High-activity ni-ca bimetallic catalyst, and preparation method and application thereof

Abstract

The application discloses a high-activity Ni-Ca bimetallic catalyst and a preparation method and application thereof. The catalyst takes NiCa hydrotalcite as a precursor, and a supported high-dispersion Ni-Ca bimetallic catalyst is prepared through calcination reduction. The high-dispersion catalyst NiCa / Al2O3 exhibits excellent catalytic performance in the aryl ether hydrogenolysis and in-situ deoxygenation reaction of coal and model compounds thereof, can highly actively and selectively crack aryl ether bonds in coal extract residues and coal related model compounds under mild conditions, and can perform in-situ deoxygenation on oxygen-containing compounds obtained after the aryl ether bonds are cracked without hydrogenating aromatic rings, and highly selectively obtains platform chemicals, i.e. aromatic hydrocarbon compounds. The catalyst preparation method is simple, has good stability, and has a good application prospect in the catalytic hydrogenation conversion of medium and low rank coal under mild reaction conditions.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and catalytic conversion technology of coal, and relates to a bimetallic catalyst, specifically a highly active Ni-Ca bimetallic catalyst and its preparation method and application. Background Technology

[0002] Layered hydroxides (LDHs) are a class of inorganic layered materials with a special structure, formed by the interaction between interlayer anions and positively charged layers through non-covalent bonds. Their layered structure possesses a huge specific surface area, providing numerous adsorption and catalytic sites, and has been widely used in adsorption and catalysis in recent years. Porous metal oxides prepared using LDH as a precursor have also gradually attracted attention in the hydrogenolysis of lignin. CN115646495A discloses the preparation of a highly active NiCu / Al2O3 catalyst and its application in the catalytic hydrogen transfer cracking of aromatic ether CO bonds. Using isopropanol as a solvent and hydrogen source, this catalyst can selectively cleave various types of aromatic ether CO bonds at 200℃, completely converting the aromatic ethers into the corresponding aromatic monomers and cyclohexanol. Although this catalyst can achieve the directional conversion of various types of aromatic ethers, it cannot remove oxygen from the aromatic ethers and cannot avoid the hydrogenation of the aromatic ring. Summary of the Invention

[0003] One of the objectives of this invention is to provide a method for preparing a highly active Ni-Ca bimetallic catalyst, which is simple and easy to operate.

[0004] The second objective of this invention is to provide a highly active Ni-Ca bimetallic catalyst prepared by the above method, wherein the active metal has high dispersibility and high catalytic activity.

[0005] The third objective of this invention is to provide applications of the aforementioned highly active Ni-Ca bimetallic catalyst.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a highly active Ni-Ca bimetallic catalyst, comprising the following steps:

[0008] (1) Weigh Ni(NO3)2·6H2O, Ca(NO3)2·4H2O, Al(NO3)3·9H2O and urea respectively in a molar ratio of 1:1:1:14, and dissolve them in deionized water. After ultrasonic dispersion, stir and reflux at 120-130℃ for 6h, let stand and age at room temperature for 12h, filter, wash, and vacuum dry the filter cake to obtain NiCa-LDH;

[0009] (2) The precursor NiCa-LDH was transferred to a tube furnace, heated from room temperature to 500°C in air atmosphere and held for 2 hours. After cooling to room temperature, the metal oxide NiCa-LDO (LDO: layered oxide) was obtained.

[0010] (3) The metal oxide NiM-LDO was reduced by raising the temperature from room temperature to 460℃ for 2 hours under a hydrogen atmosphere, and then cooled to room temperature to obtain the catalyst NiCa / Al2O3.

[0011] Preferably, the vacuum drying temperature in step (1) is 70-90℃ and the drying time is 24h.

[0012] Preferably, the heating rate in steps (2) and (3) is 2-3℃ / min.

[0013] Secondly, the present invention provides a highly active Ni-Ca bimetallic catalyst prepared by the above-described preparation method.

[0014] The highly active Ni-Ca bimetallic catalyst is composed of NiCa / Al2O3, wherein the Al2O3 support exists in an amorphous form, the active metal component nickel nanoparticles are uniformly distributed on the surface of the Al2O3 support, and nickel-calcium alloy nanoparticles are uniformly grown on the pore walls of the Al2O3 nanosheets. The particle size of the nickel nanoparticles in NiCa / Al2O3 is about 4-6 nm, and the average pore size of the catalyst is 10.9 nm.

[0015] Thirdly, the present invention provides the application of the above-mentioned highly active Ni-Ca bimetallic catalyst in the hydrodeoxygenation conversion of coal-derived model compounds or low- and medium-rank coal extraction residues.

[0016] The reaction substrate, NiCa / Al2O3 catalyst, and n-hexane were sequentially added to a high-pressure reactor. The reaction substrate was a coal-derived model compound or a residue from low- to medium-rank coal extraction. After replacing the air in the reactor with H2 2-3 times, H2 at a predetermined initial hydrogen pressure was introduced. The reactor was then placed in a heating furnace and rapidly heated to the preset reaction temperature, which was maintained for a set time. After the reaction was completed, the high-pressure reactor was rapidly cooled, the reaction mixture was collected and filtered, and the filtrate components were analyzed by GC / MS. The catalyst was recovered and reused after magnetic separation.

[0017] Preferably, the reaction temperature is 180℃, the reaction pressure is 1-5MPa, and the reaction time is 2-4h.

[0018] Preferably, the catalyst accounts for 30% of the mass of the reaction substrate.

[0019] Preferably, the coal-derived model compound is selected from one of diphenyl ether, dibenzyl ether, benzylphenyl ether, and benzylnaphthyl ether.

