Palladium supported magnetic silica nanofluid, preparation method, application and oil displacement agent

Abstract

The application discloses a kind of palladium supported magnetic silica nanofluid, preparation method, application and oil displacement agent, obtain nanofluid using green bio-based fluid, and the effect of stable dispersion is generated by microbial metabolism surface active substance;Magnetic core can be recycled by the action of magnetic field, and shell material provides stable dispersion capacity, and supported palladium can inhibit the plugging damage of formation by microbial propagation;Bioactive ingredients and nanoparticles can synergistically improve oil recovery, and its oil recovery mechanism is revealed through micro-dispersion oil droplet and imbibition experiment, and core displacement experiment effect is remarkable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biological nano oil displacement, and particularly relates to a palladium-loaded magnetic silica nanofluid, a preparation method, application and oil displacement agent. BACKGROUND

[0002] Nanomaterials are very small in size, between atoms, molecules and macroscopic systems, and their special structure produces four effects, namely small size, quantum, surface and interface effects, and exhibits unique physical and chemical properties. As a new type of oil reservoir displacement technology, nanofluid displacement has the advantages of good injectivity, small reservoir damage, strong oil displacement capacity and intelligent response, and has attracted widespread attention. Nanomaterials for oilfields can be roughly divided into metal and silica inorganic nanomaterials, organic carbon and cellulose nanomaterials, polymer microspheres, surfactant nanoemulsions and other materials (MD molecular film and 2-D intelligent nano black card) and the like.

[0003] The preparation of nanomaterials mainly has two techniques, top-down and bottom-up. The top-down method relies on using various distribution techniques to produce isolated atoms from bulk materials, while the bottom-up method starts from metal salt precursors (dissolved in solvents), which are reduced in a chemical reaction, and then form nanoparticles through a nucleation process, and then form clusters. In the bottom-up method, the use of a suitable capping agent is very important for controlling the particle size, shape and stability of the obtained nanomaterials. Traditional nanomaterial synthesis methods mainly include physical and chemical methods. Among them, physical methods such as sputtering, arc discharge and ball milling require high equipment for the reaction and have high energy consumption; chemical methods such as microemulsion method, coprecipitation method and sol-gel method use toxic reagents, have poor degradability and easily cause environmental pollution.

[0004] Based on the above technical problems existing in the prior art, the present application provides a nanometer palladium-loaded magnetic silica fluid, a preparation method, application and oil displacement agent. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a palladium-loaded magnetic silica nanofluid, a preparation method, application and oil displacement agent.

[0006] The present application adopts the following technical solutions:

[0007] In a first aspect, a palladium-loaded magnetic silica nanofluid is provided:

[0008] The magnetic Fe3O4 nanometer precursor is prepared by a double microemulsion method;

[0009] TEOS hydrolysis is used as a shell material;

[0010] Palladium was synthesized using Pseudomonas aeruginosa fermentation broth and loaded onto the surface of magnetic silica nanomaterials.

[0011] Secondly, a method for preparing palladium-supported magnetic silica nanofluids is provided, comprising:

[0012] Step 1: Use Pseudomonas aeruginosa for culturing and fermentation to purify the metabolites, in which glycolipids and amino acid active ingredients are produced.

[0013] Step 2: Magnetic Fe3O4 nano-precursors were prepared using a dual microemulsion method;

[0014] Step 3: Hexane, TEOS, pure water and ethanol are stirred evenly and then added to the reverse microemulsion. The mixture is heated and stirred at 50°C for 1 hour to promote the condensation reaction of TEOS. After centrifugation at 5°C and 8000 rpm, the supernatant is discarded and the precipitate is collected. The precipitate is washed with ethanol and pure water to obtain magnetic nanofluid.

[0015] Step 4: Add PdCl2 and Pseudomonas aeruginosa fermentation supernatant to a container and stir magnetically at 70°C for 5 hours to obtain palladium nanofluid.

[0016] Step 5: Add the palladium nanofluid dropwise to the magnetic nanofluid and heat and stir at 70°C for 3 hours to fully load the palladium nanofluid modified by the microbial metabolic supernatant onto the Fe3O4@SiO2 surface.

[0017] Further, in step 3, the reverse microemulsion is formed by stirring 28g of n-hexanol, 20g of n-hexane and 7g of Triton X-100 at 40°C for 10min.

