CN110218576B

CN110218576B - Efficient selective catalytic oxidation desulfurization method for diesel oil

Info

Publication number: CN110218576B
Application number: CN201910450873.5A
Authority: CN
Inventors: 姚月; 梅世铎; 吕树祥; 韶佩佩
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2021-06-25
Anticipated expiration: 2039-05-28
Also published as: CN110218576A

Abstract

The invention relates to a method for high-efficiency catalytic oxidation desulfurization of diesel oil, which comprises the steps of contacting a titanium nano material catalyst and an oxidant with the diesel oil, and selectively catalytically oxidizing the diesel oil to remove a second component under the condition that a first component competes for oxygen consumption; the diesel comprises a first component and a second component; the first component comprises one or more of olefins, aromatics, or naphthenes; the second component is a sulfur-containing compound, and comprises one or more of mercaptan, thioether, thiophene, benzothiophene, dibenzothiophene or 4, 6-dimethyldibenzothiophene. The titanium nano material catalyst prepared by the invention selectively removes macromolecular sulfur-containing compounds such as dimethyldibenzothiophene (DMDBT) and the like in diesel under the condition of competitive oxidation of complex components such as olefin, cycloparaffin, aromatic hydrocarbon and the like, the desulfurization efficiency of the diesel reaches 98.2%, and the titanium nano material catalyst has good application prospect in the field of oxidative desulfurization of the diesel.

Description

Efficient selective catalytic oxidation desulfurization method for diesel oil

Technical Field

The invention belongs to the field of diesel oil desulfurization, and particularly relates to a method for high-efficiency selective catalytic oxidation desulfurization of diesel oil.

Background

With the development of economy, the quantity of motor vehicles in China is increased in geometric multiples, and the emission of SOx from diesel oil of diesel vehicles is one of the important reasons for air pollution at present. Especially in the middle east region of China recently, large-area severe air pollution has seriously influenced the development of economy and the health of the people. China already sets stricter environmental protection laws and regulations to promote the upgrading of fuel oil, and foresees that air pollution is not removed and oil products are upgraded more frequently.

The Oxidation Desulfurization (ODS) technology has natural removal advantages on fused ring thiophene sulfides and derivatives thereof which are difficult to remove by hydrodesulfurization, substances which are difficult to hydrogenate are relatively easy to oxidize, and the purpose of deep desulfurization of diesel oil is achieved by extraction, adsorption, filtration and the like. In the prior art, the research method for diesel oil oxidative desulfurization usually takes fixed components (alkanes such as normal hexane or decalin) as a simulant of diesel oil, and catalytic removal of quantitative sulfide (mostly DBT) is carried out in the form of H₂O₂In the case of an oxidizing agentUnder the condition, the removal efficiency of the sulfide is generally higher, the condition is mild, and the operation is simple.

However, real diesel oil is a mixed species with a much more complex structure, the components of the real diesel oil also comprise substances such as olefin, aromatic hydrocarbon, naphthenic hydrocarbon and the like, a simulated oil system with a single fixed component has obvious disadvantages, recently, many researches focus on the simulation, catalytic evaluation is carried out on a catalytic oxidation desulfurization system in a system closer to the real diesel oil, the result is not optimistic, and researches find that the components of the diesel oil such as olefin, aromatic hydrocarbon and the like are easier to be oxidized, so that the removal efficiency of sulfur-containing compounds is reduced, and the simulation exists objectively in most catalytic oxidation desulfurization systems, and the oxidation process of the competitive components not only compete for consuming the oxidant, but also can cause the reduction of the quality of the diesel oil.

Meanwhile, in diesel oil, sulfides mainly comprise thiophene and derivatives thereof, and the content of the sulfides accounts for more than 85% of the total content, wherein macromolecular sulfur-containing compounds such as Benzothiophene (BT), Dibenzothiophene (DBT), dimethyldibenzothiophene (DMDBT) and the like account for more than 70% of the total content of the thiophene. However, in the existing catalytic oxidation desulfurization technology, the removal effect of thiophene (Th), Benzothiophene (BT) or Dibenzothiophene (DBT) is usually good, but the removal effect of macromolecular sulfur-containing compounds such as dimethyldibenzothiophene (DMDBT) is not optimistic, so that in the catalytic oxidation desulfurization technology, the problem of competitive oxidation of complex components such as olefin, naphthene and aromatic hydrocarbon in diesel oil is overcome, and the selective removal of macromolecular sulfur-containing compounds such as dimethyldibenzothiophene (DMDBT) in diesel oil is desirable.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for high-efficiency selective catalytic oxidation desulfurization of diesel oil.