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

[0021] 1. A layered oxide mesoporous material, NiCa / Al2O3, was prepared via co-precipitation using a hydrotalcite-like material as a precursor. The unique layered structure not only uniformly disperses the active metal component but also confines it within the hydrotalcite layers, improving catalyst stability. Furthermore, the CO2 generated during the hydrolysis of urea, acting as a precipitant, also contributes to pore formation, facilitating the exposure of active sites and thus enhancing catalyst activity. This highly dispersed catalyst, NiCa / Al2O3, exhibits excellent catalytic performance in the hydrolysis and in-situ deoxygenation of aromatic ethers in low- and medium-rank coals and their model compounds. The type and yield of products can be effectively controlled by adjusting reaction conditions.

[0022] 2. The catalyst NiCa / Al2O3 catalyzes the hydrogenation and cracking of organic matter in the extraction residues of Runbei lignite and Shaerhu sub-bituminous coal into aromatics without hydrogenating aromatic rings under low IHP (1MPa). The resulting soluble substances have a simple composition and are easy to separate from pure aromatics.

[0023] 3. The catalyst NiCa / Al2O3 activates H2 to H…H and free H under high IHP (4MPa) conditions. - These active hydrogen species work together to efficiently convert the extract residues of Runbei lignite and Shaerhu sub-bituminous coal into alkylcycloalkanes that can be used as liquid chemicals and clean liquid fuels with a variety of important applications.

[0024] 4. The catalyst preparation method of this invention is simple, has good stability, and mild reaction conditions, and has good application prospects in the catalytic hydrogenation conversion of low- and medium-rank coals. Attached Figure Description

[0025] Figure 1 These are the thermogravimetric curves of NiZn-LDH, NiMg-LDH, and NiCa-LDH;

[0026] Figure 2 These are the XRD patterns of the precursor, the calcined sample, and the sample after H2 reduction;

[0027] Figure 3 The N2 adsorption-desorption curves and pore size distributions of NiCa-LDH, NiCa-LDO, and NiCa / Al2O3 are shown.

[0028] Figure 4 These are scanning electron microscope (SEM) images of NiZn-LDH, NiMg-LDH, NiCa-LDH, NiZn / Al2O3, NiMg / Al2O3, and NiCa / Al2O3.

[0029] Figure 5These are transmission electron microscope (TEM) images of NiZn / Al2O3(ac), NiMg / Al2O3(df), and NiCa / Al2O3(gi);

[0030] Figure 6 XRPES spectra of the samples (a), Ni 2p (b), and high-resolution energy dispersive spectra of NiCa / Al2O3 Al 2p (c) and O1s (d);

[0031] Figure 7 The left image shows the H2-TPR curves of Ni / Al2O3 and NiCa / Al2O3, and the right image shows the CO2-TPD curve of NiCa / Al2O3.

[0032] Figure 8 These are the FTIR spectra of NiZn / Al2O3, NiMg / Al2O3, and NiCa / Al2O3;

[0033] Figure 9 This is the total ion chromatogram of the NiCa / Al2O3 catalytic hydrogenation conversion of OBMDB;

[0034] Figure 10 The effects of temperature and time on the conversion rate and product selectivity of dibenzyl ether;

[0035] Figure 11 This is a reaction pathway diagram of dibenzyl ether under NiCa / Al2O3 catalysis;

[0036] Figure 12 It is SP A-1 and SP B-1 Distribution of aromatic hydrocarbons;

[0037] Figure 13 It is ER A and ER B Reaction pathway diagram of hydrogenation cracking of organic macromolecules;

[0038] Figure 14 The effects of temperature, hydrogen pressure, and time on PA conversion and product selectivity;

[0039] Figure 15 This is the total ion chromatogram of the product obtained from the catalytic hydrogenation conversion of PA;

[0040] Figure 16 This is a reaction pathway diagram of the hydrogenation conversion of PA on NiCa / Al2O3;

[0041] Figure 17 It is SP A-2 and SP B-2 Distribution of medium-cycloalkanes;

[0042] Figure 18 It is ERA and ER B Reaction pathway diagram of hydrogenation of organic macromolecules. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0044] Example 1: Preparation of NiCa / Al2O3

[0045] The product was prepared using a ternary coprecipitation method. The specific steps are as follows: Ni(NO3)2·6H2O (5.8 g, 0.02 mol), Ca(NO3)2·4H2O (4.72 g, 0.02 mol), Al(NO3)3·9H2O (7.52 g, 0.02 mol), and urea (16.8 g, 0.28 mol) were added to a round-bottom flask, followed by the addition of 200 mL of deionized water. After ultrasonic dispersion, the mixture was placed in an oil bath and refluxed at 125 °C for 6 h with stirring. It was then allowed to stand at room temperature for 12 h to age. The mixture was then filtered, washed, and the filter cake was dried in a vacuum drying oven at 80 °C for 24 h to obtain NiCa-LDH (LDH: layered hydroxide).

[0046] The precursor NiCa-LDH was heated from room temperature to 500℃ at a heating rate of 2.5℃ / min in a tube furnace under air atmosphere and held for 2 hours. After cooling to room temperature, the metal oxide NiCa-LDO (LDO: layered oxide) was obtained. This metal oxide NiM-LDO was then reduced from room temperature to 460℃ at a heating rate of 2.5℃ / min under H2 atmosphere for 2 hours. After cooling to room temperature, the catalyst NiCa / Al2O3 was obtained.

[0047] Comparative Example 1: Preparation of Ni / Al2O3

[0048] The catalyst was prepared using a ternary coprecipitation method. The preparation steps were the same as in Example 1, except that Ca(NO3)2·4H2O was not added, resulting in Ni / Al2O3 catalyst.

[0049] Comparative Example 2: Preparation of NiZn / Al2O3

[0050] The catalyst was prepared using a ternary coprecipitation method. The preparation steps were the same as in Example 1, except that 5.96 g of Zn(NO3)2·6H2O was added to obtain the catalyst NiZn / Al2O3.

[0051] Comparative Example 3: Preparation of NiMg / Al2O3

[0052] The catalyst NiMg / Al2O3 was prepared using a ternary coprecipitation method. The preparation steps were the same as in Example 1, except that 5.12 g of Mg(NO3)2·6H2O was added to obtain the catalyst.

