JP2003003176A - New dewaxing aid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-cooling dewaxing method using a lower hydrocarbon solvent, which is effective for light and heavy wax-containing hydrocarbon oils and is problematic for chlorine compounds and low molecular acids. Develop a dewaxing aid that can be dewaxed without using naphthalene condensate or vinyl acetate copolymer. SOLUTION: The side chain has a polyalkyl methacrylate (1) having an alkyl chain length of 10 to 20 carbon atoms and a weight average molecular weight of 10,000 to 800,000, and the side chain has 1 carbon atom.
Having an alkyl chain length of 6 to 30 and a weight average molecular weight of 10.0
A mixture of polyalkyl acrylate (2) having a mass ratio of (1) to (2) of (1) :( 2) = 9: 1 to 100: 1, and a wax-containing carbon 0.001 to 1.00 mass% is added to the hydrogen oil.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dewaxing aid used in a solvent dewaxing method with a lower hydrocarbon in a lubricating oil production process, and particularly to a wax-containing hydrocarbon oil and a dewaxing agent in the dewaxing process. The auxiliary agent is dissolved in a lower hydrocarbon solvent and internally cooled by the heat of vaporization to precipitate the wax present in the wax-containing hydrocarbon oil, and the deposited wax is liquid /
The present invention relates to a dewaxing auxiliary agent used in a dewaxing method for separating a solid by a solid separation method to produce a dewaxed oil.

[0002]

2. Description of the Related Art Generally, in order to produce a hydrocarbon oil from a crude oil, first, the crude oil is distilled under atmospheric pressure, and the residual oil is further distilled under reduced pressure to obtain various wax-containing hydrocarbon oils of low to high viscosity. Separate into vacuum distillation bottoms. Further, bright stock, which is a wax-containing hydrocarbon oil having the highest viscosity, can be produced by subjecting these to a solvent deasphalting treatment from the vacuum distillation residual oil to remove the asphalt content.

The thus obtained wax-containing hydrocarbon oil of various viscosities is subjected to a series of treatments such as a combination of solvent extraction, hydrorefining and dewaxing, or a combination of hydrocracking, solvent extraction, hydrorefining and dewaxing. Processed to hydrocarbon oil.

The dewaxing step among the above-mentioned production steps is a step of producing a low pour point hydrocarbon oil by removing the wax content in the wax-containing hydrocarbon oil.

When the dewaxing step is carried out industrially, a solvent dewaxing method is generally used which is capable of treating wax-containing hydrocarbon oils such as light type and heavy type. In the solvent dewaxing method, a wax-containing hydrocarbon oil, a dewaxing solvent, and a dewaxing auxiliary agent are dissolved, and wax is precipitated while cooling to form a slurry. This slurry is supplied to a solid / liquid separator (filtration, centrifugation, etc.), and after separation, the dewaxing solvent is removed to obtain dewaxed oil.

The solvent dewaxing method is roughly divided into two methods. One is a mixture of ketones (acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK) and mixtures thereof), and aromatic hydrocarbons (benzene, toluene, xylene) (MEK /
It is a method of lowering the cooling cost by increasing the cooling temperature by utilizing its solubility. This method is widely used and can be dewaxed without using a dewaxing aid, but in order to improve the filtration efficiency and the dewaxed oil yield especially in heavy oil, the dewaxing aid is used. used. The other method is to use lower hydrocarbons (propane, propylene, butane, pentane, etc.) and internally cool them by the heat of vaporization by adjusting the pressure and reduce the cooling cost by self-cooling (Exxon process). )
Is. In this method, a dewaxing aid is essential,
In particular, for light and heavy wax-containing hydrocarbon oils, it has been essential to use an alkylnaphthalene polymer.

A factor limiting the throughput in the solvent dewaxing process is the filtration rate at which the wax is separated from the slurry. This rate is affected by the crystal structure of the deposited wax. The crystal structure of the deposited wax is influenced by the operating conditions in the dewaxing process. Especially the cooling rate,
By changing the conditions such as stirring speed and cooling temperature, the size, crystal structure, and state of oil in the precipitated wax will change significantly even with the same wax-containing hydrocarbon oil, affecting the filtration rate and the yield of dewaxed oil. Exert. In particular, when ketones are used as a dewaxing solvent, when the wax-containing hydrocarbon oil is heavy, the filtration rate is lowered, the dewaxed oil yield is reduced, the filter is clogged, and the like, which often causes troubles. In order to improve the filtration rate and the dewaxed oil yield, various process improvements and various methods for adding a dewaxing aid have been investigated.
On the other hand, lower hydrocarbons such as propane dewaxing, such as propane dewaxing, are difficult to evaluate in the laboratory due to the difficulty of handling the solvent used. However, since the correlation between the evaluation in the laboratory and the actual equipment could not be obtained, the study has been limited. Further, at present, the use of an alkylnaphthalene condensate is indispensable in an actual machine, and in recent years, due to environmental problems and the like, it is desired to reduce the cost of the dewaxing aid and the chlorine content in the dewaxing aid. ing.

