Biomass carbon / metal oxide nanoparticles and preparation method thereof, and carbon-based nanomaterial emulsifier and application thereof

Abstract

The invention provides biomass carbon / metal oxide nanoparticles, a preparation method of the biomass carbon / metal oxide nanoparticles, a carbon-based nanomaterial emulsifier and application of the carbon-based nanomaterial emulsifier. The preparation method of the biomass carbon / metal oxide nanoparticles comprises the following steps: sequentially performing drying treatment, carbonization treatment and crushing treatment on biomass loaded with a metal oxide precursor; the biomass carbon / metal oxide nanoparticles have the advantages of high emulsifying property, low raw material cost, no need of surface modification, simple preparation process, high practicability and convenience in popularization and application; the carbon-based nano-material emulsifier containing biomass carbon / metal oxide nano-particles can enhance the emulsifying capacity of a nano-composite oil displacement system, realizes efficient oil washing and emulsification expansion sweep, solves the problem of poor emulsification oil displacement effect of the composite oil displacement system under an alkali-free condition, and has important significance on efficient development of medium and low permeability reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum development, specifically to the technical field of enhancing crude oil recovery, and in particular to biomass carbon / metal oxide nanoparticles and a preparation method thereof, a carbon-based nanomaterial emulsifier and an application thereof. Background Art

[0002] The crude oil recovery rate of most oil fields in my country after water injection development is generally no more than 40%, and there is still a problem that most of the crude oil is retained in the formation and has not been developed. In order to further improve the crude oil recovery rate and achieve increased and stable production of old oil fields, chemical flooding technology has been widely used in my country and has achieved good industrial application results. Nanocarbon materials improve the viscoelasticity and stability of the flooding system by adsorbing on the oil-water interface, and can also form a stable emulsion, which is conducive to improving the recovery rate of crude oil.

[0003] CN113248669B discloses a method for preparing an amphiphilic graphene-type oil-displacing material, which belongs to the field of oilfield chemical technology. The nanographene oxide is asymmetrically modified by an interfacial reaction method to prepare a Janus amphiphilic nanographene material; wherein the hydrophobic side modification is achieved by reacting a long-chain organic amine with an epoxy group on the surface of the graphene oxide, and the hydrophilic side modification is achieved by using a cerium salt as an initiator and a compound containing a polyoxyethylene chain segment as a monomer through a grafting reaction on the surface of the graphene oxide. This nanographene oil-displacing material has the advantages of low dispersion difficulty, good salt and temperature resistance, excellent long-term dispersion stability, small dosage, and good oil-displacing effect, and can be used as an oil-displacing agent for high-temperature and high-salt oil reservoirs.

[0004] CN112980415B discloses a multi-grafting site nano-carbon material and an active nano-carbon material and a preparation method thereof and an oil displacement system for ultra-low permeability oil reservoirs. Under the action of a catalyst, the multi-grafting site nano-carbon material is contacted with an activating agent for an activation reaction to obtain an active nano-carbon material. The surface-modified active nano-carbon is applied to an oil displacement system for ultra-low permeability oil reservoirs, so that the oil displacement system for ultra-low permeability oil reservoirs has a high interfacial activity and the oil-water interfacial tension is reduced by 10 - 2 mN / m order of magnitude, which can significantly improve the oil washing efficiency.