[0053] Characterization of catalysts:

[0054] (1) Thermogravimetric analysis

[0055] To investigate the decomposition of NiZn-LDH, NiMg-LDH, and NiCa-LDH during calcination, thermogravimetric analysis was performed on each. Figure 1 As shown, the TG curves all exhibit two distinct weight loss steps, indicating that the thermal decomposition of NiM-LDH involves two processes. Within the temperature range of 30-200℃, the thermal weight loss rates of the samples were 12.8%, 13.6%, and 15.8%, respectively. This is attributed to the removal of physically adsorbed water and interlayer water, a physical process in which the hydrotalcite retains its layered structure. The rapid mass loss (18.8%, 24.5%, and 21.4%) within the 200℃-400℃ range is attributed to the collapse of the hydrotalcite structure, accompanied by the removal of lamellar hydroxyl groups and interlayer anions, which escape as H2O and CO2, respectively. This process disrupts the layered structure of the hydrotalcite, forming a porous mixed oxide. While the decomposition temperature of carbonates is generally between 250-600℃, this sample's decomposition occurred at a lower temperature of 200-400℃, possibly due to the autocatalytic decomposition of carbonates by Ni within the hydrotalcite. The mass loss of NiM-LDH plateaus after 450℃, indicating that it exists stably as NiM-LDO after calcination at 500℃. Comparison of the three curves reveals that the final weight loss temperature of NiZn-LDH is around 380℃, while that of NiMg-LDH and NiCa-LDH is around 431℃ and 449℃, respectively. This difference is related to the decomposition of LDH nanosheets. Furthermore, the second weight loss peak of the NiMg-LDH and NiCa-LDH samples shifts significantly to higher temperatures, suggesting that the introduction of Mg / Ca improves the thermal stability of LDH.

[0056] (2) XRD analysis

[0057] like Figure 2 As shown, all LDH samples exhibited sharp and strong characteristic diffraction peaks of hydrotalcite at 2θ = 11.2° (003), 23.1° (006), 34.9° (012), 39.1° (015), 47.0° (018), and 60.8° (110) (JCPDS-14-0191), indicating the successful preparation of layered hydrotalcite materials. The crystallinity of the LDHs followed the order NiZn > NiMg > NiCa, which is consistent with... and The radius is related to Ca 2+ An excessively large radius may cause deformation of the layered structure after it is incorporated into the hydrotalcite layer. On the other hand, the low crystallinity of NiCa-LDH may also be due to the strong interactions between metal ions and... and Ca 2+The mismatch in ionic radii leads to more structural defects in NiCa-LDH. The presence of these defect sites facilitates the exposure of active Ni metal sites, resulting in higher catalytic activity and better stability in the CHC reaction. According to the Bragg equation 2dsinθ=nλ, the interlayer spacing (d) calculated using the (003) crystal plane is respectively... and According to the formula c = 3d 003 The lattice parameters of LDHs are as follows: and The characteristic diffraction peaks of LDH disappeared after calcination due to the collapse of the layered structure, and the sample existed in the form of metal oxides. From the XRD pattern of the low crystallinity of the calcined sample, it can be seen that 2θ = 37.4°, 43.7°, and 63.3° correspond to the peaks of NiO and / or NiAl2O4 / Ni2AlO4 (JCPDS-78-0643), respectively. Due to peak overlap and low crystallinity, it is difficult to clearly distinguish the different phases. Furthermore, no characteristic peaks of Al2O3 were clearly observed in the figure, indicating that Al2O3 exists in an amorphous form. This may be due to the fact that Al... 3+ It dissolved into the NiO lattice. The diffraction pattern of the H2-reduced sample showed diffraction peaks at 2θ = 44.5° and 51.7°, corresponding to NiO, respectively. 0 The (111) and (200) crystal planes (JCPDS-87-0712) have low diffraction peak intensities because NNPs collapse and are released from the hydrotalcite solid solution during H2 reduction and are uniformly dispersed in the layered structure of the support Al2O3, resulting in low crystallinity of the material.

[0058] (3) Surface physical properties

[0059] like Figure 3 As shown, all samples (NiCa-LDH, NiCa-LDO, and NiCa / Al2O3) exhibited typical type IV isotherms and type H3 hysteresis loops within a relative pressure range of 0.4–1.0, indicating the presence of mesopores with irregular pore structures. These mesopores are likely slit-like mesopores formed by the stacking of sheet-like material. The pore size distribution diagram shows that the samples are predominantly composed of 3–7 nm mesopores, with a small amount of micropores and wide mesopores of 15–20 nm. Table 1 lists the physical properties of the samples, where the specific surface area of ​​the calcined NiCa-LDO sample is approximately 214 m². 2 g -1This is a typical hydrotalcite mixed oxide, which can be attributed to the formation of Ni2Al2O4 / NiAl2O4 mixed oxides on the sample. The pore size of NiCa-LDO is slightly larger than that of NiCa-LDH, while the specific surface area is slightly lower. This is due to the gradual decomposition of anions between the LDH layers during calcination, and the removal of interlayer water and CO2, leading to a slight decrease in the particle size of the calcined product, which occupies a small amount of Al2O3 channels. The specific surface area of ​​the reduced sample is slightly lower, possibly due to pore collapse during the reduction process. This uniform channel structure can be used to confine Ni... 0 The growth of the active phase is used to limit the sintering of the active phase during the reaction. On the other hand, NiCa / Al2O3 has a wide pore size distribution. This mesoporous material can provide nickel nanoparticles with a high specific surface area and large pores and pore volume, allowing reaction products to be discharged in time and reducing the occurrence of side reactions. The high catalytic activity of mesoporous metal oxides in the alcoholysis of lignin is related to the diffusion effect of the mesoporous structure.

