Green hydrogenation method for crude anthracene by using electrochemical reactor

Abstract

The invention relates to a novel process for realizing green hydrogenation of crude anthracene by using an electrochemical reactor under normal temperature and normal pressure conditions, and particularly relates to a process for realizing refined utilization of crude anthracene resources by using a solid proton conductor type electrochemical reactor under external electric energy to oxidize a hydrogen supply substance into protons and electrons at an anode, protons reach a cathode through a proton exchange membrane, and are combined with electrons at the cathode to be reduced into adsorbed hydrogen, so that high-selectivity graded gradient hydrogenation is performed on a crude anthracene complex system. According to the method, high-selectivity graded gradient hydrogenation is performed on a crude anthracene complex system by utilizing the characteristic that an electrochemical reactor generates in-situ hydrogen at a cathode, the intermolecular association effect of crude anthracene components is destroyed after hydrogenation, and fine separation and high-valued application of the components are realized. The new process realizes green and safe hydrogenation, reduces energy consumption and operation risk, improves the overall efficiency of the reactor, reduces the equipment cost, and completes effective utilization of crude anthracene resources and maximization of fine chemical value.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical engineering, and in particular relates to a new method for realizing green hydrogenation of crude anthracene under normal temperature and pressure conditions by utilizing an electrochemical reactor. Background Art

[0002] Anthracene oil is a very important fraction in the distillation process of coal tar. It mainly contains important aromatic components such as anthracene, phenanthrene, carbazole, pyrene, fluoranthene, etc. The output is about 20% to 25% of high-temperature coal tar. At present, the utilization of anthracene oil includes as raw material oil for the production of carbon black, blending with asphalt as fuel oil, or full hydrogenation to prepare liquid fuel. Traditional utilization methods do not target the characteristics of the various components of anthracene oil.

[0003] After the anthracene oil component is treated with a solvent, crude anthracene, which mainly contains three aromatic components: anthracene, phenanthrene, and carbazole, can be obtained. The traditional separation of crude anthracene components is a process of solvent extraction, distillation, etc. Due to the association effect between aromatic molecules, separation and purification are difficult, and the process has the disadvantages of high energy consumption and low efficiency. Through selective hydrogenation, the association effect between aromatic molecules is destroyed, which is beneficial to the efficient separation of crude anthracene components. Traditional catalytic hydrogenation technology uses hydrogen as a reducing agent and selects a suitable catalyst to hydrogenate polycyclic aromatic hydrocarbons at a suitable temperature and pressure to generate hydrogenated products. However, the catalytic hydrogenation refining process of crude anthracene requires high temperature and high hydrogen pressure. First, deep hydrogenation requires a high concentration of adsorbed hydrogen on the catalyst surface; second, the solubility of hydrogen is low, resulting in the need for a higher hydrogen pressure in the reaction; third, the selectivity of the hydrogenated product is poor, which makes it difficult to meet the separation requirements and high-value applications of anthracene oil.

[0004] The electrochemical reactor uses the characteristics of electrons as powerful and sustainable reagents to activate the substrate through cathode surface reduction, successfully solving the problem of difficulty in transferring hydrogen to the catalyst surface in traditional three-phase reactions. It converts the processes of hydrogen dissolution, mass transfer and dissociative adsorption in existing hydrogenation methods into an electrochemical in-situ generation of catalyst-adsorbed hydrogen, and directly undergoes liquid-phase hydrogenation reactions with the adsorbed unsaturated reactants. This hydrogenation method can achieve sufficient catalyst surface adsorbed hydrogen concentration at room temperature and pressure, eliminating the high pressure, high energy consumption and equipment complexity caused by hydrogen mass transfer resistance in external hydrogen supply methods, and based on the characteristics that the electrochemical reaction processes at the cathode and anode are both independent and coupled to each other, graded refining and quality improvement can be achieved through selective deep hydrogenation. Summary of the invention

