A porous spherical catalyst, a preparation method thereof and application of the catalyst in upgrading of hydrothermal crude oil from sludge water

Abstract

The application discloses a kind of porous spherical catalyst and its preparation method and application in catalytic sludge hydrothermal crude oil upgrading, it is related to catalyst preparation technical field.The preparation method of porous spherical catalyst disclosed in the application uses reducing sugar as carbon source and reducing agent simultaneously, by controlling the proportion between reducing sugar, metal active component and solvent, the porous spherical catalyst with abundant mesoporous structure is constructed, which can promote the mass transfer of reactants in the catalytic process;And carbon particles are dispersed in the pores formed by metal active component on the catalyst, which can inhibit the carbon deposition occurring in the catalytic process.The upgrading reaction of hydrothermal crude oil using the prepared porous spherical catalyst can obtain high-quality biofuel, and the calorific value of the obtained biofuel is similar to that of biofuel prepared from biomass.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a porous spherical catalyst, its preparation method, and its application in catalytic hydrothermal crude oil upgrading of sludge. Background Technology

[0002] With the development of society, economy, and urbanization, the output of urban sewage sludge has been increasing year by year, a large part of which is kitchen waste rich in oil. Utilizing the oil in urban sewage sludge can not only turn waste into treasure but also reduce the burden on the environment. However, current methods for treating urban sewage sludge mainly include incineration, landfill, and use as building materials; methods for the resource utilization and treatment of oil in sewage sludge still need to be explored.

[0003] Oils and fats are compounds composed of C, H, and O elements. They can be hydrodeoxygenated to obtain hydrocarbons, which can be used as biofuels. Various biofuel production processes have been developed both domestically and internationally, including biofuel production from biomass and biofuel production from single oils or fatty acids through deoxygenation. Using urban sludge as raw material to prepare biofuel is also a biofuel production route. To prepare biofuel through this route, urban sludge needs to be hydrothermally treated to prepare sludge hydrothermal crude oil, and then the obtained sludge hydrothermal crude oil is subjected to catalytic upgrading reaction. The biofuel prepared in this way has excellent quality, high calorific value, and low viscosity. Moreover, this route can also realize the "turning waste into treasure" of sludge. However, this reaction route faces some challenges: (1) The composition of sludge hydrothermal crude oil is complex and the viscosity is high, which can easily lead to catalyst carbon deposition during catalytic upgrading; (2) Most catalysts used for oil or fatty acid deoxygenation are microporous catalysts, such as catalysts obtained by loading metals such as Ni and Pt onto oxides, carbon supports, or molecular sieves. The catalysts prepared in this way have large mass transfer resistance and slow reaction rate.

[0004] To address the problem of easy carbon buildup on catalysts, coating the catalytically active components on the catalyst is a feasible approach. The coating layer outside the active components can isolate the active components, prevent sintering, and reduce carbon buildup.

[0005] Existing technology discloses a NiSn / C core-shell composite nanocatalyst, its preparation method, and its application. Citric acid is used as a carbon source and reducing agent to construct a hydrophobic carbon shell layer on the surface of the NiSn bimetallic material, which can improve the stability of the catalyst by inhibiting carbon deposition. However, even though citric acid can form new pore structures during decomposition and carbonization, the pore structure in this catalyst is still mainly composed of micropores and mesopores with a pore size of only about 10 nm. Therefore, when this catalyst is used to catalyze the upgrading reaction of sludge hydrothermal crude oil, the reactants are still prone to blockage in the catalyst pores, which is not conducive to mass transfer. Summary of the Invention

[0006] To address the problem that existing technologies cannot simultaneously solve the issues of easy carbon deposition in catalysts and the unfavorable pore structure for mass transfer of sludge, hydrothermal, and crude oil, this invention provides a method for preparing porous spherical catalysts. By using reducing sugars as both a carbon source and a reducing agent, a porous spherical catalyst with a rich mesoporous structure is constructed. The average pore size of the catalyst is above 20 nm, and carbon particles are dispersed in the pores formed by the metal active components on the catalyst, which can inhibit carbon deposition during the catalytic process.

[0007] Another object of the present invention is to provide a porous spherical catalyst.

[0008] Another objective of this invention is to provide an application of a porous spherical catalyst in the hydrothermal upgrading of catalytic sludge crude oil.

