A method for preparing modified activated carbon for oil and gas recovery

Abstract

The present invention belongs to the technical field of activated carbon preparation, and relates to a method for preparing modified activated carbon for oil and gas recovery, comprising the following steps: (1) activated carbon pretreatment; (2) activated carbon modification treatment; (3) high-temperature curing treatment; and (4) post-treatment. The present invention modifies the basic properties of coconut shell activated carbon by rationally controlling the reaction ratio of the modifier solution and the preparation process. The prepared activated carbon for oil and gas recovery has an increased adsorption specific surface area, significantly improved adsorption capacity, enhanced strength, and increased butane working capacity value, effectively improving the working efficiency and recovery effect of the oil and gas recovery system, reducing the oil and gas emission concentration, and being beneficial to environmental protection and resource recycling. At the same time, a balance is found between efficient oil and gas recovery and economic cost control, making the prepared activated carbon suitable for oil and gas recovery in skid-mounted gas stations, and providing a highly valuable solution for optimizing the oil and gas recovery system in skid-mounted gas stations.

Description

Technical Field

[0001] The invention belongs to the technical field of activated carbon preparation, and relates to a method for preparing modified activated carbon for oil and gas recovery. Background Art

[0002] With increasingly stringent environmental protection requirements, oil vapor recovery at skid-mounted gas stations has become a critical step in reducing volatile organic compound (VOC) emissions. Skid-mounted gas stations generate significant amounts of oil vapor during the storage and distribution of fuel products. Direct discharge of this oil vapor not only wastes resources, but also pollutes the environment and poses safety risks. Activated carbon adsorption is a commonly used oil vapor recovery technology, but conventional activated carbon, due to its adsorption capacity, strength, and butane working capacity, struggles to meet the efficient recovery requirements of the complex operating conditions of skid-mounted gas stations. Therefore, developing a process for preparing activated carbon with high adsorption performance, high strength, and a good butane working capacity is crucial. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing modified activated carbon for oil and gas recovery. The specific technical solution is as follows:

[0004] A method for preparing modified activated carbon for oil and gas recovery comprises the following steps:

[0005] (1) Activated carbon pretreatment: washing and drying the coconut shell activated carbon;

[0006] (2) Activated carbon modification: add the pretreated coconut shell activated carbon to the modifier solution, ultrasonically oscillate in an ultrasonic oscillator at room temperature for 2-4 hours, and then transfer the mixture to a rotary evaporator and dry it by rotary evaporation at 60-80 °C;

[0007] The modifier solution is an anhydrous ethanol solution of a silane coupling agent, a metal nitrate and an organic polymer dispersant;

[0008] The initial specific surface area of the coconut shell activated carbon is S, the initial strength of the coconut shell activated carbon is P, the ratio of the mass of the silane coupling agent to the mass of the coconut shell activated carbon is x, the ratio of the mass of the metal nitrate to the mass of the coconut shell activated carbon is y, and the ratio of the mass of the organic polymer dispersant to the mass of the coconut shell activated carbon is z; the relationship between S, P, x, y and z is as follows:

[0009] 2≤S·P·(x 1 / 2 +y 2 +z 2 )·10 -5 ≤6;

[0010] Where S is in square meters per gram, P is in Newton, x is in the range of 0.7 to 1.6, y is in the range of 0.4 to 0.9, and z is in the range of 0.18 to 0.45.

[0011] (3) High temperature curing treatment: Place the coconut shell activated carbon dried by rotary evaporation in a tubular furnace and heat it to 300-400°C at a heating rate of 5-10°C / min under nitrogen protection for 1-2 hours;

[0012] (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment is washed with deionized water and dried.

[0013] The present invention removes surface impurities by cleaning, and the activated carbon reaches a stable initial state after drying; through oscillation treatment in an ultrasonic oscillator, the uniform distribution of the activator is promoted, so that the activated carbon is fully in contact with and reacts with the modifier, the activation time is reduced, and the micropores are more uniform; rotary evaporation drying is performed to make the modifier evenly adhere to the surface of the activated carbon; high-temperature curing treatment causes the modifier to chemically bond and polymerize with the surface of the activated carbon at high temperature, regulates the pore structure and strength, significantly increases the specific surface area of the activated carbon, and makes the micropore structure more developed, greatly improves the adsorption capacity of hydrocarbon substances in oil and gas, enhances the structural stability and adsorption performance of the activated carbon, improves the overall oil and gas recovery efficiency, and reduces emissions; high-temperature curing treatment forms a more stable carbon skeleton structure inside the activated carbon, which can withstand higher airflow impact and mechanical stress in the oil and gas recovery system, is not easy to break, reduces the problems of decreased adsorption efficiency and equipment blockage caused by activated carbon pulverization, and effectively extends the service life; after the high-temperature curing treatment, the unreacted modifier is removed by cleaning and dried to obtain the final modified activated carbon product.