[0005] The present invention provides a new method for realizing green hydrogenation of crude anthracene at room temperature and pressure by using an electrochemical reactor. Specifically, the method aims at fine utilization of crude anthracene resources. In view of the problems of harsh conditions, poor selectivity of hydrogenation products, and difficulty in separation and purification of traditional catalytic hydrogenation methods, the method utilizes the characteristics of in-situ hydrogen generation at the cathode of the electrochemical reactor to perform highly selective graded gradient hydrogenation on the complex system of crude anthracene. After hydrogenation, the intermolecular association effect of the crude anthracene components is destroyed, and fine separation and high-value application of the components are realized. The new process realizes green and safe hydrogenation, reduces energy consumption and the danger of operation, improves the overall efficiency of the reactor, reduces equipment costs, and completes the effective utilization of crude anthracene resources and maximizes the value of fine chemicals.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A green hydrogenation method for crude anthracene using an electrochemical reactor is used for the purpose of rationally utilizing crude anthracene resources. A solid proton conductor electrochemical reactor is used. Under external electric energy, the hydrogen supply material is oxidized into protons and electrons at the anode, and the protons reach the cathode through the proton exchange membrane, and are reduced to adsorbed hydrogen at the cathode by combining with electrons. The complex system of crude anthracene is highly selectively hydrogenated in a graded gradient. Most of the 2-3-ring polycyclic aromatic hydrocarbons in crude anthracene are saturatedly hydrogenated, nitrogen- and sulfur-containing heteroatom organic compounds are completely removed, and polycyclic aromatic hydrocarbons that are difficult to convert, especially polycyclic aromatic hydrocarbons with more than four rings, are also hydrogenated to a high degree of depth.

[0008] The external electric energy refers to the constant current mode, and the current density is 4-12 mA / cm 2 .

[0009] The temperature of the crude anthracene hydrogenation reaction occurring at the cathode is controlled at 20-25°C.

[0010] The hydrogen supply material of the anode is hydrogen gas or water.

[0011] The proton exchange membrane is a perfluorosulfonic acid proton exchange membrane.

[0012] The catalyst layer of the cathode is one of Pt-Ni, Pt-Pd and Pt-Ru, and the loading amount of the alloy catalyst is 0.5-4.5 mg / cm 2 .

[0013] The concentration of the crude anthracene mixed solution at the cathode is 4-10 g / L, the solvent is a mixed solution of DMF and sulfuric acid, and the flow rate is 20-120 mL / min.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1) The present invention provides a new safe and green reaction process for the graded gradient hydrogenation process of crude anthracene complex system. It utilizes the low electrochemical window of hydrogen donors to produce in-situ adsorbed hydrogen to directly participate in the liquid phase reaction, coordinates and strengthens the reaction process, avoids the conventional high-pressure hydrogenation method, reduces energy consumption and operational hazards, and can realize the engineering of clean hydrogenation refining of crude anthracene.

[0016] 2) The solid proton conductor electrochemical reaction system proposed in the present invention overcomes the shortcomings of traditional liquid electrolyte electrochemical hydrogenation reactions that are difficult to control, have poor product selectivity, and are difficult to purify. It has the characteristics that the cathodic and anodic electrochemical reaction processes are both independent of each other and coupled to each other. Based on this, a unique and efficient multi-process integrated coupled intensified reaction device is provided. Through highly selective graded gradient hydrogenation, the refined separation and high-value utilization of each component are achieved, and the mass transfer resistance and activation resistance are reduced, thereby improving the overall efficiency of the reactor and reducing equipment costs.

[0017] 3) Most of the 2-3-ring polycyclic aromatic hydrocarbons in crude anthracene were saturated with hydrogen, and organic compounds containing nitrogen and sulfur heteroatoms were completely removed. Polycyclic aromatic hydrocarbons that are more difficult to convert, especially those with four or more rings, were also hydrogenated to a high degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of electrochemical deep hydrogenation of crude anthracene in the present invention.

