CN106590734A - Enrichment and separation method for basic nitrides in shale diesel oil - Google Patents

Abstract

The invention relates to a method for enriching and separating basic nitrogen compounds in shale diesel oil. The core of the method is a separation method combining solvent refining and column chromatography. Mix the used extractant with the shale oil diesel fraction in proportion for solvent refining, and obtain the extracted oil that is initially enriched in basic nitrogen compounds after refining; the extracted oil is used as the raw material for deep enrichment of basic nitrogen compounds, and then further concentrated by column chromatography Separation, solvent removal, and vacuum drying give basic nitrides.

Description

A method for the enrichment and separation of basic nitrogen compounds in shale diesel oil

technical field

The application belongs to the technical field of shale oil processing, and in particular relates to a method for enriching and separating basic nitrides in shale diesel oil.

Background technique

Shale oil is a potential energy source with abundant reserves in the world, and its total storage capacity far exceeds that of petroleum. Compared with natural petroleum, shale oil contains a large amount of unsaturated hydrocarbons and non-hydrocarbon compounds such as N, S, and O. In China, shale oil is mostly used as fuel for extensive combustion, which produces a large amount of NO _x and SO ₂ during the combustion process, causing environmental pollution and low energy utilization value. Nitrogen compounds in oil products can generally be divided into basic nitrogen compounds and non-basic nitrogen compounds. The existence of basic nitrides has a direct impact on the reprocessing and utilization of shale oil, and they are toxic substances to be removed or transformed, but they are very valuable chemical raw materials. Basic nitrides are widely used in industry, medicine, preservatives, flotation agents, synthetic materials and other fields. In recent years, the research on extracting basic nitrogen compounds from coal tar, shale oil and petroleum products has attracted extensive attention of researchers at home and abroad.

At present, the extraction methods of basic nitrogen compounds in shale oil mainly include solvent refining, complexation separation, acid-base elution, column chromatography, thin-layer chromatography, and combinations of the above methods.

Solvent refining is a new separation technology developed rapidly in the 20th century, that is, solvent extraction. The method adopted is based on the principle of similar miscibility. The difference is selectively separated, and the separation effect is better.

The complexation separation method applies the Lewis acid-base theory, and the complexing agent and the basic nitrogen compound form a complex and layer the oil phase under the complexing force of the Lewis acid and the Lewis base, thereby separating the basic nitrogen compound from the Oil separation. However, the direct treatment of shale oil by complexation refining is ineffective. Chinese patent CN 103937522 A discloses a method for separating nitrogen-containing compounds in coal tar. The complexing separation agent used contains metal chlorides, phosphates and halogenated salts, wherein the mass ratio of metal chlorides to halogenated salts is 0.05-0.2, phosphoric acid The mass ratio of the salt to the halogenated salt is 0.04-0.15, and the mass ratio of the complexing separation agent to the coal tar is 0.05-0.7. The method realizes the selective and rapid separation of nitrogen-containing compounds in coal tar, and the separation effect is good. However, the cost of the complexing and separating agent used in this method is relatively high, and the preparation is relatively complicated.

Acid-base elution is based on the basic nitrides are basic, and the principle of acid-base neutralization is used to react with strong acids to separate the basic nitrides. U.S. Patent US 52637 is to add a kind of relatively shale oil has higher volatility easy-to-miscible non-polar diluent, or adopt the method of direct heating, to reduce the viscosity of shale oil, then use a kind of formic acid, Selective solvents composed of one or more of acetic acid and trichloroacetic acid are used to extract nitrogen compounds, and 76.38% and 87.62% of nitrogen can be removed with formic acid and acetic acid, respectively. This method has high selectivity, but it needs to use a large amount of acid and alkali, and has high requirements for equipment anticorrosion.

Column chromatography belongs to liquid-solid adsorption chromatography, which is a technique based on the principle of adsorption-dissolution. Using various intermolecular forces such as van der Waals force and hydrogen bonds between the two phases, when the mixture solution is added to the stationary phase, each component in the mixture is adsorbed on the solid surface with different strengths of action. Due to the different adsorption capacity of the adsorbent for each substance, the components with strong adsorption are less distributed in the mobile phase, while the components with weak adsorption are distributed more in the mobile phase, so that the components in the mixture are effectively separated.

Thin-layer chromatography belongs to solid-liquid adsorption chromatography. It is a trace separation and analysis method. It has the advantages of simple equipment, fast speed, good separation effect, and high sensitivity. However, it is only suitable for the separation of small amounts of samples.