[0018] Furthermore, in step 4, the fermentation broth contains a large amount of reducing substances that can reduce palladium ions. Continuous heating is required to increase the reaction rate and obtain palladium nanofluid.

[0019] Further, step 1 includes:

[0020] Step 1.1, prepare the fermentation culture medium, wherein the culture medium includes:

[0021] The carbon sources are glucose and corn steep liquor powder;

[0022] The nitrogen sources are NaNO3 and CaMg(NO3)4;

[0023] The phosphorus source is K2HPO4;

[0024] Corn oil;

[0025] The trace elements are a mixture of ZnSO4·7H2O, CuSO4·5H2O, Ni(NO3)2·6H2O, MnSO4·4H2O and FeSO4·7H2O;

[0026] Sterilize the culture medium in a high-pressure steam oven at 121°C for 20 minutes. After it cools naturally, take it out and perform inoculation in a clean bench.

[0027] Step 1.2: Obtain the microbial fermentation supernatant;

[0028] Take out the refrigerated *Pseudomonas aeruginosa*, thaw and activate it at room temperature for 15 min, inoculate 1 ml of bacterial suspension into the culture medium, seal with a sealing film, and place in a constant temperature incubator at 37℃ and 180 rpm for 72 h of mixing and shaking. Use an ultrasonic cell disruptor to sonicate the fermentation broth for 10 min, with 6 seconds of sonication followed by 4 seconds of sonication. Place the fermentation broth in a 50 ml centrifuge tube and centrifuge at 4℃ and 8000 rpm for 15 min to remove precipitates and obtain the supernatant. Heat the supernatant at 260℃ using a distillation apparatus to obtain the distillate. Filter the distillate using a combination of vacuum pump, filter paper, and suction flask to obtain the purified *Pseudomonas aeruginosa* fermentation supernatant.

[0029] Further, step 1 includes the step of analyzing the components of the Pseudomonas aeruginosa fermentation supernatant.

[0030] Furthermore, step 2, which uses a dual microemulsion method to prepare magnetic Fe3O4 nano-precursors, includes:

[0031] Add n-hexanol, n-hexane, and Triton X-100 to a container and stir at 40°C for 10 min to form a microemulsion. Add FeSO4·7H2O and FeCl3·6H2O and stir until fully dissolved. Add methylamine and maintain the reaction for 5 min. Then add concentrated NH3·H2O dropwise until the color turns black, while keeping the mixture stirred continuously.

[0032] Furthermore, in step 3, the magnetic nanofluid is obtained by using ultrasound to disperse the nanoparticles uniformly. The ultrasound parameters are set to 20 seconds per cycle, 2 seconds per interval, and a total of 30 cycles.

[0033] Further, step 4 includes detecting the surface plasmon resonance band (SPR) of the palladium nanoparticles using UV-Vis to confirm the synthesis of the nanoparticles.

[0034] Thirdly, this invention provides an application of palladium-loaded magnetic silica nanofluid in enhancing oil recovery.

[0035] Fourthly, an oil displacement agent is provided, comprising the palladium-supported magnetic silica nanofluid.

[0036] Furthermore, in the palladium-loaded magnetic silica nanofluid, the palladium loading is less than 10 wt%.

[0037] The beneficial effects of this invention are:

[0038] The palladium-loaded magnetic silica nanofluid, its preparation method, its application, and its oil displacement agent described in this invention utilize a green bio-based liquid to obtain the nanofluid. The surface-active substances produced by microbial metabolism have a stable dispersion effect. The magnetic core can be recycled and reused with the help of a magnetic field, while the shell material provides stable dispersion capabilities. The palladium loading can inhibit the blockage damage to the formation caused by microbial reproduction. The bioactive components and nanoparticles can synergistically improve the oil recovery rate. The oil recovery mechanism was revealed through microscopic stripping of oil droplets and percolation experiments. The core displacement experiment showed significant results, demonstrating the advantages of being bio-friendly and having great application potential. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the optimal concentration of the *Pseudomonas aeruginosa* fermentation supernatant in an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram showing the Zeta potential detection results of the particle size of the bio-nanofluid in an embodiment of the present invention.

