Preparation method of copper-mediated multi-active-site catalyst and application of copper-mediated multi-active-site catalyst in thermal dissolution polymerization of low-rank coal

Abstract

The invention discloses a preparation method of a copper-mediated multi-active-site catalyst and application of the copper-mediated multi-active-site catalyst in thermal dissolution polymerization of low-rank coal, copper nitrate, cobalt nitrate and cerous nitrate are dissolved in deionized water in proportion, heated and stirred to be uniform, and a sodium hydroxide solution is dropwise added for co-precipitation to obtain turbid liquid; and carrying out low-temperature crystallization, high-temperature hydrothermal treatment, centrifugal washing to be neutral, vacuum drying, grinding into powder, high-temperature calcination, cooling and hydrogen reduction to finally obtain the Cu / CoOx-CeO2 catalyst. The catalyst has the advantages of excellent hydrogenation reduction capacity, high product selectivity, low preparation cost and the like, and low-rank coal depolymerization can be realized in various reaction solvents; for hydrogenation reaction of dimer or monomer model compounds such as 2-phenoxy-1-phenethyl alcohol, not only can catalytic transfer hydrogenolysis of C-O bonds be realized in low-carbon alcohol, but also intramolecular self-hydrogen transfer hydrogenolysis can be realized by utilizing self structural characteristics of a substrate, so that the atom utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic depolymerization of low-rank coal, and in particular to a method for preparing a copper-mediated multi-active site catalyst and its application in thermal dissolution polymerization of low-rank coal. Background Art

[0002] Catalytic depolymerization technology selectively breaks weak covalent bonds (such as ether bonds and methylene bridge bonds) in the coal macromolecular skeleton, dissociating it into small molecular compounds, thereby providing abundant hydrocarbon resources for downstream industries, significantly improving the utilization efficiency of low-rank coal, and reducing carbon emissions from direct combustion. However, existing technologies face multiple challenges:

[0003] Organic matter in coal is primarily composed of aromatic structural units containing side chains connected by bridge bonds. Compared to high-rank coal, low-rank coal is less metamorphic, exhibits less condensation of aromatic rings within its structural units, and has higher H / C / O ratios, resulting in stronger reactivity and a significant retention of the macromolecular architecture of the coal-forming plants. Furthermore, low-rank coal structural units are primarily connected by CO and C-C bonds, with CO bonds being more easily activated than C-C bonds. Breaking the CO bridges between structural units under relatively mild conditions to promote the release of organic matter is an ideal process for the depolymerization of low-rank coal. However, the liquid products obtained from low-rank coal depolymerization are complex in composition and low in quality, making them difficult to directly utilize. Catalytic hydroconversion (CHC) of low-rank coal utilizes the composition and structural characteristics of coal to tailor the bridges between organic structural units in the presence of a catalyst by manipulating reaction conditions. The resulting liquid products are also hydrorefined to produce liquid oils and high-value-added chemicals, enabling the clean and efficient utilization of low-rank coal. Catalysts are a key factor influencing the conversion of low-rank coal into carbon (CHC). They play a crucial role in activating hydrogen, promoting hydrogenation, and removing heteroatoms during the CHC process. To date, numerous researchers have conducted extensive basic research on catalysts for the hydroconversion of low-rank coal. The catalysts used are primarily categorized as iron-based, transition metal, acid, and solid superbase catalysts. While traditional iron-based catalysts are relatively low-cost and widely available, their catalytic activity is relatively limited. They are prone to agglomeration during the reaction, resulting in poor dispersion and, in turn, impacting catalytic efficacy and efficiency. Transition metal catalysts, while highly active, are often expensive, and some transition metals are environmentally toxic, presenting both cost and environmental challenges in large-scale application. Acid catalysts are highly corrosive to equipment, making post-reaction product separation and catalyst recovery difficult, increasing subsequent processing costs and process complexity. Solid superbase catalysts, on the other hand, exhibit poor stability and are prone to deactivation in complex reaction systems, making it difficult to maintain sustained, efficient catalytic performance. Furthermore, most catalytic hydrogenolysis reactions require an external hydrogen source, increasing production costs. Therefore, under mild reaction conditions, improving the product yield, monomer selectivity and atom utilization during the depolymerization of low-rank coal is particularly important for the clean and efficient utilization of low-rank coal. Summary of the Invention