[0060] Table 1 Surface physical properties of the samples

[0061]

[0062] (4) Electron microscopy analysis

[0063] like Figure 4 As shown, LDHs are uniformly grown on the Al2O3 support surface in a petal-like pattern by a large number of disordered stacked nanosheets, and grow in situ along a direction perpendicular to the support surface, exhibiting high dispersion. Each component is uniformly dispersed on the hydrotalcite material layers, and after H2 reduction, a highly dispersed bimetallic nanocatalyst with uniform composition is obtained. After hydrogen reduction, the sample still maintains a plate-like structure, but during calcination and reduction, the interlayer anions CO32-... 2- The formation and removal of CO2 causes the nanosheets to shrink, allowing the active metal components to migrate from the oxide layers and distribute uniformly on the nanosheets. Because the active components are confined within the nanosheets, Ni... 2+ Aggregation was suppressed, resulting in high dispersion of nickel nanoparticles on the support surface after reduction. Furthermore, the removal of interlayer H2O and CO2 led to the formation of new mesopores on the oxide nanosheet support, with some NiM alloy nanoparticles growing uniformly on the pore walls of the nanosheets. This open structure facilitates contact between reactants and active components, explaining the high activity and stability exhibited in the hydrogenation reaction of coal-related model compounds.

[0064] High-resolution transmission electron microscopy image of the sample ( Figure 5The catalyst exhibits a layered nanosheet stacked structure, which originates from the layered structure of the hydrotalcite precursor, consistent with the scanning electron microscopy analysis. Nickel nanoparticles are uniformly distributed on the Al2O3 support surface. Size analysis of particles selected from different regions of the catalyst showed an average diameter of 2-7 nm, with no obvious agglomeration. This is attributed to the high specific surface area and layered nanosheet morphology of the in-situ prepared catalyst, which promotes the dispersion of nickel nanoparticles. The particle size of nickel nanoparticles in NiCa / Al2O3 is approximately 4-6 nm, while the average pore size of the catalyst is approximately 10.9 nm. Therefore, some nickel nanoparticles can enter the pores of the support, and this confined structure effectively inhibits the aggregation and loss of nickel nanoparticles during the catalytic process. Furthermore, the nickel nanoparticles are part of the laminations, which also serve a confining function, preventing the encapsulated nickel nanoparticles from agglomerating during catalytic hydrogenation. The lattice fringes measured in the high-resolution transmission electron microscopy image correspond to the (111) and (200) crystal planes of Ni, which is consistent with the X-ray diffraction analysis results.

[0065] (5) X-ray photoelectron spectroscopy

[0066] To investigate the valence state distribution of nickel species in the catalyst and the interaction between the active component nickel and the support, surface energy dispersive spectroscopy (EDS) analysis was performed on three materials: NiZn / Al₂O₃, NiMg / Al₂O₃, and NiCa / Al₂O₃. Nuclear charge correction was performed using 284.8 eV of C 1s as the standard to eliminate the charging effect proposed by Neimark et al. Figure 6 As shown in figure a, the surfaces of all three samples contain elements such as Ni, C, O, N, and Al, with C and N originating from the decomposition of urea. Peak fitting of the Ni 2p spectrum reveals that the binding energy around 852.4 eV belongs to metallic Ni. 0 The binding energies near 855.7 and 873.0 eV are attributed to nickel oxide formed by the oxidation of nickel nanoparticles. The presence of nickel oxide may be due to the oxidation of surface nickel nanoparticles caused by catalyst exposure to air, but more importantly, it is due to the strong interaction between Ni and Al₂O₃, i.e., the presence of some Ni-O-Al bonds. Two satellite peaks were observed near 861.4 eV and 878.7 eV, indicating that Ni… 2+ It exists in a high-spin state. Furthermore, the Al 2p spectrum in NiCa / Al2O3 shows typical Al 2p at 73.7 eV. 3 / 2 The peak. The spectrum of O 1s ( Figure 6 The main peak at 530.6 eV in d) comes from lattice oxygen.

[0067] (6) Characterization of H2 temperature-programmed reduction

[0068] H2 temperature-programmed reduction characterization is commonly used to analyze Ni species, reduction degree, and metal-support interactions on catalyst surfaces. For example... Figure 7 As shown, the reduction process of Ni / Al2O3 mainly includes two ranges: the reduction peak at 196℃ corresponds to the reduction of nickel oxide on the catalyst surface with weak interaction with the support, where H2 easily approaches and reduces these surface Ni species. The main peak at 522℃ corresponds to the reduction of Ni2AlO4 and NiAl2O4, due to the strong interaction between Ni and the alumina support. The introduction of Ca shifts the reduction temperature of the main peak to a higher temperature (620℃), indicating that the introduction of Ca enhances the interaction between the metal and the support. The CO2-TPD curve of NiCa / Al2O3 shows a weakly basic site at 89℃ and a moderately strong basic site at 389℃, indicating that NiCa / Al2O3 is moderately strong basic.

[0069] (7) Infrared analysis

[0070] like Figure 8 As shown, the infrared spectra of the three materials are not significantly different, with the 3696 cm⁻¹ spectrum showing the most significant difference. -1 The nearby absorption peak is attributed to the -OH stretching vibration of H₂O in the interlayer. (1660 cm⁻¹) -1 The absorption peak near the catalyst is attributed to the bending vibration of the -OH groups of crystal water on the layers and surface. This is due to a certain amount of water adsorbed on the catalyst surface and inserted into the interlayer voids. 460 cm⁻¹ -1 The absorption peak at 840 cm⁻¹ is attributed to the stretching vibration of Ni-O. -1 and 1400cm -1 The nearby peaks are attributed to the stretching vibration absorption peaks of Ni-O or OMO (M = Ni or Al). The FTIR characterization results correspond to the XRD spectrum results, further confirming the lamellar structure of the hydrotalcite, and indicating a certain interaction between the active component and the support.