[0041] Figure 3 This is a transmission electron microscope image of the bio-nanomaterials in the embodiments of the present invention;

[0042] Figure 4 The Fourier transform infrared image of the bio-nanomaterials in the embodiments of the present invention;

[0043] Figure 5a , Figure 5b This is a schematic diagram of the magnetic induction detection results of bio-nanomaterials in an embodiment of the present invention. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features and advantages of the present invention, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present application can be combined with each other.

[0045] Example 1

[0046] Example 1 of this application provides a method for obtaining Pseudomonas aeruginosa fermentation supernatant, including:

[0047] S1.1, Prepare a high-efficiency fermentation medium. The medium is prepared in an Erlenmeyer flask. The carbon source is 10 g / L glucose and 4 g / L corn steep liquor powder; the nitrogen source is 1.6 g / L NaNO3 and 0.4 g / L CaMg(NO3)4; the phosphorus source is 1.6 g / L K2HPO4; 1 ml / L trace elements; and 5 ml / L corn oil. The trace elements include 0.6 g / L ZnSO4·7H2O, 0.5 g / L CuSO4·5H2O, 0.3 g / L Ni(NO3)2·6H2O, 0.5 g / L MnSO4·4H2O, and 0.5 g / L FeSO4·7H2O. The medium is sterilized in a high-pressure steam autoclave at 121℃ for 20 minutes. After natural cooling, it is removed and inoculated into the culture medium in a clean bench.

[0048] S1.2, Obtaining the supernatant from microbial fermentation: Pseudomonas aeruginosa, stored in the laboratory, was thawed and activated at room temperature for 15 minutes. 1 ml of bacterial culture was inoculated into the culture medium, sealed with a sealing film, and placed in a constant temperature incubator at 37°C and 180 rpm for 72 hours of mixing and shaking. The fermentation broth was then sonicated for 10 minutes using an ultrasonic cell disruptor, with 6 seconds of sonication followed by a 4-second interval. The fermentation broth was then placed in a 50 ml centrifuge tube and centrifuged at 4°C and 8000 rpm for 15 minutes to remove precipitates and impurities, thus obtaining the supernatant. To remove inorganic salt impurities from the fermentation broth, a distillation apparatus was used to heat the broth at 260°C to obtain the distillate. Finally, the distillate was filtered using a combination of a vacuum pump, filter paper, and suction flask to obtain the final purified Pseudomonas aeruginosa fermentation supernatant.

[0049] S1.3, Component analysis of Pseudomonas aeruginosa fermentation supernatant;

[0050] a. Acid precipitation: The pH of the fermentation broth was adjusted to 2 with HCl and left to stand overnight at 4°C. A small amount of white precipitate was produced, indicating the presence of a small amount of lipopeptide surfactants.

[0051] b. TLC: Take 0.1g of sample into a test tube, add 5mL of concentrated H2SO4, seal the test tube and hydrolyze at 100℃ for 4h. After the hydrolysate cools, add sufficient BaCO3 to neutralize, add pure water and pour it all into a centrifuge tube, centrifuge at 4500rpm for 10min, collect the supernatant into the sample tube, concentrate at 40℃ for 30min and set aside. Spot the sample on a silica gel plate for thin-layer chromatography, add developing solvent, spray color reagent and heat to 105℃ to develop color until the spots are clear, indicating that a large amount of glycolipids and lipopeptides are present.

[0052] c. Chromatographic and mass spectrometric analyses were performed using liquid chromatography-mass spectrometry (LC-MS). The experimental conditions were as follows: mobile phase A was 0.1% formic acid aqueous solution, mobile phase B was acetonitrile solution, flow rate was 0.3 ml / min, injection volume was 5 μL, chromatographic column was Waters BEH C18 2.1*100 mm 1.7 μm, mass spectrometry scan range was 100-1400 m / z (first stage), sheath gas temperature was 350℃, sheath gas flow rate was 12 L / min, ESI+ mode voltage was 4000 V, ESI- mode voltage was 3200 V, and the presence of rhamnolipids was detected.

[0053] e. Measure the CMC (Cryo-Concentration Mixture). Dilute the purified *Pseudomonas aeruginosa* fermentation supernatant by 1, 10, 100, 1000, and 10000 times, respectively, and measure the surface tension value. Take the 10% volume concentration at the inflection point as the optimal concentration. (See graph for example.) Figure 1 As shown.

