A method for improving the yield of oxygenates in low rank coal derived solubles
By combining ozone oxidation pretreatment with magnetic Co-CuFe2O4 nanosphere catalyst, the problems of low liquefaction yield and poor selectivity of derived soluble components in low-rank coal were solved, achieving efficient directional conversion of low-rank coal and high-yield product preparation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YULIN UNIV
- Filing Date
- 2024-04-01
- Publication Date
- 2026-06-23
Smart Images
Figure CN118146820B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of low-rank coal pretreatment technology, and particularly relates to a method for improving the yield of oxygen-containing compounds in low-rank coal-derived solubles. Background Technology
[0002] Low-rank coal is a mixture of macromolecular compounds composed of various chemical bonds and functional groups, as well as low-molecular-weight molecules. It is primarily composed of heteroatoms such as C, H, O, and N, forming an extremely complex three-dimensional macromolecular structure. Low-rank coal reserves are abundant, and its utilization as a raw material for obtaining high-value-added organic chemicals and clean liquid fuels has unique advantages. Therefore, the implementation of low-rank coal resource conversion processes is particularly important.
[0003] Under current technology, commonly used pretreatment methods for low-rank coal include H2O2 aqueous solution oxidation, NaOCl aqueous solution oxidation, and ruthenium ion catalytic oxidation. These pretreatment methods often require long reaction cycles and are relatively uneconomical for large-scale production applications. Therefore, it is necessary to optimize reaction conditions or develop new processes to improve and overcome these shortcomings. In this invention, ozone, as a strong oxidant, has the advantages of fast reaction, easy preparation, low dosage, and no secondary pollution.
[0004] Many researchers both domestically and internationally have synthesized low-cost, high-efficiency, and environmentally friendly catalysts, but their application in the field of low-rank coal liquefaction is limited. The effective utilization and targeted conversion of low-rank coal still faces significant challenges. Based on the current state of industrial development, this paper proposes a method to improve the yield of oxygen-containing compounds in low-rank coal-derived solubles. This method aims to effectively overcome the problems of low yield and poor selectivity of derivative soluble components in traditional low-rank coal liquefaction processes, obtaining high yields of oxygen-containing compounds from low-rank coal-derived solubles. It also aims to achieve a new process for the targeted tailoring of low-rank coal under mild conditions, which is of great significance for the efficient and comprehensive utilization of low-rank coal. Summary of the Invention
[0005] To overcome the technical problems of low yield and poor selectivity of derivative soluble components in traditional low-rank coal liquefaction, this invention discloses a method for improving the yield of oxygen-containing compounds in low-rank coal derivative solubles, thereby increasing the yield of oxygen-containing compounds in low-rank coal derivative solubles.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for increasing the yield of oxygen-containing compounds in low-rank coal-derived solubles specifically includes the following steps:
[0008] Step a: First, pretreat the low-rank coal with ozone oxidation;
[0009] Step b: Then, magnetic Co-CuFe2O4 nanosphere catalysts were prepared by a one-pot hydrothermal method.
[0010] Step c: The prepared Co-CuFe2O4 nanosphere catalyst is then used to catalyze the ethanololysis reaction of low-rank coal after ozone oxidation pretreatment.
[0011] Further, step a, the specific steps for ozone oxidation pretreatment of low-rank coal:
[0012] Place 10g of low-rank coal into a high-pressure reactor and use an ozone generator at 3nL / min. -1 O3 with a volume fraction of 1%-1.5% is continuously introduced at a flow rate;
[0013] The high-pressure reactor is then heated to 30-70℃ and held for 1-9 hours to obtain low-rank coal pretreated by ozone oxidation.
[0014] Further, step b, the specific steps for preparing the magnetic Co-CuFe2O4 nanosphere catalyst:
[0015] Step S1: First, disperse a certain amount of cobalt salt, copper salt, and iron salt in 70ml of deionized water and stir evenly at room temperature for later use.
[0016] Step S2: Then transfer the mixed solution obtained in step S1 to a polytetrafluoroethylene-lined hydrothermal reactor, slowly inject a certain amount of hydrazine hydrate, and then heat the reactor to 180°C and keep it at that temperature for 12 hours.
[0017] Step S3: Cool the solution obtained in step S2 to room temperature, centrifuge the sample, and wash it several times alternately with deionized water and ethanol.
[0018] Step S4: Place the obtained solid sample in a vacuum drying oven and dry it at 100℃ for 8 hours to obtain magnetic Co-CuFe2O4 nanospheres.
[0019] Furthermore, in step S1, cobalt acetate is selected as the cobalt salt, copper acetate is selected as the copper salt, and iron acetylacetone is selected as the iron salt, and the molar ratio of cobalt acetate, copper acetate, and iron acetylacetone is 1:19:40, 1:9:20, 3:17:40, 1:4:10, and 1:3:8.