Contacting the titanium nano material catalyst and the oxidant with diesel oil, heating to 40-60 ℃, and reacting for 0.5-4 h. The second component is removed by selective catalytic oxidation of diesel fuel in the event that the first component competes for oxygen consumption.

Preferably, the diesel oil is selected from the group consisting of hydrorefined diesel oil, bunker fuel oil and diesel blend oil. Comprises a first component and a second component; the first component comprises one or more of olefins, aromatics, or naphthenes; the second component is a sulfur-containing compound, and comprises one or more of mercaptan, thioether, thiophene, benzothiophene, dibenzothiophene or 4, 6-dimethyldibenzothiophene.

Preferably, the preparation method of the framework heteroatom type titanium nanotube (M-TiNTs) comprises the following steps: adding organic titanium sources such as n-butyl titanate, isopropyl titanate and the like, metal salts of corresponding types and acid liquor into a crystallization kettle with a polytetrafluoroethylene lining, stirring the mixture at 90 ℃ for hydrolysis for 48 hours, then adding NaOH solution, carrying out hydrothermal crystallization at 100-180 ℃ for 24-96 hours, naturally cooling the mixture to room temperature, washing the obtained white solid with deionized water until the pH value is approximately equal to 7, and drying the white solid to obtain the sodium type heteroatom titanium nanotube (Na-M-TiNTs).

Further, 1-3g of prepared sodium type heteroatom titanium nano-tube (Na-M-TiNTs) is added with 300-800mL0.01-0.50mol/L HCl solution, the mixture is stirred for 8-16h at normal temperature after being sealed, the mixture is kept stand, filtered, washed by deionized water until the pH value is approximately equal to 7, and dried to obtain hydrogen type heteroatom titanium nano-material catalysts with different shapes.

The preparation method of the heteroatom titanium nanosheet and the heteroatom nanoparticles comprises the steps of carrying out crystal transformation treatment under the condition of incomplete crystallization, and carrying out acid treatment or induction (such as 10g of PDDA (polymeric dimethyl ketone) treatment on the surface of a titanium tube to obtain an artificially selected nanocrystal fragment product.

Preferably, an organic titanium source, a metal salt and an acid solution are added into a crystallization kettle, the mixture is stirred at 80-100 ℃ and hydrolyzed for 40-60 hours, then NaOH solution is added, hydrothermal crystallization is carried out for 12-24 hours at 100-180 ℃, then the mixture is naturally cooled to room temperature, the obtained solid is washed by deionized water until the pH value is approximately 7, roasting is carried out for 3 hours at 300-500 ℃, after a sample is cooled, 0.2-2mol/L of acid solution is added for treatment, the mixture is stirred at normal temperature for 10-15 hours after sealing, standing is carried out, the solid obtained by suction filtration is washed by deionized water until the pH value is approximately 7, and then drying is carried out at 70-90 ℃ to obtain the heteroatom titanium nanosheet nano-material catalyst mixed by titanium and titanium nano particles.

And the organic titanium source is one or a mixture of two of tetrabutyl titanate and tetraisopropyl titanate.

The metal salt is one or a mixture of more than two of ferric salt, copper salt and vanadium salt, and the molar ratio of the metal salt to the titanium is 0.01-0.1.

Further, the ferric salt is ferric nitrate and ferric chloride; the copper salt is copper nitrate or copper chloride; the vanadium salt is ammonium metavanadate, vanadyl sulfate and vanadyl dichloride.

Preferably, the metal salt is iron nitrate, copper nitrate and ammonium metavanadate according to a mass ratio of 1-3: 1-6: 2-5.