[0054] Example 2

[0055] Example 2 of this application provides a method for synthesizing bio-nanofluids, comprising:

[0056] S2.1, Fe3O4 precursor was prepared using a dual microemulsion method. 28g of n-hexanol, 20g of n-hexane, and 7g of Triton X-100 were added to a 300ml conical flask and stirred at 40℃ for 10min to form a microemulsion. 0.2g of FeSO4·7H2O and 0.2g of FeCl3·6H2O were added and stirred slowly to dissolve them completely. 2ml of methylamine was added and the reaction was maintained for 5min. Subsequently, concentrated NH3·H2O was added dropwise until the color turned black, while stirring continuously. During this process, vigorous stirring was avoided to prevent the introduction of excessive oxygen and excessively high temperature, which could cause the nanoparticle size to increase.

[0057] S2.2, in a 50ml beaker, add 5ml n-hexane, 0.2ml TEOS, 2ml pure water, and 3ml ethanol. After stirring well, add the mixture to the reverse microemulsion. Since TEOS and water are poorly miscible, while ethanol is well miscible with both, this avoids the phenomenon of turbidity and stratification during the reaction. TEOS molecules diffuse from the hydrophobic phase to the hydrophilic phase, undergoing hydrolysis and aggregation around the Fe3O4 precursor. The addition of ethanol, on the one hand, allows the organic groups to replace the non-bridged hydroxyl groups on the Fe3O4 surface, reducing particle attraction and agglomeration; on the other hand, it reduces the interfacial tension of water, allowing for better formation of the SiO2 coating layer and improving particle stability. Continue stirring at 50℃. The reaction was heated and stirred for 1 hour to further promote the condensation reaction of TEOS. After centrifugation at 5°C and 8000 rpm, the supernatant was discarded and the precipitate was collected. The precipitate was washed five times with ethanol and pure water and centrifuged repeatedly. Finally, the volume was adjusted to 150 ml of magnetic nanofluid, and the nanoparticles were dispersed evenly by ultrasound. The ultrasound parameters were set to 20 seconds each time, 2 seconds interval, and a total of 30 times. The resulting magnetic nanofluid had good stability because the SiO2 coating on the ferrite contained abundant hydrophilic silanol groups, which could attract a large number of water molecules and promote the good solubility and monodispersion of the nanoparticles in water.

[0058] S2.3, add 0.02g of PdCl2 and 20ml of Pseudomonas aeruginosa fermentation supernatant to another conical flask, and bring the volume to 100ml with pure water. Stir magnetically at 70℃ for 5h. During this process, the color of the liquid changes from light gray to brown and finally to black, confirming the synthesis of nanoparticles. The position, symmetry, narrowness and / or width of the SPR can not only provide information about the presence of nanoparticles, but also about their shape, size, aggregation or oxidation. For example, spherical particles have only one scattering peak, while rod-shaped, triangular prism and cubic shapes show multiple scattering peaks. The maximum absorption peak at 350-450nm is the typical SPR detection range for palladium nanoparticles.

[0059] S2.4, palladium nanofluid was added dropwise to magnetic nanofluid, and the mixture was heated and stirred at 70°C for 3 hours to allow the palladium nanofluid modified by the microbial metabolic supernatant to be fully loaded on the Fe3O4@SiO2 surface. The volume was adjusted to 200 ml with pure water to finally obtain palladium-loaded (Fe3O4@SiO2-Pd) magnetic nanofluid mediated by Pseudomonas aeruginosa fermentation supernatant. The separation ability of the magnetic nanoparticles was observed using a neodymium magnet.

[0060] S2.5 Characterization tests were performed on the powder. The morphology and size of the nanoparticles were characterized using SEM-EDX and TEM. The SEM-EDX test procedure was as follows: a small amount of powder sample was directly attached to a conductive adhesive and sputtered with gold for 45 seconds using a Quorum SC7620 sputtering coating instrument at a speed of 10 mA. The sputtering target was pure gold. Subsequently, the morphology of the sample was captured by SEM, and point and area scans were performed by energy dispersive spectroscopy (EDS). The accelerating voltage for morphology imaging was 3 kV, and the accelerating voltage for energy dispersive spectroscopy mapping imaging was 15 kV. The detector was an SE2 secondary electron detector.