[0009] Another objective of this invention is to provide a method for catalytic hydrothermal crude oil upgrading of sludge.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution:

[0011] A method for preparing a porous spherical catalyst includes the following steps:

[0012] S1. A reducing sugar and a metal salt are dissolved in a solvent and subjected to a solvothermal reaction at a temperature of 120–250°C for 1–24 h. After the reaction is completed, a porous spherical catalyst precursor is obtained.

[0013] S2. The porous spherical catalyst precursor obtained in step S1 is placed in an oxidizing atmosphere for calcination at a temperature of 200–600°C for 1–12 hours.

[0014] The molar ratio of reducing sugar to metal salt in step S1 is 1:(0.5-10);

[0015] In step S1, the mass ratio of reducing sugar to solvent is 1:(50-600).

[0016] In a specific embodiment of the present invention, the reducing sugar in step S1 is arbitrarily selected from one or more of glucose, fructose, xylose, and chitosan; the metal salt is arbitrarily selected from one or more of iron salt, cobalt salt, nickel salt, copper salt, manganese salt, and zinc salt; the solvent is arbitrarily selected from one or more of water, methanol, ethanol, isopropanol, and ethylene glycol; the oxidizing atmosphere in step S2 can be oxygen and / or air; after obtaining the porous spherical catalyst precursor in step S1, it needs to be dried.

[0017] In step S1, the present invention mixes reducing sugar and metal salt and they undergo a solvothermal reaction together. The reducing sugar can act as a reducing agent, reducing the metal ions in the metal salt to elemental metals through the reduction of aldehyde groups. The aldehyde groups of the reducing sugar itself are oxidized to carboxyl groups. At the same time, the elemental metals and the unreduced metal salts can form a porous metal framework under solvothermal conditions. Then, the oxidized reducing sugars will attach to the pores of the metal framework to form a porous spherical catalyst precursor.

[0018] In step S2, when the porous spherical catalyst precursor is calcined in an oxidizing atmosphere, the oxidized reducing sugars attached to the pores of the metal framework protect the elemental metal. Therefore, the elemental metal will not undergo oxidation during calcination (in the art, the final step in catalyst preparation usually requires calcining the catalyst precursor in a reducing atmosphere to reduce the metal ions in the precursor to elemental metal). Meanwhile, the metal salts in the metal framework that are not reduced by the reducing sugars are converted into solid metal oxides during calcination. Simultaneously, the oxidized reducing sugars themselves carbonize, forming carbon particles dispersed in the porous metal framework. This acts as a kind of "carbon coating" on the metal framework, inhibiting carbon deposition on the catalyst itself during the catalytic reaction and adjusting the catalyst pore size to a suitable level (carbon particle accumulation can reduce the pore size).

[0019] In step S1, the mass ratio of reducing sugar to solvent is controlled at 1:(50-600) to control the absolute amount of reducing sugar. When the amount of reducing sugar is too small, there are too few carbon particles attached to the metal framework, making it difficult to achieve the effect of "carbon coating" on the metal framework. When the amount of reducing sugar is too large, firstly, the reducing sugar is difficult to fully dissolve in the solvent, and secondly, there are too many carbon particles attached to the metal framework. Since carbon itself is not a catalytically active substance, this reduces the catalytic activity of the catalyst.

[0020] The molar ratio of reducing sugar to metal salt in step S1 is controlled at 1:(0.5~10) because when there is too much metal, most of the reducing sugar is consumed by the oxidation reaction of the metal. Therefore, in the final catalyst, there are too few carbon particles attached to the porous metal framework, which cannot play the role of "carbon coating" on the metal framework and the regulation of catalyst pore size. When there is too little metal, there is too much reducing sugar, resulting in too many carbon particles in the final catalyst, which leads to too small catalyst pore size. This is also not conducive to the mass transfer of reactants in the catalytic sludge upgrading process. Moreover, carbon itself is not a catalytically active substance. Too many carbon particles will "bury" the catalytically active components (i.e., elemental metals) in the metal framework, which reduces the catalytic activity of the catalyst.

[0021] Preferably, the reducing sugar in step S1 is glucose and / or fructose.

[0022] Preferably, the mass ratio of reducing sugar to solvent in step S1 is 1:(80-300).

[0023] If there is too little solvent, it will not be enough to fully dissolve the sugar and metal salt; if there is too much solvent, it will not only waste solvent and heat, but also reduce the number of carbon particles attached to the metal framework, thus reducing the carbon particles' ability to inhibit carbon deposition.