The iron and copper bimetallic system is a pair of paired catalytic centers with obvious synergistic effect commonly used in a plurality of oxidation reactions. In the reaction of degrading methylene blue by catalytic oxidation, the copper-iron mass ratio is about 2 generally, and the effect is optimal; meanwhile, because the variable valence state of the vanadium metal is rich, the catalytic oxidation effect is obvious, and the titanium metal is a pair of catalytic active centers with obvious synergistic catalytic action, the multi-metal composite catalytic system is designed for the oxidation desulfurization reaction.

Furthermore, the oxidizing agent is hydrogen peroxide or tert-butyl hydroperoxide or cumene hydroperoxide (cumene hydroperoxide).

And the oxygen-sulfur ratio is 2.3-6, and the catalyst accounts for 0.5-5 wt% of the system.

Compared with the prior art, the invention has the beneficial effects that:

1. the titanium nano material catalyst of the invention contacts with an oxidant, and can generate Ti-O-O-H-eta with selective oxidation activity on the surface of the titanium nano material¹And Ti-O-O-H-eta²The intermediate active matter with the configuration can selectively catalyze and oxidize sulfur-containing compounds in diesel oil without being influenced by olefin, naphthenic hydrocarbon and aromatic hydrocarbon in a diesel oil simulant, so that the problems of low desulfurization efficiency and diesel oil quality reduction caused by competitive oxidation of the olefin, the naphthenic hydrocarbon or the aromatic hydrocarbon in the diesel oil in the prior art are solved.

2. According to the invention, by controlling the content of the second metal heteroatom and the pickling concentration of the framework heteroatom titanium nanomaterial, the catalyst has good selective catalytic oxidation removal efficiency for BT, DBT and the like, and also has good selective catalytic oxidation removal efficiency for macromolecular sulfide 4,6-DMDBT, and therefore, the titanium nanomaterial catalyst has a good application prospect in the field of oxidative desulfurization of diesel oil.

3. The invention adopts the heteroatom titanium nano material as the catalyst, the titanium nano material catalyst is prepared by a hydrothermal synthesis method, the preparation method is simple, the cost is low, the yield is high, and after the reaction is finished, the titanium nano material catalyst can be separated and recovered only by a simple filtration method.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention. In the examples, the hydrofined diesel oil, the bunker fuel oil and the diesel blend oil are diesel oil samples diluted by n-octane.

Example 1

Preparation of sodium type heteroatom titanium nanotubes (Na-Fe-TiNTs):

in a 50mL flask, 4mL of tetrabutyltitanate and 20mL of ethanol were added, stirred at room temperature for 1 hour, and then 0.076g of ferric nitrate and 4mL of 0.5M/L hydrochloric acid were added, and hydrolyzed at 90 ℃ for 48 hours. And (3) after sealing, placing the crystallization kettle in an oven at 150 ℃ for hydrothermal crystallization for 24 hours, then naturally cooling to room temperature, and cleaning the obtained solid with deionized water until the pH value is approximately equal to 7. And drying the obtained solid in an oven at 80 ℃ to obtain the sodium-type framework heteroatom titanium nanotube (Na-Fe-TiNTs).

Example 2

Preparation of hydrogen type iron heteroatom titanium nanotubes (H-Fe-TiNTs):

2g of the prepared sodium type iron heteroatom titanium nanotube (Na-Fe-TiNTs) is added with 500mL of 0.01mol/L HCl solution, the mixture is stirred for 12 hours at normal temperature after being sealed, and is kept stand and the titanium nanotube solid obtained by suction filtration is washed by deionized water until the pH value is approximately equal to 7. And drying the obtained iron heteroatom titanium nanotube solid in an oven at 80 ℃ overnight to obtain the hydrogen type iron heteroatom titanium sodium type nanotube (H-Fe-TiNTs).

Example 3

Preparing an iron heteroatom titanium nano material catalyst:

in a 50mL flask, 4mL of tetrabutyltitanate and 20mL of ethanol were added, stirred at room temperature for 1 hour, and then 0.076g of ferric nitrate and 4mL of 0.5M/L hydrochloric acid were added, and hydrolyzed at 90 ℃ for 48 hours. And (3) after sealing, placing the crystallization kettle in an oven at 150 ℃ for hydrothermal crystallization for 12 hours, then naturally cooling to room temperature, and cleaning the obtained solid with deionized water until the pH value is approximately equal to 7. After hydrogen ion exchange, 500mL of 0.2mol/L HCl solution is added, the mixture is sealed and stirred for 12 hours at normal temperature, the mixture is kept stand, and the solid obtained by suction filtration is washed by deionized water until the pH value is about equal to 7. And drying the obtained solid in an oven at 80 ℃ overnight to obtain the iron heteroatom titanium nano material catalyst mixed by the titanium nano sheets and the titanium nano particles.