[0071] Example 2: Catalytic hydrogenation cracking of the model compound dibenzyl ether

[0072] 0.10 g of the model compound dibenzyl ether, 0.03 g of catalyst, and 20 mL of n-hexane were sequentially added to a 100 mL high-pressure reactor. The air inside the reactor was replaced three times with 1 MPa H2 or N2. Then, H2 at a predetermined initial hydrogen pressure (IHP) or N2 at a predetermined initial nitrogen pressure (INP) was introduced. The reactor was placed in a heating furnace and rapidly heated to a preset temperature, maintaining this temperature for a set time. After the reaction was complete, the high-pressure reactor was rapidly cooled, the reaction mixture was collected and filtered, and the filtrate components were analyzed by GC / MS. The catalyst was recovered and reused after magnetic separation. The conversion rate of the model compound was calculated as the ratio of the converted model compound to the original model compound, i.e., m(converted model compound) / m(original model compound).

[0073] Table 2 compares the catalytic performance of different catalysts for the hydrogenation cracking of dibenzyl ether. Compared with previous studies, the conversion rate of dibenzyl ether on NiCa / Al2O3 and the selectivity for the target product toluene are significantly higher than those of other catalysts. Figure 9 As shown, after reacting at 180℃ and 1 MPa IHP for 2 h, dibenzyl ether was completely converted to toluene. NiCa / Al2O3 exhibited good activity in >CO- bond cleavage and in-situ removal of oxygen atoms. Compared with Ni / Al2O3, pure Ni loaded onto Al2O3 showed poor catalytic activity and selectivity, while the introduction of the promoter metal Ca significantly improved the catalytic performance. There are two different explanations for the promoting effect: the catalyst is basic, and the abundant -OH groups provide a conduction pathway that plays an important role in the activation of H2; there is electron transfer between the two metals in the catalyst and their strong interaction, which efficiently activates H2 as an active hydrogen species. The active hydrogen species reach adsorption / desorption equilibrium on the support, thus significantly improving the activity of the catalyst and the selectivity of the target product.

[0074] Table 2 Catalytic hydrogenation cracking of dibenzyl ether using different catalysts

[0075]

[0076] Reaction conditions: 100 mg dibenzyl ether, 30 mg catalyst, 20 mL n-hexane

[0077] [1]LIU XX,ZONG ZM,LI WT,et al.A recyclable and highly activemagnetic solid superbase for hydrocracking CO bridged bonds in sawdust[J].Fuel Process Technol,2017,159:396-403.

[0078] [2]ZHANG M,WEI XY,YANG Z,et al.Catalytic hydroconversion of theextraction residue from Naomaohulignite over an active and separable magneticsolid superbase[J].Fuel,2018,226:410-416.

[0079] [3]NIU S,WEI XY,LI ZX,et al.Catalytic hydroconversion ofRunbeilignite over a highly active solid superacid[J].Chemistryselect,2020,5:6646-6651.

[0080] like Figure 10 As shown, with increasing reaction temperature, both the conversion rate of dibenzyl ether and the selectivity of the target product toluene increase monotonically. When the temperature exceeds 120℃, the conversion rate of dibenzyl ether increases sharply. This is because the active sites on NiCa / Al2O3 are activated at this temperature, efficiently activating H2 and promoting the conversion of >C in dibenzyl ether. alk -O- bridging bonds are broken. Furthermore, the selectivity of toluene is consistently much higher than that of benzaldehyde and benzyl alcohol, and this trend becomes more pronounced with increasing reaction temperature, indicating that >C alk Benzyl alcohol, generated from the cleavage of the -O-bridge bond, also undergoes dehydroxylation to some extent. Furthermore, increasing the temperature favors the conversion of benzaldehyde and benzyl alcohol to toluene, thus improving the selectivity for toluene. The effect of reaction time on the conversion rate of dibenzyl ether is similar to that of temperature; that is, the conversion rate of dibenzyl ether and the selectivity for toluene increase monotonically with increasing reaction time. When the reaction time is 120 min, dibenzyl ether is completely converted to toluene. Toluene originates from two sources: the cleavage of the >CO- bond in dibenzyl ether catalyzed by NiCa / Al2O3 and / or the dehydroxylation of benzyl alcohol. It is well known that the hydrogenation reaction of aromatic rings preferentially proceeds due to the removal of heteroatoms, but no aromatic ring hydrogenation products were detected in the product. This indicates that the alkaline catalyst NiCa / Al2O3 can effectively promote the cleavage of the >CO- bond in dibenzyl ether without hydrogenating the aromatic ring, thereby obtaining aromatic hydrocarbons with high selectivity.

[0081] Based on the intermediate types and distribution of NiCa / Al2O3-catalyzed dibenzyl ether products, possible reaction pathways can be inferred. For example... Figure 11 As shown, the active metallic component Ni in the catalyst NiCa / Al2O3 can activate H2 into H…H. H…H then undergoes heterolytic cleavage into free H under the action of the moderately alkaline NiCa / Al2O3. - and H fixed on the catalyst surface + Active H - For >C alk The breaking of the -O bridging bond is crucial. The strong electron-withdrawing ability of the oxygen atom in dibenzyl ether causes the two adjacent carbon atoms to exhibit positive charge, and the free H... - Easily attacked by carbon atoms adjacent to oxygen, inducing >C alk-O- bridging bonds cleave to generate toluene and benzyloxy anions, the latter binding to H+ anchored on the NiCa / Al2O3 surface. + The formation of benzyl alcohol or the loss of H at the benzylic position - Benzaldehyde is formed, and due to its poor stability, the reaction to form benzyl alcohol is more readily carried out. The generated benzaldehyde also readily forms benzyl alcohol under the influence of H…H. The benzylic position of benzyl alcohol is easily affected by H…H. - The attack and release of OH - Toluene is eventually produced.