Dewaxing aids have hitherto been lower hydrocarbons,
The following techniques are known techniques for a self-cooling type dewaxing method such as propane dewaxing. Japanese Patent Sho 49
-46361 and JP-A-53-129202 describe the effect of using an alkylnaphthalene condensate or a mixture with a polyalkylmethacrylate. The alkylnaphthalene condensate is generally obtained by the Friedel-Crafts reaction using chlorinated paraffin as a raw material, so that it cannot be said that the chlorine content contained therein is completely absent. In recent years, products that do not use chlorine-containing raw materials have been strongly desired due to the problem of generation of dioxins, etc. in all fields, and similar problems with dewaxing aids due to equipment corrosion and post-process catalyst poisoning problems. There is a tendency.

Japanese Patent Publications 45-15379 and 49-2
6922, JP-A-54-11104, and JP-A-53-12
1804, JP-A-60-217218, JP-A-61-2
47793 describes the effect of the mixed use of ethylene vinyl acetate copolymer and various drugs. However, a compound having a vinyl acetate group may be decomposed by heat or the like to generate acetic acid. Acetic acid has a corrosive effect not only on iron but also on metals such as SUS, and therefore becomes a concern for the apparatus.

In the external cooling dewaxing method using a ketone as a dewaxing solvent, JP-A-54-12310 is used.
2, JP-A-57-30792, JP-A-7-31656
7, JP-A-55-89392, JP-B-7-116454
Describes the effect of using polyalkyl (meth) acrylate and polyvinylpyrrolidone. However, these have the effect of increasing the efficiency of filtration, and are mainly used for heavy oils such as bright stock, and cannot be produced without filter aids for lower hydrocarbons and propane dewaxing. In such a self-cooling type dewaxing method, due to the difference in the solvent used and the cooling method, no effect can be obtained for the wax-containing hydrocarbon oils of light type and heavy type, and the use of an alkylnaphthalene condensate is essential. There is. For self-cooling dewaxing processes, there is a further need for effective chlorine-free auxiliaries.

[0011]

The problem to be solved by the present invention is that in the self-cooling type dewaxing method using a lower hydrocarbon solvent using the dewaxing aid described in the prior art, the wax-containing wax carbonization is performed. Depending on the type of hydrogen oil, there is a lack of general versatility, or the disadvantages that these compounds cannot be avoided due to their structure and manufacturing (containing chlorine, products during decomposition corrode the equipment, etc.) To do. That is,
It has an effect on light type and heavy type wax-containing hydrocarbon oils, and has an alkylnaphthalene condensate that cannot avoid containing chlorine compounds in production or a reactive monomer that may release a low molecular acid when structurally decomposed. It is to develop a dewaxing aid for a self-cooling system that uses a lower hydrocarbon solvent that can be dewaxed without using a vinyl acetate copolymer or the like.

[0012]

In order to solve these above problems, the present inventor diligently investigated a test method that correlates with an actual machine, and as a result, a self-cooling method using a lab-scale lower hydrocarbon solvent was used. A dewaxing method was developed. Evaluation of various drugs using the evaluation method revealed that some drugs may liberate low molecular weight acid during alkylnaphthalene condensate or structural decomposition which cannot avoid containing chlorine compounds in production. In a self-cooling type dewaxing method using a lower hydrocarbon solvent, without using a vinyl acetate copolymer having a reactive monomer, not only in a heavy system,
It has been found that it is also effective for wax-containing hydrocarbon oils such as light type, that is, it can improve the filtration rate and dewaxed oil yield.

