CN107286006A - A kind of method that catalyzed alcoholysis lignin prepares Acetovanillone and acetosyringone - Google Patents

Abstract

The invention discloses a method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin. The method uses lignin as a raw material, carries out microwave alcoholysis in an alcoholic solvent containing a loaded metal catalyst, cools, filters and Washing to obtain liquid products based on vanilla ethyl ketone and acetosyringone, the supported metal catalyst is composed of active center Co and carrier; the present invention proposes a Environmentally friendly, low-cost supported metal catalyst, under microwave heating conditions, realizes efficient degradation of lignin, and prepares two types of compounds with higher yields: vanilla ethyl ketone and acetyl syringone; this method has mild reaction conditions and short heating time , the reaction efficiency is higher.

Description

A method for preparing vanilla ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin

technical field

The invention relates to the technical field of lignin utilization, in particular to a method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin.

Background technique

Today, the world's energy consumption crisis, serious environmental pollution and other issues are increasingly concerned. The massive use of fossil fuels such as coal by human beings has not only caused the exhaustion of energy resources, but also seriously polluted the environment with the waste gas and wastewater discharged. Biomass energy, as an emerging energy with good development prospects, is a renewable energy in which solar energy is stored in plants in the form of chemical energy, and is known as the best renewable energy.

Biomass is mainly composed of cellulose, hemicellulose and lignin. Lignin is a natural organic polymer compound, second only to cellulose in quantity. It is estimated that 150 billion tons of lignin can be produced by plant growth in the world every year. As a by-product of the wood hydrolysis industry and the paper industry, due to insufficient utilization, it has become an environmental pollutant and seriously polluted the environment. Therefore, although lignin resources are very rich, they need to be rationally utilized.

Catalytic liquefaction of lignin has become an important method for lignin degradation because of its relatively mild reaction conditions and relatively low energy consumption. Solvents and catalysts play an important role in atmospheric pressure catalytic liquefaction of lignin, which can not only improve lignin conversion rate, but also increase product selectivity.

Chinese patent (CN 102295547 A) reacts the oxidant and lignin in an alkaline solution. After the reaction, the reaction solution is acidified, extracted, concentrated and rectified to obtain vanilla ethyl ketone and acetosyringone. Gas chromatography analysis shows that the The purities were 97.3% and 98.2%, respectively. According to investigations, vanilla ethyl ketone and acetosyringone are not only widely used in the perfume industry, but also important raw materials for organic synthesis. They can be used in medicine to synthesize drugs and have important value. Transition metal catalysts such as cobalt, copper, iron, and zinc are good redox catalysts, so it is very important to choose a suitable supported metal catalyst to improve product selectivity and yield.

Contents of the invention

In view of the above-mentioned problems, the object of the present invention is to provide a method for preparing vanillyl ethyl ketone and acetosyringone under the action of a supported metal catalyst under microwave-assisted heating, using alcohols as solvents.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows: a method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin. Microwave alcoholysis in a solvent, cooling, filtering and washing to obtain liquid products mainly composed of vanillyl ethyl ketone and acetosyringone, and the supported metal catalyst is composed of active center Co and a carrier.

Fe is introduced into the supported metal catalyst of the present invention as an auxiliary agent, and the carrier is one of Al ₂ O ₃ , CeO ₂ , ZrO ₂ , and MgO. As a catalyst promoter, Fe can provide more electron holes and improve the catalytic activity of Co, thereby promoting the breaking of CH or CC bonds of lignin and increasing the yield of target products. The acidity and alkalinity of these four carriers are different, and the depolymerization effect can be compared.

Alcohol solvent of the present invention is Virahol. Alcohol solvents are mostly used in the degradation of lignin due to their dissolution and hydrogen supply.

The operation steps of the method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin of the present invention are as follows:

1) Preparation of supported metal catalysts by impregnation method;

2) Weigh a certain quality of lignin and alcohol solvent, add to the reaction tank and mix, then add a certain quality of supported metal catalyst to mix, put the reaction tank into the microwave reactor, at a temperature of 100-180 ℃, the microwave power is React for 5-60 minutes under the condition of 600 W;

3) After the reaction is completed, take out the reaction tank to cool naturally, filter the product and wash it with a solvent to obtain a liquid product mainly composed of vanillyl ethyl ketone and acetosyringone.

