Preparation of boron-containing catalyst and application of boron-containing catalyst in hydrogenation reaction of cyclic compound

Abstract

The invention discloses preparation of a boron-containing catalyst and application of the boron-containing catalyst in hydrogenation reaction of cyclic compounds. The catalyst at least comprises nickel of a zero-valent species, nitrogen of a pyrrole nitrogen species, and carbon and boron species of SP2 and SP3. The preparation method comprises the following steps: reacting polyvinylpyrrolidone with nickel ions to form a complex, reacting phenolic resin with phenylboronic acid to form a complexed stable boron-containing high polymer, and reacting under the protection of inert gas to obtain the boron-containing catalyst which is stable in air. The catalyst has good activity and stability on hydrogenation of cyclic compounds such as naphthalene, benzene, cyclic carbonate and dimerized butanol aldehyde. The nickel species are anchored and dispersed and protected by the boron-carbon-nitrogen compound and the boron species is promoted, so that the hydrogenation catalytic activity and the stability of the catalyst are improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts and preparation thereof, and in particular to the preparation of a boron-containing catalyst and application thereof in hydrogenation reaction of cyclic compounds. Background Art

[0002] Cyclic compounds have many uses. For example, aromatic ring derivatives are rich in Shaanxi long flame coal, which can be used in liquid organic hydride hydrogen storage technology. Liquid organic hydride hydrogen storage has many advantages, such as reversible catalytic reaction, recyclable reactants and products, safe and convenient storage and transportation, high room temperature hydrogen storage capacity (about 60-75 kg H2 / m 3, mass fraction of 6-8 wt%), etc. This technology can be used to solve the problems of spatial mismatch (different regional energy supply and demand, centralized and distributed demand) and time mismatch (diurnal fluctuations, seasonal fluctuations) of energy. For example, in Northwest my country, wind power and solar energy resources are very abundant, but due to the instability of photovoltaic, wind power and other power generation methods, a large amount of "wind and power abandonment" is generated. If it can be transported in the form of organic liquid in the relatively unbalanced energy supply and demand between the western and eastern regions of my country, the problem of uneven regional distribution of energy can be solved. In countries with abundant hydropower resources such as Northern Europe and Canada, the cyclic seasonal storage and release of liquid organic hydrides can also be used to solve the problem of seasonal mismatch between energy and demand. In relatively energy-poor areas such as Japan and Singapore, hydrogen energy and chemicals can be obtained at the same time by very cheap and safe means such as shipping. It is also convenient and safe to transport fuel from a centralized location to various fuel stations. Liquid organic hydride hydrogen storage technology uses unsaturated organic matter as a medium (such as methylnaphthalene, toluene, biphenyl, etc.). On the one hand, it can efficiently utilize coal tar and increase its added value. On the other hand, it can effectively reduce carbon emissions, control CO2 emissions from the source, and reduce environmental pollution. Due to the increase in steric hindrance of aromatic ring-rich derivatives during hydrogenation, the difficulty of adsorption on the active sites of the catalyst increases, resulting in a significant decrease in the reaction rate. In addition, cyclic compounds containing heteroatoms are also hydrogenated in some cases, such as propylene carbonate (1,2-Propanediol cyclic carbonate) is hydrogenated to 1,2-propylene glycol and methanol, and 2,6-dimethyl-1,3-dioxan-4-ol (2,6-Dimethyl-1,3-dioxan-4-ol) and dibutyl aldehyde (4-Hydroxy-α,6-dimethyl-1,3-dioxane-2-ethanol) containing oxygen heterocycles are hydrogenated to diols. Due to the presence of heteroatoms, the difficulty of hydrogenation is significantly increased. In the hydrogenation process of cyclic compounds, since the prices of precious metals such as platinum and palladium with good activity are very high, non-precious metals are used as catalysts as much as possible, but the catalytic efficiency of non-precious metals is relatively low. Although the commonly used catalysts such as Raney nickel and nickel / activated carbon are not expensive, they are unstable in air and easily deactivated under acidic conditions. However, many times, the acidic system is in the presence of carboxylic acid raw materials or by-products. Therefore, it is very important to develop a cheap, efficient and stable catalyst for the hydrogenation of cyclic compounds under mild conditions. Summary of the invention

[0003] The purpose of the present invention is to provide a highly efficient, low-cost, highly selective and highly active boron-containing catalyst to make up for the deficiencies of the existing catalysts in the above-mentioned background technology.

