A marine biomass desulfurization catalyst and a preparation method thereof

Abstract

The application discloses a marine biomass desulfurization catalyst and a preparation method thereof, and belongs to the field of catalysis technology. The catalyst is prepared by taking marine biomass as a carbon source carrier, slowly adding a metal aqueous solution into the carbon source carrier to prepare a uniformly dispersed carbon metal solution, mixing the uniformly dispersed carbon metal solution with sodium hydroxide to perform a hydrothermal synthesis reaction to obtain a catalyst precursor, performing centrifugal washing on the catalyst precursor, and then performing heat treatment on the obtained filter cake to prepare the marine biomass desulfurization catalyst. The catalyst prepared by the application mainly takes marine biomass as a porous carbon carrier, is cheap and easy to obtain, and is green and environment-friendly, as compared with traditional porous carbon materials such as polyacrylonitrile and polyethylene glycol. Meanwhile, the desulfurization catalyst is prepared into a nanowire morphology by a hydrothermal synthesis method, has small metal aggregation degree, more metal active centers per unit area, large metal dispersity, and good adsorption and desulfurization performance.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a marine biomass desulfurization catalyst. Background Technology

[0002] Automobile exhaust contains large amounts of sulfur oxides, the emission of which leads to ozone layer depletion, acid rain formation, reduced soil fertility, and harm to human health. Therefore, desulfurization from petroleum fuels and their intermediate products is crucial for environmental protection and human safety. Adsorption desulfurization, due to its mild reaction conditions, low octane number loss, and ability to achieve deep desulfurization, is currently a hot research topic. The core of adsorption desulfurization lies in developing high-performance adsorbents. Currently, adsorbents mainly include metal oxides, zeolites, metal-organic frameworks, and carbon materials, among which carbon materials are widely used as adsorbents due to their low cost, high specific surface area, and adjustable porosity.

[0003] Currently, carbon materials loaded with transition metals have been used for adsorption desulfurization. Besides possessing a large surface area, these materials can also desulfurize liquid fuels by forming metal-sulfur complexes. The adsorption of sulfur-containing compounds by carbon materials mainly depends on the distribution of their surface metal active sites and the number of oxygen-containing functional groups. Therefore, developing green, environmentally friendly, inexpensive, and readily available porous carbon materials is of great significance for preparing high-performance desulfurization adsorbents.

[0004] With the rise of the marine economy, seeking solutions from the ocean is one way to address the shortage of fossil resources. The ocean, with its vast area and abundant biological resources, is an ideal environment for developing biomass energy. Biomass materials have advantages such as abundant sources and renewability, and have significant application prospects in the field of sustainable energy materials development. Marine biomass, including seaweed, kelp, and algae, are themselves natural porous carbon materials, inexpensive, readily available, and abundant in species, and can replace traditional porous carbon materials such as polyacrylonitrile and polyethylene glycol. Using these biomass materials as porous carbon supports for desulfurization catalysts, the research and development of high-performance desulfurization catalysts has significant ecological, economic, and social benefits, and currently, marine biomass such as seaweed, kelp, and algae have not been used to prepare desulfurization catalysts. Summary of the Invention

[0005] The purpose of this invention is to provide a marine biomass desulfurization catalyst and its preparation method. This catalyst primarily uses marine biomass as a porous carbon support, making it inexpensive, readily available, and environmentally friendly. Furthermore, the desulfurization catalyst is synthesized into a nanowire morphology via hydrothermal synthesis, exhibiting low metal aggregation, numerous active metal centers per unit area, and high metal dispersion, thus demonstrating excellent adsorption and desulfurization performance.

[0006] To achieve the above-mentioned technical objectives, this invention proposes a marine biomass desulfurization catalyst, characterized in that the catalyst comprises a carbon source support made from marine biomass and a metal active component, wherein the mass ratio of the metal active component to the carbon source support is 1:1~3; the mesoporous specific surface area and mesoporous pore volume of the catalyst are respectively 85~100 m². 2 / g, 0.150~0.170 cm 3 / g.