In step 2) of the present invention, the mass ratio of lignin to the supported metal catalyst is 1:0.3-1; from the experimental results, it can be seen that when the mass ratio of the catalyst is 0.3-1, the yield of the final product presents a curve change, so the catalyst The amount of the catalyst has a direct impact on the yield of the final product; when the amount of the catalyst is lower than 0.3, the yield of the final product will drop significantly, and when the amount of the catalyst is higher than 0.8, the yield of the product will also drop significantly.

The method for preparing loaded metal catalyst by impregnation method among the present invention is as follows:

1) Weigh Co(NO ₃ ) ₂ 6H ₂ O into a beaker, fully dilute it with deionized water to form a solution, impregnate an equal volume on the carrier, stir and impregnate at room temperature for 24 h;

2) Dry the catalyst precursor at 85 ^° C for 12 h in a drying oven, and calcine the catalyst precursor in a muffle furnace at 500 ^° C for 4 h in an air atmosphere;

3) The calcined catalyst was reduced in 90 mL/min H ₂ atmosphere for 1.5 h at a reduction temperature of 550 ^° C to obtain a Co-supported metal catalyst.

The loaded amount of Co in the supported metal catalyst of the present invention is 5%, and the mol ratio of Co and Fe in the supported metal catalyst is 1:0.3～0.8, can know from experimental result: Co and Fe in the supported metal catalyst of the present invention When the molar ratio is 1:0.3, the yield of the final product reaches a peak value, and when it exceeds 0.3 or is less than 0.3, the yield of the final product all decreases.

The advantage of the present invention is that: by improving the traditional lignin degradation method, the present invention proposes an environment-friendly, low-cost supported metal catalyst, which can realize high-efficiency degradation of lignin under microwave heating conditions and produce a higher yield Two types of compounds: vanillyl ethyl ketone and acetosyringone; this method has the advantages of mild reaction conditions, shorter heating time and higher reaction efficiency.

Description of drawings

Fig. 1 is the impact of different carrier catalysts on the efficient preparation of vanilla ethyl ketone and acetosyringone distribution by lignin alcoholysis in Example 3-5 of the present invention;

Fig. 2 is the influence of Co/Fe molar ratio on the efficient preparation of vanilla ethyl ketone and acetosyringone distribution by lignin alcoholysis in the embodiment 6-8 of the present invention;

Fig. 3 is the effect of catalyst dosage on the efficient preparation of vanilla ethyl ketone and acetosyringone distribution by lignin alcoholysis in Examples 9-11 of the present invention;

Fig. 4 is the effect of reaction temperature on the distribution of vanillyl ethyl ketone and acetosyringone efficiently prepared by lignin alcoholysis in Examples 12-16 of the present invention;

Fig. 5 is the effect of reaction time on the distribution of vanillyl ethyl ketone and acetosyringone in the efficient preparation of lignin alcoholysis in Examples 17-20 of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1: Weigh 1 g of lignin and 16 mL of isopropanol and mix them into a reaction tank, put the reaction tank into a microwave reactor, set the microwave power to 600 W, and react for 30 min at a certain reaction temperature of 120 °C. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Example 2

a. Weigh 2.47 g Co(NO ₃ ) ₂ ·6H ₂ O into a beaker, fully dilute it with deionized water to form a solution, impregnate an equal volume on 10 g Al ₂ O ₃ carrier, stir and impregnate at room temperature for 24 h. Then put it into a drying oven at 85 ^° C and dry for 12 h to obtain a catalyst precursor. In an air atmosphere, the catalyst precursor is calcined at 500 ^° C in a muffle furnace for 4 h. Finally, the calcined catalyst was reduced in 90 mL/min H ₂ atmosphere for 1.5 h at a reduction temperature of 550 ^° C to obtain a catalyst 5% Co/Al ₂ O ₃ .

b. Weigh 1 g of lignin and 16 mL of isopropanol and mix them into the reaction tank, add 0.5 g of catalyst 5%Co/Al ₂ O ₃ and mix them in the reaction tank, put the reaction tank into the microwave reactor, set The microwave power was 600 W, and the reaction was carried out at a certain reaction temperature of 120 °C for 30 min. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Example 3~5

a. 5% Co/ZrO ₂ , 5% Co/CeO ₂ , 5% Co/MgO catalyst preparation process adopts step a in Example 2, the difference is that different carriers ZrO ₂ , CeO ₂ and MgO are used to prepare catalysts .

b. The degradation step of lignin and catalyst in isopropanol solvent adopts step b in Example 2, the difference is that the types of catalysts added are 5% Co/ZrO ₂ , 5% Co/CeO ₂ , 5% Co /MgO.