[0004] To achieve the above object, the present invention adopts the following technical solution: 1) Dissolve polyvinyl pyrrolidone in a solvent to form a solution A, and stir at 30-70°C for 1-12 hours; dissolve a soluble nickel salt in water to form a solution B; mix the above two solutions A and B, and stir the mixture for 2-48 hours, then remove water and ethanol by a rotary evaporator at 40-80°C to obtain a solid, then wash it with deionized water for 3-10 times, and dry it to obtain a light green precursor PN of the catalyst; In the above step 1), the solvent in solution A is any one of ethanol, methanol or propanol, and the soluble nickel salt in solution B is any one of nickel acetate, nickel nitrate, nickel chloride or nickel acetylacetonate.

[0005] 2) Take phenolic resin and light green precursor PN and dissolve them in ethanol solvent, then add phenylboronic acid, stir and react at a temperature of 20-70°C for 2-24h, and dry at 80-120°C to remove the solvent to obtain a solid powder; In the above step 2), the amount of the light green precursor PN added is 1 to 30 times the mass of the phenolic resin, and the amount of phenylboric acid added is 0.33 to 5 times the mass of the phenolic resin.

[0006] 3) The solid powder obtained in step (2) is heated to 450-800°C at a rate of 1-8°C / min under inert gas protection, maintained for 3-24 hours, the volatile part is blown away, and finally cooled to room temperature under inert gas protection, and the catalyst PNNB that can exist stably in air is obtained.

[0007] In the above step 3), the inert gas is at least one of nitrogen or argon, and the heating rate is preferably 2-5°C / min.

[0008] Synthesis mechanism of the boron-containing catalyst of the present invention: First, pyrrole nitrogen in polyvinyl pyrrolidone reacts with nickel ions to form a coordination complex; then, a stable boron-containing polymer is formed by the reaction of phenolic resin and phenylboric acid, and the nickel complex is wrapped; then, a pyrolysis and carbonization reaction is carried out under the protection of an inert gas to obtain a boron-carbon-nitrogen compound, and the nickel species is anchored and dispersed, which can stably maintain a zero-valent state under air, and has good activity and stability for the hydrogenation of cyclic compounds such as naphthalene, benzene, cyclic carbonates, and dimer butanol aldehyde.

[0009] Another object of the present invention is to provide application of the above boron-containing catalyst in hydrogenation reaction of cyclic compounds.

[0010] Add cyclic compounds, prepared catalyst PNNB and solvent to the autoclave. Before heating, purge with nitrogen, replace with hydrogen and pressurize to 2~6MPa, then heat to the specified temperature (60~150℃) to start hydrogenation reaction. After the reaction, use gas chromatography (GC-FID) to detect and analyze the product composition, and calculate its conversion rate and selectivity; taking toluene hydrogenation to produce methylcyclohexane as an example, the conversion rate of toluene and the selectivity of the target product are defined as: According to calculation, the conversion rate of toluene is 99% and the selectivity of the target product is 99%, which proves that the catalyst PNNB prepared by the present invention has good catalytic activity.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The nickel species in the catalyst are anchored and dispersed, and have high activity; the catalyst has a large amount of SP2 carbon, and through the Pi-Pi effect, has a good adsorption capacity for cyclic compounds, and has good activity for the hydrogenation of cyclic compounds such as naphthalene, benzene, cyclic carbonate, dimer butanol aldehyde, etc.; unlike palladium carbon, nickel carbon and other catalysts that are flammable in dry air, the catalyst of the present invention can also be stable in air due to the stability of the boride; due to the protection of the boron carbon nitride, the catalyst is also very stable in water solvents and can tolerate a certain acidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a physical picture of the catalyst prepared in Example 1 of the present invention.

[0013] Figure 2 This is a physical picture of the catalyst precursor PN prepared in Example 1 of the present invention.

[0014] Figure 3 It is the infrared FTIR spectrum of the catalyst prepared in Example 1 of the present invention.

[0015] Figure 4 This is the carbon element XPS spectrum of the catalyst prepared in Example 1 of the present invention.