[0007] This invention provides a method for preparing a marine biomass desulfurization catalyst. The method involves using marine biomass as a carbon source carrier, slowly adding an aqueous metal solution to the carbon source carrier to form a uniformly dispersed carbon-metal solution, and then using a hydrothermal synthesis method to obtain the marine biomass desulfurization catalyst.

[0008] Generally, the preparation method of the catalyst described in this invention is as follows: First, marine biomass is pretreated. After drying, grinding, and sieving, the pretreated marine biomass is mixed with graphene derivatives in a certain proportion to serve as a carbon source carrier. Water, an oxygen-containing weak acid, a reducing agent, and a basic carbonate are thoroughly mixed to prepare a metal aqueous solution. Under the action of an ultrasonic cell disruptor, the metal aqueous solution is slowly added to the carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The uniformly dispersed carbon-metal solution is mixed with a certain concentration of sodium hydroxide and placed in a hydrothermal synthesis reactor to react and obtain the catalyst precursor. The catalyst precursor after the hydrothermal reaction is centrifuged and washed. Then, the obtained filter cake is heat-treated in a suspension oven to prepare a marine biomass desulfurization catalyst.

[0009] Generally, the marine biomass can be one or more of the following: seaweed, kelp, and sedge. The pretreatment involves washing the surface of the marine biomass with clean water to remove mud and sand, then cutting it into 5-10 cm pieces and placing it in an ultrasonic cleaner for ultrasonic cleaning.

[0010] Generally, the mass ratio of the marine biomass to the graphene derivative is 1:0.1~0.3.

[0011] Generally, the oxygen-containing weak acid is one or more of formic acid, carbonic acid, hypochlorous acid, and hydrofluoric acid; the reducing agent can be one or more of potassium borohydride, sodium borohydride, and ethanol; and the basic carbonate can be one of basic copper carbonate, basic zinc carbonate, and basic nickel carbonate, with the basic carbonate serving as a metal source.

[0012] Generally, the mass ratio of water, oxygen-containing weak acid, reducing agent, and basic carbonate in the metal aqueous solution is 1:1:0.1:1~5.

[0013] Generally, the ultrasonic crusher has a power of 100~300 W and a time of 30~90 min.

[0014] Generally, the ratio of the metal aqueous solution to the carbon source support is 1:1 to 3.

[0015] Generally, the concentration of sodium hydroxide is 2 mol / L, and the ratio of carbon metal solution to sodium hydroxide is 1:2~5.

[0016] Generally, the temperature of the hydrothermal synthesis reactor is 150~250℃, and the time is 90~180 min.

[0017] Generally, the centrifugal washing speed is 5000~10000 r / min and the time is 10~15 min.

[0018] Generally, the heat treatment temperature is 200~500℃ and the time is 1~5 h. Beneficial effects

[0019] (1) The catalyst prepared by this invention mainly uses marine biomass as a porous carbon support. Compared with traditional porous carbon materials such as polyacrylonitrile and polyethylene glycol, it is cheaper, more readily available, and environmentally friendly.

[0020] (2) The desulfurization catalyst is made into a nanowire morphology by hydrothermal synthesis. It has a small degree of metal aggregation, a large number of metal active centers per unit area, and a large metal dispersion, which has good adsorption and desulfurization performance. Implementation

[0021] The following specific examples further illustrate the content of this invention. These embodiments are merely for illustrating the technical solutions of this invention more clearly and should not be construed as limiting the scope of protection of this invention. Example 1