[0082] Example 3: Catalytic hydrogenation cracking of other model compounds

[0083] As shown in Table 3, under the same conditions, NiCa / Al2O3 still exhibits good hydrocracking activity for other coal-related model compounds. The conversion rate of benzyl phenyl ether and the selectivity for the target product aromatics are both 100%, which is attributed to the active H+. - Promoted >C alk The cleavage of -O- bridging bonds and in-situ removal of oxygen atoms were observed. Furthermore, NiCa / Al2O3 exhibited good hydrocracking activity for benzyl naphthyl ether and diphenyl ether, among others. These results provide important reference value for the high-yield production of aromatic hydrocarbons from the catalytic hydrocracking of low- and medium-rank coals.

[0084] Table 3 Catalytic hydrogenation cracking of other model compounds by NiCa / Al2O3

[0085]

[0086] Reaction conditions: 100 mg substrate, 30 mg catalyst, 20 mL n-hexane, 180 °C, IHP 1 MPa, 2 h

[0087] Example 4: Extraction residue of Runbei lignite (ER) A ) and Shar Lake secondary bituminous coal extraction residues (ER) B Catalytic hydrocracking on NiCa / Al2O3

[0088] (1)ER A Catalytic hydrocracking: Take 1g of ER A 0.3 g of NiCa / Al₂O₃ and 20 mL of n-hexane were placed in a 100 mL high-pressure reactor and reacted at 180 °C and 1 MPa under IHP for 4 h. The reaction mixture was then transferred and filtered under reduced pressure to obtain a residue and a filtrate. The residue was repeatedly extracted with an equal volume of carbon disulfide / acetone mixed solution using ultrasonic extraction. The extract and filtrate were combined to obtain the soluble component SP. A-1 The composition of the products was analyzed by GC / MS.

[0089] (2)ER BCatalytic hydrocracking: Take 1g of ER B 0.3 g of NiCa / Al₂O₃ and 20 mL of n-hexane were placed in a 100 mL high-pressure reactor and reacted at 180 °C and 1 MPa under IHP for 4 h. The reaction mixture was then transferred and filtered under reduced pressure to obtain a residue and a filtrate. The residue was repeatedly extracted with an equal volume of carbon disulfide / acetone mixed solution using ultrasonic extraction. The extract and filtrate were combined to obtain the soluble component SP. B-1 The composition of the products was analyzed by GC / MS.

[0090] like Figure 12 As shown, SP A-1 and SP B-1 The types and quantities of compounds detected were relatively simple; detailed compound names and contents are listed in Table 4. ER A and ER B The soluble components obtained from the hydrocracking were found to contain only alkanes and aromatics; no cycloalkanes or heteroatom-containing compounds were detected. A-1 and SP B-1 Medium-chain alkanes have higher RC (77.6% and 67.9%), and the carbon number distribution is concentrated in the C... 12 -C 27 Straight-chain alkanes have a wide range of applications, including solvents, chemical feedstocks, and liquid fuels. The distribution of straight-chain alkanes also provides important information for coal sample analysis (depositional environment, evolutionary degree, and parent material type). Generally, straight-chain alkanes with <20 carbon atoms originate from bacteria and algae, while those with >20 carbon atoms originate from higher terrestrial plants. Based on this, it is inferred that the biological origin of Runbei lignite and Shaerhu sub-bituminous coal is composed of both lower and higher plants, with lower plants making a more significant contribution to both types of low- and medium-rank coals. 12 -C 20 The straight-chain alkane content (52.3% and 52.8%) is C 21 -C 27 These alkanes are 2-3 times higher than those in Runbei lignite or Shaerhu sub-bituminous coal (25.3% and 15.1%), and they are derived from the aromatic rings of the macromolecules of Runbei lignite or Shaerhu sub-bituminous coal. This means that these substituents are attached to the aromatic rings of the two types of coal residues.

[0091] SP A-1 and SP B-1 The detected aromatic hydrocarbons mainly consisted of 1-4 rings, primarily naphthalene and its homologues (8.8% and 9.5%, respectively). The source of these aromatic hydrocarbons was NiCa / Al2O3 catalytic ER. A and ER B >C in the macromolecular skeleton structure ar -C alkOr >CX bridge bond cleavage and in-situ removal of heteroatoms. In addition, the seven biphenyl compounds detected (2.0% and 2.4%) included two methylbiphenyls and five dimethylbiphenyls. Methylbiphenyls are important organic chemical raw materials, commonly used as pharmaceutical and material intermediates. Eight fluorenes and their homologues were detected. Fluorenes may originate from the cyclization reaction of 2-ethylbiphenyl under catalysis. Fluorenes are also important organic synthesis raw materials, commonly used in pharmaceuticals, synthetic resins, photosensitive materials, and various auxiliaries. They can also be used to produce wetting agents, detergents, and liquid crystal compounds. These results indicate that NiCa / Al2O3 exhibits excellent catalytic activity and good aromatic selectivity in the hydrocracking of Runbei lignite and Shaerhu sub-bituminous coal under low hydrogen pressure (1 MPa). The simple soluble components can be separated to obtain pure aromatics.

[0092] Table 4SP A-1 and SP B-1 Aromatic hydrocarbons detectable by GC / MS

[0093]

[0094] Table 4SP A-1 and SP B-1 Aromatic hydrocarbons detectable by GC / MS (continued)

[0095]

[0096]

[0097] According to GC / MS analysis, NiCa / Al2O3 catalyzes ER A and ER B The distribution of products in the soluble components of hydrocracking was analyzed to infer the hydrocracking mechanism of organic macromolecules in the coal residue. For example... Figure 13 As shown, the solid base catalyst NiCa / Al2O3 activates H2 and heterolytically cleaves H2 into free H+. - and H fixed on the catalyst surface + Active H - This is particularly important for the cracking of >CO- bridging bonds in coal. For macromolecular structures where oxygen atoms are directly linked to aromatic rings, H... - Prioritize attacking aromatic carbons with higher hyperdelocalization energy values ​​in alkoxy aromatics, inducing >C ar The cleavage of the -O- bond yields alkyl aromatics and alkoxy anions, the latter reacting with H atoms anchored on the catalyst surface. + The combined alkanols continue in H - Under the action of dehydroxylation to generate C 12 -C 27 Straight-chain alkanes. In structures where the oxygen atom is not directly bonded to the aromatic ring, both carbon atoms on either side of the oxygen atom may be affected by H... -The attack, inducement > C alk The cleavage of the -O- bond produces products in H... + and H - Further dehydroxylation eventually produces alkyl (m=1-4) substituted aromatics and alkanes (n=12-27).