[0016] Figure 5 This is the XPS spectrum of nickel element of the catalyst prepared in Example 1 of the present invention.

[0017] Figure 6 This is the XPS spectrum of the boron element of the catalyst prepared in Example 1 of the present invention.

[0018] Figure 7 This is the nitrogen element XPS spectrum of the catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further explained below with reference to specific embodiments.

[0020] Example 1 (1) Dissolve 8.88 g of polyvinyl pyrrolidone in 100 mL of ethanol solution and stir at 30 °C for 1 h; dissolve 9.92 g of nickel acetate hydrate Ni(AC)2.4H2O in 50 mL of water; mix the above two solutions A and B, and stir the mixture at 30 °C for 24 h. Then, remove water and ethanol by rotary evaporator at 70 °C to obtain a solid. After washing with deionized water for 5 times, dry it again at 120 °C to obtain the light green precursor PN-1 of the catalyst.

[0021] (2) Dissolve 1 g of phenolic resin in 10 mL of ethanol solvent, take 1 g of light green precursor PN and stir at 30 °C for 5 h, then add 1 g of phenylboric acid and continue stirring for 5 h, and remove the solvent by rotary evaporation at 80 °C. After drying, the obtained solid is ground into powder.

[0022] (3) Under the protection of argon atmosphere at a flow rate of 100 mL / min, the temperature was raised to 600 °C at a rate of 5 °C / min and maintained for 4 h. The temperature was then lowered to room temperature and the catalyst PNNB-1 was obtained.

[0023] Product structure characterization: Figure 3 This is the infrared FTIR spectrum of the catalyst prepared in Example 1 of the present invention. Figure 3 It can be seen that there is 3377cm in the spectrum -1 、3322cm -1 、3220cm -1 、3140cm -1 、2921cm -1 、2851cm -1 、1458cm -1 、1436cm -1 、1432cm -1 、1384cm -1 、1363cm -1 、1347cm -1 、1323cm -1 、1251cm -1 、1108cm -1 、970cm -1 、927cm -1 、781cm -1 、697cm -1 The catalyst contains a large number of saturated CC or CH vibrations on the aromatic ring (2800-3140cm -1 )、BO(1347cm-1 )、CB(1458cm -1 )OH (3200–3600 cm -1 )、CN(1323cm -1 )、NH(3322cm -1 )、Benzene ring (600-900cm -1 ) and other functional groups.

[0024] Figure 4 This is the carbon element XPS spectrum of the catalyst prepared in Example 1 of the present invention. Figure 4 It can be seen that there are three main types of carbon: the main one is SP2 carbon with a binding energy of 284 eV, which comes from the conjugated aromatic ring structure; the second is SP3 carbon with a binding energy of 285.5 eV and carbon in the C=O structure with a binding energy of 288.2 eV.

[0025] Figure 5 This is the XPS spectrum of nickel element of the catalyst prepared in Example 1 of the present invention. Figure 5 It can be seen that the nickel species is mainly zero-valent nickel with a binding energy of 852.2 eV.

[0026] Figure 6 This is the XPS spectrum of the boron element of the catalyst prepared in Example 1 of the present invention. Figure 6 It can be seen that the binding energy of boron species is 192 eV of boron.

[0027] Figure 7 This is the nitrogen element XPS spectrum of the catalyst prepared in Example 1 of the present invention. Figure 7 It can be seen that the nitrogen species are mainly nitrogen with a binding energy of 399 eV, which is a pyrrolic nitrogen species.

[0028] Example 2 (1) Dissolve 8.88 g of polyvinyl pyrrolidone in 100 mL of a mixed solution of methanol and ethanol and stir at 70 °C for 2 h; dissolve 10.32 g of nickel chloride in 100 mL of water; mix the two solutions and stir the mixture at 70 °C for 12 h, then remove the water and alcohol solution using a rotary evaporator at 50 °C to obtain a solid, then wash it three times with deionized water and dry it again at 100 °C to obtain a light green precursor PN-2 of the catalyst.

[0029] (2) Dissolve 1 g of phenolic resin in 10 mL of ethanol solvent, take 2 g of light green precursor PN-2 and stir at 30 °C for 24 h, then add 0.33 g of phenylboric acid and continue stirring for 2 h. Remove the solvent by rotary evaporation at 80 °C, and grind the solid to powder after drying.