[0020] Furthermore, in step S2, the ratio of the amount of hydrazine hydrate used to the amount of deionized water used in step S1 is (5-20):100.
[0021] Further, in step c, the specific process of the low-rank coal ethanol hydrolysis reaction after pretreatment by ozone oxidation catalyzed by magnetic Co-CuFe2O4 nanospheres is as follows:
[0022] (1) The magnetic Co-CuFe2O4 nanospheres and the low-rank coal pretreated by ozone oxidation were placed in a 1000mL high-pressure reactor and 200mL of ethanol was added.
[0023] (2) After replacing the air in the reactor cavity with N2, 1MPa N2 was introduced and the reaction was carried out at 300℃ for 2 hours. After the reaction was completed, the reactor was cooled to room temperature.
[0024] (3) The reaction mixture was completely extracted with ethanol to obtain the ethanol-soluble substance, i.e., the light component;
[0025] (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.
[0026] This invention also discloses the application of magnetic Co-CuFe2O4 nanospheres prepared by the above method in the catalytic ethanololysis reaction of low-rank coal-related model compounds.
[0027] Compared with the prior art, the beneficial effects of the present invention are:
[0028] (1) During the ozone oxidation of low-rank coal, the content of oxygen-containing groups in the coal structure first increases and then decreases as the oxidation degree of coal deepens. This is because the oxygen absorption of coal reaches saturation during the oxidation process, and a secondary oxidation reaction gradually begins. The secondary oxidation is accompanied by a large consumption of oxygen-containing groups and the generation of gases such as CO2, which in turn reduces the content of active groups and causes passivation of the active centers of coal. Excessive ozone oxidation pretreatment is also accompanied by coal weight loss, thus affecting the subsequent utilization value and performance of coal. Therefore, appropriate ozone oxidation pretreatment can effectively improve the activity of low-rank coal.
[0029] (2) Using cobalt acetate, copper acetate and iron acetylacetone as cobalt source, copper source and iron source respectively, and hydrazine hydrate as strong reducing agent, magnetic Co-CuFe2O4 nanospheres were obtained by one-pot hydrothermal method. In the obtained magnetic Co-CuFe2O4 nanospheres, the cobalt, copper and iron species were well dispersed and no obvious agglomeration was produced. The preparation process does not require calcination, the process is green and simple, the safety and stability are high, the production cycle is short, and the obtained magnetic nanospheres have the potential for large-scale application.
[0030] (3) The prepared magnetic Co-CuFe2O4 has high stability; the prepared magnetic Co-CuFe2O4 nanosphere catalyst also has inherent magnetic characteristics, and the catalyst can be easily recovered by an external magnetic field; when it is applied to the catalytic ethanol decomposition reaction of low-rank coal after ozone oxidation pretreatment and the catalytic ethanol decomposition reaction of low-rank coal-related model compounds, it shows excellent catalytic activity, can effectively crack the CH-O- bridge bond, significantly improve the yield of direct liquefaction, greatly improve the yield of oxygen-containing compounds in the derived solubles, provide a way of thinking for the preparation of value-added chemical precursors, and realize the efficient and high-value utilization of low-rank coal. Attached Figure Description
[0031] Figure 1 The X-ray diffraction pattern of the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention;
[0032] Figure 2 The images shown are scanning electron microscope (SEM) images, elemental distribution diagrams, and electron energy spectrum diagrams of the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention.
[0033] Figure 3 The images shown are transmission electron microscope (TEM) images and particle size distribution diagrams of the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention.
[0034] Figure 4 The X-ray photoelectron spectrum of the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention;
[0035] Figure 5 The graph shows the yield of the catalytic ethanol hydrolysis derivative of low-rank coal in Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment using the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention.
[0036] Figure 6 Fourier transform infrared spectrum of the light component of low-rank coal catalytic ethanol hydrolysis in Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment, prepared by magnetic Co-CuFe2O4 nanospheres in Example 1 of this invention.
[0037] Figure 7 The distribution diagram of the core group components of the light components in the catalytic ethanol hydrolysis of low-rank coal in Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment, using the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 of this invention. Detailed Implementation
[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] Under current technology, commonly used low-rank coal pretreatment methods often require long reaction cycles, resulting in relatively poor economic efficiency for large-scale production applications. Therefore, it is necessary to optimize reaction conditions or develop new processes to improve and overcome these shortcomings. Addressing these issues in current industrial production, this invention uses ozone as a strong oxidant, which has advantages such as rapid reaction, easy preparation, low dosage, and no secondary pollution. Cobalt acetate, copper acetate, and iron acetylacetone are used as cobalt, copper, and iron sources, respectively, and hydrazine hydrate is used as a strong reducing agent. Magnetic Co-CuFe2O4 nanospheres are obtained using a one-pot hydrothermal method. This catalyst preparation process is green, simple, and safe. It modifies the morphology, structure, and size of the catalyst to a certain extent, without producing significant agglomeration, increasing the specific surface area of the catalyst to obtain more active sites, and compensating for some of the defects of traditional metal oxide catalysts.