[0004] In response to the above-mentioned problems, the purpose of the present invention is to provide a method for preparing a single-metal copper-mediated multi-active site catalyst and its application in the thermal dissolution polymerization of low-rank coal. The catalyst has the advantages of excellent hydrogenation reduction ability, the ability to achieve low-rank coal depolymerization in a variety of reaction solvents, high product selectivity and low preparation cost. For the hydrogenation reaction of dimer or monomer model compounds such as 2-phenoxy-1-phenylethanol, it can not only realize the catalytic transfer hydrogenolysis of the CO bond in the low-carbon alcohol, but also utilize the structural characteristics of the substrate itself to realize intramolecular self-hydrogen transfer hydrogenolysis, thereby improving the atomic utilization rate.

[0005] In order to solve the problems of the prior art, the technical solution adopted by the present invention is:

[0006] A method for preparing a copper-mediated multi-active site catalyst comprises the following steps:

[0007] (1) Weighing copper nitrate trihydrate, cobalt nitrate hexahydrate, and cerium nitrate hexahydrate, adding them to a deionized water solution, heating and stirring until uniformly dispersed to obtain solution A, wherein the concentration of copper metal salt in solution A is 5-15 mg / mL, and the concentration of cobalt and cerium metal salts is 25-35 mg / mL;

[0008] (2) Weighing sodium hydroxide solution and adding it to deionized water, stirring at room temperature until uniformly dispersed, to obtain solution B, wherein the concentration of sodium hydroxide in solution B is 0.5 to 2.0 mol / L;

[0009] (3) Under magnetic stirring conditions of 300-500 r / min and a reaction temperature of 30-60°C, solution B was added dropwise to solution A to obtain a suspension; the suspension was first placed at 30-60°C for crystallization for 2-5 hours, then transferred to the reaction system, heated to 80-110°C, and allowed to stand for 12-15 hours;

[0010] (4) The suspension obtained in step (3) is centrifuged and washed to neutrality; the obtained precipitate is vacuum dried for 6 to 12 hours, ground into powder, and then calcined at 500 to 650° C. for 2 to 3 hours; after cooling to 10 to 20° C., hydrogen is introduced for reduction to obtain a single metal copper-mediated multi-active site catalyst, which is recorded as Cu / CoOx-CeO2.

[0011] Furthermore, in step S1, the mass ratio of copper nitrate trihydrate to cobalt nitrate hexahydrate is 1:3, and the mass ratio of cobalt nitrate hexahydrate to cerium nitrate hexahydrate is 1:1.

[0012] Furthermore, in step S3, the reaction system is a polytetrafluoroethylene reactor, which is placed in a vacuum drying oven preheated to 80-110° C. and heated, and the suspension is cooled to room temperature and then added to the reactor.

[0013] Furthermore, in step S4, calcination is carried out in a muffle furnace, and the heating rate during the calcination process is set to 2-5°C / min; during the reduction process, the flow rate of hydrogen is 20-60 mL / min, the reduction temperature is 500-600°C, and the reduction time is 1-3 hours.

[0014] Furthermore, the powder calcination temperature is 600°C, the heating rate is 5°C / min, and the calcination time is 2h; the reduction temperature is 550°C, the hydrogen flow rate is 50mL / min, the heating rate is 10°C / min, and the reduction time is 2h.

[0015] Furthermore, the actual loading amount of the metallic copper in the prepared catalyst is 3 to 20 wt%, and the metallic cobalt and cerium exist in various oxidation states.