[0030] (3) Under the protection of a nitrogen atmosphere at a flow rate of 30 mL / min, the temperature was raised to 800°C at a rate of 10°C / min and maintained for 3 h. The temperature was then lowered to room temperature and the catalyst PNNB-2 was obtained.

[0031] Example 3 (1) Dissolve 88.8 g of polyvinyl pyrrolidone in 500 mL of ethanol solution; dissolve 77.1 g of nickel nitrate hydrate Ni(NO3)2·6H2O in 500 mL of water; mix the two solutions and stir the mixture at 50°C for 48 hours, then remove water and ethanol by rotary evaporator at 70°C to obtain a solid, then wash it with deionized water 10 times and dry it again at 70°C to obtain a light green precursor PN-3 of the catalyst.

[0032] (2) Take 1 g of phenolic resin and dissolve it in 100 mL of acetone solvent. Take 30 g of light green precursor PN-3 and stir it at 70 °C for 24 h. Then add 3 g of phenylboric acid and continue stirring for 5 h. Then evaporate it at 120 °C to remove the solvent. After drying, the solid is ground into powder.

[0033] (3) Under the protection of a nitrogen atmosphere at a flow rate of 100 mL / min, the temperature was raised to 450°C at a rate of 1°C / min and maintained for 24 h. The temperature was then lowered to room temperature and the catalyst PNNB-3 was obtained.

[0034] Example 4 (1) Dissolve 40 g of polyvinyl pyrrolidone in 500 mL of ethanol solution; dissolve 35 g of nickel acetate hydrate Ni(AC)2.4H2O and 1 g of nickel acetylacetonate in 500 mL of water; mix the two solutions and stir the mixture at 70 °C for 2 hours, then remove water and ethanol at 40 °C using a rotary evaporator under reduced pressure to obtain a solid, then wash it with deionized water 5 times and dry it again at 70 °C to obtain a light green precursor PN-4 of the catalyst.

[0035] (2) Dissolve 1 g of phenolic resin in 100 mL of acetone solvent, take 30 g of light green precursor PN-4 and stir at 70 °C for 24 h, then add 5 g of phenylboric acid and continue stirring for 5 h, and remove the solvent by rotary evaporation at 80 °C. After drying, grind the solid into powder.

[0036] (3) Under the protection of argon atmosphere at 100 mL / min, the temperature was raised to 700°C at a rate of 1°C / min and maintained for 10 h. The temperature was then lowered to room temperature and the catalyst PNNB-4 was obtained.

[0037] Example 5 Hydrogenation reaction of cyclic compounds 30 mL of toluene and the prepared PNNB-1 powdered catalyst were added to a 100 mL stainless steel high-pressure reactor. After nitrogen purging, it was replaced with hydrogen and pressurized to 2 MPa. Stirring was started and heated to the specified temperature of 100 °C, and the hydrogenation reaction was started (the intermediate pressure was maintained at 4 MPa). After 10 h of reaction time, the product composition was detected and analyzed by gas chromatography (GC-FID). The conversion rate of toluene hydrogenation was 99% and the selectivity was 99%.

[0038] The reaction equation is as follows: .

[0039] Example 6 Hydrogenation reaction of cyclic compounds In a 100mL stainless steel high-pressure reactor, 30mL cyclohexane, 5g 1-methylnaphthalene and 200mg prepared PNNB-1 powdered catalyst were added. After nitrogen purging, the mixture was replaced with hydrogen and pressurized to 5MPa. The mixture was stirred and heated to a specified temperature of 120°C to start the hydrogenation reaction. After 12h of reaction time, the product composition was analyzed by gas chromatography (GC-FID). The conversion rate of 1-methylnaphthalene hydrogenation was 99%, and the selectivity of 1-methyldecalin was 98%.

[0040] The reaction equation is as follows: .

[0041] Example 7 Hydrogenation reaction of cyclic compounds In a 100mL stainless steel high-pressure reactor, 30mL cyclohexane solvent, 2g ethylene carbonate and 100mg prepared PNNB-2 catalyst were added. After nitrogen purging, the mixture was replaced with hydrogen and pressurized to 3MPa. The mixture was stirred and heated to a specified temperature of 150°C to start the hydrogenation reaction. After 12h of reaction time, the product composition was analyzed by gas chromatography (GC-FID). The conversion rate of ethylene carbonate hydrogenation was 95%, and the products were ethylene glycol and methanol.