[0098] Example 5: ER A ER B Catalytic hydrogenation and upgrading of model compound 9-phenanthrene (PA) on NiCa / Al2O3

[0099] (1)ER A Catalytic hydrogenation upgrading: Take 1g of ER A (Residue from Lignite Extraction in Runbei), 0.3 g of NiCa / Al2O3, and 20 mL of n-hexane were placed in a 100 mL high-pressure reactor and reacted at 180 °C and 5 MPa for 4 h. After the reactor was removed and cooled to room temperature, the reaction mixture was transferred and filtered under reduced pressure to obtain a residue and a filtrate. The residue was repeatedly extracted with an equal volume of carbon disulfide-acetone mixture using ultrasonic extraction. The extract and filtrate were combined to obtain the soluble component SP. A-2 The composition of the products was analyzed by GC / MS.

[0100] (2)ER B Catalytic hydrogenation upgrading: Take 1g of ER B (Extraction residue of Shaerhu sub-bituminous coal), 0.3 g of NiCa / Al2O3 and 20 mL of n-hexane were placed in a 100 mL high-pressure reactor and reacted at 180 °C and 5 MPa for 4 h. After the reactor was removed and cooled to room temperature, the reaction mixture was transferred and filtered under reduced pressure to obtain a filter residue and a filtrate. The filter residue was repeatedly ultrasonically extracted with an equal volume of carbon disulfide-acetone mixture. The extract and filtrate were combined to obtain the soluble component SP. B-2 The composition of the products was analyzed by GC / MS.

[0101] like Figure 14 As shown, PA was completely converted within the tested temperature range. This is because the dehydroxylation of PA to phenanthrene was rapidly completed under alkaline NiCa / Al2O3 conditions. Therefore, the hydrogenation of the aromatic ring of phenanthrene is the rate-determining step of this reaction. Phenanthrene is further converted into partially hydrogenated and fully hydrogenated products under the action of H…H. When the reaction temperature is 180℃, the yield of fully hydrogenated phenanthrene (PHP) is as high as 95.6%, including (4a) S ,4b S ,8a R ,10a R )-PHP、(4a S ,4b S ,8a R ,10a S )-PHP、(4aS ,4b S ,8a S ,10a S )-PHP、(4a R ,4b S ,8a R ,10a S )-PHP and (4a R ,4b S ,8a S ,10a R )-PHP5 stereochemical configurations of all-hydrophenanthrene. In addition, (4a S ,4b S ,8a S ,10a S )-PHP and (4a R ,4b S ,8a S ,10a R ) - PHP's return rate is much higher than the other three. Figure 15 The high selectivity of the cis product indicates that phenanthrene hydrogenation proceeds via a diatomic process. However, the selectivity of the cis product decreases when the temperature exceeds 180°C. This is because the trans-perhydrophenanthrene is a thermodynamically stable product, and increasing temperature favors increasing the selectivity of the trans product. IHP has a more significant effect on the distribution of PA hydrogenation products. The selectivity of perhydrophenanthrene increases with increasing IHP, among which (4a) S ,4b S ,8a S ,10a S The selectivity of 1,2,3,4,5,6,7,8-octahydrophenanthrene was consistently higher than that of other all-hydrogen products. The selectivity of 1,2,3,4,5,6,7,8-octahydrophenanthrene initially increased rapidly and then decreased. This is because increasing the initial hydrogen pressure favors the hydrogenation of the aromatic ring, and H…H preferentially hydrogenates to both sides of the phenanthrene ring. 1,2,3,4,5,6,7,8-octahydrophenanthrene continues to hydrogenate to both sides of the phenanthrene ring. … Hydrogenation to phenanthrene under the action of H.

[0102] Since the hydrogenation of polycyclic aromatic hydrocarbons is a first-order reaction involving sequential hydrogenation of one ring at a time, the hydrogenation of the first aromatic ring is completed rapidly. However, as the number of aromatic rings increases, the hydrogenation rate of the last aromatic ring may be an order of magnitude slower than that of the first ring. Therefore, the selectivity of all-hydrophenanthrene increases with the extension of reaction time, and (4a) S ,4b S ,8a S ,10a S -PHP selectively maintains the highest level.

[0103] like Figure 16As shown, based on the types and distribution of PA hydrogenation intermediates, possible reaction pathways for PA hydrogenation are proposed. NiCa / Al2O3 activates H2 into active H…H, which is indispensable for the hydrogenation of aromatic rings. The weakly bonded H…H undergoes heterolytic cleavage under the action of NiCa / Al2O3 to release H…H. - H - Attacking the positively charged carbon atom adjacent to -OH on PA induces >C ar -O bond cleavage and in-situ dehydroxylation to generate phenanthrene. Phenanthrene preferentially hydrogenates under the action of H…H to form octahydrophenanthrene, which is further hydrogenated to generate a series of hydrogenation products with different spatial configurations.