[0014] The present invention determines the dosage range of the silane coupling agent, metal nitrate, and organic polymer dispersant based on the initial specific surface area S and initial strength P of the activated carbon, thereby rationally controlling the reaction ratio of the system. Precisely controlling the dosage of the silane coupling agent allows for more effective chemical bonding on the activated carbon surface, optimizing its microstructure and significantly enhancing its adsorption efficiency for oil and gas molecules. The rational addition of the metal nitrate helps form specific active sites within the activated carbon, further increasing its adsorption capacity and selectivity, enabling the activated carbon to more efficiently capture oil and gas molecules in complex oil and gas environments. Appropriate use of the organic polymer dispersant not only ensures uniform dispersion of the various reagents in the system and prevents agglomeration, but also modifies the activated carbon's pore structure, enhancing its mass transfer performance and thus improving its overall adsorption kinetics.

[0015] The present invention effectively improves the adsorption capacity, strength and butane working capacity of activated carbon in the oil and gas recovery system, while avoiding the cost increase caused by excessive use of reagents and the problem of failure to achieve the expected performance improvement due to insufficient dosage, thereby finding an ideal balance between efficient oil and gas recovery and economic cost control.

[0016] Furthermore, the coconut shell activated carbon has an initial specific surface area of not less than 1000 square meters per gram, and an initial strength of not less than 200 Newtons.

[0017] Furthermore, in step (1), the coconut shell activated carbon is washed with deionized water for 3-5 times and then dried at 100-120° C. for 12-24 hours.

[0018] Furthermore, in step (2), the ultrasonic frequency is 30-50 kHz.

[0019] Furthermore, in step (4), the coconut shell activated carbon after high temperature curing treatment is washed with deionized water for 2-3 times and dried at 150-200° C. for 8-12 hours.

[0020] Furthermore, the silane coupling agent is one or more of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, and γ-aminopropyltriethoxysilane, preferably γ-aminopropyltriethoxysilane.

[0021] Furthermore, the metal nitrate is one or more of ferric nitrate, copper nitrate, and sodium nitrate, preferably copper nitrate.

[0022] Furthermore, the organic polymer dispersant is one or more of polyvinyl pyrrolidone, polymethyl methacrylate, and polyvinyl alcohol, preferably polyvinyl pyrrolidone.

[0023] The beneficial effects of the present invention are:

[0024] The present invention modifies the basic properties of coconut shell activated carbon through reasonable control of the reaction ratio of the modifier solution and the preparation process. The adsorption specific surface area of the prepared activated carbon for oil and gas recovery is improved, and the specific surface area can be increased to 2000-2500 square meters / gram. It has stronger adsorption affinity for various hydrocarbon substances in the oil and gas of skid-mounted gas stations, the oil and gas adsorption efficiency can be increased by 30%-50%, and the adsorption capacity is significantly improved; the strength is enhanced, and the compressive strength can reach 300-400 Newtons; the butane working capacity value is increased, and the butane working capacity value can reach 12-15 grams / 100 milliliters, and the adsorption capacity for major oil and gas components such as butane is increased, thereby improving the working efficiency and recovery effect of the oil and gas recovery system, reducing the oil and gas emission concentration, and being beneficial to environmental protection and resource recycling; at the same time, a balance is found between efficient oil and gas recovery and economic cost control, so that the prepared activated carbon is suitable for oil and gas recovery in skid-mounted gas stations, providing a very valuable solution for the optimization of the oil and gas recovery system of skid-mounted gas stations. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] Example 1:

[0027] A method for preparing modified activated carbon for oil and gas recovery comprises the following steps:

[0028] (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1050 m2 / g and an initial strength of 210 N was selected, washed three times with deionized water, and dried at 100 °C for 24 h;

[0029] (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 2 h in an ultrasonic oscillator with an ultrasonic frequency of 30 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 60 °C.

[0030] In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 1.5 times the mass of coconut shell activated carbon; the mass of copper nitrate is 0.8 times the mass of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.4 times the mass of coconut shell activated carbon; and the mass of solvent anhydrous ethanol is 10 times the mass of coconut shell activated carbon;

[0031] (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 300 °C at a heating rate of 5 °C / min under nitrogen protection for 2 hours;

[0032] (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed twice with deionized water and dried at 150 °C for 12 hours to obtain the modified activated carbon product.