That is, according to the present invention, a wax-containing hydrocarbon oil and a dewaxing aid are dissolved in a lower hydrocarbon solvent and self-cooled to deposit a wax, and the deposited wax is removed by a liquid / solid separation method. Used in a dewaxing method of obtaining wax oil, having a side chain with an alkyl chain length of 10 to 20 carbon atoms and a weight average molecular weight of 10,000 to 800,
000 polyalkyl methacrylate (1) and a polyalkyl acrylate (2) having a side chain of an alkyl chain length of 16 to 30 carbon atoms and a weight average molecular weight of 10,000 to 800,000, wherein ) And (2) in a mass ratio of (1) :( 2) = 91 to 100: 1, and is added at 0.001 to 1.00 mass% with respect to the wax-containing hydrocarbon oil. The present invention also relates to a solvent dewaxing method using a lower hydrocarbon solvent, which is a wax auxiliary agent and uses the above dewaxing auxiliary agent, and further to a dewaxing auxiliary agent in which the lower hydrocarbon solvent is propane.

The dewaxing method in which the dewaxing aid of the present invention is effective is a dewaxing method of a lower hydrocarbon solvent. For example,
Propane, propylene, and hydrocarbons that are gaseous at room temperature
Butane and butene can be used. Particularly, propane is generally widely used as a dewaxing solvent.

The alkyl group (1) has 10 to 20 carbon atoms.
As the alkyl methacrylate of, even a single
There may be a distribution. Common examples are decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate, octadecyl methacrylate, nonadecyl methacrylate,
Examples thereof include copolymers of eicosylmethacrylate and the like and mixtures thereof, or mixtures of these polymers. More preferably, the polymethacrylate is not single but has a width in carbon number, and further, polymethacrylate in which the carbon number of 14 or more of the alkyl group is 60% or more is desirable.

In (2), the alkyl group has 16 to 30 carbon atoms.
Of alkyl acrylates, which may be single or distributed. As a general example, a copolymer of hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, docosyl acrylate, tetracosyl acrylate, etc., or a mixture thereof, or a mixture of these polymers. Can be given. More preferably, the polymethacrylate is not single but has a width in the number of carbon atoms, and further, polymethacrylate in which the number of carbon atoms of 18 or more in the alkyl group is 80% or more is desirable.

The existing mass ratio of (1) and (2) is
(1): Within the range of 9: 1 to 1001 as shown in (2), it is desirable in terms of performance. More preferably,
(1): Within the range of 20: 1 to 50: 1 in terms of (2), it is desirable in terms of performance. If the ratio of (2) is too high or too low, the filtration rate and the oil yield are deteriorated, which is not desirable.

Further, (1) has an alkyl chain length of 10 to 20 carbon atoms and a weight average molecular weight of 10,000 to 800,
It is preferably 000. Also, (2) is a carbon number 1
Weight average molecular weight 10,0 having an alkyl chain length of 6 to 30
It is preferably from 00 to 800,000. When the weight average molecular weight is less than 10,000, the performance as a dewaxing aid is lowered, and a higher molecular weight is more effective,
When the weight average molecular weight is more than 800,000, the solubility in the dewaxed hydrocarbon oil or the dewaxing solvent deteriorates,
The viscosity becomes high and handling becomes difficult.

The synthesis of (1) can be performed by any conventional method. For example, it can be obtained by an esterification reaction of an alcohol having 10 to 20 carbon atoms and methacrylic acid, and radical polymerization using a peroxide or an azobis compound as an initiator or thermal polymerization by heating. However, the weight average molecular weight is 10,000 to 800,
It is also possible to use reaction conditions such as temperature and the use of a chain transfer agent so as to bring the range to 000. Generally, the higher the reaction temperature, the lower the weight average molecular weight, and the lower the reaction temperature, the higher the weight average molecular weight. Also, the addition of a chain transfer agent lowers the weight average molecular weight. By utilizing the above tendency, it is easy to bring the weight average molecular weight into the specified range.

Similarly, the synthesis of (2) is an arbitrary method according to the prior art. For example, it is possible to obtain (2) by an esterification reaction of an alcohol having 16 to 30 carbon atoms and acrylic acid, and radical polymerization using a peroxide or an azobis compound as an initiator, or thermal polymerization by heating. is there. However, the weight average molecular weight is 10,000 to 80
It is also possible to use reaction conditions such as temperature and the use of a chain transfer agent in order to set the range to 50,000. Similar to the above (1), it is easy to set the weight average molecular weight within the specified range.