[0024] Preferably, the molar ratio of reducing sugar to metal salt in step S1 is 1:(0.8-1.6).

[0025] If too little reducing sugar is added, it will be insufficient to reduce the metal. If too much reducing sugar is added, it will increase the carbon content in the catalyst, reduce the metal content, decrease the number of catalytic active sites, and reduce the catalytic efficiency.

[0026] Preferably, the metal salt in step S1 is a nickel salt and a cobalt salt.

[0027] Bimetallic catalysts often exhibit higher activity than monometallic catalysts. This invention uses nickel and cobalt to construct a porous metal framework, resulting in a catalyst with higher catalytic activity.

[0028] More preferably, the molar ratio of nickel salt to cobalt salt in step S1 is (1-3):1.

[0029] Preferably, the oxidizing atmosphere in step S2 is air.

[0030] Preferably, the solvent in step S1 is water and / or methanol.

[0031] The present invention also protects a porous spherical catalyst prepared by the above preparation method.

[0032] The porous spherical catalyst prepared by the preparation method provided in this invention has an overall porous spherical framework composed of metal elements and metal oxides, and carbon elemental particles are also dispersed in the channels of the porous spheres.

[0033] Preferably, the molar ratio of elemental metal to metal oxide in the porous spherical catalyst is (0.8-1.2):1.

[0034] Metallic elements act as the catalytically active components in catalysts, while the catalytic activity of metal oxides decreases significantly. When the molar ratio of metallic elements to metal oxides in porous spherical catalysts is (0.8–1.2):1, the resulting porous spherical catalysts exhibit higher catalytic activity.

[0035] Preferably, the average pore size of the porous spherical catalyst is 20–50 nm.

[0036] The average pore size of the catalyst is 20-50 nm, which is beneficial to the mass transfer of reactants during the catalytic process. Therefore, using porous spherical catalysts with a pore size of 20-50 nm to catalyze the upgrading reaction of sludge hydrothermal crude oil results in biofuel with a higher calorific value.

[0037] Preferably, the specific surface area of ​​the porous spherical catalyst is 90–100 m². 2 / g.

[0038] When the specific surface area is within the above range, it indicates that the pore size of the porous spherical catalyst obtained by the present invention is more suitable for the mass transfer of reactants in the hydrothermal crude oil upgrading reaction of sludge.

[0039] This invention also protects the application of the above-mentioned porous spherical catalyst in the hydrothermal upgrading of catalytic sludge crude oil.

[0040] This invention also protects a method for hydrothermal crude oil upgrading of catalytic sludge, comprising the following steps:

[0041] The sludge hydrothermal crude oil and the above-mentioned porous spherical catalyst are added to a solvent, and the reaction system is carried out under a reducing atmosphere or an inert atmosphere with a pressure of 1-3 MPa for 1-12 hours and a reaction temperature of 200-350℃. After the reaction is completed, biofuel can be obtained.

[0042] In specific embodiments of the present invention, the solvent may be water or an alkane, preferably an alkane; the reducing atmosphere may be H2, and the inert atmosphere may be N2.

[0043] Preferably, the mass ratio of sludge hydrothermal crude oil to porous spherical catalyst is (5-10):1.

[0044] The conventional ratio of reactants to catalyst is usually 10:1; however, crude oil reactants are complex and the reaction is difficult, so the proportion of catalyst needs to be increased appropriately; but too much catalyst is also not advisable, otherwise the cost-effectiveness will be too low and the catalyst cost will be too high.

[0045] Preferably, the mass ratio of sludge hydrothermal crude oil to solvent is 1:(2-10).

[0046] After the reaction, the alkane solvent directly serves as part of the bio-oil. If there is too much solvent, the calorific value of the sludge bio-oil cannot be reflected, and the calorific value of the bio-oil is approximately equal to the calorific value of the solvent. If there is too much crude sludge oil, its viscous properties are not conducive to the mass transfer process of the catalytic upgrading reaction.

[0047] More preferably, the solvent is a straight-chain alkane with 6 or more carbon atoms.

[0048] Straight-chain alkanes with 6 or more carbon atoms are the main components of fuels such as gasoline, diesel, and kerosene. Using straight-chain alkanes with 6 or more carbon atoms as solvents in the hydrothermal crude oil upgrading reaction of sludge allows biofuel to be obtained without separation after the reaction.

