JPS6326156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying paraffinic hydrocarbons, and more particularly to a method for purifying paraffinic hydrocarbons, which is characterized by bringing paraffinic hydrocarbons into contact with activated carbon and activated clay impregnated with sulfuric acid. .

Conventionally, when paraffinic hydrocarbons are purified in large quantities, washing with sulfuric acid and alkali has been used. However, the use of sulfuric acid has problems such as corrosion of equipment, inconvenience and danger of handling, complexity of equipment such as mixing tanks and sedimentation tanks, and by-product of tar-like waste sulfuric acid containing a large amount of impurities. Therefore, a simpler method is required even for large-scale purification, but as described above, this method cannot be used for small-scale purification or regeneration because it has many problems. On the other hand, paraffinic hydrocarbons are widely used industrially, and because they are used repeatedly as solvents, or because they have deteriorated during transportation and storage, they cannot be used as solvents.
Alternatively, since it cannot be used as fuel, there was a widespread desire to refine or regenerate it.

The present inventor has researched a method that is simple even for large-scale processing, and simple, stable, and inexpensive even for relatively small-scale processing, and has completed the present invention. That is, in the present invention, paraffinic hydrocarbons are brought into contact with activated carbon and activated clay impregnated with sulfuric acid, so that impurities such as tar, oxidation products, coloring substances, aromatics, or olefinic hydrocarbons are removed from the sulfuric acid. It is removed from paraffinic hydrocarbons by reaction, adsorption with activated carbon or activated clay, or their synergistic action.

In the present invention, the sulfuric acid is impregnated with activated carbon, thus avoiding equipment corrosion, danger, and complication of equipment, which are problems when handling sulfuric acid as a liquid as described above, and can be used in the same way as ordinary activated carbon. be able to. That is, if the activated carbon impregnated with sulfuric acid is powdered activated carbon, it is mixed with paraffinic hydrocarbon and then filtered, and in the case of granular activated carbon, the paraffinic hydrocarbon is sent to a fixed bed or fluidized bed type adsorption tower. Processed paraffinic hydrocarbons containing no sulfuric acid can be obtained by this method. An even greater advantage is that when sulfuric acid treatment and activated clay treatment are combined, if sulfuric acid is used in liquid form, after treating paraffinic hydrocarbons with sulfuric acid, alkali treatment and water washing are performed to remove the remaining sulfuric acid, followed by activated clay treatment. However, according to the present invention, alkaline treatment and water washing can be omitted, and in the case of granular activated carbon, granular activated clay can be filled in the same adsorption tower, and in the case of powdered activated carbon, granular activated clay can be filled in the same adsorption tower. It can be used in combination with activated clay.

Furthermore, by impregnating activated carbon with sulfuric acid, it is possible to obtain the advantage of diversifying the types of impurities that can be removed or increasing the amount of impurities removed.

Activated carbon that can be used in the present invention is not particularly limited as long as it can be used as a liquid, and powdered or granular forms can also be used. A relatively large bore size is preferable because it allows easy impregnation with sulfuric acid and adsorption of impurities in paraffinic hydrocarbons. The concentration of sulfuric acid to be impregnated into activated carbon cannot be absolutely specified depending on the paraffinic hydrocarbon to be refined and the type of impurities, but it is usually 75% or more for removing olefinic hydrocarbons, and 75% or more for aromatic hydrocarbons, tar content, or sulfur compounds. To remove and improve the combustibility of kerosene, etc.,
93% or more is preferred. Therefore, 93% or more sulfuric acid is desirable for purifying paraffinic hydrocarbons containing various impurities.

In the present invention, the amount of sulfuric acid impregnated into the activated carbon varies depending on the type of activated carbon and the sulfuric acid concentration, but is generally 30 to 250%, preferably 50 to 200% by weight of the activated carbon. If the amount of sulfuric acid impregnated is less than the above range, there is no significant difference in purification effect compared to using activated carbon alone, and if it is more than the above range, the activated carbon will be saturated with sulfuric acid and free fluid sulfuric acid will exist on the surface, so sulfuric acid alone will not be effective. When used, the effects, ease of handling, etc. will be similar. The sulfuric acid-impregnated activated carbon, which has a sulfuric acid impregnated amount within the above range and has a similar appearance to activated carbon alone, has superior refining ability not only due to the effects of sulfuric acid or activated carbon alone, but also due to the synergistic effect. show.