[0061] TEM testing procedure: Disperse the sample in an aqueous solution and sonicate for 10 minutes. Add the dispersed liquid dropwise onto a copper grid. After drying, use a TEM to photograph the sample morphology. The accelerating voltage is 200 kV, and the thermionic emission electron gun is a W filament. FTIR is used to characterize the functional groups on the surface of nanoparticles and analyze the structure of biological organic matter. The testing procedure is as follows: Take 1-2 mg of powder sample and 200 mg of pure KBr, grind them evenly, place them in a mold, press them into a transparent sheet on a hydraulic press, and place the sheet into an FTIR instrument for testing. The wavenumber range is 4000-400 cm⁻¹. -1 32 scans, 4cm resolution -1 ;like Figure 5a , Figure 5b As shown, the magnetic properties of bio-nanomaterials were analyzed using VSM. The test conditions were: 5cm electrode diameter, room temperature, and a measurement sensitivity of 5 × 10⁻⁶. -7 emu, moment measurement range 5×10 -7 emu~10 3 emu, maximum magnetic field 2.17T@16.2mm pole spacing;

[0062] It should be noted that palladium can also be replaced by copper, silver, zinc, cobalt, and nickel.

[0063] This indicates that bio-nanofluids exhibit the Tyndall effect, respond well to magnetic fields, have a viscosity <30 cp, and good injectability, such as... Figures 2-4 As shown, the Zeta potential is -48.2 mV, the nanoparticles have a negative charge on their surface, and can maintain stable dispersion over a long period of time. TEM shows that the nanoparticle size is only 30-50 nm, exhibiting a core-shell structure with a shell of about 10 nm. FTIR indicates that the main functional groups C=O and CN participate in the surface modification of the nanoparticles. VSM shows that the material has good superparamagnetism, with a high saturation magnetization of 11.3 emu / g and a coercivity of only 1.8 G, indicating good application potential.

[0064] Example 3

[0065] Embodiment 3 of this application provides a method for measuring interfacial tension using the spin drop method, comprising:

[0066] Different concentrations of bio-nanofluids were injected into the sample tube using a microinjector, and oil droplets were sent to the center of the liquid to place the droplets in a certain centrifugal force field to avoid contact with the sample tube surface. The instrument speed was adjusted to 8000 rpm. At this time, the oil droplets were elongated under the combined action of centrifugal force and interfacial tension. The interfacial tension values ​​of different concentrations of nanofluids were obtained by video image analysis.

[0067] Embodiment 3 of this application provides a microscopic oil stripping experimental method, including:

[0068] Static oil droplet removal: Quartz plates were pretreated at 90℃ for 1 hour, then immersed in a mixed solution (concentrated H2SO4:H2O2 = 1:4) to remove residual organic impurities on the surface. After rinsing with pure water multiple times and drying, crude oil was dripped onto the surface of the quartz plate and quickly inverted into a square container containing a magnetic silica fluid loaded with nano-palladium as an oil displacement agent. The changes in the oil droplets were observed. Dynamic oil film removal: One end of a capillary tube was immersed in simulated oil. Under the action of capillary force, crude oil entered the tube. The tube was slowly inverted at 90° and repeated multiple times to cover the inner wall of the capillary tube with an oil film. Formation water and an oil displacement agent were drawn in in the same way, and the removal effect on the oil film was observed. The differences in oil film removal on the inner wall of different sluices were observed under a microscope.

[0069] Embodiment 3 of this application provides an experimental method for percolating crude oil using an oil displacement agent, comprising:

[0070] A 0.5 mD dense core was thoroughly dried in an oven for 8 hours and its initial mass was measured. The core was then evacuated for 24 hours using a vacuum pump. The core was then saturated with simulated formation water for 72 hours using pressure difference. The saturated core was removed, its surface was wiped dry, and its mass was measured. The volume of saturated pore water was calculated. The core was then displaced with simulated oil at a rate of 0.5 mL / min until oil was continuously observed at the outlet. The core was then soaked in simulated oil for 72 hours to establish bound water saturation. The oil on the core surface was wiped clean, and the core mass was measured. The volume of saturated simulated oil was calculated using the oil-water density difference. The core was then quickly transferred to a percolation bottle, and crude oil was percolated using an oil displacement agent. Simulated formation water was used as a control to compare the crude oil percolation capacity.