[0040] The highly active Co-CuFe2O4 nanosphere catalyst significantly improved the conversion of low-rank coal-related model compounds and the catalytic ethanololysis of low-rank coal after ozone oxidation pretreatment, thereby increasing the yield of direct liquefaction and the yield of oxygen-containing compounds in the derived solubles.
[0041] Example 1
[0042] A method for increasing the yield of oxygen-containing compounds in low-rank coal-derived solubles specifically includes the following steps:
[0043] 1. Ozone oxidation pretreatment of low-rank coal
[0044] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 O3 with a volume fraction of 1.5% is continuously introduced at a flow rate.
[0045] (2) Heat the autoclave to 50°C and hold for 3 hours to obtain low-rank coal after oxidation pretreatment.
[0046] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0047] (1) Disperse 0.1g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0048] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0049] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0050] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanospheres.
[0051] The X-ray diffraction patterns of the magnetic Co-CuFe2O4 nanospheres prepared above are attached. Figure 1 The diffraction peaks (2θ) at angles of 29.80°, 35.46°, 43.74°, 53.86°, 56.77°, and 62.32° can be attributed to reflections from the (220), (311), (400), (422), (511), and (440) lattice planes, which belong to Co-CuFe2O4 (Standard Card No. 36-0153). The observed diffraction peaks indicate that these nanoparticles possess a single-phase cubic spinel structure and exhibit good catalytic activity.
[0052] In the preparation of magnetic Co-CuFe₂O₄ nanospheres, the hydrothermal treatment process dominated the formation of the nanospheres. Furthermore, the introduction of hydrazine hydrate increased the system pressure. Clearly, the CoFe₂O₄ and CuFe₂O₄ generated in the alkaline environment combined to form a unique multimetallic composite structure without the formation of other impurities. These results indicate that Co-CuFe₂O₄ nanospheres can be rapidly prepared via a one-pot hydrothermal synthesis method without the need for calcination.
[0053] As attached Figure 2 and attached Figure 3 As shown, the Co-CuFe2O4 particles are relatively uniformly distributed and small in size, with an average particle size of 12.2 nm. Slight agglomeration occurs between the Co-CuFe2O4 nanoparticles, attributed to magnetic interactions and van der Waals forces between the nanoparticles. Electron spectroscopy analysis confirms that Co, Cu, Fe, and O are the main constituent elements of the Co-CuFe2O4 nanospheres, and these four elements are highly dispersed throughout the nanospheres. Furthermore, the relative atomic ratios of Co / Cu and Cu / Fe are close to the expected values. These analyses indicate that the Co-CuFe2O4 nanospheres prepared by the one-pot hydrothermal method have a uniform texture.
[0054] The X-ray photoelectron spectra of the magnetic Co-CuFe2O4 nanospheres prepared above are attached. Figure 4 As shown, the main chemical elements in Co-CuFe2O4 nanospheres are Co, Cu, Fe, and O. In the fitted spectrum of O 1s, the two fitted peaks at 530.5 and 531.9 eV are attributed to the lattice oxygen of the metal oxides (Co-O, Cu-O, and Fe-O) and the hydroxyl groups adsorbed on the catalyst surface, respectively. Each Co 2p peak, Cu 2p peak, and Fe 2p peak contains 2p... 3 / 2 and 2p 1 / 2 Two main peaks and two satellite peaks. In the fitted spectrum of Co 2p, the fitted peaks at 780.6 and 796.6 eV and the satellite peaks at 786.4 and 803.4 eV confirm that Co 2+ The presence of Cu 2p is confirmed by the fitting peaks at 934.3 and 954.3 eV and the satellite peaks at 942.2 and 962.5 eV in the Cu 2p fitted spectrum. 2+ The presence of Cu, and the fitting peaks at 932.8 and 952.5 eV, prove that Cu + The presence of Fe2p is confirmed by the fitting peaks at 713.3 and 726.3 eV and the satellite peaks at 719.3 and 732.9 eV in the Fe2p fitted spectrum. 3+ The presence of Fe, and the fitting peaks at 710.7 and 724.2 eV, prove that Fe 2+ The presence of [the catalyst] was observed. Combined with X-ray diffraction analysis, it was found that the catalyst synthesized via a one-pot hydrothermal method was mainly composed of a Co-CuFe2O4 crystal structure.
[0055] Example 2
[0056] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0057] 1. Ozone oxidation pretreatment of low-rank coal
[0058] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0059] (2) Heat the autoclave to 30°C and hold for 3 hours to obtain low-rank coal after oxidation pretreatment.