[0033] After testing, the modified activated carbon has a specific surface area of 2320 square meters / gram, a compressive strength of 365 Newtons, and a butane working capacity of 14.2 grams / 100 milliliters. The indicators before and after treatment are shown in Table 1:

[0034] Table 1 Various indicators before and after treatment

[0035]

[0036] Example 2:

[0037] A method for preparing modified activated carbon for oil and gas recovery comprises the following steps:

[0038] (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1100 m2 / g and an initial strength of 220 N was selected, washed with deionized water four times, and dried at 110 °C for 18 h;

[0039] (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 3 h in an ultrasonic oscillator with an ultrasonic frequency of 40 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 70 °C.

[0040] In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 1.2 times the mass of coconut shell activated carbon; the mass of copper nitrate is 0.64 times the mass of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.24 times the mass of coconut shell activated carbon; and the mass of solvent anhydrous ethanol is 8 times the mass of coconut shell activated carbon;

[0041] (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 350 °C at a heating rate of 8 °C / min under nitrogen protection for 1.5 hours;

[0042] (4) Post-treatment: The coconut shell activated carbon after high-temperature curing was washed with deionized water three times and dried at 180 °C for 10 hours to obtain the modified activated carbon product.

[0043] After testing, the modified activated carbon has a specific surface area of 2300 square meters / gram, a compressive strength of 350 Newtons, and a butane working capacity of 13.5 grams / 100 milliliters. The indicators before and after treatment are shown in Table 2:

[0044] Table 2 Various indicators before and after treatment

[0045]

[0046] Example 3:

[0047] A method for preparing modified activated carbon for oil and gas recovery comprises the following steps:

[0048] (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1150 m2 / g and an initial strength of 230 N was selected, washed with deionized water five times, and dried at 120 °C for 12 h;

[0049] (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 4 h in an ultrasonic oscillator with an ultrasonic frequency of 50 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 80 °C.

[0050] In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 0.8 times the mass of coconut shell activated carbon; the mass of copper nitrate is 0.45 times the mass of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.2 times the mass of coconut shell activated carbon; and the mass of solvent anhydrous ethanol is 6 times the mass of coconut shell activated carbon;

[0051] (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 400 °C at a heating rate of 10 °C / min under nitrogen protection for 1.0 h.

[0052] (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed twice with deionized water and dried at 200 °C for 8 hours to obtain the modified activated carbon product.

[0053] After testing, the modified activated carbon has a specific surface area of 2280 m2 / g, a compressive strength of 340 Newtons, and a butane working capacity of 12.8 g / 100 ml. The indicators before and after treatment are shown in Table 3:

[0054] Table 3 Various indicators before and after treatment

[0055]

[0056] Comparative Example 1:

[0057] A method for preparing modified activated carbon for oil and gas recovery comprises the following steps:

[0058] (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1150 m2 / g and an initial strength of 230 N was selected, washed with deionized water five times, and dried at 120 °C for 12 h;

[0059] (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 4 h in an ultrasonic oscillator with an ultrasonic frequency of 50 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 80 °C.

[0060] In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 1.9 times the mass of coconut shell activated carbon; the mass of copper nitrate is 1.2 times the mass of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.54 times the mass of coconut shell activated carbon; and the mass of solvent anhydrous ethanol is 10 times the mass of coconut shell activated carbon;

[0061] (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 400 °C at a heating rate of 10 °C / min under nitrogen protection for 1.0 h.

[0062] (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed twice with deionized water and dried at 200 °C for 8 hours to obtain the modified activated carbon product.

[0063] After testing, the modified activated carbon has a specific surface area of 1953 square meters / gram, a compressive strength of 278 Newtons, and a butane working capacity of 10.3 grams / 100 milliliters. The indicators before and after treatment are shown in Table 4:

[0064] Table 4 Various indicators before and after treatment

[0065]

[0066] The activated carbon performance testing methods in the above examples and comparative examples are as follows:

[0067] 1. Strength: Use the compression test method. (1) Select a representative sample of activated carbon particles and weigh a certain mass of the sample using a balance of appropriate precision. (2) Place the sample in the center of the test platform of the compression instrument. Start the compression instrument and apply pressure to the activated carbon particles until the particles break. Record the pressure value displayed by the compression instrument at this time. This value is the crushing strength of the activated carbon particles.