[0016] The second object of the present invention is to provide an application of a catalyst in the thermal dissolution polymerization of low-rank coal, adding the reactants and the catalyst to the reaction system in a mass ratio of 3:1 to 6:1, adding the reaction solvent to the reactants in a volume mass ratio of 0.2 to 0.4 mL / mg, and adding the reaction solvent to the reaction system under a 0.3 to 0.6 MPa nitrogen or hydrogen atmosphere; setting the temperature of the reaction system to 120 to 300°C, and the reaction time to 0.5 to 2 hours.

[0017] Furthermore, after the reaction is completed, the system is cooled to room temperature, the gas in the system is collected, the product and the catalyst are separated by filtration, and the liquid product is detected by GC / MS.

[0018] Furthermore, the reaction solvent is methanol, ethanol, isopropanol or n-hexane; the reaction gas is nitrogen or hydrogen, and the reactant is dimer or low-rank coal; the heating rate during the reaction is 10-15°C / min, and the stirring speed is 200-340r / min.

[0019] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The copper-mediated multi-active site catalyst of the present invention has a simple preparation process and low cost, has high catalytic activity, and can achieve hydrogenolysis of the reverse substrate with high selectivity in a variety of reaction solutions and under different reaction conditions;

[0022] 2. This invention uses inexpensive and readily available copper as the active metal site in the catalyst, combining it with cobalt and cerium, both of which have various oxidation states, to create a catalyst with multiple active sites. The introduction of cobalt significantly improves the catalyst's dispersibility, and the synergistic effect of the bimetallic oxide support and the active components significantly enhances the catalyst's hydrogenolysis ability.

[0023] 3. The obtained catalyst Cu / CoOx-CeO2 has strong magnetism and is easy to recycle, which provides great convenience for the separation and reuse of the catalyst after the low-rank coal reaction.

[0024] 4. Cu / CoOx-CeO2 can not only realize the catalytic transfer hydrogenolysis of CO bonds in low-carbon alcohols, but also utilize the structural characteristics of the substrate itself to realize intramolecular self-hydrogen transfer hydrogenolysis, thereby improving the atomic utilization rate.

[0025] 5. The Cu / CoOx-CeO2 catalyst of the present invention is used for the depolymerization of low-rank coal and the hydrogenolysis reduction of dimers. The catalyst preparation process is short, the reaction equipment and operation method are simple, and the reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 XRD patterns of the catalysts prepared in Example 1 and Comparative Examples 1 to 3 of the present invention;

[0027] Figure 2 This is a SEM image of the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention;

[0028] Figure 3 TEM image of the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention;

[0029] Figure 4 This is a graph showing the conversion of 2-phenoxy-1-phenylethanol catalyzed by the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention at different reaction temperatures;

[0030] Figure 5 This is a graph showing the conversion of 2-phenoxy-1-phenylethanol catalyzed by the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention at different reaction times;

[0031] Figure 6 This is the product distribution diagram of the catalytic reaction of 1-acetophenone and 1-phenylethanol by the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention;

[0032] Figure 7 This is a diagram showing the conversion of 2-phenoxy-1-acetophenone catalyzed by the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention;

[0033] Figure 8 This is the product yield and product distribution diagram of the catalytic depolymerization of Zhaotong lignite catalyzed by the Cu / CoOx-CeO2 catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] If no specific experimental steps or conditions are specified in the examples, the conventional experimental procedures or conditions described in the literature in this field can be followed. If the manufacturer of the reagents or instruments is not indicated, they are all conventional reagents that can be purchased commercially.

[0036] Example 1

[0037] Preparation of Cu / CoOx-CeO2 catalyst

[0038] 500 mg of copper nitrate trihydrate, 1.5 g of cobalt nitrate hexahydrate, and 1.5 g of cerium nitrate hexahydrate were dissolved in 50 mL of deionized water, and the mixture was heated and stirred to obtain a solution A.

[0039] 25 mL of 1 M NaOH solution B was added dropwise to solution A, heated to 55°C and stirred for crystallization for 2 h. The solution was then transferred to a polytetrafluoroethylene reactor and heated at 100°C for 12 h.