[0060] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0061] (1) Disperse 0.2g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0062] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0063] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0064] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0065] Example 3
[0066] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0067] 1. Ozone oxidation pretreatment of low-rank coal
[0068] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0069] (2) Heat the autoclave to 40°C and hold for 3 hours to obtain low-rank coal after oxidation pretreatment.
[0070] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0071] (1) Disperse 0.3g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0072] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0073] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0074] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0075] Example 4
[0076] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0077] 1. Ozone oxidation pretreatment of low-rank coal
[0078] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0079] (2) Heat the autoclave to 60°C and hold for 3 hours to obtain low-rank coal after oxidation pretreatment.
[0080] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0081] (1) Disperse 0.4g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0082] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0083] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0084] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0085] Example 5
[0086] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0087] 1. Ozone oxidation pretreatment of low-rank coal
[0088] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0089] (2) Heat the autoclave to 70°C and hold for 3 hours to obtain low-rank coal after oxidation pretreatment.
[0090] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0091] (1) Disperse 0.5g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0092] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0093] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0094] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0095] Example 6
[0096] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0097] 1. Ozone oxidation pretreatment of low-rank coal
[0098] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0099] (2) Heat the autoclave to 50°C and hold for 1 hour to obtain low-rank coal after oxidation pretreatment.
[0100] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0101] (1) Disperse 0.4g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0102] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0103] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0104] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0105] Example 7
[0106] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0107] 1. Ozone oxidation pretreatment of low-rank coal
[0108] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0109] (2) Heat the autoclave to 50°C and hold for 5 hours to obtain low-rank coal after oxidation pretreatment.
[0110] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0111] (1) Disperse 0.4g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0112] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0113] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0114] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0115] Example 8
[0116] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0117] 1. Ozone oxidation pretreatment of low-rank coal
[0118] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0119] (2) Heat the autoclave to 50°C and hold for 7 hours to obtain low-rank coal after oxidation pretreatment.
[0120] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0121] (1) Disperse 0.4g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0122] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0123] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0124] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0125] Example 9
[0126] The preparation process of a magnetic Co-CuFe2O4 nanosphere catalyst is as follows:
[0127] 1. Ozone oxidation pretreatment of low-rank coal
[0128] (1) Place 10g of low-rank coal into a high-pressure autoclave and use an ozone generator to generate 3nL / min. -1 A continuous flow rate of 1.5% O2 was introduced. 3。
[0129] (2) Heat the autoclave to 50°C and hold for 9 hours to obtain low-rank coal after oxidation pretreatment.
[0130] 2. Preparation of magnetic Co-CuFe2O4 nanosphere catalysts
[0131] (1) Disperse 0.4g cobalt salt, 0.7g copper salt and 2.5g iron salt in 70mL deionized water and stir evenly at room temperature for later use.
[0132] (4) Transfer the above mixed solution to a 100ml polytetrafluoroethylene-lined hydrothermal reactor, slowly inject 7mL of hydrazine hydrate, and then place it in a 180℃ drying oven to react for 12h.
[0133] (5) After cooling the above solution to room temperature, take it out and centrifuge the sample at a speed of 5000 rpm for 3 min. Then wash it several times with deionized water and ethanol alternately until it is neutral.
[0134] (6) The obtained solid sample is vacuum dried at 100℃ for 8h to obtain magnetic Co-CuFe2O4 nanosphere catalyst.
[0135] The magnetic Co-CuFe2O4 nanosphere catalysts prepared in Examples 1-5 were used for the catalytic ethanololysis of benzylphenyl ether.
[0136] Reaction conditions: The catalyst was evaluated in a programmed temperature-controlled, high-pressure, mechanically stirred microreactor.
[0137] Benzylphenyl ether was used as the reaction substrate. The reaction conditions were: initial nitrogen pressure of 1 MPa, reaction temperature of 300℃, reaction time of 120 min, 0.05 g of reaction substrate, 20 ml of ethanol as the solvent, and 0.05 g of catalyst.
[0138] After the reaction was completed, the high-pressure reactor was cooled to room temperature and the reaction mixture was removed. The filtered filtrate was analyzed by gas chromatography-mass spectrometry. The performance analysis results of the Co-CuFe2O4 nanosphere catalyst for the catalytic ethanololysis of low-rank coal-related model compounds are shown in Table 1 below.
[0139] Table 1. Performance analysis results of catalytic ethanololysis of model compounds related to low-rank coal in Examples 1-5.
[0140]
[0141] As shown in Table 1, the main products of the conversion of benzyl phenyl ether catalyzed by the magnetic Co-CuFe2O4 nanosphere catalysts in Examples 1-5 were aromatics, especially toluene and other aromatics (diphenylethane and benzyltoluene). The conversion rate of benzyl phenyl ether reached 100% only under the catalysts in Examples 1 and 4, with the highest yield of aromatics and total product obtained under the catalyst in Example 1. The introduction of magnetic Co-CuFe2O4 nanospheres facilitates the breaking of the >CH-O- bridging bonds in benzyl phenyl ether. In summary, the magnetic Co-CuFe2O4 nanospheres in Example 1 are a more suitable catalyst for improving the ethanol production rate of low-rank coal under ozone pre-oxidation.