Contents of the invention

The present invention aims at the problems existing in the above-mentioned prior art, and provides a method for enriching and separating basic nitrogen compounds in shale diesel oil. The method adopts a separation method combining solvent refining and column chromatography, which is simple and feasible to operate, and can separate basic nitrogen compounds from hydrocarbons, non-basic nitrogen compounds, and phenolic compounds, so that the basic nitrogen compounds in shale oil can be obtained Effective enrichment separation.

Technical scheme of the present invention comprises the following steps:

The extractant and shale diesel are mixed in a molar ratio of 0.3-2:1 for stirring reaction. After standing for a period of time, the oil product is divided into two layers. The extractant in the upper layer and the lower layer can be recovered by vacuum distillation and recycled; After the lower layer removes the extractant, the extracted oil that is initially enriched in basic nitrogen compounds is obtained; the extracted oil is concentrated and separated by column chromatography, acid extracts basic compounds, alkali neutralizes acid, solvent back extracts basic nitrogen compounds, solvent removal, vacuum Dry to obtain basic nitrides.

The extractant is one or more of N,N-dimethylformamide, furfural, dimethylsulfoxide and N-methylpyrrolidone.

The stirring reaction temperature is 50-80°C.

The settling time is 10-50min.

The column chromatography solid adsorbent is silica gel.

The mobile phase of the column chromatography is a mixed solution of petroleum ether and benzene/methanol.

The volume ratio of the benzene/methanol mixed solution in the column chromatography mobile phase is 1-2:1.

Described acid is hydrochloric acid, and concentration is 3mol/L.

Described alkali is sodium hydroxide or potassium hydroxide.

Described solvent is n-hexane.

The advantages and effects of the present invention are as follows:

The invention adopts a separation method combining solvent refining and column chromatography, which is simple and feasible to operate, can separate basic nitrogen compounds from hydrocarbons, non-basic nitrogen compounds and phenolic compounds, and is beneficial to the enrichment and separation of basic nitrogen compounds. At the same time, the use of a large amount of acid and alkali aqueous solutions is avoided, and the extraction agent can be recycled, which greatly reduces the production cost, and effectively enriches and separates the basic nitrogen compounds in shale oil, improving the comprehensive utilization of shale oil At the same time, it is beneficial to the processing and refining of shale oil.

Description of drawings

Figure 1 is the chromatogram of the final product.

detailed description

Example 1

Mix 90ml of N,N-dimethylformamide with 300ml of shale diesel (the molar ratio is 0.3:1), heat and stir in a water bath, set the heating temperature to 50°C, and pour it into a separatory funnel after stirring The sample was separated into layers, and after standing for 10 minutes, the oil product in the lower layer was distilled to obtain extracted oil and N,N-dimethylformamide, and N,N-dimethylformamide was recycled. The extracted oil was separated by column chromatography, 50g of silica gel was weighed, and chromatographically eluted with 80mL of petroleum ether and 80mL of benzene/methanol mixed solution (1:1 by volume) in sequence. The obtained benzene/methanol eluate was extracted 3 times with water to separate the benzene layer solution, then extracted the benzene layer solution with 3mol/L HCl to obtain the inorganic layer, and neutralized the inorganic layer with 6mol/L NaOH solution to PH = 11, then adding n-hexane for extraction three times, extracting the basic nitrogen compound from the water phase, and distilling off the solvent to obtain the basic nitrogen compound.

Example 2

Mix the extractant dimethyl sulfoxide and shale diesel at a molar ratio of 0.5:1 for a stirring reaction. The stirring reaction temperature is 50°C. After standing and settling for 20 minutes, the oil product is divided into two layers. Recover by vacuum distillation and recycle; the lower layer removes the extractant to obtain the extracted oil that is initially enriched with basic nitrogen compounds; the extracted oil is concentrated and separated by column chromatography, acid extraction of basic compounds, alkali neutralization of acid, and solvent back extraction Basic nitrides, solvent removal, and vacuum drying to obtain basic nitrides. The column chromatography solid adsorbent is silica gel; the column chromatography mobile phase is petroleum ether, benzene/methanol mixed solution; the volume ratio of benzene/methanol mixed solution is 1:1; other steps are the same as in Example 1.

Example 3

The extraction agent N-methylpyrrolidone and shale diesel are mixed in a molar ratio of 1:1 for stirring reaction. The stirring reaction temperature is 70°C. After standing for 50 minutes, the oil product is divided into two layers. Recover by vacuum distillation and recycle; the lower layer removes the extractant to obtain the extracted oil that is initially enriched with basic nitrogen compounds; the extracted oil is concentrated and separated by column chromatography, acid extraction of basic compounds, alkali neutralization of acid, and solvent back extraction Basic nitrides, solvent removal, and vacuum drying to obtain basic nitrides. The column chromatography solid adsorbent is silica gel; the column chromatography mobile phase is petroleum ether, benzene/methanol mixed solution; the volume ratio of benzene/methanol mixed solution is 1.2:1; other steps are the same as in Example 1.