[0042] The reaction equation is as follows: .

[0043] Example 8 Hydrogenation reaction of cyclic compounds In a 100mL stainless steel autoclave, 30mL of water, 5g of 30% water-containing 2,6-dimethyl-1,3-dioxane-4-ol solution and 200mg of the prepared PNNB-3 catalyst were added. After nitrogen purging, it was replaced with hydrogen and pressurized to 5MPa. It was stirred and heated to a specified temperature of 60°C to start the hydrogenation reaction. After 24h of reaction time, the product composition was analyzed by gas chromatography (GC-FID). The conversion rate of 2,6-dimethyl-1,3-dioxane-4-ol hydrogenation was 99%, and the products were 1,3-butanediol and ethanol. After the catalyst was filtered, it was used 10 times under the same reaction conditions without a significant decrease in activity.

[0044] The reaction equation is as follows: .

[0045] Example 9 Hydrogenation reaction of cyclic compounds In a 100mL stainless steel high-pressure reactor, 30mL of water, 5g of a 30% water-containing dimer butanol aldehyde solution and 200mg of the prepared PNNB-3 catalyst were added. After nitrogen purging, the mixture was replaced with hydrogen and pressurized to 6MPa. The mixture was stirred and heated to a specified temperature of 100°C to start the hydrogenation reaction. After 12h of reaction time, the product composition was analyzed by gas chromatography (GC-FID). The hydrogenation conversion rate of dimer butanol aldehyde was 99%, and the product was 1,3-butanediol.

[0046] The reaction equation is as follows: .

[0047] Comparative Example Using nickel / activated carbon as a catalyst, the reaction was carried out according to the steps in Example 8, and the product composition was detected and analyzed by gas chromatography (GC-FID). The conversion rate of 2,6-dimethyl-1,3-dioxane-4-ol hydrogenation was 92%. At the same time, since there was a large amount of water and a small amount of carboxylic acid impurities in the substrate, Ni was easily lost during the catalyst utilization process and the zero-valent nickel species was oxidized and deactivated. After three applications, the conversion rate dropped to 51%.

Claims

1. A method for preparing a boron-containing catalyst, characterized in that: The following steps are involved: 1) Dissolve polyvinyl pyrrolidone in a solvent to form a solution A, and stir at 30-70°C for 1-12 hours; dissolve a soluble nickel salt in water to form a solution B; mix the above two solutions A and B, and stir the mixture for 2-48 hours, then remove water and ethanol by a rotary evaporator at 40-80°C to obtain a solid, then wash it with deionized water for 3-10 times, and dry it to obtain a light green precursor PN of the catalyst; 2) Take phenolic resin and light green precursor PN and dissolve them in ethanol solvent, then add phenylboric acid, stir and react at a temperature of 20-70°C for 2-24h, and dry at 80-120°C to remove the solvent to obtain a solid powder; 3) The solid powder obtained in step (2) is heated to 450-800°C at a rate of 1-8°C / min under inert gas protection, maintained for 3-24 hours, the volatile part is blown away, and finally cooled to room temperature under inert gas protection, and the catalyst PNNB that can exist stably in air is obtained.

2. A method for preparing a boron-containing catalyst as claimed in claim 1, characterized in that: In step 1), the solvent in solution A is any one of ethanol, methanol or propanol, and the soluble nickel salt in solution B is any one of nickel acetate, nickel nitrate, nickel chloride or nickel acetylacetonate.

3. A method for preparing a boron-containing catalyst as claimed in claim 1, characterized in that: In step 2), the amount of the light green precursor PN added is 1 to 30 times the mass of the phenolic resin, and the amount of phenylboric acid added is 0.33 to 5 times the mass of the phenolic resin.

4. A method for preparing a boron-containing catalyst as claimed in claim 1, characterized in that: In step 3), the inert gas is at least one of nitrogen or argon, and the heating rate is 2-5°C / min.

5. Use of the boron-containing catalyst prepared by the method as claimed in claim 1 in the hydrogenation reaction of cyclic compounds.

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