The dewaxing aid of the present invention may contain other components as long as the effects of the present invention are not impaired.
In terms of dewaxing performance (in terms of filtration rate and improvement of dewaxed oil yield), it is considered that they can be used in combination, copolymers of alkyl acrylate and alkyl methacrylate, polymers of olefins and vinyl acetate or (meth) acrylate, etc. Copolymers of

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In order to evaluate the product of the present invention,
A lab-scale self-cooling method was used. This method
A wax-containing hydrocarbon oil is dissolved in a dewaxing solvent (normal hexane) and placed in a flask with a condenser which is kept warm with depressurizable urethane or the like. While adjusting the degree of vacuum, by vaporizing the solvent and then condensing with a condenser and returning to the system,
The heat of vaporization internally cools the system, and the cooling rate is 2 ° C / min.
A slurry was produced by cooling to 36 ° C. Then, the wax is separated from the slurry by filtration, and the dewaxing solvent is removed to obtain a dewaxed oil.
The filtration rate and the dewaxing oil yield at this time were measured to evaluate the performance of the dewaxing aid.

[0023]

EXAMPLES The present invention will be described below with reference to synthetic examples, examples, comparative examples, and test methods of (1) and (2). The present invention is a synthetic example of these (1) and (2). However, the present invention is not limited to Examples, Comparative Examples and test methods.

Synthesis Example 1 12 to 18 carbon atoms (C12 = 20%, C14 = 25%,
C16 = 25%, C18 = 30%) 40 parts of alkyl methacrylate and 60 parts of mineral oil were placed in a flask equipped with a stirrer, a nitrogen blowing tube, a thermometer, and a condenser.
After sufficiently substituting with nitrogen, 0.1 part of AIBN (azobisisobutyronitrile) as an initiator was added, and the mixture was heated to 100 ° C. and aged at the same temperature for 8 hours to give a polymer having a weight average molecular weight of 420,000. Alkyl methacrylate was obtained. The compound obtained by this operation was used as an auxiliary agent (A).

Synthesis Example 2 Carbon number 18 to 22 (C18 = 42%, C20 = 15%,
(C22 = 43%) Alkyl acrylate (40 parts) and mineral oil (60 parts) were placed in a flask equipped with a stirrer, a nitrogen blowing tube, a thermometer, and a condenser, and nitrogen was sufficiently replaced for 3 hours to prepare an initiator AIBN (0.1 part). The mixture was added, heated to 100 ° C., and aged at the same temperature for 8 hours to obtain a polyalkyl acrylate having a weight average molecular weight of 310,000. The compound obtained by this operation was used as an auxiliary agent (B).

Synthesis Example 3 Carbon number 6 to 10 (C6 = 5%, C8 = 75%, C10 =
20%) 40 parts of alkyl methacrylate and 60 parts of mineral oil
Part was placed in a flask equipped with a stirrer, a nitrogen blow-in tube, a thermometer, and a condenser, and nitrogen substitution was sufficiently performed for 3 hours, 0.1 part of AIBN initiator was added, and the mixture was heated to 100 ° C. and kept at the same temperature for 8 hours. By aging for a time, a polyalkyl methacrylate having a weight average molecular weight of 370,000 was obtained. The compound obtained by this operation was used as an auxiliary agent (C).

Synthesis Example 4 Carbon number 12 to 15 (C12 = 20%, C13 = 31%,
C14 = 33%, C15 = 16%) 40 parts of alkyl acrylate and 60 parts of mineral oil are stirred, a nitrogen blowing tube,
Put in a flask equipped with a thermometer and a condenser, sufficiently perform nitrogen substitution for 3 hours, add 0.1 part of AIBN as an initiator, heat to 100 ° C., and age for 8 hours to obtain a weight average molecular weight. 410,000 polyalkyl acrylates were obtained. The compound obtained by this operation was used as an auxiliary agent (D).

Test Method A wax-containing hydrocarbon oil (light type, heavy type) was added to normal hexane (2.3 times by mass with respect to the wax-containing hydrocarbon oil) and added thereto.
The mixture was heated at 0 ° C. to be dissolved, and the dewaxing aid synthesized above was added thereto, and the mixture was stirred and cooled to −36 ° C. at a cooling rate of 2 ° C./min while adjusting the degree of pressure reduction. After that, a filter equipped with a filter cloth used in an actual apparatus was put into a slurry composed of wax, normal hexane, a dewaxing oil, and a dewaxing aid, and vacuum filtration was performed at 600 mmHg. At this time, the time when the amount of the filtrate reached 50 ml was measured, and the filtration rate was calculated from the following formula. The obtained filtrate and normal hexane contained in each of the wax collected in the filter after filtration were removed by vacuum topping with an evaporator, the weight of each was measured, and the dewaxed oil yield was calculated from the following formula. I asked.