[0005] However, the carbon nanoparticles used in the above-mentioned prior art all involve surface modification and have complicated preparation processes. Therefore, it is necessary to develop biomass carbon / metal oxide nanoparticles and preparation methods thereof, carbon-based nanomaterial emulsifiers and applications thereof. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides biomass carbon / metal oxide nanoparticles and a preparation method thereof, a carbon-based nanomaterial emulsifier and an application thereof. The preparation method of the biomass carbon / metal oxide nanoparticles comprises: subjecting biomass loaded with a metal oxide precursor to drying treatment, carbonization treatment and pulverization treatment in sequence; the biomass carbon / metal oxide nanoparticles of the present invention have strong emulsification performance, low raw material cost, no need for surface modification, simple preparation process, strong practicality, and are easy to promote and use; the carbon-based nanomaterial emulsifier containing the biomass carbon / metal oxide nanoparticles can enhance the emulsification ability of a nano-composite oil displacement system, achieve efficient oil washing and emulsification expansion, solve the problem of poor emulsification oil displacement effect of a composite oil displacement system under alkali-free conditions, and is of great significance for the efficient development of medium and low permeability oil reservoirs.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] One of the purposes of the present invention is to provide a method for preparing biomass carbon / metal oxide nanoparticles, the preparation method comprising the following contents:

[0009] The biomass is immersed in a metal oxide precursor aqueous solution, and then taken out and sequentially dried, carbonized and crushed to obtain biomass carbon / metal oxide nanoparticles.

[0010] The preparation method of the present invention sequentially performs drying treatment, carbonization treatment and pulverization treatment on biomass loaded with metal oxide precursors to obtain biomass carbon / metal oxide nanoparticles; the prepared biomass carbon / metal oxide nanoparticles have strong emulsification properties, use biomass as a carbon-based source, have low raw material costs, and do not require surface modification, have a simple preparation process, are highly practical, and are easy to promote and use.

[0011] As a preferred technical solution of the present invention, the biomass includes any one of straw, fruit shell or bamboo, or a combination of at least two of them.

[0012] Preferably, the metal oxide precursor is a soluble metal salt.

[0013] Preferably, the metal ions of the soluble metal salt include Zn 2+ , Fe 3+ , Ca 2+ Mg 2+ 、Co 2+ 、Ni 2+ , Cu 2+ or Mn 2+ Any one or a combination of at least two of the following, wherein the anion of the soluble metal salt comprises Cl - Br - 、NO3- or CH3COO - Any one or a combination of at least two of the following.

[0014] Preferably, the concentration of the metal oxide precursor aqueous solution is 1-20wt%, for example 1wt%, 3wt%, 5wt%, 7wt%, 9wt%, 10wt%, 12wt%, 15wt%, 16wt%, 18wt% or 20wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0015] As a preferred technical solution of the present invention, before soaking, the biomass is washed;

[0016] Preferably, the washing comprises placing the biomass in ethanol and water in sequence for 2-5 times of washing respectively.

[0017] As a preferred technical solution of the present invention, the soaking time is 10-15h, for example 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h or 15h, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0018] Preferably, the temperature of the drying treatment is 80-120°C, for example 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0019] Preferably, the drying treatment time is 4-24h, for example 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0020] As a preferred technical solution of the present invention, the carbonization treatment is carried out in a muffle furnace.

[0021] Preferably, the carbonization treatment is carried out under a nitrogen protective atmosphere.

[0022] Preferably, the heating rate of the carbonization treatment is 5-20°C / min, for example, 5°C / min, 7°C / min, 9°C / min, 10°C / min, 11°C / min, 13°C / min, 15°C / min, 17°C / min, 18°C / min or 20°C / min, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0023] Preferably, the temperature of the carbonization treatment is 600-900°C, for example 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0024] Preferably, the temperature holding time of the carbonization treatment is 1-10h, for example 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] As a preferred technical solution of the present invention, the pulverization process is mechanical pulverization.

[0026] Preferably, the mechanical pulverization includes any one of ball milling, disc milling or gas milling.