[0022] Two types of marine biomass, *Ulva prolifera* and *Leptochloa macrophylla*, were pretreated by rinsing with clean water and ultrasonic washing. The pretreated *Ulva prolifera* and *Leptochloa macrophylla* were then dried, ground, and sieved. A mixture of 10 g of the pretreated *Ulva prolifera* and *Leptochloa macrophylla* was mixed with 1 g of graphene derivative to serve as a carbon source carrier. 5 g of formic acid, 0.5 g of potassium borohydride, and 5 g of basic copper carbonate were slowly added to 5 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 300 W ultrasonic cell disruptor, 10 g of the aqueous metal solution was slowly added to 10 g of the carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 30 min. 15 g of the uniformly dispersed carbon-metal solution was mixed with 30 g of 2 mol / L sodium hydroxide and reacted in a hydrothermal synthesis reactor to obtain the catalyst precursor. The hydrothermal synthesis reaction temperature was 150 °C and the reaction time was 90 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 10 min at a speed of 5000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 200℃ for 1 h to prepare a marine biomass desulfurization catalyst, which was denoted as S1.

[0023] Example 2

[0024] Two types of marine biomass, *Ulva prolifera* and kelp, were pretreated by rinsing with clean water and ultrasonic washing. The pretreated *Ulva prolifera* and kelp were then dried, ground, and sieved. A mixture of 20 g of the pretreated *Ulva prolifera* and *Lycopodium clavatum* was mixed with 4 g of graphene derivative to serve as a carbon source carrier. 5 g of carbonic acid, 0.5 g of sodium borohydride, and 10 g of basic zinc carbonate were slowly added to 5 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 100 W ultrasonic cell disruptor, 10 g of the aqueous metal solution was slowly added to the 20 g carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 60 min. 10 g of the uniformly dispersed carbon-metal solution was mixed with 30 g of 2 mol / L sodium hydroxide and placed in a hydrothermal synthesis reactor to react and obtain the catalyst precursor. The hydrothermal synthesis reaction temperature was 150 °C and the reaction time was 90 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 10 min at a speed of 8000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 300℃ for 2 h to prepare a marine biomass desulfurization catalyst, which was denoted as S2.

[0025] Example 3

[0026] Two types of marine biomass, kelp and *Echinochloa crus-galli*, were pretreated by rinsing with clean water and ultrasonic washing. The pretreated kelp and *Echinochloa crus-galli* were then dried, ground, and sieved. A mixture of 15 g of the pretreated kelp and *Echinochloa crus-galli* was mixed with 1.5 g of graphene derivative to serve as a carbon source carrier. A mixture of 5 g of carbonic acid and hypochlorous acid, 0.5 g of ethanol, and 15 g of basic zinc carbonate were slowly added to 5 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 200 W ultrasonic cell disruptor, 10 g of the aqueous metal solution was slowly added to 20 g of the carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 60 min. 10 g of the uniformly dispersed carbon-metal solution was mixed with 40 g of 2 mol / L sodium hydroxide and reacted in a hydrothermal synthesis reactor to obtain the catalyst precursor. The hydrothermal synthesis reaction temperature was 200 °C and the reaction time was 90 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 15 min at a speed of 10000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 400℃ for 5 h to prepare a marine biomass desulfurization catalyst, which was designated as S3.

[0027] Example 4

[0028] Marine biomass, including *Ulva prolifera*, was pretreated by rinsing with clean water and ultrasonic washing. The pretreated *Ulva prolifera* was then dried, ground, and sieved. A mixture of 20 g of the pretreated kelp and *Gnaphalium affine* was mixed with 6 g of graphene derivative to serve as a carbon source carrier. 15 g of hydrofluoric acid, 1.5 g of ethanol, and 60 g of basic nickel carbonate were slowly added to 15 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 300 W ultrasonic cell disruptor, 5 g of the aqueous metal solution was slowly added to the 15 g carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 90 min. 10 g of the uniformly dispersed carbon-metal solution was mixed with 50 g of 2 mol / L sodium hydroxide and reacted in a hydrothermal synthesis reactor to obtain the catalyst precursor. The hydrothermal synthesis reaction temperature was 250 °C and the reaction time was 150 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 15 min at a speed of 10000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 500℃ for 4 h to prepare a marine biomass desulfurization catalyst, which was designated as S4.