[0071] The simulated oil-water interfacial tension was 22.51 mN / m. As a control, under centrifugal force, a bio-nanofluid with a concentration of only 100 ppm could easily elongate and disperse oil droplets, reducing the interfacial tension to 4.2 mN / m. Microscopic oil droplet stripping showed that nanoparticles could rapidly separate oil droplets from the quartz plate, causing them to rise to the upper surface and disperse into sheet-like oil films. The wedge-shaped structure separated the oil droplets by "shoveling" them. Dynamic oil film stripping experiments showed that nanoparticles have a large specific surface area and strong adsorption capacity, enabling them to "roll up" the remaining oil. Permeation experiments showed that the bio-nanofluid increased the permeation of crude oil by 117.9% compared to simulated formation water, demonstrating a significant effect. Furthermore, the core surface was clean, and oil droplets were efficiently separated from the core surface. Oil displacement experiments were conducted using cores with permeability of 8 mD, 50 mD, and 130 mD, respectively. The bio-nanofluid showed good results in medium-to-high permeability cores, increasing the recovery rate by approximately 20.3%.

[0072] In summary, the palladium-loaded magnetic silica nanofluid synthesized via Pseudomonas aeruginosa fermentation supernatant provided in this application embodiment can be applied to enhance oil recovery, is environmentally friendly, and has a significant oil displacement effect.

[0073] This invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims.

Claims

1. A palladium-loaded magnetic silica nanofluid, characterized in that: a magnetic Fe3O4 nano precursor is prepared by a double microemulsion method; TEOS hydrolysis is used as a shell material; palladium is synthesized on the surface of the magnetic silica nanomaterial by using a Pseudomonas aeruginosa fermentation liquor; specifically: a magnetic Fe3O4 nano precursor is prepared by a double microemulsion method, 28 g of n-hexanol, 20 g of n-hexane, and 7 g of Triton X-100 are added to a 300-ml conical flask, the microemulsion is formed by stirring at 40°C for 10 min, 0.2 g of FeSO4·7H2O and 0.2 g of FeCl3·6H2O are added, and the mixture is fully dissolved by slow stirring, 2 ml of methylamine is added to keep the reaction for 5 min, then concentrated NH3·H2O is added dropwise until the color turns black, and the mixture is kept under constant stirring to obtain the magnetic Fe3O4 nano precursor; TEOS hydrolysis is used as a shell material: 5 ml of n-hexane, 0.2 ml of TEOS, and 2 ml of pure water and 3 ml of ethanol are added to a 50-ml beaker, the mixture is stirred uniformly and then added to the reverse microemulsion, since TEOS and water have poor mutual solubility, but ethanol can be well miscible with both, the reaction of the two is avoided, TEOS molecules diffuse from the hydrophobic phase to the hydrophilic phase, hydrolysis and condensation occur around the Fe3O4 precursor, ethanol is added to replace the non-bridging hydroxyl groups on the surface of the Fe3O4, reduce the attraction between particles, and reduce the agglomeration ability of particles; the interfacial tension of water is reduced, the SiO2 coating layer is better formed, and the stability of the particles is improved; the mixture is continuously heated and stirred at 50°C for 1 h to further promote the condensation reaction of TEOS; the upper liquid is discarded after centrifugation at 5°C and 8000 rpm, and the precipitate is collected; the precipitate is washed with ethanol and pure water five times, and the precipitate is repeatedly collected by centrifugation; the magnetic nanofluid is made to a volume of 150 ml; palladium is synthesized on the surface of the magnetic silica nanomaterial by using a Pseudomonas aeruginosa fermentation liquor: 0.02 g of PdCl2 and 20 ml of Pseudomonas aeruginosa fermentation supernatant are added to another conical flask, the volume is made to 100 ml with pure water, and the mixture is stirred magnetically at 70°C for 5 h; the nanometer palladium fluid is added dropwise to the magnetic nanofluid, the mixture is heated and stirred at 70°C for 3 h, the nanometer palladium modified by the microbial metabolic supernatant is fully loaded on the surface of Fe3O4@SiO2, and the volume is made to 200 ml with pure water, and finally the Pseudomonas aeruginosa fermentation supernatant is used to synthesize the palladium-loaded (Fe3O4@SiO2-Pd) magnetic fluid.