Example 4

Mix the extractant furfural and shale diesel at a molar ratio of 1:1 for stirring reaction. The stirring reaction temperature is 60°C. After standing for 30 minutes, the oil product is divided into two layers. The extractant in the upper layer and the lower layer can be distilled under reduced pressure. Recovery and recycling; after the lower layer removes the extractant, the extracted oil that is initially enriched with basic nitrogen compounds is obtained; the extracted oil is concentrated and separated by column chromatography, acid extraction of basic compounds, alkali neutralization of acid, and solvent back extraction of basic nitrogen compounds , solvent removal, and vacuum drying to obtain basic nitrides. The column chromatography solid adsorbent is silica gel; the column chromatography mobile phase is petroleum ether, benzene/methanol mixed solution; the volume ratio of benzene/methanol mixed solution is 1:1; other steps are the same as in Example 1.

Example 5

Mix the extractant N, N-dimethylformamide and shale diesel oil in a molar ratio of 2:1 for stirring reaction. The stirring reaction temperature is 80°C. After standing for 50 minutes, the oil product is divided into two layers, the upper layer and the lower layer. The extractant can be recovered by vacuum distillation and recycled; after the lower layer removes the extractant, the extracted oil that is initially enriched with basic nitrogen compounds is obtained; the extracted oil is concentrated and separated by column chromatography, acid extracts basic compounds, alkali neutralizes acid, Solvent back extraction of basic nitrides, solvent removal, and vacuum drying to obtain basic nitrides. The column chromatography solid adsorbent is silica gel; the column chromatography mobile phase is petroleum ether, benzene/methanol mixed solution; the volume ratio of benzene/methanol mixed solution is 2:1; other steps are the same as in Example 1.

Implementation results

The final product enriched in Example 4 was characterized by gas chromatography-mass spectrometry (GC-MS), and the results are shown in FIG. 1 and Table 1. Table 2 shows the gradient enrichment results of basic nitrides in Example 4.

The basic nitrogen compounds in shale oil can be effectively enriched and separated by combining solvent refining and column chromatography. The relative mass fraction of basic nitrogen compounds is gradually concentrated from 12.08% of the extracted oil to that of the final enriched product. 69.48%. In the final product of enrichment and separation, 60 kinds of basic nitrogen compounds were identified, mainly alkyl-substituted compounds such as aniline, pyridine, quinoline, and isoquinoline.

The GC-MS result of table 1 final product

Table 2 Gradient enrichment results of basic nitrogen compounds in shale diesel

Claims (10)

1. a kind of method of shale diesel oil neutral and alkali nitride concentration and separation, its feature：The method is comprised the following steps：Will extraction Agent is mixed by a certain percentage with shale oil diesel oil distillate, is stirred reaction at a certain temperature, standing sedimentation for a period of time after Oil product is divided into two-layer, and the extractant of the upper and lower can be reclaimed by vacuum distillation, be recycled.Obtain after the de- extractant of lower floor The tapped oil of preliminary concentration basic nitrogen compound.Tapped oil Jing column chromatography concentrating and separating, acid extracting alkali compoundss, in alkali and acid, Solvent back suction carries basic nitrogen compound, desolventizing, is vacuum dried to obtain basic nitrogen compound.

2. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：Extraction The mass ratio that agent is taken with shale diesel oil is 0.3-2：1.

3. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1 and 2, its feature exist In：Described extractant is one or more of DMF, furfural, dimethyl sulfoxide, N-Methyl pyrrolidone.

4. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：Institute The stirring reaction temperature stated is 50-80 DEG C.

5. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：It is heavy The drop time is 10-50min.

6. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：Post Chromatography solid adsorbent is silica gel, and mobile phase is petroleum ether, benzene/methanol mixed solution.

7. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 6, it is characterised in that：Post In chromatogram flow phase, the volume ratio of benzene/methanol mixed solution is 1-2：1.

8. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：Institute The acid stated is hydrochloric acid, and concentration is 3mol/L.

9. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that：Institute The alkali stated can use sodium hydroxide or potassium hydroxide.

10. the method for a kind of shale diesel oil neutral and alkali nitride concentration and separation according to claim 1, it is characterised in that： Described solvent is normal hexane.