[0029] Example 5

[0030] Kelp, a marine biomass, was pretreated by rinsing with clean water and ultrasonic washing. The pretreated kelp was then dried, ground, and sieved. 20 g of the pretreated kelp was mixed with 4 g of graphene derivative to serve as a carbon source carrier. A mixture of 15 g formic acid and hydrofluoric acid, 1.5 g of potassium borohydride and sodium borohydride, and 30 g of basic nickel carbonate were slowly added to 15 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 300 W ultrasonic cell disruptor, 10 g of the aqueous metal solution was slowly added to the 20 g carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 90 min. 10 g of the uniformly dispersed carbon-metal solution was mixed with 50 g of 2 mol / L sodium hydroxide and reacted in a hydrothermal synthesis reactor to obtain a catalyst precursor. The hydrothermal synthesis reaction temperature was 200 °C and the reaction time was 180 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 15 min at a speed of 8000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 500℃ for 2 h to prepare a marine biomass desulfurization catalyst, which was designated as S5.

[0031] Example 6

[0032] Two types of marine biomass, *Echinochloa crus-galli* and *Echinochloa chinensis*, were pretreated by rinsing with clean water and ultrasonic washing. The pretreated *Echinochloa crus-galli* and *Echinochloa chinensis* were then dried, ground, and sieved. 20 g of the pretreated *Echinochloa crus-galli* and *Echinochloa chinensis* were mixed with 2 g of graphene derivative to serve as a carbon source carrier. 10 g of carbonic acid, a mixture of 1 g of potassium borohydride and sodium borohydride, and 50 g of basic copper carbonate were slowly added to 10 g of deionized water and thoroughly mixed to prepare an aqueous metal solution. Under the action of a 150 W ultrasonic cell disruptor, 10 g of the aqueous metal solution was slowly added to 20 g of the carbon source carrier to prepare a uniformly dispersed carbon-metal solution. The ultrasonic disruption time was 90 min. 10 g of the uniformly dispersed carbon-metal solution was mixed with 30 g of 2 mol / L sodium hydroxide and placed in a hydrothermal synthesis reactor to react and obtain the catalyst precursor. The hydrothermal synthesis reaction temperature was 200℃ and the reaction time was 120 min. The catalyst precursor after hydrothermal reaction was centrifuged and washed for 10 min at a speed of 8000 r / min. The resulting filter cake was then placed in a suspension oven and heat-treated at 300℃ for 3 h to prepare a marine biomass desulfurization catalyst, which was designated as S6. Comparative Example 1

[0033] Accurately weigh 10 g of polyethylene glycol and 10 g of nickel acetate tetrahydrate, grind for about half an hour until there are no obvious large particles, and then heat the obtained sample in a tube furnace. Heat to 400℃ and hold for 4 hours in a nitrogen atmosphere. The catalyst obtained after cooling is recorded as R1. Comparative Example 2

[0034] Accurately weigh 10 g of polyacrylonitrile and 15 g of nickel acetate tetrahydrate, grind for about half an hour until there are no obvious large particles, and then heat the obtained sample in a tube furnace. Heat to 300°C and hold for 4 hours under a nitrogen atmosphere. The catalyst obtained after cooling is denoted as R2.

[0035] Sample testing

[0036] This invention prepares model oil by dissolving thiophene in n-octane with a sulfur concentration of 50 ppm. The reaction is carried out in a fixed bed, with 1 g of catalyst placed in the optimal temperature zone of a stainless steel tube, both the upper and lower sections filled with quartz sand. Before the adsorption experiment, the adsorbent is reduced by reducing gas H2 at 400°C at a flow rate of 30 mL / min for 4 h. After the adsorbent is reduced, n-octane containing simulated sulfur is fed into the adsorber for adsorption and desulfurization. Test samples are collected from the effluent at fixed time intervals. When the sulfur content in the received test sample is greater than 1 ppm, the total test time is the catalyst breakthrough time; when the sulfur content in the received test sample reaches 50 ppm, the total desulfurization amount of the catalyst is the catalyst's saturated adsorption capacity.