[0049] Preferably, the reaction time is 2 to 4 hours.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The catalyst prepared by this invention, based on the "carbon coating" effect of carbon particles, can inhibit carbon deposition, and the catalyst channel structure has abundant mesopores, which can promote the mass transfer of reactants during the catalytic process. Therefore, the porous spherical catalyst prepared by this invention can be used to upgrade the hydrothermal crude oil from sludge to obtain high-quality biofuel. The calorific value of the obtained biofuel is similar to that of biofuel prepared from biomass, and can reach up to 40.92 MJ / kg. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the porous spherical catalyst obtained in this invention.

[0053] Figure 2 The pore size distribution diagrams are of the catalysts obtained in Examples 1, 3, and 4 of this invention.

[0054] Figure 3 The above are XPS images of the catalysts obtained in Examples 1, 3, and 4 of this invention.

[0055] Figure 4 The images shown are SEM and TEM images of the catalyst obtained in Example 1 of this invention, where (a) is an SEM image and (b) and (c) are TEM images.

[0056] Figure 5 The images show the XRD patterns of the catalysts obtained in Examples 1, 3, and 4 of this invention.

[0057] Figure 6 The images show the SEM image of the catalyst obtained in Example 1 of this invention and the corresponding elemental mapping diagrams.

[0058] Figure 7 The image shows the HAADF diagram of the catalyst obtained in Example 1 of this invention.

[0059] Figure 8 The image shows the HAADF diagram of the catalyst obtained in Example 1 of this invention and the corresponding elemental mapping diagram. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0061] Example 1

[0062] A method for preparing a porous spherical catalyst includes the following steps:

[0063] S1. Glucose was dissolved in isopropanol with the metal salts nickel nitrate and cobalt nitrate and carried out a solvothermal reaction. The mass ratio of glucose to isopropanol was 1:524. The solvothermal reaction temperature was 200℃ and the solvothermal reaction time was 4h. After the reaction was completed, a porous spherical catalyst precursor was obtained.

[0064] S2. The porous spherical catalyst precursor obtained in step S1 is placed in an oxidizing atmosphere for calcination at a temperature of 350°C for 7 hours.

[0065] In step S1, the molar ratio of glucose to metal salt (total amount of nickel nitrate and cobalt nitrate) is 1:6, and the molar ratio of nickel nitrate to cobalt nitrate in the metal salt is 2:1.

[0066] The porous spherical catalyst prepared in Example 1 above is designated as SN-0.5.

[0067] Example 2

[0068] A method for preparing a porous spherical catalyst, wherein the difference from Example 1 is:

[0069] In step S1, the molar ratio of glucose to metal salt is 1:3, and the mass ratio of glucose to isopropanol is 1:262.

[0070] The porous spherical catalyst prepared in Example 2 above is designated as SN-1.

[0071] Example 3

[0072] A method for preparing a porous spherical catalyst, wherein the difference from Example 1 is:

[0073] In step S1, the molar ratio of glucose to metal salt is 1:1.5, and the mass ratio of glucose to isopropanol is 1:131.

[0074] The porous spherical catalyst prepared in Example 3 above is designated as SN-2.

[0075] Example 4

[0076] A method for preparing a porous spherical catalyst, wherein the difference from Example 1 is:

[0077] In step S1, the molar ratio of glucose to metal salt is 1:1, and the mass ratio of glucose to isopropanol is 1:87.33.

[0078] The porous spherical catalyst prepared in Example 4 above is designated as SN-3.

[0079] Example 5

[0080] A method for catalytic hydrothermal crude oil upgrading of sludge includes the following steps:

[0081] The sludge hydrothermal crude oil and the porous spherical catalyst NH-0.5 obtained in Example 1 were added to the organic solvent n-dodecane, and the reaction system was carried out under a hydrogen atmosphere at a pressure of 3 MPa for 3 hours and a reaction temperature of 280°C. After the reaction was completed, biofuel was obtained.

[0082] The mass ratio of sludge hydrothermal crude oil to porous spherical catalyst is 10:1;

[0083] The mass ratio of sludge hydrothermal crude oil to organic solvent is 1:9.

[0084] Example 6

[0085] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0086] The sludge hydrothermal crude oil and the porous spherical catalyst SN-1 obtained in Example 2 were added to the organic solvent n-dodecane for reaction.