[0027] As a preferred technical solution of the present invention, the preparation method comprises the following contents:

[0028] The biomass is sequentially placed in ethanol and water for 2-5 times of washing, and then placed in a metal oxide precursor aqueous solution with a concentration of 1-20wt% for immersion for 10-15h, and then taken out and placed in an oven at a temperature of 80-120°C for drying for 4-24h, and the dried product is placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, and the heating rate of the carbonization treatment is controlled to be 5-20°C / min, the temperature is 600-900°C, and the temperature holding time is 1-10h. After cooling to room temperature, the carbonized product is crushed to obtain biomass carbon / metal oxide nanoparticles;

[0029] The biomass includes any one of straw, fruit shell or bamboo or a combination of at least two of them; the metal oxide precursor is a soluble metal salt; the metal ions of the soluble metal salt include Zn 2+ , Fe 3+ , Ca 2+ Mg 2+ 、Co 2+ 、Ni 2+ , Cu 2+ or Mn 2+ Any one or a combination of at least two of the following, wherein the anion of the soluble metal salt comprises Cl - Br - 、NO3 - or CH3COO - Any one or a combination of at least two of the following: the pulverizing process is mechanical pulverizing; the mechanical pulverizing includes any one of ball milling, disc milling or gas milling.

[0030] The second object of the present invention is to provide a biomass carbon / metal oxide nanoparticle, which is prepared by the preparation method described in the first object.

[0031] Preferably, the mass ratio of biomass carbon to metal oxide in the biomass carbon / metal oxide nanoparticles is 1:(5-6), for example 1:5, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59 or 1:6, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0032] Preferably, the particle size of the biomass carbon / metal oxide nanoparticles is 0.05-5 μm, for example, 0.05 μm, 0.1 μm, 0.15 μm, 0.25 μm, 0.35 μm, 0.45 μm, 0.5 μm, 0.6 μm, 0.75 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0033] It is worth noting that the morphology of the biomass carbon / metal oxide nanoparticles of the present invention is irregular and approximately spherical; the particle size of the biomass carbon / metal oxide nanoparticles of the present invention can be controlled by the type, concentration, reaction ratio, etc. of the metal ions.

[0034] The biomass carbon / metal oxide nanoparticles of the present invention can be adsorbed on the oil-water interface through hydrogen bonds, π-π bonds and other interactions with crude oil, forming a three-dimensional barrier at the oil-water interface to hinder the aggregation of crude oil droplets, thereby stabilizing the emulsion, and the emulsification and viscosity-increasing effect is obvious, and has a relatively broad application prospect in improving crude oil recovery.

[0035] The third object of the present invention is to provide a carbon-based nanomaterial emulsifier. The dispersion obtained by preparing the biomass carbon / metal oxide nanoparticles described in the second object with water is the carbon-based nanomaterial emulsifier.

[0036] Preferably, the mass percentage of biomass carbon / metal oxide nanoparticles in the carbon-based nanomaterial emulsifier is 0.001-0.05wt%, for example, 0.001wt%, 0.003wt%, 0.005wt%, 0.007wt%, 0.009wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt% or 0.05wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0037] The carbon-based nanomaterial emulsifier of the present invention can greatly improve the stability and viscosity of the emulsion by introducing biomass carbon / metal oxide nanoparticles.

[0038] The fourth object of the present invention is to provide an application of a carbon-based nanomaterial emulsifier, and to apply the carbon-based nanomaterial emulsifier described in the third object to an oil displacement system for medium and low permeability oil reservoirs.

[0039] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0040] (1) The method for preparing biomass carbon / metal oxide nanoparticles of the present invention uses biomass as a carbon-based source, has a low raw material cost, and does not require surface modification. The preparation process is simple, has strong practicality, and is easy to promote and use;

[0041] (2) The biomass carbon / metal oxide nanoparticles of the present invention can interact with crude oil through hydrogen bonds, π-π bonds, etc. and adsorb on the oil-water interface, forming a three-dimensional barrier at the oil-water interface to hinder the aggregation of crude oil droplets, thereby stabilizing the emulsion, and the emulsification and viscosity-increasing effect is obvious, which has a relatively broad application prospect in improving crude oil recovery;