[0040] After the reaction, the reactor was cooled to room temperature, and the suspension was centrifuged and washed until neutral, and then dried in a vacuum drying oven at 80°C for 12 hours. It was then ground into powder using an agate grinder, placed in a porcelain boat, and calcined in a muffle furnace at a heating rate of 5°C / min to 600°C for 2 hours. After cooling to 10-20°C, the temperature was increased to 550°C at a heating rate of 10°C / min under a flow rate of H2 of 50 mL / min and maintained for 2 hours to obtain the Cu / CoOx-CeO2 catalyst. The reduced catalyst was stored in a desiccator.

[0041] Comparative Example 1

[0042] The preparation method is similar to that of Example 1, except that only 500 mg of copper nitrate trihydrate and 1.5 g of cobalt nitrate hexahydrate are added to solution A. The product is recorded as Cu / CoOx catalyst.

[0043] Comparative Example 2

[0044] The preparation method is similar to that of Example 1, except that only 500 mg of copper nitrate trihydrate and 1.5 g of cerium nitrate hexahydrate are added to solution A. The product is recorded as Cu / CeO2 catalyst.

[0045] Comparative Example 3

[0046] The preparation method is similar to that of Example 1, except that 50 mg of copper nitrate trihydrate, 1.5 g of cobalt nitrate hexahydrate and 1.5 g of cerium nitrate hexahydrate are added to solution A. The product is recorded as Cu L / CoOx-CeO2 catalyst.

[0047] Comparative Example 4

[0048] The preparation method is similar to that of Example 1, except that 50 mg of copper nitrate trihydrate, 1.5 g of cobalt nitrate hexahydrate and 1.5 g of lanthanum nitrate hexahydrate are added to solution A. The product is recorded as Cu / CoOx-La2O3 catalyst.

[0049] Comparative Example 5

[0050] The preparation method is similar to that of Example 1, except that 500 mg of copper nitrate trihydrate, 1.5 g of cobalt nitrate hexahydrate and 1.5 g of ferric nitrate nonahydrate are added to solution A. The product is recorded as Cu / CoOx-FeOx catalyst.

[0051] Figure 1 The X-ray diffraction patterns of the catalysts prepared in Example 1 and Comparative Examples 1-3 are shown. As can be seen from the figures, diffraction peaks of Cu (43.29°, 50.43°, 74.13°) and characteristic peaks of CeO2 at 28.55°, 33.08°, 25.34°, 47.47°, 56.33°, 59.08°, 69.40°, 76.69°, 79.06°, and 88.41° were detected in the catalysts. The oxidation peak intensity of Co oxide was very weak, and the diffraction peak of metallic Co in the Cu / CoOx-CeO2 catalyst almost disappeared, indicating that the introduction of Co improved the dispersibility of the catalyst.

[0052] Figure 2 This is a scanning electron microscope (SEM) spectrum of the Cu / CoOx-CeO2 catalyst prepared in Example 1. The figure clearly shows that the Cu / CoOx-CeO2 catalysts are stacked together to form a dense structure with relatively uniform particle size. Pores and voids exist between the particles, which are conducive to substrate adsorption and hydrogenolysis.

[0053] Figure 3 This is a transmission electron microscopy (TEM) image of the Cu / CoOx-CeO2 catalyst prepared in Example 1. The image shows the catalyst exhibiting a regular polygonal shape, with relatively small and evenly distributed copper particles. The stable CoOx-Cu-CeO2 interface provides the catalyst with strong adsorption capacity, good electron transfer, and excellent catalytic performance.

[0054] Example 2 Hydrogenolysis of 2-phenoxy-1-phenylethanol

[0055] 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of catalyst and 20 mL of reaction solvent were added to the autoclave, which was sealed and filled with nitrogen to replace the air in the autoclave three times, and then filled with 0.5 MPa nitrogen or hydrogen.