[0068] 2. Butane working capacity: Tested in accordance with the standard GB / T20449-2006 activated carbon butane working capacity test method.

[0069] 3. Specific surface area: Refer to the method of measuring the specific surface area of solid substances based on the BET principle of gas adsorption in GB / T19587-2004.

[0070] From the comparative data of the embodiments and comparative examples in Tables 1-4 above, it can be seen that the modification method of the present invention can effectively improve the specific surface area, strength and butane working capacity value of coconut shell activated carbon. Therefore, the activated carbon prepared by the present invention is loaded into the adsorption tower of the oil and gas recovery system of the skid-mounted gas station. When the oil and gas pass through the adsorption tower, the oil and gas molecules are adsorbed in the micropores of the activated carbon, which can effectively separate the oil and gas from the air, significantly improve the oil and gas recovery efficiency, and reduce the pollution of oil and gas emissions to the environment. It has excellent application effects. After the activated carbon is saturated with adsorption, the modified activated carbon can be regenerated by decompression desorption or purge desorption and recycled.

[0071] At the same time, the present invention finds a balance between efficient oil and gas recovery and economic cost control, making the prepared activated carbon suitable for oil and gas recovery in skid-mounted gas stations, and will provide a valuable solution for the optimization of the oil and gas recovery system of skid-mounted gas stations.

[0072] In addition, reasonable filling methods and system design, as well as efficient regeneration processes, can further fully utilize the adsorption properties of activated carbon, ensure that activated carbon can be used for oil and gas recovery in a long-term and stable manner, and improve the efficiency and economy of the entire oil and gas recovery system.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing modified activated carbon for oil and gas recovery, characterized in that: The steps include: (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1050 m2 / g and an initial strength of 210 N was selected, washed three times with deionized water, and dried at 100 °C for 24 h; (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 2 h in an ultrasonic oscillator with an ultrasonic frequency of 30 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 60 °C. In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 1.5 times the mass of coconut shell activated carbon; The mass of copper nitrate is 0.8 times that of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.4 times that of coconut shell activated carbon; the mass of solvent anhydrous ethanol is 10 times that of coconut shell activated carbon; (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 300 °C at a heating rate of 5 °C / min under nitrogen protection for 2 hours; (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed twice with deionized water and dried at 150 °C for 12 hours to obtain the modified activated carbon product.

2. A method for preparing modified activated carbon for oil and gas recovery, characterized in that: The steps include: (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1100 m2 / g and an initial strength of 220 N was selected, washed with deionized water four times, and dried at 110 °C for 18 h; (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 3 h in an ultrasonic oscillator with an ultrasonic frequency of 40 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 70 °C. In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 1.2 times the mass of coconut shell activated carbon; The mass of copper nitrate is 0.64 times that of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.24 times that of coconut shell activated carbon; the mass of solvent anhydrous ethanol is 8 times that of coconut shell activated carbon; (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 350 °C at a heating rate of 8 °C / min under nitrogen protection for 1.5 hours; (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed with deionized water three times and dried at 180 °C for 10 hours to obtain the modified activated carbon product.

3. A method for preparing modified activated carbon for oil and gas recovery, characterized in that: The steps include: (1) Activated carbon pretreatment: Coconut shell activated carbon with a specific surface area of 1150 m2 / g and an initial strength of 230 N was selected, washed with deionized water five times, and dried at 120 °C for 12 h; (2) Activated carbon modification: The pretreated coconut shell activated carbon was added to the modifier solution and ultrasonically oscillated at room temperature for 4 h in an ultrasonic oscillator with an ultrasonic frequency of 50 kHz. The mixture was then transferred to a rotary evaporator and dried by rotary evaporation at 80 °C. In the modifier solution, the mass of γ-aminopropyltriethoxysilane is 0.8 times the mass of coconut shell activated carbon; the mass of copper nitrate is 0.45 times the mass of coconut shell activated carbon; the mass of polyvinyl pyrrolidone is 0.2 times the mass of coconut shell activated carbon; and the mass of solvent anhydrous ethanol is 6 times the mass of coconut shell activated carbon; (3) High temperature curing treatment: The coconut shell activated carbon dried by rotary evaporation was placed in a tubular furnace and heated to 400 °C at a heating rate of 10 °C / min under nitrogen protection for 1.0 h. (4) Post-treatment: The coconut shell activated carbon after high-temperature curing treatment was washed twice with deionized water and dried at 200 °C for 8 hours to obtain the modified activated carbon product.

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