[0042] (3) The carbon-based nanomaterial emulsifier of the present invention can greatly improve the stability and viscosity of the emulsion by introducing biomass carbon / metal oxide nanoparticles, and can enhance the emulsification ability of the nano-composite oil recovery system, achieve efficient oil washing and emulsification expansion, and solve the problem of poor emulsification oil recovery effect of the composite oil recovery system under alkali-free conditions, which is of great significance for the efficient development of medium and low permeability oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a scanning electron microscope image of the biomass carbon / zinc oxide nanoparticles obtained in Example 1;

[0044] Figure 2 is the EDS spectrum of the biomass carbon / zinc oxide nanoparticles obtained in Example 1;

[0045] Figure 3 is a scanning electron microscope image of the biomass carbon / copper oxide nanoparticles obtained in Example 2;

[0046] Figure 4 is the EDS spectrum of the biomass carbon / copper oxide nanoparticles obtained in Example 2;

[0047] Figure 5 is a scanning electron microscope image of the biomass carbon / iron oxide nanoparticles obtained in Example 3;

[0048] Figure 6 This is the EDS energy spectrum of the biomass carbon / iron oxide nanoparticles obtained in Example 3. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0050] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0051] Example 1

[0052] This embodiment provides a method for preparing biomass carbon / zinc oxide nanoparticles, the preparation method comprising the following contents:

[0053] Wheat straw is selected as biomass, 5 g of biomass is sequentially placed in 100 mL of ethanol and 100 mL of deionized water for washing twice, then placed in 100 mL of 1 wt% zinc acetate aqueous solution for immersion for 12 hours, then taken out and placed in an oven at a temperature of 80°C for drying for 5 hours, the dried product is placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, the heating rate of the carbonization treatment is controlled to be 5°C / min, the temperature is 600°C, the temperature holding time is 2 hours, and after cooling to room temperature, the carbonized product is pulverized, including placing the carbonized product in a planetary ball mill and ball milling at a speed of 400 rpm for 12 hours to obtain biomass carbon / zinc oxide nanoparticles.

[0054] The mass ratio of biomass carbon to zinc oxide in the biomass carbon / zinc oxide nanoparticles obtained in this embodiment is 1:(5-6), and the particle size of the biomass carbon / zinc oxide nanoparticles is 0.5-2 μm; the scanning electron microscope image of the biomass carbon / zinc oxide nanoparticles obtained in this embodiment is as follows Figure 1 As shown, it can be seen that the nanoparticles are irregular and approximately spherical; the EDS spectrum of the biomass carbon / zinc oxide nanoparticles obtained in this example is as follows Figure 2 As shown, it can be seen that the elements of the nanoparticles are mainly C, O, and Zn, which further proves that the nanomaterial is biomass carbon / zinc oxide nanoparticles.

[0055] Example 2

[0056] This embodiment provides a method for preparing biomass carbon / copper oxide nanoparticles, the preparation method comprising the following contents:

[0057] Fruit shells were selected as biomass, 5 g of biomass was sequentially placed in 100 mL of ethanol and 100 mL of deionized water for washing twice, then placed in 100 mL of a 15 wt% copper nitrate aqueous solution for immersion for 12 h, then taken out and placed in an oven at a temperature of 90 ° C for drying for 6 h, the dried product was placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, the heating rate of the carbonization treatment was controlled to be 5 ° C / min, the temperature was 800 ° C, the temperature was kept for 4 h, and after cooling to room temperature, the carbonized product was pulverized, including placing the carbonized product in a disc mill and grinding it at a speed of 600 rpm for 1 h to obtain biomass carbon / copper oxide nanoparticles.

[0058] The mass ratio of biomass carbon to copper oxide in the biomass carbon / copper oxide nanoparticles obtained in this embodiment is 1:(5-6), and the particle size of the biomass carbon / copper oxide nanoparticles is 0.5-2 μm; the scanning electron microscope image of the biomass carbon / copper oxide nanoparticles obtained in this embodiment is as follows Figure 3 As shown, it can be seen that the nanoparticles are irregular and approximately spherical; the EDS spectrum of the biomass carbon / copper oxide nanoparticles obtained in this example is as follows Figure 4 As shown, it can be seen that the elements of the nanoparticles are mainly C, O, and Cu, which further proves that the nanomaterial is biomass carbon / copper oxide nanoparticles.