The liquid product was qualitatively detected by GC/MS, and the relationship between the peak areas of two high-yield products (vanillyl ethyl ketone and acetosyringone) in the liquid product was directly obtained. The effect of different catalysts on the distribution of lignin alcoholysis products is shown in Fig. 1.

Example 6

a. Weigh 2.47 g Co(NO ₃ ) ₂ 6H ₂ O in a beaker, then weigh 1.80 g Fe(NO ₃ ) ₃ 9H ₂ O in a beaker, fully dilute with deionized water to form a solution, etc. Volume impregnation on 10 g Al ₂ O ₃ support, stirred and impregnated at room temperature for 24 h. Then put it into a drying oven at 85 ^° C and dry for 12 h to obtain a catalyst precursor. In an air atmosphere, the catalyst precursor is calcined at 500 ^° C in a muffle furnace for 4 h. Finally, the calcined catalyst was reduced in 90 mL/min _H2 atmosphere for 1.5 h at a reduction temperature of 550 ^° C to obtain a Co _- Fe/ _Al2O3 bimetallic catalyst with a Co loading of 5%, The Co/Fe molar ratio is 1:0.5.

b. Weigh 1 g of lignin and 16 mL of isopropanol, mix them into the reaction tank, add 0.5 g of bimetallic catalyst Co-Fe/Al ₂ O ₃ and mix them in the reaction tank, put the reaction tank into the microwave reactor , set the microwave power to 600 W, and react for 30 min at a certain reaction temperature of 120 °C. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Embodiment 7~8:

a. Co loading is 5%, Co/Fe molar ratio is 1:0.3, 1:0.8 bimetallic catalyst Co-Fe/Al ₂ O ₃ preparation process adopts step a in embodiment 6, the difference is to weigh respectively The catalyst was prepared by mixing 1.08 g and 2.89 g of Fe(NO ₃ ) ₃ ·9H ₂ O and 2.47 g of Co(NO ₃ ) ₂ ·6H ₂ O salt solution.

b. The degradation step of lignin and catalyst in isopropanol solvent adopts the b step in Example 2, the difference is that the catalyst types added are that the Co loading is 5%, and the Co/Fe molar ratio is 1:0.3, 1:0.8 bimetallic catalyst Co-Fe/Al ₂ O ₃ .

The liquid product was qualitatively detected by GC/MS, and the relationship between the peak areas of two high-yield products (vanillyl ethyl ketone and acetosyringone) in the liquid product was directly obtained. The effect of different catalysts on the distribution of lignin alcoholysis products is shown in Figure 2.

Example 9: Weigh 1 g of lignin and 16 mL of isopropanol and mix them into a reaction tank, and add a bimetallic catalyst Co-Fe/Al ₂ O with Co loading: 5%, Co/Fe molar ratio: 1:0.3 ₃ are mixed together in the reaction tank, and the catalyst consumption is 0.3g. Put the reaction tank into a microwave reactor, set the microwave power to 600 W, and react for 30 min at a certain reaction temperature of 120 °C. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Examples 10-11: The steps of degradation of lignin and catalyst in isopropanol solvent are as in Example 9, except that the amount of added catalyst is 0.8 g and 1 g respectively.

The liquid product was qualitatively detected by GC/MS, and the relationship between the peak areas of two high-yield products (vanillyl ethyl ketone and acetosyringone) in the liquid product was directly obtained. The effect of different catalysts on the distribution of lignin alcoholysis products is shown in Figure 3.

Example 12: Weigh 1 g of lignin and 16 mL of isopropanol and mix them into a reaction tank, and add a bimetallic catalyst Co-Fe/Al ₂ O with Co loading: 5%, Co/Fe molar ratio: 1:0.3 ₃ are mixed together in the reaction tank, and the catalyst consumption is 0.8g. Put the reaction tank into a microwave reactor, set the microwave power to 600 W, and react for 30 min at a certain reaction temperature of 100 °C. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Examples 13-16: The degradation steps of lignin and catalyst in isopropanol solvent adopt the steps in Example 12, except that the reaction temperatures are 120 °C, 140 °C, 160 °C, and 170 °C, respectively.