The activated clay used in the present invention is preferably one that is commercially available and has a standard for refining paraffinic hydrocarbons. The combination of sulfuric acid-impregnated activated carbon and activated clay can not only handle a wider range of impurities compared to the use of sulfuric acid-impregnated activated carbon or activated clay alone, but also the combination of sulfuric acid-impregnated activated carbon with alkalis, sodium hypochlorite, and (or ) Compared to the case where water washing, or sulfuric acid and/or water washing and activated clay are used in combination, the apparatus is much simpler, and therefore has the advantage of being easier to operate and maintain.

In the present invention, the method of bringing sulfuric acid-impregnated activated carbon or activated clay into contact with paraffinic hydrocarbons is to mix the powder with paraffinic hydrocarbons and then pass through separation, or to continuously or intermittently feed paraffinic hydrocarbons into a container filled with granules. A method of sending liquid directly is used. In this case, the time for contacting the paraffinic hydrocarbon and the sulfuric acid-impregnated activated carbon varies depending on the shape of the activated carbon, the sulfuric acid concentration, the amount of impregnation, or the type of oil, but is generally preferably 10 minutes to 10 hours.

If it is shorter than the above range, the treatment will not be sufficient, and if it is longer, sulfation of paraffinic hydrocarbons may occur, so it is desirable to avoid this. Further, the contact temperature is preferably 5 to 40°C, preferably 10 to 35°C; at temperatures lower than the above range, the purification effect is insufficient, and at higher temperatures, there is a risk of undesirable side effects. The contact time between the activated whiteness and the paraffinic hydrocarbon varies depending on the type of oil, the type of activated clay, etc., so it cannot be uniformly specified, but it is usually 5 minutes or more. Furthermore, if the oil contains impurities that cannot be removed by sulfuric acid-impregnated activated carbon or (and) activated clay, or if they occur during the above treatment steps or if a high degree of purification is required, lipophilic materials may be added to the continuous form. An oil purification method using a porous body formed to form microscopic voids (Japanese Patent Application Laid-open No.
52-96604) can be used in combination as a post-treatment. That is, paraffinic hydrocarbons are mixed with a liquid that is substantially immiscible with the hydrocarbons and has a relatively higher solubility for impurities than the hydrocarbons, and the hydrocarbon phase of the resulting mixed liquid has lipophilic properties. Purified paraffinic hydrocarbons are obtained by immersing one end of a porous body formed by molding a material to form continuous fine voids, and from the other end which hangs down to the outside beyond the outer wall of the container.

Liquids that can be used in the present invention include water, low molecular weight alcohols such as methanol and ethanol, polyhydric alcohols such as ethylene glycol and glycerin, and inorganic or organic acids such as hydrochloric acid and acetic acid, either singly or in combination of two or more. Can be mentioned. Furthermore, depending on the type of impurity, the liquid may contain an appropriate auxiliary agent, such as alkalis such as caustic soda or caustic potash, or a compound that reacts with the impurity to increase its solubility in the liquid, such as EDTA or polyamine. Chelating reagents such as these can be added.

Lipophilic porous materials that can be used in the present invention include lipophilic and hydrophobic synthetic polymers such as polyethylene, polypropylene, polyvinyl chloride and copolymers thereof, polyvinylidene chloride and copolymers thereof, or polystyrene and copolymers thereof; One or two types selected from lipophilic and hydrophobic natural polymers such as wool and kapoku, metals, synthetic polymers that are originally hydrophilic but have undergone hydrophobic treatment, natural polymers, minerals, etc. There are combinations of the above. In addition, the form is that the fiber is made into non-woven fabric or knitted fabric,
There are no particular limitations, such as sponges or granules bonded or fused under pressure. Other properties required of the porous body include the speed at which the oil to be treated rises through the porous body, the time required for it to reach a height of /cm above the liquid level;
It is desirable that the height achieved after 30 minutes is at least 2 cm.

Paraffinic hydrocarbons to which the present invention can be applied include normal, pental, isopental, normal, hexane, isohexane, normal heptane, isoheptane, 2,2,4-trimethylpentane, octane, etc., which are used alone as a solvent. Examples include kerosene, aliphatic naphtha, mineral spirits, petroleum ether, ligroin, and benzine, which are mixtures of hydrocarbons and carbon atoms of various types and are used as solvents or fuels.
The paraffinic hydrocarbons mentioned above are widely used industrially, and when they need to be purified for repeated reuse, when they need to be purified for use in high-purity and precision products, and when they need to be purified for a long period of time. The present invention can be used in cases where fuel has deteriorated due to storage or poor storage conditions, or when it is necessary to improve combustion conditions when used as fuel.