[0142] The low-rank coal raw coal and the low-rank coal pretreated by ozone oxidation in Examples 1-9 were used in the ethanol decomposition reaction.
[0143] Reaction conditions: The effect of ozone oxidation pretreatment was evaluated in a programmed temperature-controlled, high-pressure, mechanically stirred microreactor.
[0144] Low-rank coal and the low-rank coal after oxidation pretreatment in Examples 1-9 were used as reaction substrates. The reaction conditions were: initial nitrogen pressure of 1 MPa, reaction temperature of 300℃, reaction time of 120 min, 1 g of reaction substrate, and 20 ml of ethanol as the reaction solvent.
[0145] After the reaction was completed, the high-pressure reactor was cooled to room temperature and the reaction mixture was removed. The reaction mixture was then completely extracted with ethanol to obtain the ethanol-soluble component, i.e., the light component. Subsequently, extraction was continued with an equal volume of a mixed solvent of acetone and carbon disulfide to obtain an equal volume of a solvent-soluble component of the mixed solvent of acetone and carbon disulfide, i.e., the heavy component. The obtained light components were analyzed and compared. The yield comparison of each component in the ethanololysis reaction is shown in Table 2 below, and the group component distribution of the low-rank coal-derived solubles after the ethanololysis reaction is shown in Table 3 below.
[0146] Table 2 Yields of each component in the ethanololysis reaction of raw coal and low-rank coal after oxidative pretreatment in Examples 1-9
[0147] Low-rank coal samples Yield of light components (wt%) Yield of heavy components (wt%) Total yield (wt%) raw coal 6.5 7.3 13.8 Example 1 13.4 11.5 24.9 Example 2 7.3 8.2 15.5 Example 3 9.9 9.4 19.3 Example 4 11.6 9.1 20.7 Example 5 9.5 7.9 17.4 Example 6 10.4 8.2 18.6 Example 7 10.8 11.1 21.9 Example 8 9.6 10.1 19.7 Example 9 8.5 9.6 18.1
[0148] Table 3. Distribution of group components of soluble derivatives after ethanololysis of raw coal and low-rank coal pretreated in Examples 1-9.
[0149]
[0150] Ethanol effectively swells low-rank coal, making its structure more porous. Furthermore, the solvent's strong nucleophilicity induces the breaking of stronger covalent bonds, leading to higher yields in the ethanololysis of low-rank coal. As shown in Table 2, the ethanololysis of low-rank coal after oxidative pretreatment in Example 1 achieved the highest yield (24.9 wt%), with light components reaching 13.4 wt% and heavy components reaching 11.5 wt%. GC / MS analysis revealed eight groups of organic compounds (alkanes, cycloalkanes, alkenes, cycloalkenes, aromatics, oxygen-containing compounds, nitrogen-containing compounds, and sulfur-containing compounds). Table 3 shows the relative content of each group. It can be observed that the relative content of oxygen-containing compounds was highest (54.3%) in the oxidatively pretreated low-rank coal of Example 1, which is attributed to ozone action on the coal and aligns with the purpose of oxidative pretreatment. Therefore, the low-rank coal pretreated with ozone oxidation in Example 1 was selected as the substrate for subsequent non-catalytic and catalytic ethanololysis.
[0151] The application of the Co-CuFe2O4 nanospheres prepared in Example 1 to low-rank coal-related model compounds, and to the catalytic ethanololysis reaction of low-rank coal in Xiaojihan, Yulin, Shaanxi Province after ozone oxidation pretreatment in Example 1, can be explained by comparing non-catalytic ethanololysis and catalytic ethanololysis reactions.
[0152] The following examples illustrate the two applications mentioned above.
[0153] Application Example 1
[0154] In the non-catalytic ethanololysis reaction of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment in Example 1, without the addition of the magnetic Co-CuFe2O4 nanospheres prepared in Example 1, the specific application process is as follows:
[0155] (1) Place 20g of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, which was pretreated by ozone oxidation in Example 1, into a 1000mL high-pressure reactor and add 200mL of ethanol.
[0156] (2) After replacing the air in the reactor cavity with N2, 1MPa N2 was introduced and the reaction was carried out at 300℃ for 2 hours. After the reaction was completed, the reactor was cooled to room temperature.
[0157] (3) Use ethanol to completely extract the reaction mixture to obtain ethanol-soluble substances, i.e. light components, and conduct detection, analysis and comparison of the light components;
[0158] (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.
[0159] The preparation method, performance indicators, and catalytic effect of magnetic Co-CuFe2O4 nanospheres are described in detail with reference to the accompanying drawings. This embodiment is only used to explain the present invention and does not constitute a limitation on the scope of protection of the present invention.