[0056] The temperature was raised to 120-300°C at a heating rate of 15°C / min, and the reaction was carried out at a rotation speed of 240 r / min for 30-150 min. After the reaction, the high-pressure reactor was cooled to room temperature, the gas in the reactor was collected, the catalyst was filtered and separated, and the product distribution was characterized and analyzed by GC-MS.

[0057] Example 3 Effect of Different Catalysts on the Hydrogenolysis of 2-Phenoxy-1-Phenylethanol

[0058] Reaction conditions: 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of the catalyst prepared in Example 1 and Comparative Examples 1 to 5, 20 mL of isopropanol, and 0.5 MPa N2.

[0059] As shown in Table 1, the Cu / CeO2 catalyst exhibited weak activity for the CHC reaction of 2-phenoxy-1-phenylethanol (2-PPE-ol), achieving a substrate conversion of only 60.42%, with phenol (PhOH) and 1-phenylethanol (1-PEA) as the primary products. The Cu / CoOx catalyst converted 71.13% of 2-PPE-ol to ethylbenzene (EtBz), PhOH, 1-PEA, and acetophenone (1-AcPH), but with low product selectivity. In contrast, the Cu / CoOx-CeO2 catalyst exhibited excellent CHC performance, achieving complete conversion of 2-PPE-ol under the same conditions, with cyclohexanol (CyOH) and EtBz as the only products. The inability to convert 2-PPE-ol upon decreasing the Cu loading suggests that the Cu species is crucial for the hydrogenolysis of the β-O-4 bond. Furthermore, replacing CeO2 with La2O3 resulted in complete conversion of 2-PPE-ol, but with a significant decrease in product selectivity. This is likely due to the different electronic structure and surface properties of La2O3 compared to CeO2, leading to multiple side reaction pathways during the reaction. After the introduction of Cu / CoOx-FeOx catalyst, the hydrogenolysis products of 2-PPE-ol were primarily phenol and 1-PEA. This is likely due to the relatively small number of active sites in the Cu / CoOx-FeOx catalyst and the weak ability of FeOx to adsorb and activate 2-PPE-ol molecules.

[0060] Table 1 Effect of different catalysts on the hydrogenolysis of 2-phenoxy-1-phenylethanol

[0061]

[0062] Example 4 Effect of Different Reaction Solvents and Reaction Atmospheres on the Hydrogenolysis of 2-Phenoxy-1-Phenylethanol

[0063] Reaction conditions: 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of the catalyst prepared in Example 1, 20 mL of reaction solvent, and reaction time of 2 h.

[0064] Table 2 Effects of different reaction solvents and reaction atmospheres on the hydrogenolysis of 2-phenoxy-1-phenylethanol

[0065]

[0066] As can be seen from Table 2, when isopropanol was used as the reaction solvent, 2-phenoxy-1-phenylethanol was completely converted under either H or N atmosphere, and the product selectivity reached 100% under N atmosphere. However, at this reaction temperature and reaction atmosphere, 2-phenoxy-1-phenylethanol did not undergo hydrogenolysis when methanol, ethanol, and n-hexane were used as the reaction solvents. After increasing the reaction temperature to 240°C, 2-phenoxy-1-phenylethanol was successfully converted to ethylbenzene, phenol, and 1-phenylethanol when methanol or ethanol was used as the reaction solvent under N atmosphere.

[0067] Under a hydrogen atmosphere, using n-hexane as the reaction solvent, at a reaction temperature of 180°C, complete conversion of 2-phenoxy-1-phenylethanol was achieved, but the yield of phenoxyethylbenzene was relatively high. After increasing the temperature to 240°C, in a reaction system with isopropanol and n-hexane as the reaction solvents under a hydrogen atmosphere, the main product of the hydrogenolysis of 2-phenoxy-1-phenylethanol remained unchanged, while the yield of phenoxyethylbenzene decreased, demonstrating the good applicability of the Cu / CoOx-CeO2 catalyst.