As mentioned above, the present invention allows paraffinic hydrocarbons to be easily and safely purified regardless of the amount of paraffinic hydrocarbons. Because hydrocarbons can be purified and used effectively, they are extremely useful as a means of improving quality, reducing product costs, saving resources, improving thermal efficiency by improving combustibility, and purifying exhaust gas.

The invention will be further illustrated by examples.

Example 1 Yellow-colored kerosene stored in a polyethylene container for about two years was brought into contact with layers of granular activated carbon impregnated with 100% by weight of 93% sulfuric acid and activated clay formed into granules for a contact time of 30 minutes each. The liquid was sent to The obtained recycled kerosene is colorless and transparent, and the total acid value is 0.502mgKOH/g of colored kerosene, and 0.012mg of recycled kerosene.
It was KOH/g. When the colored oil was used in a kerosene stove, solid matter due to tar was observed on the wick within 3 days, and an odor was detected. On the other hand, recycled kerosene had no odor and no abnormalities were observed even after using it for about a month.

Example 2 The recovered naphtha recovered from the waste air in the towel printing process using aliphatic naphtha as thinner was colored brown and had a strong odor, and could not be reused as it was.
Add 10% by weight of powdered activated carbon impregnated with 130% sulfuric acid, stir for 15 minutes and filter, add 10% by weight of powdered activated clay to the liquid, stir for 10 minutes and pass again to regenerate colorless and transparent. I got naphtha. Even when this naphtha was reused, no abnormalities were observed in both product quality and process.

Comparative Example 1 To the same recovered aliphatic naphtha used in Example 2, 2% by weight of 95% sulfuric acid was added and stirred for 15 minutes to separate the sulfuric acid and the aliphatic naphtha based on the difference in specific gravity. This naphtha is washed with water and separated based on the difference in specific gravity, and then 5
% sodium hydroxide aqueous solution and water to obtain recycled naphtha. As mentioned above, although the effort and time required for recycling are greater in Comparative Example 1 than in Example 2, the recycled thinner obtained in Comparative Example 1 has a transparent appearance, but when reused, the color of the product changes. Some turbidity was observed.

Example 3 Normal hexane, which is used to extract oil from oil-containing wastewater, turns brown and develops a strange odor when used repeatedly. This n-hexane was passed through an adsorption tower with a height of 80 cm filled with granular activated carbon impregnated with 150% by weight of 98% sulfuric acid at a flow rate of 10 cm/min, and then passed through an activated clay adsorption tower under the same conditions to make it colorless. Obtained transparent regenerated normal hexane. This normal hexane was confirmed by gas chromatography to be the same as new product.

Comparative Example 2 5% by weight of 98% sulfuric acid was added to the normal hexane used in Example 3, stirred for 5 minutes, normal hexane and sulfuric acid were separated by the difference in specific gravity, washed with water, and normal hexane and water were separated again by the difference in specific gravity. The mixture was then passed through an activated clay adsorption tower under the same conditions as in Example 3 to obtain very slightly colored regenerated normal hexane. Several kinds of impurities were detected in the regenerated normal hexane by gas chromatography, and the types of impurities sometimes changed when the lot of normal hexane sample was changed. This indicates that the sample contains impurities that cannot be removed by washing with sulfuric acid.

Example 4 After passing ligroin containing trace amounts of iron, thiocyanate complex and tar through an adsorption tower with a height of 60 cm filled with granular activated carbon impregnated with 50% by weight of 93% sulfuric acid at a flow rate of 8 cm/min, The ligroin obtained by passing through the activated clay adsorption tower under the same conditions contained iron and thiocyanate complex salts.
% caustic soda aqueous solution was mixed and stirred, and when left to stand for 30 minutes, the mixture was separated into a ligroin phase containing moisture and an aqueous phase containing iron hydroxide. 50 mesh polyethylene powder was molded into the ligroin phase to a density of 300 g/1, and one end of a round rod bent into a ∩ shape was immersed.
The other end was allowed to hang outside over the side wall of the container. Colorless and transparent recycled ligroin was obtained from the other end of this polyethylene rod.

Claims (1)

[Claims] 1. A method for purifying paraffinic hydrocarbons, which comprises bringing the paraffinic hydrocarbons into contact with activated carbon and activated clay impregnated with sulfuric acid.