[0160] Application Example 2
[0161] In the catalytic ethanololysis reaction of low-rank coal in Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment, the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 were added. The specific application process is as follows:
[0162] (1) Place 5g of magnetic Co-CuFe2O4 nanospheres and 20g of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, which has undergone ozone oxidation pretreatment in Example 1, into a 1000mL high-pressure reactor and add 200mL of ethanol.
[0163] (2) After replacing the air in the reactor cavity with N2, 1MPa N2 was introduced and the reaction was carried out at 300℃ for 2 hours. After the reaction was completed, the reactor was cooled to room temperature.
[0164] (3) The reaction mixture was completely extracted with ethanol to obtain the ethanol-soluble substance, i.e., the light component;
[0165] (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.
[0166] The obtained light components were analyzed and compared. A comparison of the results of non-catalytic ethanololysis and catalytic ethanololysis is shown in the appendix. Figure 5 Appendix Figure 6 and attached Figure 7 The obtained heavy components were analyzed and compared. A comparison of the results of non-catalytic ethanololysis and catalytic ethanololysis is shown in the appendix. Figure 5 ;
[0167] From the appendix Figure 5 It can be seen that the yield of the derived solubles was significantly improved after the introduction of magnetic Co-CuFe2O4 nanospheres. Specifically, the yields of the light and heavy components increased by 75.4% and 67.8%, respectively, with an overall yield increase of 71.9%.
[0168] The distribution of functional groups in the non-catalytic ethanol solubles and catalytic ethanololysis solubles of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment in Example 1 was analyzed using Fourier transform infrared spectroscopy. (See attached...) Figure 6 It can be seen that, based on the type of functional groups, the FTIR bands can be divided into four regions: (1) 3800-3000 cm⁻¹ -1 (2) 3000-2800cm -1 (3) 1800-900cm -1 (4) 900-700cm -1 FTIR spectra show that the distribution of functional groups differs between the non-catalytic and catalytic ethanol hydrolysis solubles. The catalytic ethanol hydrolysis solubles show differences in functional group distribution at 3400 cm⁻¹. -1 The characteristic band intensity of the catalytic ethanol hydrolysis product is significantly weaker than that of the non-catalytic ethanol hydrolysis soluble product. Combined with GC / MS analysis results, this is because esterification of alcohol species and dehydroxylation of phenol species occurred during catalytic ethanol hydrolysis. In the non-catalytic ethanol hydrolysis soluble product, -CH3 is most prominent at 2966 cm⁻¹. -1 Nearby asymmetric stretching vibrations, >CH2 at 2920 cm -1 Nearby asymmetric stretching vibrations and -CH3 at 1445 cm -1 The asymmetric deformation vibrations in the vicinity are stronger than those in the catalytic ethanololysis solubles, indicating that aliphatic compounds are more abundant in the non-catalytic ethanololysis solubles than in the catalytic ethanololysis solubles. The 1731 cm⁻¹ region in the catalytic ethanololysis solubles... -1The intensity of the characteristic bands in the vicinity is higher than that in the non-catalytic ethanol hydrolysis solubles. This is because the esterification of alcohol species leads to an increase in ester species. The 1048 cm⁻¹ band in the catalytic ethanol hydrolysis solubles... -1 The intensity of the characteristic spectral bands in the vicinity is higher than that of the non-catalytic ethanol hydrolysis solubles, indicating that the magnetic Co-CuFe2O4 nanospheres effectively cleave >CH-O- and >C. ar Simultaneously with the -O- bridging bond, ethanol, as a reactant, reacted with soluble small molecules. Some species formed oxygen-containing compounds other than esters during esterification, which was also confirmed by GC / MS analysis. (950-650 cm⁻¹) -1 Four deformable vibrations of >CH in out-of-plane aromatic compounds can be observed on the characteristic bands within the region, and are respectively attributed to isolated out-of-plane aromatic >CH (880-879 cm⁻¹). -1 ), two adjacent hydrogen atoms outside each aromatic ring plane (811-809 cm) -1 ), 3 adjacent hydrogen atoms outside the aromatic ring plane (778-776 cm) -1 ) and four adjacent hydrogen atoms outside the plane of each aromatic ring (750-747 cm) -1 Furthermore, the overall absorbance of the non-catalytic ethanol hydrolysis solubles in this region is higher than that of the catalytic ethanol hydrolysis solubles, indicating that the non-catalytic ethanol hydrolysis solubles contain a higher content of aromatic ring compounds and a higher degree of aromatic ring condensation.
