h, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexanol is 93%.

[0044] Table 1 shows the catalyst preparation process of different carriers of γ-Al 2 O 3 With TiO 2 The effect of ratio on the hydrodeoxygenation effect of guaiacol.

[0045] Implementation Cases catalyst Conversion rate (mol%) Cyclohexanol (mol%) Cyclohexane (mol%) 1 <![CDATA[10Ni-5Co / γ-Al 2 THE 3 -Uncle 2 (2∶1)]]> 100 95 1 2 <![CDATA[10Ni-5Co / γ-Al 2 THE 3 -Uncle 2 (1∶1)]]> 100 90 - 3 <![CDATA[10Ni-5Co / γ-Al 2 THE 3 -Uncle 2 (1∶2)]]> 100 81 2

[0046] Table 2 shows the effects of different reaction temperatures for implementation cases 1, 4 to 6.

[0047] Implementation Cases Reaction temperature (℃) Conversion rate (mol%) Cyclohexanol (mol%) Cyclohexane (mol%) 4 160 41 12 - 5 180 80 48 - 1 200 100 95 1 6 220 100 81 2

[0048] Table 3 shows the effects of different reaction times for implementation cases 7 to 10.

[0049] Implementation Cases Reaction time (h) Conversion rate (mol%) Cyclohexanol (mol%) Cyclohexane (mol%) 7 1 99 90 - 8 2 100 94 2 9 3 100 94 2 10 4 100 93 3

[0050] The above embodiments are the implementation modes adopted by the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a titanium aluminum oxide supported NiCo catalyst and applying it to the hydrodeoxygenation of lignin-derived phenolic compounds, characterized in that: The catalyst is based on γ-Al2O3 as the acidic active site, modified by adding TiO2, loaded with Ni metal with hydrogenation activity and Co metal that can also increase the selectivity of the target product, and prepared by sol-gel, impregnation, calcination and reduction methods according to a certain proportion. The preparation method is as follows: 1) A certain amount of isopropyl titanate was added to 15 mL of anhydrous ethanol for ultrasonic dispersion (10 min), and then γ-Al2O3 powder was added thereto in a certain proportion, and magnetic stirring was carried out in a 30°C water bath for 30 min. 2) The mixture in step 1 was added dropwise to a mixed solution of ethanol, acetic acid and water in appropriate proportions, magnetically stirred in a water bath at 30° C. for 6 h, and then aged at room temperature for 12 h. 3) After the aging in step 2 is completed, the supernatant is discarded, and the gel is centrifuged and washed 2 to 6 times. After washing, the water is removed in an 80° C. forced air drying oven. 4) Grind the solid obtained in step 3 and place it in a crucible, and calcine it at high temperature for a certain period of time to finally obtain a catalyst carrier. 5) A certain proportion of Ni and Co is impregnated onto the catalyst carrier obtained in step 4 by an impregnation method, and moisture is removed in a forced air drying oven at 105°C. 6) Grinding the solid obtained in step 5 and placing it in a crucible, calcining it at high temperature for a certain period of time to obtain a catalyst precursor, and then reducing it at high temperature to obtain the final catalyst.

2. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: The carrier of the catalyst is prepared by a sol-gel method, the acid component of the catalyst is γ-Al2O3, and the metal active components are Ni and Co metals.

3. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: The molar ratio of γ-Al2O3 to TiO2 is 1:0.5-2, and the mass ratio of the metal active component to the oxide carrier is 0.10-0.

15.

4. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: In step 2), the concentration of acetic acid is 99%, the ratio of ethanol, acetic acid and water is 5:2:2, the total volume of the mixed solution is 18-27 mL, the water bath temperature is 20-40° C., the speed of magnetic stirring is 600-800 rpm, and the aging time is 8-12 h.

5. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: In step 4), the powder is calcined at 450-600° C. in an air atmosphere for 3-6 hours to obtain a carrier.

6. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: In step 5), the metal compound is first dissolved in 10-15 mL of deionized water, a certain amount of carrier is added to the solution, stirred at room temperature for 5-12 hours, and then the mixture is transferred to a 80-105° C. air dryer and dried for 3-6 hours to remove moisture.

7. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, characterized in that: In step 6), the ground powder is calcined at 450-600° C. in an air atmosphere for 2-6 h, and then reduced in a tubular furnace at 400-600° C. in a 10 mol % H 2 / 90 mol % N 2 mixed gas atmosphere for 4-6 h to obtain a catalyst.

8. The NiCo / γ-Al2O3-TiO2 catalyst according to claim 1, guaiacol, and a solvent are added to a high-pressure reactor to form a reaction system, wherein the amount of guaiacol added is 1 to 5 mmol, the amount of the catalyst used is 0.05 to 0.1 g, and the solvent is isopropyl alcohol (IPA).

9. Carry out the reaction at a temperature of 160-240°C in a hydrogen atmosphere for 0.5-4 hours. After the reaction is completed, separate the catalyst to obtain the target product.

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