2. A method of preparing a palladium-loaded magnetic silica nanofluid as claimed in claim 1, characterized in that, including: Step 1, Pseudomonas aeruginosa is cultured and fermented, and the metabolites are purified, wherein the metabolites produce glycolipids and amino acid active ingredients: Step 1.1, a fermentation medium is prepared, wherein the medium includes: carbon sources are glucose and corn syrup dry powder; nitrogen sources are NaNO3 and CaMg(NO3)4; phosphorus sources are K2HPO4; corn oil; Trace elements are a mixture of ZnSO4·7H2O, CuSO4·5H2O, Ni(NO3)2·6H2O, MnSO4·4H2O and FeSO4·7H2O; The culture medium is sterilized in a high-pressure steam boiler at 121℃ for 20 minutes, and after natural cooling, the medium is taken out and inoculated on a clean bench; Step 1.2, obtaining microbial fermentation supernatant: The refrigerated Pseudomonas aeruginosa is taken out, thawed and activated at room temperature for 15 minutes, inoculated with 1ml of bacterial solution in the culture medium, covered with a sealing film, and placed in a constant temperature incubator at 37℃ and 180rpm for 72 hours of mixed shaking. The fermentation broth is ultrasonically broken by an ultrasonic cell disruptor for 10 minutes, with 6 seconds of ultrasonic treatment and 4 seconds of interval each time. The fermentation broth is placed in a 50ml centrifuge tube, and the centrifuge parameters are adjusted to 4℃, 8000rpm and centrifuged for 15 minutes. The precipitate is removed to obtain the supernatant. The supernatant is heated to 260℃ by a distillation device to obtain a distillate. The distillate is filtered by a vacuum pump, filter paper and a suction filter bottle combination device to obtain the purified Pseudomonas aeruginosa fermentation supernatant. Step 2, the magnetic Fe3O4 nano precursor is prepared by a double microemulsion method, including: In a container, n-hexanol, n-hexane and Triton X-100 are added and stirred at 40℃ for 10 minutes to form a microemulsion. FeSO4·7H2O and FeCl3·6H2O are added and stirred to dissolve completely. Methylamine is added and the reaction is maintained for 5 minutes. Then, concentrated NH3·H2O is added dropwise until the color turns black, and the stirring is maintained. Step 3, n-hexane, TEOS, pure water and ethanol are stirred uniformly and then added to the reverse microemulsion. The mixture is heated and stirred at 50℃ for 1 hour to promote the condensation reaction of TEOS. The mixture is centrifuged at 5℃ and 8000rpm, and the supernatant is discarded. The precipitate is collected and washed with ethanol and pure water to obtain the magnetic nanofluid. Step 4, PdCl2 and the Pseudomonas aeruginosa fermentation supernatant are added to a container and stirred magnetically at 70℃ for 5 hours to obtain a nanometer palladium fluid. Step 5, the nanometer palladium fluid is added dropwise to the magnetic nanofluid, and the mixture is heated and stirred at 70℃ for 3 hours to allow the nanometer palladium modified by the microbial metabolic supernatant to be fully loaded on the surface of Fe3O4@SiO2.

3. The method for preparing palladium-supported magnetic silica nanofluid according to claim 2, characterized in that, Step 1 includes the step of detecting the components of the Pseudomonas aeruginosa fermentation supernatant.

4. The method for preparing palladium-supported magnetic silica nanofluid according to claim 2, characterized in that, In step 3, the magnetic nanofluid is obtained by ultrasonic dispersion of the nanoparticles, with ultrasonic parameters set at 20s each time, 2s interval, and a total of 30 times.

5. The method of claim 2, wherein the palladium-loaded magnetic silica nanofluid is prepared by the steps of: (a) mixing palladium nanoparticles and a magnetic silica nanofluid; (b) adding a reducing agent to the mixture of step (a); and (c) washing and drying the mixture of step (b). Step 4 includes the step of detecting the surface plasmon resonance band (SPR) of the nanometer palladium by UV-Vis, which is used to confirm the synthesis of the nanoparticles.

6. The use of the palladium-loaded magnetic silica nanofluid according to any one of claims 1 or 2 in enhancing the recovery of crude oil.

7. An oil displacement agent, characterized by, The oil displacement agent comprises the palladium-loaded magnetic silica nanofluid according to any one of claims 2-6.

8. The oil displacement agent according to claim 7, characterized in that, In the palladium-loaded magnetic silica nanofluid, the palladium loading is less than 10wt%.

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