The liquid product was qualitatively detected by GC/MS, and the relationship between the peak areas of two high-yield products (vanillyl ethyl ketone and acetosyringone) in the liquid product was directly obtained. The effect of different catalysts on the distribution of lignin alcoholysis products is shown in Figure 4.

Example 17: Weigh 1 g of lignin and 16 mL of isopropanol and mix them into a reaction tank, and add a bimetallic catalyst Co-Fe/Al ₂ O with Co loading: 5%, Co/Fe molar ratio: 1:0.3 ₃ are mixed together in the reaction tank, and the catalyst consumption is 0.8g. Put the reaction tank into a microwave reactor, set the microwave power to 600 W, and react at a certain reaction temperature of 140 °C for 5 min. After the reaction is complete, take out the digestion tank and let it cool down naturally. The product was filtered and washed with the solvent isopropanol, and the filtered liquid product was uniformly dissolved in isopropanol to 20 mL, and the liquid product was to be detected.

Examples 18-20: The degradation steps of lignin and catalyst in isopropanol solvent adopt the steps in Example 17, except that the reaction time is 15 min, 45 min, and 60 min, respectively.

The liquid product was qualitatively detected by GC/MS, and the relationship between the peak areas of two high-yield products (vanillyl ethyl ketone and acetosyringone) in the liquid product was directly obtained. The effect of different catalysts on the distribution of lignin alcoholysis products is shown in Figure 5.

It should be noted that the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any combination or equivalent transformation made on the basis of the above embodiments belongs to the protection scope of the present invention.

Claims (7)

1. a method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin, is characterized in that, described method takes lignin as raw material, microwave alcoholysis in the alcoholic solvent containing loaded metal catalyst, after After cooling, filtering and washing, a liquid product mainly composed of vanillyl ethyl ketone and acetosyringone is obtained, and the supported metal catalyst is composed of active center Co and a carrier. 2. the method for preparing vanillyl ethyl ketone and acetosyringone by catalytic alcoholysis of lignin as claimed in claim 1, is characterized in that, introduces Fe as auxiliary agent in the described supported metal catalyst, and described carrier is _Al2 One of O ₃ , CeO ₂ , ZrO ₂ , and MgO. 3. the method for preparing vanillyl ethyl ketone and acetosyringone by catalytic alcoholysis of lignin as claimed in claim 1, is characterized in that, described alcoholic solvent is Virahol. 4. the method for preparing vanillyl ethyl ketone and acetosyringone by catalytic alcoholysis of lignin as claimed in claim 1 or 2 or 3, is characterized in that, the operating steps of described method are as follows: 1) Preparation of supported metal catalysts by impregnation method; 2) Weigh a certain quality of lignin and alcohol solvent, add to the reaction tank and mix, then add a certain quality of supported metal catalyst to mix, put the reaction tank into the microwave reactor, at a temperature of 100-180 ℃, the microwave power is React for 5-60 minutes under the condition of 600 W; 3) After the reaction is completed, take out the reaction tank to cool naturally, filter the product and wash it with a solvent to obtain a liquid product mainly composed of vanillyl ethyl ketone and acetosyringone. 5. The method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin according to claim 1, wherein the mass ratio of lignin to the supported metal catalyst in step 2) is 1:0.3 ~1. 6. catalytic alcoholysis lignin as claimed in claim 2 prepares the method for vanillyl ethyl ketone and acetosyringone, it is characterized in that, in the described loaded metal catalyst, the loading of Co is 5%, in the loaded metal catalyst The molar ratio of Co to Fe is 1:0.3-0.8. 7. The method for preparing vanillyl ethyl ketone and acetosyringone by catalyzing the alcoholysis of lignin as claimed in claim 4, characterized in that, the method for preparing the supported metal catalyst by impregnation in the step 1) is as follows: 1) Weigh Co(NO ₃ ) ₂ 6H ₂ O into a beaker, fully dilute it with deionized water to form a solution, impregnate an equal volume on the carrier, stir and impregnate at room temperature for 24 h; 2) Dry the catalyst precursor at 85 ^° C for 12 h in a drying oven, and calcine the catalyst precursor in a muffle furnace at 500 ^° C for 4 h in an air atmosphere; 3) The calcined catalyst was reduced in 90 mL/min H ₂ atmosphere for 1.5 h at a reduction temperature of 550 ^° C to obtain a Co-supported metal catalyst.