[0087] Example 7

[0088] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0089] The sludge hydrothermal crude oil and the porous spherical catalyst SN-2 obtained in Example 3 were added to the organic solvent n-dodecane for reaction.

[0090] Example 8

[0091] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0092] The sludge hydrothermal crude oil and the porous spherical catalyst SN-3 obtained in Example 4 were added to the organic solvent n-dodecane for reaction.

[0093] Example 9

[0094] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0095] The reaction temperature is 320℃.

[0096] Example 10

[0097] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0098] The organic solvent is n-hexadecane.

[0099] Example 11

[0100] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0101] The organic solvent is n-octadecane.

[0102] Example 12

[0103] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0104] The mass ratio of sludge hydrothermal crude oil to organic solvent is 1:5.

[0105] Example 13

[0106] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0107] The mass ratio of sludge hydrothermal crude oil to organic solvent is 1:1.

[0108] Comparative Example 1

[0109] A method for preparing a porous spherical catalyst, wherein the difference from Example 1 is:

[0110] In step S1, the molar ratio of glucose to metal salt is 0.5:1, and the mass ratio of glucose to isopropanol is 1:43.64.

[0111] The porous spherical catalyst prepared in Comparative Example 1 is designated as SN-6.

[0112] Comparative Example 2

[0113] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0114] The sludge hydrothermal crude oil and the porous spherical catalyst obtained in Comparative Example 1 were added to the organic solvent n-dodecane for reaction.

[0115] Comparative Example 3

[0116] A method for catalytic hydrothermal crude oil upgrading of sludge, wherein the difference from Example 5 is:

[0117] Using coconut bark as biomass raw material, bio-crude oil was first obtained by hydrothermal treatment at 350°C and 3MPa hydrogen. Then, the bio-crude oil and the porous spherical catalyst obtained in Example 1 were added to the organic solvent n-dodecane for reaction to obtain biofuel.

[0118] Performance testing

[0119] BET adsorption tests were performed on the porous spherical catalysts obtained in Examples 1-4 to obtain pore structure data of the catalysts.

[0120] The theoretical calorific value, viscosity, and density of the biofuels obtained in Examples 5-13 and Comparative Examples 2-3 were calculated.

[0121] Specific performance test data are shown in Tables 1-2 below. Figures 1-8 As shown:

[0122] Table 1. Catalyst performance test data

[0123]

[0124]

[0125] Note: In Table 1 above, the average pore size of Example 1 "~75" means that the average pore size is about 75nm, and the same applies below; all data of Example 2 are between those of Example 1 and Example 3.

[0126] Table 2. Biofuel Performance Test Data

[0127]

[0128] Note: The viscosity and density of the biofuel obtained in Comparative Example 2 in Table 2 above are similar to those of the biofuel obtained in Example 13.

[0129] As can be seen from the data in Tables 1 and 2, when the mass ratio of reducing sugar to solvent in step S1 is within the preferred range of 1:(80-300) of this invention (Examples 2-4), the resulting catalyst has a more suitable pore structure for mass transfer of reactants (average pore size ≥25nm, <75nm, belonging to mesoporous). When the mass ratio of reducing sugar to solvent is less than 1:300 (Example 1), it indicates that the absolute amount of reducing sugar is too small, and there are too few carbon particles attached to the metal framework, making it difficult to play the role of "carbon coating" on the metal framework. It is also difficult to adjust the pore size of the catalyst to a suitable size. Therefore, the pore size in the catalyst is larger, reaching 75nm, which belongs to the macroporous range. In the process of catalytic sludge upgrading, this is not only not conducive to the mass transfer of reactants, but also prone to carbon deposition. Therefore, when this catalyst is used to prepare biofuel, the calorific value of the biofuel is only 37.16MJ / kg.

[0130] Comparing the data from Examples 6-8 (which are biofuels prepared by catalysis using the catalysts obtained in Examples 2-4, respectively), it can be seen that when the mass ratio of reducing sugar to solvent is within the preferred range of 1:(80-300) of this invention, the absolute amount of reducing sugar is sufficient. However, when the molar ratio of reducing sugar to metal is not within the preferred range of 1:(0.8-1.6) of this invention (Example 2), the calorific value of the biofuel obtained after catalysis is reduced. When the molar ratio of reducing sugar to metal is also within the preferred range of 1:(0.8-1.6) of this invention, the ratio of metal to metal oxide on the obtained catalyst will also fall within the preferred range of (0.8-1.2):1. However, as the amount of isopropanol and metal salt added decreases (Example 4), the average pore size of the obtained catalyst decreases to ~25nm, which is more compatible with the reactants in the sludge hydrothermal crude oil upgrading process. Therefore, the sludge hydrothermal crude oil obtained by catalysis using the catalyst obtained in Example 4 has a higher calorific value.