Calculation formula of filtration rate (ml / h · cm ² )

[Equation 1] Dewaxed oil yield calculation formula (mass%)

[Equation 2]

Example 1 0.36 g of the auxiliary agent (A) of the present invention obtained in Synthetic Example 1 and 0.04 g of the auxiliary agent (B) obtained in Synthetic Example 2 were heated while heating and were light. -Based wax-containing hydrocarbon oil (200 g) was added and dissolved, and normal hexane 700 m
1 was added and dissolved, and the test was conducted according to the test method.
That is, the amounts of the auxiliary agent (A) and the auxiliary agent (B) of the present invention added were 0.
The test was conducted by setting the content to 2% by mass (0.08% in terms of pure amount of the auxiliary agent).

Example 2 0.38 g of the auxiliary agent (A) of the present invention obtained in Synthetic Example 1 and 0.02 g of the auxiliary agent (B) obtained in Synthetic Example 2 were heated while heating and were light. -Based wax-containing hydrocarbon oil (200 g) was added and dissolved, and normal hexane 700 m
1 was added and dissolved, and the test was conducted according to the test method.
That is, the amounts of the auxiliary agent (A) and the auxiliary agent (B) of the present invention added to the light and heavy wax-containing hydrocarbon oils were 0.2 and 0.2, respectively.
The test was carried out by setting the content to be% by mass (0.08% in terms of pure amount of the auxiliary agent).

Example 3 0.0396 g of the auxiliary agent (A) of the present invention obtained in Synthesis Example 1
And 0004 g of the auxiliary agent (B) obtained in Synthesis Example 2 are added and dissolved in 200 g of light-type and heavy-type wax-containing hydrocarbon oils while heating, and normal hexane 70
0 ml was added and dissolved, and the test was conducted according to the test method. That is, the addition amount of the auxiliary agent (A) and the auxiliary agent (B) of the present invention was 0.2% by mass (0.08% in terms of the total amount of the auxiliary agent) with respect to the light and heavy wax-containing hydrocarbon oils, respectively. Then, the test was conducted.

Comparative Example 1 0.40 g of the auxiliary agent (A) obtained in Synthesis Example 1 was added and dissolved in 200 g of light type, heavy type, and bright stock wax hydrocarbon oil containing bright stock, respectively, while heating. 700 ml of hexane was added and dissolved, and the test was conducted according to the test method. That is, the amount of the auxiliary agent (A) added was 0.2 for light and heavy wax-containing hydrocarbon oils, respectively.
The test was carried out by setting the content to be% by mass (0.08% in terms of pure amount of the auxiliary agent).

Comparative Example 2 0.20 g of the auxiliary agent (A) obtained in Synthesis Example 1 and 0.20 g of the auxiliary agent (B) obtained in Synthesis Example 2 were heated while heating. 200 g of heavy-type and wax-containing hydrocarbon oils were added and dissolved, respectively, and further n-hexane 70
0 ml was added and dissolved, and the test was conducted according to the test method. That is, the amount of the auxiliary agent (B) added was set to 0.2% by mass (0.08% in terms of the total amount of the auxiliary agent) with respect to each of the light type and heavy type wax-containing hydrocarbon oils, and the test was conducted. .

Comparative Example 3 0.34 g of the auxiliary agent (A) obtained in Synthesis Example 1 and 0.06 g of the auxiliary agent (B) obtained in Synthesis Example 2 were heated while heating. Add and dissolve in 200 g of heavy wax-containing hydrocarbon oil, and then add normal hexane 700
ml was added and dissolved, and the test was conducted according to the test method. That is, the amounts of the auxiliary agent (A) and the auxiliary agent (B) added were set to 0.2% by mass (0.08% in terms of the total amount of the auxiliary agent) with respect to the light and heavy type wax-containing hydrocarbon oils, respectively. , A test was conducted.

Comparative Example 4 0.38 g of the auxiliary agent (A) obtained in Synthesis Example 3 and 0.02 g of the auxiliary agent (D) obtained in Synthesis Example 3 were heated and heated to a light type or heavy type wax-containing wax. Hydrocarbon oil (200 g) was added and dissolved, and normal hexane (700 ml) was added and dissolved, and the test was conducted according to the test method. That is,
The amount of each of the auxiliary agent (A) and the auxiliary agent (D) added was set to 0.2% by mass (0.08% in terms of the total amount of the auxiliary agent) with respect to the light and heavy wax wax-containing hydrocarbon oils, and the test was conducted. Was done.

