Preparation method of nitrogen-doped carbon catalyst and application of nitrogen-doped carbon catalyst in oil desulfurization

Abstract

The invention relates to a preparation method of a nitrogen-doped carbon catalyst and application of the nitrogen-doped carbon catalyst in oil desulfurization, and the preparation method comprises the following steps: at room temperature, pre-treating active carbon, fully grinding the pre-treated active carbon in an agate mortar, adding a precursor, and grinding or ball-milling to obtain the nitrogen-doped carbon catalyst. And fully mixing, transferring into a high-temperature atmosphere tubular resistance furnace, vacuumizing, introducing nitrogen for three times, heating to 600-900 DEG C, keeping for 2-4 hours, cooling, and grinding to obtain the nitrogen-doped carbon catalyst. The catalyst prepared by grinding and calcining the ionic liquid serving as a precursor and the activated carbon has the characteristics of low cost and easiness in recovery from a reaction system, and when the catalyst is applied to a catalytic oxidation extraction desulfurization process, the initial sulfur content of fuel oil is 600ppm at 40 DEG C, the desulfurization rate within 120 minutes is up to 95% or above, and the catalyst has a wide application prospect. And the preparation process does not need to introduce a solvent, is free of metal doping, and has the advantages of low cost, easiness in obtaining, high catalytic desulfurization efficiency, long service life and the like.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a preparation method of a nitrogen-doped carbon catalyst and application of the catalyst in oil desulfurization. Background Art

[0002] In the past few decades, industry has developed rapidly, but environmental problems have also become increasingly prominent. Although clean and renewable energy has been vigorously developed since the 21st century, due to cost and technical limitations, the production capacity of clean energy has not yet reached the standard of large-scale industrial production. Global crude oil demand and supply continue to grow, and fossil energy still dominates the global energy market. In 2023, fossil fuels accounted for 81% of the global energy structure. During the oil processing process, sulfur compounds in crude oil will remain in the oil products, and a large amount of sulfur oxides (SO x ), causing environmental problems such as smog and acid rain. SO x It is a factor of air pollution. The chemical composition of fuel oil is mainly hydrocarbons and aromatics. The sulfides in it are mainly divided into two categories, one is acyclic sulfides, and the other is cyclic sulfides such as benzothiophene (BT), dibenzothiophene (DBT) and DBT alkyl derivatives. Reducing the sulfur content in fuel oil and effectively improving air pollution is the focus of future research.

[0003] Oxidative extraction coupled desulfurization is a desulfurization technology that combines oxidation and extraction technologies, which can effectively reduce the time required for desulfurization and improve the desulfurization efficiency. The metal-based ionic liquid ([Bmim]Cl / CoCl2) catalytic system studied by Xu Hang et al. showed a high desulfurization effect. The graphene-loaded metal catalytic system studied by He Jing et al. can achieve a desulfurization efficiency of 88.5%. However, the above-mentioned system still has the disadvantages of difficult catalyst recovery and high metal doping cost, and the desulfurization efficiency needs to be further improved. Therefore, it is particularly important to develop a catalyst that is both efficient, economical and easy to recover, which is of great significance for promoting the development and application of oxidative extraction coupled desulfurization technology. Summary of the invention

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: A preparation method of a nitrogen-doped carbon catalyst comprises the following steps: pre-treating activated carbon at room temperature, grinding the pre-treated activated carbon in an agate mortar for 8-10 minutes, adding a precursor and grinding or ball milling the activated carbon to fully mix the two, and then moving the mixture into a high-temperature atmosphere tubular resistance furnace, evacuating the mixture, introducing nitrogen three times, heating the mixture to 600-900°C and maintaining the temperature for 2-4 hours, cooling the mixture to room temperature, and grinding the mixture again to obtain a nitrogen-doped carbon catalyst, wherein the mass ratio of the activated carbon to the precursor is 1-5:1-5.

[0005] In further optimization, the precursor is a nitrogen-containing organic compound or an ionic liquid with different anions and cations.

[0006] Further optimization, the nitrogen-containing organic compound or the ionic liquid with different anions and cations is one of melamine, dicyandiamide, N-ethylimidazole, 1-ethyl-3-methylimidazole dicyandiamide, 1-hexyl-3-methylimidazole dicyandiamide, 1-ethyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole bromide, 1-propyl-3-methylimidazole dicyandiamide, 1-ethyl-3-ethylimidazole dicyandiamide, 1-ethyl-3-propylimidazole dicyandiamide, 1-methyl-3-methylimidazole dicyandiamide, 1-ethyl-3-methylimidazole nitrate, 1-propyl-3-butylimidazole nitrate, and 1-decyl-3-methylimidazole dicyandiamide.

[0007] Application of a nitrogen-doped carbon catalyst in oil desulfurization.