Example 4

Preparation of hydrogen type iron heteroatom titanium nanoparticles:

in a 50mL flask, 4mL of tetrabutyltitanate and 20mL of ethanol were added, stirred at room temperature for 1 hour, and then 0.076g of ferric nitrate and 4mL of 0.5M/L hydrochloric acid were added, and hydrolyzed at 90 ℃ for 48 hours. And (3) after sealing, placing the crystallization kettle in an oven at 150 ℃ for hydrothermal crystallization for 24 hours, then naturally cooling to room temperature, and cleaning the obtained solid with deionized water until the pH value is approximately equal to 7. After hydrogen ion exchange, 500mL of 0.5mol/L HCl solution is added, the mixture is sealed and stirred for 12 hours at normal temperature, the mixture is kept stand, and the solid obtained by suction filtration is washed by deionized water until the pH value is about equal to 7. And drying the obtained solid in an oven at 80 ℃ overnight to obtain the hydrogen type iron heteroatom titanium nano-particles.

Example 5

Preparing a hydrogen type iron-copper-vanadium heteroatom titanium nanotube:

in a 50mL flask, 4mL of tetrabutyltitanate and 20mL of ethanol were added, stirred at room temperature for 1 hour, and then 0.076g of iron nitrate, 0.152g of copper nitrate, 0.22g of ammonium metavanadate and 4mL of 0.5M/L hydrochloric acid were added, and hydrolyzed at 90 ℃ for 48 hours. And (3) after sealing, placing the crystallization kettle in an oven at 150 ℃ for hydrothermal crystallization for 24 hours, then naturally cooling to room temperature, and cleaning the obtained solid with deionized water until the pH value is approximately equal to 7. And hydrogen type iron composite heteroatom titanium nanotubes are obtained after hydrogen ion exchange.

Example 6

10mg of the catalyst prepared in example 2 was weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of an n-octane solution of DBT and 4,6-DMDBT, 5mL of xylene, and 10mL of t-butyl hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. And after the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using Gas Chromatography (GC), wherein the removal rate is 97.6 percent, and peaks of DBT and 4,6-DMDBT in the oil phase disappear after the reaction.

Example 7

10mg of the catalyst prepared in example 3 were weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of an n-octane solution of DBT and 4,6-DMDBT and 10mL of a t-butyl hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. And after the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using Gas Chromatography (GC), wherein the removal rate is 97.6%, and peaks of DBT and 4,6-DMDBT in the oil phase almost disappear after the reaction.

Example 8

10mg of the catalyst prepared in example 4 were weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of an n-octane solution of DBT and 4,6-DMDBT and 10mL of a t-butyl hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. And after the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using Gas Chromatography (GC), wherein the removal rate is 90.6%, the peak of DBT in the oil phase disappears after the reaction, and the 4,6-DMDBT does not completely disappear.

Example 9

10mg of the catalyst prepared in example 3 was weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of hydrorefined diesel oil and 10mL of t-butyl hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. After the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using a Gas Chromatography (GC) with the removal rate of 97.6 percent.

Example 10

10mg of the catalyst prepared in example 3 were weighed into a 100mL reactor, 15mL (1000 ppmw sulfur) of bunker fuel oil and 10mL of t-butyl hydroperoxide solution were added, the temperature was raised to 45 ℃ and the reaction time was 2 hours. After the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using a Gas Chromatography (GC) with the removal rate of 97.3 percent.

Example 11

10mg of the catalyst prepared in example 3 was weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of diesel blend oil and 10mL of cumene hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. After the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using a Gas Chromatography (GC) with the removal rate of 96.2 percent.