[0068] Example 5 Effect of Reaction Temperature on Hydrogenolysis of 2-Phenoxy-1-Phenylethanol

[0069] Reaction conditions: 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of the catalyst prepared in Example 1, 20 mL of isopropanol, 0.5 MPa N2, reaction time: 2 h.

[0070] Figure 4 The effects of different reaction temperatures on the catalytic conversion of 2-phenoxy-1-phenylethanol are shown. At a reaction temperature of 140°C, the conversion of 2-phenoxy-1-phenylethanol was 63.56%. Increasing the reaction temperature to 160°C resulted in complete conversion of 2-phenoxy-1-phenylethanol, but the yield of phenoxyethylbenzene in the product was relatively high, at 10.54%. Further increases in the reaction temperature maintained the conversion of 2-phenoxy-1-phenylethanol, but the yield of phenoxyethylbenzene in the product initially decreased and then increased. The product selectivity was highest at 180°C, so a reaction temperature of 180°C was selected for subsequent studies.

[0071] Example 6 Effect of Reaction Time on Hydrogenolysis of 2-Phenoxy-1-Phenylethanol

[0072] Reaction conditions: 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of the catalyst prepared in Example 1, 20 mL of isopropanol, 0.5 MPa N2, reaction temperature: 180°C.

[0073] Figure 5 The effect of different reaction times on the hydrogenolysis conversion of 2-phenoxy-1-phenylethanol is shown. When the reaction time was 0.5 h, the conversion of 2-phenoxy-1-phenylethanol was 30.22%, and only ethylbenzene, phenol, and 1-phenylethanol were detected in the product. Extending the reaction time to 1.5 h resulted in complete conversion of 2-phenoxy-1-phenylethanol, with a yield of phenoxyethylbenzene in the product of 9.17%. Further extending the reaction time to 2 h resulted in only ethylbenzene and cyclohexanol in the product. This demonstrates that extending the reaction time not only increases the conversion of 2-phenoxy-1-phenylethanol but also promotes the conversion of intermediate products to ethylbenzene and cyclohexanol.

[0074] Example 7 Catalytic Conversion of 1-Acetophenone and 1-Phenylethanol

[0075] Reaction conditions: 80 mg of 1-phenylethanol or 1-acetophenone, 20 mg of the catalyst prepared in Example 1, 20 mL of isopropanol, 0.5 MPa N2, reaction temperature: 160°C.

[0076] Figure 6 The product distribution diagram for the Cu / CoOx-CeO2-catalyzed conversion of 1-acetophenone and 1-phenylethanol is shown. The figure shows that when 1-acetophenone is used as the reaction substrate, it is first reduced to 1-phenylethanol. Only after complete conversion of 1-acetophenone can significant amounts of ethylbenzene and minor amounts of 1-phenylethanol be detected in the product. However, when 1-phenylethanol is used as the reaction substrate, only ethylbenzene is detected in the product, even if 1-phenylethanol is not fully converted. This indicates that during the reaction, 1-acetophenone is first reduced to 1-phenylethanol, which can then be directly dehydrated to ethylbenzene.

[0077] Example 8 Catalytic Conversion of 2-Phenoxy-1-acetophenone

[0078] Reaction conditions: 80 mg of 2-phenoxy-1-acetophenone, 20 mg of the catalyst prepared in Example 1, 20 mL of isopropanol, 0.5 MPa N2, reaction temperature: 180°C.

[0079] Figure 7The product distribution diagram for the catalytic conversion of 2-phenoxy-1-acetophenone catalyzed by Cu / CoOx-CeO2 is shown in the figure. As can be seen from the results, no product formation was detected within the first 0.5 h of the reaction using 2-phenoxy-1-acetophenone as the substrate. After the reaction time was extended to 1 h, approximately 69.24% of the 2-phenoxy-1-acetophenone was converted into 2-phenoxy-1-phenylethanol, phenoxyethylbenzene, ethylbenzene, cyclohexanol, phenol, 1-phenylethanol, and 1-acetophenone, with a yield of 2-phenoxy-1-phenylethanol of 29.61%. This indicates that when 2-phenoxy-1-acetophenone is used as the substrate, the Cu / CoOx-CeO2 catalyst catalyzes the conversion of 2-phenoxy-1-acetophenone to a hydroxyl group (C-OH). The resulting 2-phenoxy-1-phenylethanol then undergoes hydrogenolysis to form other monomeric compounds.