[0169] From the appendix Figure 7 It can be further seen that, under the oxidative pretreatment conditions in Example 1, the compounds with higher yields in the light fractions of the non-catalytic and catalytic ethanololysis of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, are oxygen-containing compounds, alkanes, and aromatics. Among these, the oxygen-containing compounds can be further classified into alcohols, ethers, phenols, aldehydes, ketones, esters, and carboxylic acids. The soluble fraction of non-catalytic ethanololysis contains 26.53 mg / g of alkanes. -1 ) and aromatics (25.64 mg g) -1 The yield of ) was higher than that of alkanes in the soluble product of catalytic ethanol hydrolysis (7.53 mg g). -1 ) and aromatics (19.02 mg g) -1 The yield of ) while oxygen-containing compounds (76.25 mg g) -1 The yield of ) was lower than that of oxygen-containing compounds in the soluble product of catalytic ethanol hydrolysis (204.16 mg g). -1 The yield of ) may be due to the H produced after Co-CuFe2O4 nanospheres activate ethanol. + H - and + CH2CH3 promotes >C arThe breaking and dissociation of -O- and >CH-O- bridging bonds releases alkane and aromatic fragments inherent in the organic matter of low-rank coal. Simultaneously, these organic fragments strongly interact with ethanol, inducing more oxygen-containing groups to enter the soluble products of catalytic ethanol hydrolysis, thereby significantly increasing the yield of oxygen-containing compounds. The introduction of the catalyst greatly improved the yield of oxygen-containing compounds, increasing it from 76.25 mg g / L. -1 Increased to 204.16 mg g -1 The increase was 167.75%.
[0170] This demonstrates that the magnetic Co-CuFe2O4 nanospheres prepared in Example 1 can effectively promote the yield of solubles from the catalytic ethanol hydrolysis of low-rank coal from Xiaojihan, Yulin, Shaanxi Province, after ozone oxidation pretreatment in Example 1, and significantly increase the yield of oxygen-containing compounds. This is a method to improve the yield of oxygen-containing compounds in low-rank coal-derived solubles.
[0171] Application Example 3
[0172] The magnetic Co-CuFe2O4 nanospheres prepared in Example 1 were applied to the catalytic ethanololysis of low-rank coal-related model compounds. The specific application process is as follows:
[0173] (1) Place 0.5g benzylphenyl ether, 0.5g magnetic Co-CuFe2O4 nanospheres and 200mL ethanol in a 1000mL stainless steel high-pressure reactor;
[0174] (2) After purging the high-pressure reactor with N2 three times, pressurize it with 1-5MPa N2 at room temperature;
[0175] (3) Subsequently, the high-pressure reactor is heated to 220-300°C and maintained at the set temperature for a set time;
[0176] (4) After the reaction was completed, the high-pressure reactor was cooled to room temperature and the reaction mixture was removed. The filtered filtrate was analyzed by gas chromatography-mass spectrometry. The performance analysis results of Co-CuFe2O4 nanospheres for the catalytic ethanol decomposition of low-rank coal-related model compounds are shown in Table 4 below.
[0177] Table 4. Performance analysis results of Co-CuFe2O4 nanospheres for catalytic ethanololysis of low-rank coal-related model compounds.
[0178]
[0179] As shown in Table 4, during the catalytic ethanololysis of benzylphenyl ether, the conversion rate of benzylphenyl ether monotonically increased with increasing temperature, reaching 100% at 300℃. The main products in the reaction were aromatics, including toluene and other aromatics (diphenylethane and benzyltoluene), with a total aromatic yield of 92.6%. Simultaneously, the total yield of oxygen-containing compounds also reached its highest level (92.4%). Therefore, appropriately increasing the temperature helps activate ethanol, enhances the ability of Co-CuFe2O4 nanospheres to break the >CH-O- bridging bond, and promotes the complete conversion of benzylphenyl ether. The effect of pressure on the catalytic ethanololysis of benzylphenyl ether was relatively small. Under the conditions of a reaction temperature of 300℃ and a reaction time of 2 h, as the pressure increased from 0 MPa to 1 MPa, the conversion rate of benzylphenyl ether increased from 88.94% to 100%, the yields of toluene and ethoxymethylbenzene increased slowly, and the yields of phenol and alkylphenols gradually decreased. Therefore, to ensure a high yield of aromatics, a reaction temperature of 300℃ and a pressure of 1 MPa are the optimal reaction conditions. Under these conditions, the conversion rate of benzyl phenyl ether increased from 39.78% to 100% as the reaction time increased from 20 min to 120 min. During this period, H2O generated from the activation of ethanol by Co-CuFe2O4 nanospheres... + Attacking the >CH-O-CH< bridging bond in ethoxymethylbenzene causes a decrease in the yield of ethoxymethylbenzene while the yield of toluene continues to increase. Therefore, appropriately extending the reaction time helps to improve the yield of aromatics.