[0059] Example 3

[0060] This embodiment provides a method for preparing biomass carbon / iron oxide nanoparticles, the preparation method comprising the following contents:

[0061] Bamboo was selected as biomass, 5 g of biomass was sequentially placed in 100 mL of ethanol and 100 mL of deionized water for washing twice, then placed in 100 mL of 20 wt% ferric chloride aqueous solution for immersion for 12 h, then taken out and placed in an oven at a temperature of 80 ° C for drying for 5 h, the dried product was placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, the heating rate of the carbonization treatment was controlled to be 5 ° C / min, the temperature was 700 ° C, the temperature was kept for 2 h, and after cooling to room temperature, the carbonized product was pulverized, including placing the carbonized product in a planetary ball mill and ball milling at a speed of 400 rpm for 12 h to obtain biomass carbon / iron oxide nanoparticles.

[0062] The mass ratio of biomass carbon to iron oxide in the biomass carbon / iron oxide nanoparticles obtained in this embodiment is 1:(5-6), and the particle size of the biomass carbon / iron oxide nanoparticles is 0.2-2 μm; the scanning electron microscope image of the biomass carbon / iron oxide nanoparticles obtained in this embodiment is as follows: Figure 5As shown, it can be seen that the nanoparticles are irregular and approximately spherical; the EDS spectrum of the biomass carbon / iron oxide nanoparticles obtained in this example is as follows Figure 6 As shown, it can be seen that the elements of the nanoparticles are mainly C, O, and Fe, which further proves that the nanomaterial is biomass carbon / iron oxide nanoparticles.

[0063] Comparative Example 1

[0064] This comparative example provides a method for preparing biomass carbon nanoparticles, which comprises the following contents:

[0065] Wheat straw was selected as biomass, and 5 g of biomass was placed in 100 mL of ethanol and 100 mL of deionized water for washing twice respectively, then taken out and placed in an oven at 80 ° C for drying for 5 hours, and the dried product was placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, and the heating rate of the carbonization treatment was controlled to be 5 ° C / min, the temperature was 600 ° C, and the temperature holding time was 2 hours. After cooling to room temperature, the carbonized product was pulverized, including placing the carbonized product in a planetary ball mill and ball milling at a speed of 400 rpm for 12 hours to obtain biomass carbon nanoparticles.

[0066] That is to say, compared with Example 1, the difference of this comparative example is that the metal oxide precursor aqueous solution is omitted, and the obtained nanoparticles do not contain metal oxides.

[0067] Characterization Example 1

[0068] The dispersion obtained by preparing the biomass carbon / zinc oxide nanoparticles prepared in Example 1 with formation water is a carbon-based nanomaterial emulsifier, and the mass percentage of biomass carbon / metal oxide nanoparticles in the carbon-based nanomaterial emulsifier is 0.008wt%. The viscosity and stability of the emulsion formed by the obtained carbon-based nanomaterial emulsifier and crude oil are tested.

[0069] The crude oil used in this characterization example is Xinjiang oil and water, and the test temperature is 78°C. The carbon-based nanomaterial emulsifier and crude oil are placed in a beaker according to the water-oil volume ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1, respectively, and kept at a constant temperature of 78°C for 1h, and then dispersed with an IKA homogenizer for 1min, and the emulsification is observed with the naked eye to determine whether it is phase separated. The relevant results are shown in Table 1. It can be seen that when the water-oil volume ratio is 6:4 or below, the crude oil can be emulsified to form a stable oil-in-water emulsion, and the maximum water content can reach 60%.