[0080] Example 9 Self-hydrogen transfer hydrogenolysis of 2-phenoxy-1-phenylethanol

[0081] Reaction conditions: 80 mg of 2-phenoxy-1-phenylethanol, 20 mg of the catalyst prepared in Example 1, 20 mL of n-hexane, reaction temperature: 220° C., 2 h.

[0082] Table 3 Self-hydrogen transfer hydrogenolysis of 2-phenoxy-1-phenylethanol

[0083]

[0084] Table 3 shows the product distribution of the self-hydrogen transfer hydrogenolysis of 2-phenoxy-1-phenylethanol catalyzed by Cu / CoOx-CeO2 in a n-hexane nitrogen atmosphere. As can be seen from the results in the table, under the reaction conditions without an external hydrogen source, 2-phenoxy-1-phenylethanol can achieve self-hydrogen transfer hydrogenolysis. Based on the product distribution results, it can be inferred that in the self-hydrogen transfer hydrogenolysis process, 2-phenoxy-1-phenylethanol first removes C α The H on H-OH generates 2-phenoxy-1-acetophenone, and the generated 2-phenoxy-1-acetophenone utilizes C α The H removed from H-OH reacts as a hydrogen source to undergo hydrogenolysis to produce phenol and 1-acetophenone.

[0085] In the presence of n-hexane as a reaction solvent and 0.5 MPa of hydrogen atmosphere, highly selective hydrogenolysis of the CO bond was achieved under mild reaction conditions. In addition, in the presence of n-hexane as a reaction solvent and 0.5 MPa of nitrogen atmosphere, the C α The H-OH group can first undergo dehydrogenation reaction, and the generated hydrogen radical can be used as an internal hydrogen source for the C β The cleavage of the -O bond realizes self-hydrogen transfer hydrogenolysis (SHTH).

[0086] Example 10 Catalytic Conversion of Zhaotong Lignite

[0087] Reaction conditions: 1 g Zhaotong lignite, 250 mg catalyst prepared in Example 1, 20 mL isopropanol, 0.5 MPa N2, reaction temperature: 300°C, reaction time: 2 h.

[0088] Figure 8 This is the distribution diagram of soluble components after thermal dissolution of Zhaotong lignite catalyzed by Cu / CoOx-CeO2. When no catalyst is added, the yield of thermal dissolution of Zhaotong lignite is 18.52%. When the catalyst is added, the yield of thermal dissolution reaches 25.50%, which shows that the catalyst can effectively promote the breakage of macromolecular structure in coal and improve the yield of soluble matter. Figure 8 It can be seen from the results that the introduction of the catalyst not only improves the yield of the hot dissolution product, but also increases the relative percentage content of phenolic compounds in the product, indicating that the catalyst can still maintain good catalytic performance during the hot dissolution process of Zhaotong lignite.

[0089] In summary, the present invention uses metal Co and Ce-based oxides as carriers and utilizes a hydrothermal method to prepare a single-metal copper-supported catalyst with good morphology, structure and catalytic activity. The multiple active sites mediated by single-metal copper in the catalyst can achieve highly selective hydrogenolysis of dimer compounds in a variety of reaction solvents, and exhibit excellent catalytic activity under different hydrogen sources. In addition, based on the catalytic conversion of dimer model compounds, the present invention utilizes the structural characteristics of the substrate itself to achieve self-hydrogen transfer hydrogenolysis and improve atom utilization from the perspective of practical application. Zhaotong lignite with a low degree of metamorphism was selected as the reaction substrate to demonstrate the reactivity of the catalyst.