[0008] After further optimization, the desulfurization method is as follows: the oil to be desulfurized and the extractant in a volume ratio of 10:1-5 are fully mixed, a nitrogen-doped carbon catalyst and an oxidant are added to the mixture, and the mixture is reacted at a temperature of 10-80°C for 10-120 minutes under magnetic stirring to complete the desulfurization of the oil.

[0009] After further optimization, the amount of nitrogen-doped carbon catalyst used is 0.15~1.0% of the quality of the oil to be desulfurized.

[0010] Further optimization, the oxidant is 2-5% of the quality of the desulfurized oil.

[0011] Further optimized, the extractant is one or a mixture of acetonitrile, pyridine, furan, water, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran and the ionic liquid described in step one.

[0012] Further optimization, the oxidant is potassium persulfate complex salt, K2S2O8, Na2S2O8, (NH4)2S2O8, KHSO5, H2O2, [C n min]2[S2O8] (n=1~10).

[0013] The beneficial effects of the present invention are: 1. The catalyst prepared by grinding and calcining ionic liquid and activated carbon in the present invention has the characteristics of low cost and easy recovery from the reaction system. The catalyst is used in the catalytic oxidation extraction desulfurization process. The preparation process does not require the introduction of solvents and is free of metal doping. It has the advantages of being cheap, easy to obtain, high catalytic desulfurization efficiency, and long service life.

[0014] 2. After the nitrogen-doped carbon catalyst prepared by the present invention is used in combination with potassium permonosulfate composite salt oxidation, it shows excellent desulfurization effect and service life at 40°C. It is measured that at 40°C, the initial sulfur content of the fuel oil is 600ppm, and the desulfurization rate is as high as more than 95% within 120 minutes. After standing and stratifying, the desulfurized oil product is obtained. The lower layer catalyst can still be recycled and reused after simple washing and drying. After being recycled 4 times, it still has a desulfurization rate of more than 85%, and the desulfurization effect is significant. DETAILED DESCRIPTION

[0015] In order to more clearly understand the above-mentioned purposes, features and advantages of the present invention, the present invention is described in detail below in conjunction with specific embodiments. The following embodiments are implemented based on the technical solutions of the present invention, and detailed implementation methods and specific operating procedures are given. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the following embodiments.

[0016] Example 1 Step (1), pre-treating the activated carbon, then taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.3 g of 1-ethyl-3-methylimidazole dicyandiamide salt and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, heating to 800° C. and maintaining it for 3 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0017] Step (2), 2 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil with an initial sulfur content of 600 ppm, stirred at 40° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 40° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0018] Step (3), the desulfurization system after the reaction in step (2) is statically layered to obtain a desulfurized oil product. The lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0019] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT reached 95.33%, and the desulfurization rate of BT reached 70.5%.

[0020] Example 2 Step (1), pre-treating the activated carbon, then taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.3 g of 1-ethyl-3-methylimidazolium chloride and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, heating to 800° C. and maintaining it for 3 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0021] Step (2), 2 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil with an initial sulfur content of 600 ppm, stirred at 40° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 40° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0022] Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0023] After the desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT reached 91.2%, and the desulfurization rate of BT reached 65.3%. Example 3 Step (1), pre-treating the activated carbon, taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.6 g of 1-ethyl-3-methylimidazolium bromide and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, heating to 800° C. and maintaining it for 3 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst; Step (2), 2 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil having an initial sulfur content of 600 ppm, stirred at 40° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 40° C. for 80 min under stirring to complete the desulfurization of the fuel oil; Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0024] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT reached 94.43%, and the desulfurization rate of BT reached 71.2%.

[0025] Example 4 Step (1), pre-treating the activated carbon, taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.3 g of melamine and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, raising the temperature to 800° C. and maintaining it for 3 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0026] Step (2), 2 mL of acetonitrile and 0.03 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil with an initial sulfur content of 500 ppm, stirred at 50° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 50° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0027] Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0028] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT reached 95.33%, and the desulfurization rate of BT reached 70.4%.

[0029] Example 5 Step (1), pre-treating the activated carbon, taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.3 g of 1-hexyl-3-methylimidazole dicyandiamide salt and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, raising the temperature to 700° C. and maintaining it for 2.5 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0030] Step (2), 2 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil with an initial sulfur content of 600 ppm, stirred at 40° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 40° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0031] Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0032] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT reached 97.5%, and the desulfurization rate of BT reached 78.8%.

[0033] Example 6 Step (1), pre-treating the activated carbon, taking 0.8 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 8 min, then adding 0.3 g of 1-decyl-3-methylimidazole dicyandiamide salt and grinding it thoroughly for 40 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, heating to 600° C. and maintaining it for 2.5 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0034] Step (2), 2 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil having an initial sulfur content of 600 ppm, stirred at 50° C. for 30 min, and then 1.5 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 50° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0035] Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0036] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT was 93.9%, and the desulfurization rate of BT was 70.5%.