[0070] Characterization Example 2

[0071] The dispersion obtained by preparing the biomass carbon / copper oxide nanoparticles prepared in Example 2 with formation water is a carbon-based nanomaterial emulsifier, and the mass percentage of biomass carbon / metal oxide nanoparticles in the carbon-based nanomaterial emulsifier is 0.005wt%. The viscosity and stability of the emulsion formed by the obtained carbon-based nanomaterial emulsifier and crude oil are tested.

[0072] The crude oil used in this characterization example is Jilin oil water, the test temperature is 66°C, the carbon-based nanomaterial emulsifier and crude oil are placed in a beaker according to the water-oil volume ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, and kept at 66°C for 1h, and then dispersed with an IKA homogenizer for 1min, and the emulsification is observed with the naked eye to determine whether it is phase separated. The relevant results are shown in Table 1. It can be seen that when the water-oil volume ratio is 6:4 or below, the crude oil can be emulsified to form a stable oil-in-water emulsion, and the maximum water content can reach 60%.

[0073] Characterization Example 3

[0074] The dispersion obtained by preparing the biomass carbon / iron oxide nanoparticles prepared in Example 3 and formation water is a carbon-based nanomaterial emulsifier, in which the mass percentage of biomass carbon / metal oxide nanoparticles in the carbon-based nanomaterial emulsifier is 0.01wt%. The viscosity and stability of the emulsion formed by the obtained carbon-based nanomaterial emulsifier and crude oil are tested.

[0075] The crude oil used in this characterization example is Changqing oil water, the test temperature is 88°C, the carbon-based nanomaterial emulsifier and crude oil are placed in a beaker according to the water-oil volume ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, and kept at 88°C for 1h, and then dispersed with an IKA homogenizer for 1min, and the emulsification is observed with the naked eye to determine whether it is phase separated. The relevant results are shown in Table 1. It can be seen that when the water-oil volume ratio is 7:3 or below, the crude oil can be emulsified to form a stable oil-in-water emulsion, and the maximum water content can reach 70%.

[0076] Comparative Characterization Example 1

[0077] The dispersion obtained by preparing the biomass carbon nanoparticles prepared in Comparative Example 1 with formation water is a carbon-based nanomaterial emulsifier, in which the mass percentage of the biomass carbon nanoparticles in the carbon-based nanomaterial emulsifier is 0.008wt%. The viscosity and stability of the emulsion formed by the obtained carbon-based nanomaterial emulsifier and crude oil are tested.

[0078] The crude oil used in this characterization example is Xinjiang oil water, the test temperature is 78 ° C, the carbon-based nanomaterial emulsifier and crude oil are placed in a beaker according to the water-oil volume ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, and kept at 78 ° C for 1 hour, and then dispersed with an IKA homogenizer for 1 minute, and the emulsification was observed with the naked eye to determine whether it was phase separated. The relevant results are shown in Table 1. It can be seen that the pure biomass carbon nanoparticles themselves have a weak emulsification ability and cannot form a stable emulsion at a higher water content ratio.

[0079] Table 1

[0080]

[0081]

[0082] In summary, the present invention provides biomass carbon / metal oxide nanoparticles and a preparation method thereof, a carbon-based nanomaterial emulsifier and an application thereof. The preparation method of the biomass carbon / metal oxide nanoparticles comprises: sequentially subjecting biomass loaded with a metal oxide precursor to drying, carbonization and pulverization. The biomass carbon / metal oxide nanoparticles of the present invention have strong emulsification properties, low raw material costs, no need for surface modification, simple preparation process, strong practicality, and are easy to promote and use. The carbon-based nanomaterial emulsifier containing the biomass carbon / metal oxide nanoparticles can enhance the emulsification ability of the nano-composite oil displacement system, achieve efficient oil washing and emulsification expansion, solve the problem of poor emulsification oil displacement effect of the composite oil displacement system under alkali-free conditions, and is of great significance for the efficient development of medium and low permeability oil reservoirs.