[0037] The sample test results are shown in Table 1, where samples S1-S6 were prepared by the method of the present invention, and samples R1 and R2 are reference samples.

[0038] Table 1. Catalyst specific surface area and pore volume data

[0039]

[0040] Table 2 Catalyst Adsorption Desulfurization Performance

[0041]

[0042] Table 1 shows that, compared with catalysts prepared by solid-state grinding using polymers as porous carbon materials, catalysts prepared by hydrothermal synthesis using marine biomass as porous carbon materials exhibit a larger mesoporous specific surface area and mesoporous pore volume. Furthermore, according to literature, metals are the active centers for adsorption and desulfurization; a larger mesoporous specific surface area and larger mesoporous pore volume make it less prone to metal aggregation, resulting in higher metal dispersion and more active metal centers. Table 2 also shows that the marine biomass desulfurization catalyst prepared using the method of this invention has a higher breakthrough time and saturation adsorption capacity than the reference catalyst. This is mainly due to the lower degree of metal aggregation, more active centers, and higher dispersion in the catalyst sample prepared by this invention. Additionally, marine biomass such as *Ulva prolifera* are natural porous carbon materials, inexpensive, readily available, and abundant, offering higher economic benefits compared to polymer carbon materials.

[0043] It should be noted that the above description is only a preferred embodiment of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A marine biomass desulfurization catalyst, characterized in that... The catalyst comprises a carbon source support made from marine biomass and a metal active component, with a mass ratio of the metal active component to the carbon source support of 1:1 to 3; the mesoporous specific surface area and mesoporous pore volume of the catalyst are 85 to 100 m². 2 / g, 0.150~0.170 cm 3 / g; The preparation method of the marine biomass desulfurization catalyst is as follows: First, the marine biomass is pretreated. After drying, grinding, and sieving, the pretreated marine biomass is mixed with graphene derivatives to obtain a carbon source carrier. Water, oxygen-containing weak acid, reducing agent, and basic carbonate are thoroughly mixed to prepare a metal aqueous solution. Under the action of an ultrasonic cell disruptor, the metal aqueous solution is added to the carbon source carrier to form a uniformly dispersed carbon metal solution. The uniformly dispersed carbon metal solution is mixed with sodium hydroxide and subjected to a hydrothermal synthesis reaction to obtain the catalyst precursor. The catalyst precursor is centrifuged and washed, and then the obtained filter cake is heat-treated to prepare the marine biomass desulfurization catalyst.

2. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The marine biomass is one or more of the following: seaweed, kelp, and sedge. The pretreatment involves washing the mud and sand off the surface of the marine biomass with clean water, then cutting it into 5-10 cm pieces and placing it in an ultrasonic cleaner for ultrasonic fine washing.

3. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The mass ratio of marine biomass to graphene derivatives is 1:0.1~0.

3.

4. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The oxy-containing weak acid is one or more of formic acid, carbonic acid, hypochlorous acid, and hydrofluoric acid; the reducing agent is one or more of potassium borohydride, sodium borohydride, and ethanol; the basic carbonate is one of basic copper carbonate, basic zinc carbonate, and basic nickel carbonate; and the basic carbonate is a metal source.

5. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The mass ratio of water, oxygen-containing weak acid, reducing agent, and basic carbonate in the metal aqueous solution is 1:1:0.1:1~5.

6. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The ultrasonic crusher has a power of 100~300 W and a time of 30~90 min.

7. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The mass ratio of the metal aqueous solution to the carbon source support is 1:1~3.

8. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The concentration of sodium hydroxide is 2 mol / L, and the mass ratio of carbon metal solution to sodium hydroxide is 1:2~5.

9. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The hydrothermal synthesis reaction is carried out at a temperature of 150~250℃ for 90~180 min.

10. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The centrifugal washing speed is 5000~10000 r / min, and the time is 10~15 min.

11. The marine biomass desulfurization catalyst according to claim 1, characterized in that... The heat treatment temperature is 200~500℃, and the time is 1~5 h.

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