[0104] like Figure 17 As shown in Table 5, SP A-2 and SP B-2 The CCP detected 107 organic compounds. Based on the types of organic compounds and differences in functional groups within each component, these organic compounds were classified into two major groups (alkanes and cycloalkanes). A-2 and SP B-2 The CCP detected 28 types of alkanes, including 19 of them with carbon numbers distributed between C8 and C9. 26 The study included straight-chain alkanes and nine branched alkanes substituted with methyl or ethyl groups. The 79 cycloalkanes were predominantly alkyl-substituted derivatives of cyclohexane, decahydronaphthalene, perhydrophenanthrene, and perhydropyrene. Among these, bicyclohexane was the most abundant in SP... A-2 The RC (Reduction Ratio) in this fuel is as high as 22.3%. Under specific conditions, catalyst-induced rearrangement of the products during hydrogenation is the driving force behind the high yield of bicyclohexane. Bicyclohexane has a high density (0.887 g / mL) and calorific value (42.97 MJ / kg), making it one of the more studied high-density fuels. B-2 The content of alkyl perhydropyrene detected in the sample was much higher than that in SP. A-2 In the study, perhydropyrene, with its compact tetracyclic structure and high density, was identified as a good high-density fuel component. In addition, six spirocyclic compounds were detected, which are generated from the rearrangement of products during catalytic hydroconversion. Spirocycloalkanes, compared to bicyclic alkanes, exhibit higher density and better low-temperature properties when used in high-density fuels. A-2 and SP B-2 No aromatics or oxygen-containing compounds were detected, indicating that >C occurred during the hydrogenation process. alk The cleavage of the -O- bonds, the hydrogenation of aromatic rings, and the in-situ removal of heteroatoms make this hydrogenation product, composed of alkanes and cycloalkanes, potentially refined into high-density liquid fuels.

[0105] Table 5 SP A-2 and SP B-2 Cycloalkanes detectable by GC / MS

[0106]

[0107] Table 5 SP A-2 and SP B-2 Cycloalkanes detectable by GC / MS (continued)

[0108]

[0109]

[0110] Table 5 SP A-2 and SP B-2 Cycloalkanes detectable by GC / MS (continued)

[0111]

[0112] like Figure 18 As shown, the active metal component in the alkaline solid alkali NiCa / Al2O3 can activate H2 to H…H, and can further heterocleave H…H into free H. - and H anchored on the catalyst surface + Active H - It preferentially attacks the carbon atom adjacent to the oxygen atom in compound I to form a protonated intermediate, inducing >C alk The cleavage of the -O bridging bond yields alkylbenzenes or naphthalenes, which, under the action of H…H, ultimately form alkylcyclohexanes or decahydronaphthalenes. - Prioritize attacking the aromatic carbons with higher hyperlocalization energy values ​​in compound II, inducing >C ar The cleavage of the -O bond yields alkylnaphthalene-2-ol and phenanthrene. The alkylnaphthalene-2-ol undergoes dehydroxylation to form alkylnaphthalene, followed by hydrogenation of the naphthalene ring to form alkyldecahydronaphthalene. Phenanthrene, under the action of H…H, is converted to perhydrophenanthrene. Similarly, compound III, under the action of active H…H… - Under the action of [a certain process], alkylbenzene and alkyl anions are generated. Deep hydrogenation of alkylbenzene produces alkylcyclohexane, while the alkoxy anions react with H [a certain substance] fixed on the catalyst surface. + Combined to form alkyl alcohols, active H - It attacks the carbon atom adjacent to the oxygen atom in an alkyl alcohol, causing dehydration to produce an alkane.

[0113] In the description of this invention, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0114] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. The application of a highly active Ni-Ca bimetallic catalyst in the hydrodeoxygenation conversion of coal-derived model compounds or low- to medium-rank coal extraction residues, characterized in that, The specific steps are as follows: The reaction substrate, NiCa / Al2O3 catalyst, and n-hexane are sequentially added to a high-pressure reactor. The reaction substrate is a coal-derived model compound or a residue from medium- or low-rank coal extraction. After replacing the air in the reactor with H2 2-3 times, H2 at a predetermined initial hydrogen pressure of 1-5 MPa is introduced. The reactor is then placed in a heating furnace and rapidly heated to a preset reaction temperature of 180°C. o C. Maintain the set time for 2-4 hours; after the reaction is complete, rapidly cool the autoclave, collect the reaction mixture and filter it, analyze the filtrate components by GC / MS, and recover the catalyst after magnetic separation. The NiCa / Al2O3 catalyst is prepared by the following steps: (1) Weigh Ni(NO3)2·6H2O, Ca(NO3)2·4H2O, Al(NO3)3·9H2O and urea respectively in a molar ratio of 1:1:1:14, and dissolve them in deionized water. After ultrasonic dispersion, heat at 120-130 °C. o The reaction was stirred and refluxed at C for 6 hours, then aged at room temperature for 12 hours. After filtration and washing, the filter cake was dried under vacuum to obtain NiCa-LDH. (2) The precursor NiCa-LDH was transferred to a tube furnace and heated from room temperature to 500°C in an air atmosphere. o C and retain for 2 hours, then cool to room temperature and remove to obtain the metal oxide NiCa-LDO; (3) The metal oxide NiCa-LDO was heated from room temperature to 460°C in a hydrogen atmosphere. o After C reduction for 2 hours and cooling to room temperature, the catalyst NiCa / Al2O3 was obtained.

2. The application according to claim 1, characterized in that, The vacuum drying temperature in step (1) is 70-90°C. o C, drying time is 24h.

3. The application according to claim 1, characterized in that, The heating rate in steps (2) and (3) is 2-3 o C / min.

4. The application according to claim 1, characterized in that, In the NiCa / Al2O3 catalyst, the Al2O3 support exists in an amorphous form, the active metallic component nickel nanoparticles are uniformly distributed on the surface of the Al2O3 support, and nickel-calcium alloy nanoparticles are uniformly grown on the pore walls of the Al2O3 nanosheets. The particle size of the nickel nanoparticles in NiCa / Al2O3 is 4-6 nm, and the average pore size of the catalyst is 10.9 nm.

5. The application according to claim 1, characterized in that, The NiCa / Al2O3 catalyst accounts for 30% of the mass of the reaction substrate.

6. The application according to claim 1, characterized in that, The coal-derived model compound is selected from one of diphenyl ether, dibenzyl ether, benzylphenyl ether, and benzylnaphthyl ether.

Images