[0083] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0084] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0085] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0086] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing biomass carbon / metal oxide nanoparticles, characterized in that: The preparation method comprises the following contents: The biomass is immersed in a metal oxide precursor aqueous solution, and then taken out and sequentially dried, carbonized and crushed to obtain biomass carbon / metal oxide nanoparticles.

2. The preparation method according to claim 1, characterized in that: The biomass includes any one of straw, fruit shell or bamboo or a combination of at least two thereof; Preferably, the metal oxide precursor is a soluble metal salt; Preferably, the metal ions of the soluble metal salt include Zn 2+ , Fe 3+ , Ca 2+ Mg 2+ 、Co 2+ 、Ni 2+ , Cu 2+ or Mn 2+ Any one or a combination of at least two of the following, wherein the anion of the soluble metal salt comprises Cl - Br - 、NO3 - or CH3COO - Any one or a combination of at least two of the following: Preferably, the concentration of the metal oxide precursor aqueous solution is 1-20 wt %.

3. The preparation method according to claim 1 or 2, characterized in that: Prior to said soaking, washing said biomass; Preferably, the washing comprises placing the biomass in ethanol and water in sequence for 2-5 times of washing respectively.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The soaking time is 10-15h; Preferably, the drying process is carried out in an oven; Preferably, the temperature of the drying treatment is 80-120°C; Preferably, the drying process takes 4-24 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The carbonization treatment is carried out in a muffle furnace; Preferably, the carbonization treatment is carried out under a nitrogen protective atmosphere; Preferably, the heating rate of the carbonization treatment is 5-20°C / min; Preferably, the temperature of the carbonization treatment is 600-900°C; Preferably, the temperature holding time of the carbonization treatment is 1-10 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The pulverization process is mechanical pulverization; Preferably, the mechanical pulverization includes any one of ball milling, disc milling or gas milling.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following contents: The biomass is sequentially placed in ethanol and water for 2-5 times of washing, and then placed in a metal oxide precursor aqueous solution with a concentration of 1-20wt% for immersion for 10-15h, and then taken out and placed in an oven at a temperature of 80-120°C for drying for 4-24h, and the dried product is placed in a muffle furnace for carbonization treatment under a nitrogen protective atmosphere, and the heating rate of the carbonization treatment is controlled to be 5-20°C / min, the temperature is 600-900°C, and the temperature holding time is 1-10h. After cooling to room temperature, the carbonized product is crushed to obtain biomass carbon / metal oxide nanoparticles; The biomass includes any one of straw, fruit shell or bamboo or a combination of at least two of them; the metal oxide precursor is a soluble metal salt; the metal ions of the soluble metal salt include Zn 2+ , Fe 3+ , Ca 2+ Mg 2+ 、Co 2+ 、Ni 2+ , Cu 2+ or Mn 2+ Any one or a combination of at least two of the following, wherein the anion of the soluble metal salt comprises Cl - Br - 、NO3 - or CH3COO - Any one or a combination of at least two of the following: the pulverizing process is mechanical pulverizing; the mechanical pulverizing includes any one of ball milling, disc milling or gas milling.

8. A biomass carbon / metal oxide nanoparticle, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7; Preferably, the mass ratio of biomass carbon to metal oxide in the biomass carbon / metal oxide nanoparticles is 1:(5-6); Preferably, the particle size of the biomass carbon / metal oxide nanoparticles is 0.05-5 μm.

9. A carbon-based nanomaterial emulsifier, characterized in that: The dispersion obtained by preparing the biomass carbon / metal oxide nanoparticles according to claim 8 with water is the carbon-based nanomaterial emulsifier; Preferably, the mass percentage of biomass carbon / metal oxide nanoparticles in the carbon-based nanomaterial emulsifier is 0.001-0.05wt%.

10. An application of a carbon-based nanomaterial emulsifier, characterized in that: The carbon-based nanomaterial emulsifier described in claim 9 is applied to an oil displacement system for medium and low permeability oil reservoirs.

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