[0037] Example 7 Step (1), pre-treating the activated carbon, taking 0.9 g of the activated carbon and placing it in an agate mortar, grinding it thoroughly for 10 min, then adding 0.3 g of dicyandiamide and grinding it thoroughly for 45 min, transferring the mixed sample into a quartz boat, placing it in a high-temperature atmosphere tubular resistance furnace, evacuating and flushing with nitrogen three times, heating to 800° C. and maintaining it for 3 h, and after the sample is cooled to room temperature, grinding it thoroughly in an agate mortar to obtain a catalyst.

[0038] Step (2), 1.5 mL of acetonitrile and 0.025 g of the catalyst prepared in step (1) are mixed with 6 mL of fuel oil with an initial sulfur content of 800 ppm, stirred at 40° C. for 30 min, and then 2 mL of 20 wt % potassium permonosulfate complex salt is added, and the mixture is reacted at 40° C. for 80 min under stirring to complete the desulfurization of the fuel oil.

[0039] Step (3), statically layering the desulfurization system after the reaction in step (2) to obtain a desulfurized oil product; the lower layer catalyst can be simply washed and dried, and then directly added to the reaction system again for catalytic oxidation-extraction desulfurization.

[0040] It was determined that after desulfurization treatment using the desulfurization method of this embodiment, the desulfurization rate of DBT was 94.5%, and the desulfurization rate of BT was 72.4%.

[0041] The above shows and describes the main features, methods of use, basic principles and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements according to actual conditions, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a nitrogen-doped carbon catalyst, characterized in that: The preparation steps are as follows: pretreating the activated carbon at room temperature, grinding the pretreated activated carbon in an agate mortar for 8-10 minutes, adding the precursor and grinding or ball milling the precursor to fully mix the two, and then moving the mixture into a high-temperature atmosphere tubular resistance furnace, evacuating the mixture and introducing nitrogen three times, heating the mixture to 600-900°C and maintaining the temperature for 2-4 hours, cooling the mixture to room temperature, and grinding the mixture again to obtain a nitrogen-doped carbon catalyst, wherein the mass ratio of activated carbon to precursor is 1-5:1-5.

2. The method for preparing a nitrogen-doped carbon catalyst according to claim 1, characterized in that: The precursor is a nitrogen-containing organic compound or an ionic liquid with different anions and cations.

3. The method for preparing a nitrogen-doped carbon catalyst according to claim 1, characterized in that: The nitrogen-containing organic compound or the ionic liquid with different anions and cations is one of melamine, dicyandiamide, N-ethylimidazole, 1-ethyl-3-methylimidazole dicyandiamide, 1-hexyl-3-methylimidazole dicyandiamide, 1-ethyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole bromide, 1-propyl-3-methylimidazole dicyandiamide, 1-ethyl-3-ethylimidazole dicyandiamide, 1-ethyl-3-propylimidazole dicyandiamide, 1-methyl-3-methylimidazole dicyandiamide, 1-ethyl-3-methylimidazole nitrate, 1-propyl-3-butylimidazole nitrate, and 1-decyl-3-methylimidazole dicyandiamide.

4. Use of a nitrogen-doped carbon catalyst as claimed in claim 1 in oil desulfurization.

5. The use of a nitrogen-doped carbon catalyst in oil desulfurization as claimed in claim 4, characterized in that: The desulfurization method is: take the oil to be desulfurized and the extractant in a volume ratio of 10:1~5 and mix them thoroughly, add nitrogen-doped carbon catalyst and oxidant to the mixture, react at a temperature of 10~80℃ for 10~120min under magnetic stirring, and the desulfurization of the oil is completed.

6. The use of a nitrogen-doped carbon catalyst in oil desulfurization as claimed in claim 5, characterized in that: The amount of nitrogen-doped carbon catalyst used is 0.15~1.0% of the quality of the oil to be desulfurized.

7. The use of a nitrogen-doped carbon catalyst in oil desulfurization as claimed in claim 5, characterized in that: The oxidant is 2-5% of the quality of the desulfurized oil.

8. The use of a nitrogen-doped carbon catalyst in oil desulfurization as claimed in claim 5, characterized in that: The extractant is one or a mixture of acetonitrile, pyridine, furan, water, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran and the ionic liquid in step one.

9. The use of a nitrogen-doped carbon catalyst in oil desulfurization as claimed in claim 5, characterized in that: The oxidant is potassium persulfate complex salt, K2S2O8, Na2S2O8, (NH4)2S2O8, KHSO5, H2O2, [C n min]2[S2O8] (n=1~10).