[0019] In the figure: 1-anode catalyst layer, 2-proton exchange membrane, 3-cathode catalyst layer. DETAILED DESCRIPTION

[0020] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. Based on the examples in the present invention, all other examples obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0021] See Figure 1 As shown, a green hydrogenation method for crude anthracene using an electrochemical reactor is aimed at rationally utilizing crude anthracene resources. A solid proton conductor type electrochemical reactor is used, which is composed of a proton exchange membrane 2, a catalyst layer, a gas diffusion layer and a bipolar plate. The catalyst layer includes an anode catalyst layer 1 and a cathode catalyst layer 3. Under external electric energy, the hydrogen supply substance is oxidized into protons and electrons at the anode, and the protons reach the cathode through the proton exchange membrane 2, and are reduced to adsorbed hydrogen at the cathode by combining with electrons, so as to perform highly selective graded gradient hydrogenation on the complex system of crude anthracene.

[0022] The external electric energy refers to the constant current mode, and the current density is 4-12 mA / cm 2 .

[0023] The temperature of the crude anthracene hydrogenation reaction occurring at the cathode is controlled at 20-25°C.

[0024] The hydrogen supply material of the anode is hydrogen gas or water.

[0025] The proton exchange membrane 2 is a perfluorosulfonic acid proton exchange membrane.

[0026] The cathode catalyst layer 3 is one of Pt-Ni, Pt-Pd, and Pt-Ru, and the loading amount of the alloy catalyst is 0.5 to 4.5 mg / cm 2 .

[0027] The concentration of the crude anthracene mixed solution at the cathode is 4-10 g / L, the solvent is a mixed solution of DMF and sulfuric acid, and the flow rate is 20-120 mL / min.

[0028] Embodiment 1:

[0029] Load 4mg / cm 2 Pt-Ni / C carbon paper was used as cathode, with a loading of 0.5 mg / cm 2 The Pt gas diffusion electrode is used as the anode, and the Nafion117 membrane is used as the proton exchange membrane. The anode is fed with hydrogen at a rate of 30 mL / min; the cathode is fed with a 5 g / L crude anthracene mixed solution, and the outflowing solution is recirculated into the cathode during the reaction at a rate of 85 mL / min. The reaction temperature is 25°C. When the electrochemical reactor is operated at 4 mA / cm 2 After 0.5h of constant current operation, the products were collected for gas chromatography analysis. The hydrogenation conversion rate of anthracene, phenanthrene and carbazole in crude anthracene was 100%, and the hydrogenation products were mainly dihydrogen products and tetrahydrogen products, with a current efficiency of 87%. In Example 1 of the present invention, when the external electric energy is low and different catalytic layers act, that is, when the reaction conditions are relatively basic, the products can be simply hydrogenated to obtain products with low relative saturation, such as dihydrogen products and tetrahydrogen products, which can be used as new fuels for other pathways.

[0030] Embodiment 2:

[0031] The load was 4 mg / cm 2 Pt-Pb / C carbon paper was used as cathode, with a loading of 0.5 mg / cm 2 The Pt gas diffusion electrode is used as the anode, and the Nafion117 membrane is used as the proton exchange membrane. The anode is fed with hydrogen at a rate of 15 mL / min; the cathode is fed with a 4 g / L crude anthracene mixed solution, and the outflowing solution is recirculated into the cathode during the reaction at a rate of 20 mL / min. The reaction temperature is 25°C. When the electrochemical reactor is heated at 10 mA / cm 2After constant current operation for 1.5h, the mixed solution gradually changes from dark yellow to colorless clear solution, and the product is collected for gas chromatography analysis. The hydrogenation conversion rate of anthracene, phenanthrene and carbazole in crude anthracene is 100%. Anthracene, fluorene, naphthalene and fluoranthene are almost completely converted into full hydrogen products. After the deep hydrogenation of phenanthrene, there are no dihydrogen products and tetrahydro products in the hydrogenated products, mainly octahydrophenanthrene, and the relative content reaches 71.1%. S in N, quinoline and benzothiazole in carbazole is completely removed after hydrogenation. Embodiment 2 of the present invention, when the external electric energy is increased and different catalytic layers act, that is, when the reaction conditions are higher, the product depth can be hydrogenated, the product hydrogenation degree is higher, there is no low saturation hydrogenation product, such as dihydro products and tetrahydro products do not exist.