[0180] Co-CuFe2O4 nanospheres activate ethanol to produce active species, such as H+. + H - and CH3CH2 + The synergistic transfer of these active species plays a crucial role in the catalytic conversion of benzylphenyl ethers. Specifically, H... + First, the oxygen atom on the benzylphenyl ether is attacked to form a protonated benzylphenyl ether. The >CH-O- bridging bond in the protonated benzylphenyl ether breaks, generating phenol and a benzyl cation. Specifically, the >C in the benzylphenyl ether... ar The -O- bridging bond cannot break to form benzyl alcohol and phenyl cations because phenyl cations are extremely unstable. Benzyl cations can adsorb H+. - It can be converted to toluene, or it can accept CH3CH2O. - It is converted into ethoxymethylbenzene, while phenol can release H+. + and adsorption of CH3CH2 + It is gradually converted into ethoxybenzene. In addition, the benzyl cation can attack the ortho and para carbons in phenol to form 2-benzylphenol and 4-benzylphenol, respectively.
[0181] In summary, the Co-CuFe2O4 nanospheres synthesized using this invention exhibit high catalytic activity.
[0182] This invention significantly improves the yield of low-rank coal ethanololysis through ozone oxidation pretreatment, while simultaneously introducing more oxygen-containing functional groups into the low-rank coal. Co-CuFe2O4 nanospheres are directly obtained using a one-pot hydrothermal method. This preparation process is green, simple, and safe, and to some extent modifies the morphology, structure, and size of the catalyst, without significant agglomeration. It increases the specific surface area of the catalyst to obtain more active sites, compensating for some defects of traditional metal oxide catalysts. The highly active Co-CuFe2O4 nanospheres significantly improve the conversion of relevant model compounds in low-rank coal and the catalytic ethanololysis effect of low-rank coal after ozone oxidation pretreatment, further increasing the yield of oxygen-containing compounds.
[0183] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A method for increasing the yield of oxygen-containing compounds in low-rank coal-derived solubles, characterized in that, Specifically, the following steps are included: Step a: First, pretreat the low-rank coal with ozone oxidation; Step b: Then, magnetic Co-CuFe2O4 nanosphere catalysts were prepared by a one-pot hydrothermal method. Step c: The prepared magnetic Co-CuFe2O4 nanosphere catalyst is then used to catalyze the ethanololysis reaction of low-rank coal after ozone oxidation pretreatment. Step a, the specific steps for ozone oxidation pretreatment of low-rank coal: Place 10 g of low-rank coal into a high-pressure reactor and use an ozone generator at 3 nL / min. -1 The flow rate is continuously supplied with O3 at a volume fraction of 1%-1.5%; The high-pressure reactor is then heated to 30-70 ℃ and held for 1-9 h to obtain low-rank coal after ozone oxidation pretreatment. Step b, the specific steps for preparing the magnetic Co-CuFe2O4 nanosphere catalyst: Step S1: First, disperse a certain amount of cobalt salt, copper salt, and iron salt in 70 ml of deionized water and stir evenly at room temperature to obtain a mixed solution for later use. Step S2: Then, the mixed solution obtained in step S1 is transferred to a polytetrafluoroethylene-lined hydrothermal reactor, a certain amount of hydrazine hydrate is slowly injected, and then the polytetrafluoroethylene-lined hydrothermal reactor is heated to 180 °C and kept at that temperature for 12 h to obtain the solution. Step S3: Cool the solution obtained in step S2 to room temperature, centrifuge, and wash it several times alternately with deionized water and ethanol to obtain a solid sample; Step S4: Place the obtained solid sample in a vacuum drying oven and dry it at 100 °C for 8 h to obtain the magnetic Co-CuFe2O4 nanosphere catalyst. In step S1, cobalt acetate is selected as the cobalt salt, copper acetate is selected as the copper salt, and iron acetylacetone is selected as the iron salt. The molar ratio of cobalt acetate, copper acetate, and iron acetylacetone is 1:19:40, 1:9:20, 3:17:40, 1:4:10, or 1:3:
8.
2. The method for increasing the yield of oxygen-containing compounds in low-rank coal-derived solubles as described in claim 1, characterized in that, In step S2, the ratio of the amount of hydrazine hydrate used to the amount of deionized water used in step S1 is (5-20):
100.
3. The method for increasing the yield of oxygen-containing compounds in low-rank coal-derived solubles as described in claim 2, characterized in that, Step c, the specific process of the low-rank coal ethanol hydrolysis reaction after pretreatment by ozone oxidation catalyzed by magnetic Co-CuFe2O4 nanospheres, is as follows: (1) The magnetic Co-CuFe2O4 nanospheres and the low-rank coal pretreated by ozone oxidation were placed in a 1000 mL high-pressure reactor and 200 mL of ethanol was added. (2) After replacing the air in the cavity of the high-pressure reactor with N2, 1 MPa N2 was introduced and the reaction was carried out at 300℃ for 2 h. After the reaction was completed, the mixture was cooled to room temperature to obtain the reaction compound. (3) The reaction mixture was completely extracted with ethanol to obtain the ethanol-soluble component, i.e., the light component; (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.