[0131] A comparison of the data from Examples 5 and 9 in Table 2 shows that when the catalyst provided by this invention is used to catalyze the upgrading reaction of sludge hydrothermal crude oil, the calorific value of the resulting biofuel increases as the reaction temperature increases from 280°C to 320°C. This is because with higher temperatures, the sludge hydrothermal crude oil can more quickly overcome the reaction barrier and undergo the upgrading reaction. However, when the reaction temperature continues to increase above 350°C, the calorific value of the biofuel becomes difficult to increase further.

[0132] In the catalytic hydrothermal crude oil upgrading reaction of sludge, if the solvent in the reaction system is a straight-chain alkane with 6 or more carbon atoms (Examples 5, 10, 11), then biofuel can be obtained directly without separating the solvent after the catalytic process. As the number of carbon atoms in the solvent increases, the calorific value of the resulting biofuel also continuously increases.

[0133] The data from Examples 5, 12, and 13 show that when the mass ratio of sludge hydrothermal crude oil to solvent is higher than the preferred range of 1:(2-10) of this invention (Example 13), the calorific value of the resulting biofuel is obviously lower. This is because the sludge hydrothermal crude oil is too viscous (in terms of viscosity, Example 13 > Example 5 > Example 12, because the mass of sludge hydrothermal crude oil in Example 13 is higher than that in Example 5, and Example 5 is higher than that in Example 12). When there is too much sludge hydrothermal crude oil, it is not conducive to the mass transfer of the catalytic process, thus reducing the calorific value of the resulting biofuel.

[0134] Comparative Example 1 shows a porous spherical catalyst prepared using the method provided by this invention, where the mass ratio of reducing sugar to solvent in step S1 is higher than 1:50 (specifically 1:43.64), meaning less solvent is used. With insufficient solvent, firstly, glucose is difficult to fully dissolve in the solvent; secondly, too many carbon particles adhere to the metal framework, and since carbon itself is not a catalytically active substance, this reduces the catalytic activity of the catalyst. Based on this, the biofuel obtained by catalyzing the catalyst in Comparative Example 2 using the catalyst from Comparative Example 1 has a significantly lower calorific value and increased viscosity and density, which is detrimental to practical use.

[0135] Comparative Example 3 shows biofuel obtained by upgrading biomass feedstock. Combining the data from the examples and Comparative Example 3, it can be seen that when the present invention uses a porous spherical catalyst for catalysis, the biofuel obtained using sludge hydrothermal crude oil as feedstock has similar calorific value, viscosity, and density to biofuel prepared from biomass.

[0136] Density and viscosity are also performance parameters that need to be considered when preparing biofuels. As shown in Table 2, the biofuel obtained by using the porous spherical catalyst provided in this invention for the hydrothermal crude oil upgrading reaction of sludge exhibits a viscosity and density of 2.6–5 mm³ at 0°C. 2 / s and 0.7~0.9g / cm 3 Within this range, it is similar to biofuels produced from biomass. The American standard ASTM D6751 specifies that the viscosity of biodiesel at 40°C should be between 1.9 and 6.0 mm. 2 The viscosity measured in this invention is within the range of / s, while the viscosity measured at 0°C is higher than that at 40°C (biofuels become thinner at higher temperatures, thus reducing viscosity), but still within the range of 1.9–6.0 mm. 2 Within the range of / s, this indicates that the biofuel provided by this invention has low viscosity, which is suitable for practical application scenarios (the lower the viscosity, the better the flowability). Meanwhile, the density (at 15°C) of biodiesel is generally 0.85–0.90 g / cm³. 3 The biofuel provided by this invention is also within this range, indicating that the biofuel obtained by this invention has a lower density, which is also in line with practical application scenarios (higher density would result in a larger mass of fuel input under the same conditions, increasing fuel consumption).