Example 12

10mg of the catalyst prepared in example 5 was weighed into a 100mL reactor, 15mL (1000 ppmw sulfur content) of diesel blend oil and 10mL of cumene hydroperoxide solution were added, the temperature was raised to 50 ℃ and the reaction time was 2 hours. After the reaction is finished, cooling the reaction kettle to room temperature by using condensed water, opening the reaction kettle, filtering, separating and recovering the titanium nano material catalyst, and detecting the sulfur content of the oil phase by using a Gas Chromatography (GC) with the removal rate of 98.2%.

Comparative example 1

Comparative example 2

Catalyst and process for preparing same	Desulfurization degree%
		H-Fe-TiNTs	97.6
H-Cu-TiNTs	92.2
		H-V-TiNTs	95.3

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept, and these changes and modifications are all within the scope of the present invention.

Claims

1. A method for high-efficiency selective catalytic oxidation desulfurization of diesel oil is characterized by comprising the following steps: contacting heteroatom titanium nano material catalyst and oxidant with diesel oil, heating to 40-60 deg.C, reacting for 0.5-4h,

the preparation method of the heteroatom titanium nano material catalyst comprises the following steps: adding an organic titanium source, a metal salt and an acid solution into a crystallization kettle, stirring the mixture at a temperature of between 80 and 100 ℃, hydrolyzing the mixture for 40 to 60 hours, then adding a NaOH solution, carrying out hydrothermal crystallization at a temperature of between 100 and 180 ℃ for 24 to 96 hours, naturally cooling the mixture to room temperature, washing the obtained white solid with deionized water until the pH value is approximately equal to 7, and drying the white solid to obtain a sodium type heteroatom titanium nanotube;

or the preparation method of the heteroatom titanium nano material catalyst comprises the following steps: adding an organic titanium source, a metal salt and an acid solution into a crystallization kettle, stirring the mixture at a temperature of between 80 and 100 ℃, hydrolyzing the mixture for 40 to 60 hours, then adding a NaOH solution, carrying out hydrothermal crystallization at a temperature of between 100 and 180 ℃ for 12 to 24 hours, then naturally cooling the mixture to room temperature, washing the obtained solid with deionized water until the pH value is approximately 7, roasting the solid at a temperature of between 300 and 500 ℃ for 3 hours, cooling the sample, adding 0.2 to 2mol/L of the acid solution for treatment, sealing the sample, stirring the mixture at normal temperature for 10 to 15 hours, standing the mixture, washing the obtained solid through suction filtration with deionized water until the pH value is approximately 7, and drying the mixture at a temperature of between 70 and 90 ℃ to obtain a heteroatom titanium nano-material catalyst mixed by titanium nano;

the metal salt is a mixture of one or more of ferric salt, copper salt and vanadium salt, and the molar ratio of the metal salt to the titanium is 0.01-0.1.

2. The method for the efficient selective catalytic oxidative desulfurization of diesel oil according to claim 1, characterized in that: adding a sodium type heteroatom titanium nanotube into an HCl solution, sealing, stirring at normal temperature for 10-15 h, standing, performing suction filtration, cleaning a solid with deionized water until the pH value is approximately equal to 7, and drying at 70-90 ℃ to obtain the hydrogen type heteroatom titanium nanotube.

3. The method for the efficient selective catalytic oxidative desulfurization of diesel oil according to claim 1, characterized in that: the organic titanium source is one or a mixture of two of tetrabutyl titanate and tetraisopropyl titanate.

4. The method for the efficient selective catalytic oxidative desulfurization of diesel oil according to claim 1, characterized in that: the ferric salt is ferric nitrate and ferric chloride; the copper salt is copper nitrate or copper chloride; the vanadium salt is ammonium metavanadate, vanadyl sulfate and vanadyl dichloride.

5. The method for desulfurization by highly efficient selective catalytic oxidation of diesel oil according to claim 4, characterized in that: the metal salt is ferric nitrate, cupric nitrate and ammonium metavanadate according to the mass ratio of 1-3: 1-6: 2-5.

6. The method for the efficient selective catalytic oxidative desulfurization of diesel oil according to claim 1, characterized in that: the oxidant is hydrogen peroxide or tert-butyl hydroperoxide or cumene hydroperoxide.

7. The method for the efficient selective catalytic oxidative desulfurization of diesel oil according to claim 1, characterized in that: the oxygen-sulfur ratio is 2.3-6, and the catalyst accounts for 0.5-5 wt% of the system.