[0090] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a copper-mediated multi-active site catalyst, characterized in that: The steps include: (1) Weighing copper nitrate trihydrate, cobalt nitrate hexahydrate, and cerium nitrate hexahydrate, adding them to a deionized water solution, heating and stirring until uniformly dispersed to obtain solution A, wherein the concentration of copper metal salt in solution A is 5-15 mg / mL, and the concentration of cobalt and cerium metal salts is 25-35 mg / mL; (2) Weighing sodium hydroxide solution and adding it to deionized water, stirring at room temperature until uniformly dispersed, to obtain solution B, wherein the concentration of sodium hydroxide in solution B is 0.5 to 2.0 mol / L; (3) Under magnetic stirring conditions of 300-500 r / min and a reaction temperature of 30-60°C, solution B was added dropwise to solution A to obtain a suspension; the suspension was first placed at 30-60°C for crystallization for 2-5 hours, then transferred to the reaction system, heated to 80-110°C, and allowed to stand for 12-15 hours; (4) The suspension obtained in step (3) is centrifuged and washed to neutrality; the obtained precipitate is vacuum dried for 6 to 12 hours, ground into powder, and then calcined at 500 to 650° C. for 2 to 3 hours; after cooling to 10 to 20° C., hydrogen is introduced for reduction to obtain a single metal copper-mediated multi-active site catalyst, which is recorded as Cu / CoOx-CeO2.

2. The method for preparing a copper-mediated multi-active site catalyst according to claim 1, wherein: In step S1, the mass ratio of copper nitrate trihydrate to cobalt nitrate hexahydrate is 1:3, and the mass ratio of cobalt nitrate hexahydrate to cerium nitrate hexahydrate is 1:

1.

3. The method for preparing a copper-mediated multi-active site catalyst according to claim 1, wherein: In step S3, the reaction system is a polytetrafluoroethylene reactor, which is placed in a vacuum drying oven preheated to 80-110° C. and heated. The suspension is cooled to room temperature and then added to the reactor.

4. The method for preparing a copper-mediated multi-active site catalyst according to claim 1, wherein: In step S4, calcination is carried out in a muffle furnace, and the heating rate during the calcination process is set to 2-5°C / min; during the reduction process, the flow rate of hydrogen is 20-60 mL / min, the reduction temperature is 500-600°C, and the reduction time is 1-3 hours.

5. The method for preparing a copper-mediated multi-active site catalyst according to claim 4, wherein: The powder calcination temperature is 600°C, the heating rate is 5°C / min, and the calcination time is 2h; the reduction temperature is 550°C, the hydrogen flow rate is 50mL / min, the heating rate is 10°C / min, and the reduction time is 2h.

6. The method for preparing a copper-mediated multi-active site catalyst according to any one of claims 1 to 5, characterized in that: The actual loading amount of the metal copper in the prepared catalyst is 3-20 wt%, and the metal cobalt and cerium exist in multiple oxidation valence states.

7. Use of the catalyst according to claim 1 in thermal dissolution polymerization of low-rank coal, characterized in that: The reactants and the catalyst are added to the reaction system at a mass ratio of 3:1 to 6:1, and the reaction solvent is added to the reaction system at a volume mass ratio of the reaction solvent to the reactants of 0.2 to 0.4 mL / mg. The reaction is carried out under a nitrogen or hydrogen atmosphere of 0.3 to 0.6 MPa. The temperature of the reaction system is set at 120 to 300° C., and the reaction time is 0.5 to 2 h.

8. Use of the catalyst according to claim 7 in thermal dissolution polymerization of low-rank coal, characterized in that: After the reaction was completed, the system was cooled to room temperature, the gas in the system was collected, the product and the catalyst were separated by filtration, and the liquid product was detected by GC / MS.

9. Use of the catalyst according to claim 7 in thermal dissolution polymerization of low-rank coal, characterized in that: The reaction solvent is methanol, ethanol, isopropanol or n-hexane; the reactant is a dimer, a monomer model compound or low-rank coal; the heating rate during the reaction is 10-15°C / min, and the stirring speed is 200-340r / min.

Images