[0137] Figure 1 This is a schematic diagram of the porous spherical catalyst obtained in this invention. From... Figure 1 As can be seen, the catalyst prepared by the present invention has a porous spherical morphology. The porous framework of the porous sphere is composed of metal, and carbon particles are dispersed in the channels of the porous sphere.

[0138] Figure 2This is a pore size distribution diagram of the catalysts obtained in Examples 1, 3, and 4 of this invention. From... Figure 2 As can be seen from the above, the average pore sizes of the porous catalysts obtained in Examples 1, 3, and 4 of this invention are approximately 75 nm, 50 nm, and 25 nm, respectively.

[0139] Figure 3 These are XPS images of the catalysts obtained in Examples 1, 3, and 4 of this invention. Figure 3 The ratio of elemental metals to metal oxides in the porous catalysts obtained in Examples 1, 3, and 4 of this invention can be read from the table.

[0140] Figure 4 The images shown are SEM and TEM images of the catalyst obtained in Example 1 of this invention, where (a) is a SEM image and (b) and (c) are TEM images. Figure 4 As can be seen from (a), the porous spherical catalyst obtained in this invention has the morphology of spherical particles, and from... Figure 4 As can be seen from (b) and (c), the porous spherical catalyst contains channels.

[0141] Figure 5 The images show the XRD patterns of the catalysts obtained in Examples 1, 3, and 4 of this invention. Figure 5 As can be seen from the above, the porous catalyst obtained by the present invention contains both elemental metals and metal oxides.

[0142] Figure 6 The image shows the SEM image of the catalyst obtained in Example 1 of this invention and the corresponding elemental mapping diagram. Figure 7 The HAADF diagram of the catalyst obtained in Example 1 of this invention; Figure 8 This is the HAADF diagram of the catalyst obtained in Example 1 of the present invention and the corresponding elemental mapping diagram. According to... Figures 6-8 As can be seen, in the porous spherical catalyst of Example 1 of the present invention, carbon elements are dispersed in the catalyst in the form of carbon particles.

[0143] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a porous spherical catalyst, characterized in that, Includes the following steps: S1. A reducing sugar and a metal salt are dissolved in a solvent and subjected to a solvothermal reaction at a temperature of 120–250°C for 1–24 h. After the reaction is completed, a porous spherical catalyst precursor is obtained. S2. The porous spherical catalyst precursor obtained in step S1 is placed in an oxidizing atmosphere for calcination at a temperature of 200–600°C for 1–12 hours. The molar ratio of reducing sugar to metal salt in step S1 is 1:(0.5-10); The mass ratio of reducing sugar to solvent in step S1 is 1:(50-600); The metal salt is a cobalt salt and a nickel salt; The porous spherical catalyst prepared by the method is composed of a metal element and a metal oxide as the overall porous spherical framework, and carbon element particles are dispersed in the channels of the porous spheres; the molar ratio of the metal element to the metal oxide is (0.8~1.2):

1.

2. The method for preparing the porous spherical catalyst as described in claim 1, characterized in that, In step S1, the mass ratio of reducing sugar to solvent is 1:(80-300).

3. The method for preparing the porous spherical catalyst as described in claim 2, characterized in that, In step S1, the molar ratio of reducing sugar to metal salt is 1:(0.8-1.6).

4. A porous spherical catalyst prepared by the preparation method according to any one of claims 1 to 3.

5. The porous spherical catalyst as described in claim 4, characterized in that, The average pore size of the porous spherical catalyst is 20–50 nm.

6. The application of the porous spherical catalyst according to any one of claims 4 to 5 in the hydrothermal upgrading of catalytic sludge crude oil.

7. A method for catalytic hydrothermal crude oil upgrading of sludge, characterized in that, Includes the following steps: The sludge hydrothermal crude oil and the porous spherical catalyst described in any one of claims 4 to 5 are added to a solvent, and the reaction system is carried out under a reducing atmosphere or an inert atmosphere with a pressure of 1 to 3 MPa for 1 to 12 hours and a reaction temperature of 200 to 350°C. After the reaction is completed, biofuel can be obtained.

8. The method for hydrothermal crude oil upgrading of catalytic sludge as described in claim 7, characterized in that, The mass ratio of the sludge hydrothermal crude oil to the porous spherical catalyst is (5-10):

1.

9. The method for hydrothermal crude oil upgrading of catalytic sludge as described in claim 7, characterized in that, The mass ratio of the sludge hydrothermal crude oil to the solvent is 1:(2-10).

Images