Comparative Example 5 0.38 g of the auxiliary agent (C) obtained in Synthesis Example 3 and 0.02 g of the auxiliary agent (B) obtained in Synthesis Example 4 were heated and heated to a light type or heavy type wax containing wax. Hydrocarbon oil (200 g) was added and dissolved, and normal hexane (700 ml) was added and dissolved, and the test was conducted according to the test method. That is,
The amounts of the auxiliary agent (C) and the auxiliary agent (B) added were set to 0.2% by mass (0.08% in terms of pure auxiliary agent content) with respect to each of the light and heavy wax-containing hydrocarbon oils and tested. Was done.

Comparative Example 6 As an auxiliary agent currently used in an actual apparatus, as a typical commercial product of polyalkylnaphthalene, Leblanc AD (manufactured by Toho Chemical Industry, 70% active ingredient) auxiliary agent (E) 0.20 g
Reblanc 145 (manufactured by Toho Chemical Industry, active ingredient 40%) as a representative commercial product of polymethacrylate and polymethacrylate (F)
0.20 g was added to and dissolved in 200 g of light type and heavy type wax-containing hydrocarbon oils while heating, and 700 ml of normal hexane was further added and dissolved, and the test was performed according to the test method. That is, the amount of each of the auxiliary agent (E) and the auxiliary agent (F) added was 0.2% by mass with respect to the light type and heavy type wax-containing hydrocarbon oils (0.1% in terms of the amount of the auxiliary agent).
1%) and tested.

Comparative Example 7 A test was carried out on a light type and heavy type wax-containing hydrocarbon oil without using an auxiliary agent.

The dewaxing performance for the light wax wax-containing hydrocarbon oils obtained in Examples 1 to 3 and Comparative Examples 1 to 7 is shown in Table 1, and the dewaxing performance for the heavy wax wax-containing hydrocarbon oils is shown in Table 2. It was shown to.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

As is clear from Tables 1 and 2, when the chlorine-free dewaxing aid of the product of the present invention is used in the dewaxing step, filtration is more effective than when no dewaxing aid is added. The speed can be greatly improved. Further, even when compared with the mixed use of an alkylnaphthalene polymer and polymethacrylate, which is widely used at present in an actual apparatus, a filtration rate and a dewaxed oil yield which are equal to or higher than those obtained are obtained. For light type wax-containing hydrocarbon oils, the filtration rate of the auxiliary agent of the prior art and that of the present invention are almost the same, but the dewaxed oil yield is significantly improved. Also, for heavy type wax-containing hydrocarbon oils,
Both the filtration rate and the dewaxed oil yield are significantly improved compared to the auxiliaries of the prior art. As a result, the yield of the lubricating oil obtained by dewaxing can be increased by 5% or more, and at the same time, the oil content in the wax is lowered, and the oil content in the wax is removed, which is advantageous for the subsequent process. In addition, the filtration rate of heavy wax-containing hydrocarbon oils, which often cause problems with filtration, can be significantly improved, which shortens the filtration process time, increases the throughput, and reduces the cost of dewaxing aids. Allow down. This is a special effect of the product of the present invention.

That is, according to the product of the present invention, in the self-cooling type dewaxing method using a lower hydrocarbon solvent, it is essential to use a chlorine compound for production which has been essential for wax-containing hydrocarbon oils other than bright stock. It has become possible to further improve the filtration rate and the dewaxed oil yield without using an alkylnaphthalene condensate that cannot be avoided from being contained.

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Claims (3)

[Claims] 1. A wax-containing hydrocarbon oil and a dewaxing aid are dissolved in a lower hydrocarbon solvent and cooled to precipitate a wax, and the deposited wax is removed by a liquid / solid separation method to obtain a dewaxed oil. Used in the dewaxing method, a polyalkylmethacrylate (1) having an alkyl chain length of 10 to 20 carbon atoms in the side chain and a weight average molecular weight of 10,000 to 800,000, and 16 to 10 carbon atoms in the side chain. Weight average molecular weight of 10,000 to 80 having an alkyl chain length of 30
A mixture of 10,000 polyalkyl acrylates (2), wherein the mass ratio of (1) and (2) is (1) :( 2).
= 9: 1 to 100: 1, and is added in an amount of 0.001 to 1.00% by mass based on the wax-containing hydrocarbon oil. 2. A solvent dewaxing method of an internal cooling method using a lower hydrocarbon solvent, which uses the dewaxing aid of claim 1. 3. The dewaxing aid according to claim 1, wherein the lower hydrocarbon solvent is propane.