[0032] Embodiment 3:

[0033] The load was 4 mg / cm 2 Pt-Pb / C carbon paper was used as cathode, with a loading of 0.5 mg / cm 2 The Pt gas diffusion electrode was used as the anode, and the Nafion117 membrane was used as the proton exchange membrane. The anode was fed with distilled water at a rate of 20 mL / min; the cathode was fed with a 4 g / L crude anthracene mixed solution, and the outflowing solution was recirculated into the cathode during the reaction at a rate of 20 mL / min. The reaction temperature was 25°C. When the electrochemical reactor was heated at 12 mA / cm 2 After 2 hours of constant current operation, the mixed solution gradually changed from dark yellow to a colorless clear solution, and the products were collected for gas chromatography analysis. The hydrogenation conversion rate of anthracene, phenanthrene and carbazole in crude anthracene was 100%. Anthracene, fluorene and naphthalene were completely converted into perhydroanthracene, perhydrofluorene and perhydronaphthalene, respectively. After deep hydrogenation of phenanthrene, the hydrogenation products were mainly octahydrophenanthrene and perhydrophenanthrene, with relative contents of 69.5% and 28.9%. After deep hydrogenation of pyrene, the hydrogenation products were mainly decahydropyrene and perhydropyrene, with relative contents of 96.5% and 3.5%. N in carbazole, S in quinoline and benzothiazole were completely removed after hydrogenation.

[0034] Comparative Example 1:

[0035] The reaction was carried out in a high temperature and high pressure reactor, the reactant was crude anthracene, and the catalyst was Pt-Ni / Al 2 O 3, hydrogen is filled to replace the air in the kettle and the pressure reducing valve is adjusted to make the initial pressure in the kettle reach 4MPa, the reaction temperature is 320℃, the agitator speed is maintained at 300r / min, the reaction is carried out for 1.5h, the reactor is left to cool, the exhaust is exhausted, and the product is taken out for gas chromatography analysis. The anthracene hydrogenation conversion rate in crude anthracene reaches 93%, and the hydrogenation product accounts for 43.2% of the full hydrogen anthracene, including tetrahydroanthracene and octahydroanthracene; the phenanthrene hydrogenation conversion rate is 87%, and the full hydrogen phenanthrene accounts for 35.5% of the hydrogenation product, including dihydrophenanthrene, tetrahydrophenanthrene, and octahydrophenanthrene; the carbazole hydrogenation conversion rate is 97%, and no N-containing heteroatom compounds are detected in the hydrogenation product. Comparative Example 1 is a traditional catalytic hydrogenation, which cannot achieve selective hydrogenation. The products are dihydrogen, tetrahydrogen, octahydrogen, and full hydrogen, low saturation, high saturation, and all hydrogenation levels, and the products are difficult to grade and separate.

[0036] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A green hydrogenation method for crude anthracene using an electrochemical reactor, characterized in that: A solid proton conductor electrochemical reactor is used to oxidize the hydrogen-donating substance into protons and electrons at the anode under external electric energy. The protons reach the cathode through the proton exchange membrane and are reduced to adsorbed hydrogen by combining with electrons at the cathode. The complex system of crude anthracene is hydrogenated in a graded gradient manner.

2. A green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The external electric energy refers to the constant current mode, and the current density is 4-12 mA / cm 2 .

3. The green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The temperature of the crude anthracene hydrogenation reaction occurring at the cathode is controlled at 20-25°C.

4. The green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The hydrogen supply material of the anode is hydrogen gas or water.

5. The green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The proton exchange membrane is a perfluorosulfonic acid proton exchange membrane.

6. The green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The catalyst layer of the cathode is one of Pt-Ni, Pt-Pd and Pt-Ru, and the loading amount of the alloy catalyst is 0.5-4.5 mg / cm 2 .

7. The green hydrogenation method for crude anthracene using an electrochemical reactor according to claim 1, characterized in that: The concentration of the crude anthracene mixed solution at the cathode is 4-10 g / L, the solvent is a mixed solution of DMF and sulfuric acid, and the flow rate is 20-120 mL / min.

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