JP2520722B2 - Method for producing methylnaphthalene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing methylnaphthalenes from a severely hydrotreated kerosene fraction.

Methylnaphthalene is used as a solvent, dyeing carrier, heat carrier, etc.
Dimethylnaphthalene can be produced. This 2,6
-Dimethylnaphthalene is a raw material for polyester such as polyethylene naphthalate. This polyester is
It can be formed into synthetic fibers, films and the like having excellent properties.

[Prior Art] Methylnaphthalenes are contained in coal tar or cycle oil of fluid catalytic cracking process, but impurities such as sulfur compounds and nitrogen compounds are present in high concentration in these oils. are doing.

By the way, the above-mentioned polyester monomer 2,6-
In the synthesis of dimethylnaphthalene, high-purity methylnaphthalene having a particularly low content of the above impurities is desired for reasons such as catalyst deterioration, suppression of by-products, and improvement in yield. In particular, when isomerizing to 2,6-dimethylnaphthalene, and when it is adsorbed and separated from 2,6-dimethylnaphthalene by using zeolite or the like, it exhibits a poisoning effect on the catalyst and the adsorbent. It was found that, when methylnaphthalene is used as, the sulfur content and nitrogen content in methylnaphthalene should be at least 1 ppm or less.

Of these impurities, for nitrogen compounds, acid,
A method of removing by alkali cleaning or the like is performed. Regarding sulfur compounds, a method has been proposed in which they are heat-treated with anhydrous aluminum chloride and purified by a recrystallization method, a melt crystallization method or the like (Japanese Patent Laid-Open Nos. 62-230736 and 62-2307).
No. 37).

[Problems to be Solved by the Invention] In the above method of washing with an acid or alkali, the sulfur compound cannot be sufficiently removed, and there is a problem in treating the acid or alkali after use.

On the other hand, even with the method using anhydrous aluminum chloride, the sulfur compound cannot be reduced until the deterioration of the catalyst can be sufficiently suppressed, and there is a problem in waste treatment.

Furthermore, in order to remove the above-mentioned impurities, direct hydrogenation treatment of tar carbonate containing methylnaphthalene or cycle oil of a fluid catalytic cracking process or distillation fractions of these is carried out, and then hydrogenation of methylnaphthalene is carried out. Is inevitable, and the yield of methylnaphthalenes is greatly reduced. For this reason, there is a problem that further dehydrogenation treatment is required and the manufacturing cost is significantly increased.

On the other hand, it has been reported that a heavy aromatic compound is produced by catalytically reforming a kerosene fraction, and that methylnaphthalene is present in this heavy aromatic compound (Petroleum Society of Japan, Vol. 13, No. 16 (1970), P468-474]. However, the usual hydrodesulfurized white kerosene has a sulfur content of 30 to 40 ppm and a nitrogen content of 4 to 5 ppm, and the sulfur content and nitrogen content in the methylnaphthalene obtained by reforming the kerosene fraction are Minute 1p
It has been found that it cannot be made pm or less, and furthermore, when such a kerosene fraction is subjected to a reforming reaction, the catalyst is significantly deteriorated and the catalyst life is extremely shortened.

[Problems to be Solved by the Invention] In order to solve the above problems, the present inventor has
As a result of intensive studies, it was found that hydrodesulfurization of kerosene fraction under severe conditions surprisingly increased the yield of methylnaphthalenes. The present invention has been made based on such findings, and an object of the present invention is to provide a method for producing methylnaphthalene having a sulfur content and a nitrogen content of 1 ppm or less in good yield.

[Means for Solving the Problems] According to the present invention, after kerosene distillate is hydrotreated to reduce the sulfur content and the nitrogen content to 1 ppm or less, respectively, or normal paraffin is recovered from the hydrotreated oil. Of raffinate, and then recovering methylnaphthalene compounds from the resulting product oil.

The above kerosene fraction refers to a fraction distilled in a temperature range of 150 to 300 ° C. by a distillation separation operation, and is a direct distillation kerosene fraction obtained by distilling crude oil under atmospheric pressure, and each fraction of petroleum. It goes without saying that a fraction having the boiling point range obtained by thermal decomposition, catalytic cracking, hydrogenolysis, alkylation, or other purification treatment of the fractions, residues and the like can also be used. This kerosene fraction is first treated under severe hydrotreating conditions to reduce the sulfur and nitrogen contents to 1 ppm or less. This is 1ppm or more, while significantly shortening the life of the reforming catalyst in the reforming process, producing dimethylnaphthalene from the methylnaphthalene, isomerization of the dimethylnaphthalene,
Furthermore, when 2,6- and 2,7-dimethylnaphthalene is adsorbed and separated using zeolite or the like, the zeolite is poisoned. As the conditions for this hydrodesulfurization, for example, a catalyst in which one or more kinds of cobalt, nickel, molybdenum, tungsten and the like are supported on a carrier such as alumina or silica-alumina,
At a temperature of 250 to 430 ° C, a pressure of 10 to 200 kg / cm ² , a liquid hourly space velocity (LHSV) of 0.1 to 15 h ^-1 , and a hydrogen circulation rate of 50 to 1400 Nm ³ / kl, taking into consideration the oil type, catalytic activity, etc., Select appropriate conditions.

Raffinate is obtained by recovering normal paraffin from the above kerosene fraction, but normal paraffin can be recovered by an adsorption separation method using zeolite or a separation method by urea adduct, and is a raw material for detergents. Raffinate, which is a by-product from the process producing normal paraffins, can be advantageously used as. This raffinate contains 50-95 normal paraffins.
Those recovered by weight% are preferably used.

On the other hand, for the reforming reaction, a catalytic reforming method, which is widely used as a method for producing high octane gasoline from naphtha fraction or the like, can be adopted. In this case, for example, platinum using alumina as a carrier, or rhenium in addition to platinum, germanium, tin, iridium, using a catalyst supporting ruthenium, the temperature of 400 ~ 550 ℃, 1 ~ 50kg
It can be carried out under the conditions of a pressure of / cm ² , a liquid hourly space velocity (LHSV) of 0.1 to 3 h ⁻¹ and a hydrogen / oil molar ratio of 0.5 to 20.

Further, as a method of other reforming reaction, zeolite or crystalline aluminosilicate, silica, alumina, zirconia, titania, chromia, solid phosphoric acid, or oxides such as indium, lanthanum, manganese, cerium or tin, or, An acidic refractory containing a mixture of two or more of these, or a catalyst containing or supporting a metal such as platinum, palladium, or rhenium, at a temperature of 250 to 700 ° C., 1 to 100 kg It can also be carried out under the conditions of a pressure of / cm ² , a LHSV of 0.1 to 20 h ⁻¹ and a hydrogen / oil molar ratio of 0.5 to 20.

For this reforming reaction, a reactor having a fixed bed reactor part may be used, but it is preferable to use a reactor composed of a moving bed to which a continuous catalyst regeneration method is added in terms of efficiency.

In the oil thus produced after the reforming reaction,
Since methylnaphthalene is contained in a relatively high concentration, it is distilled, solvent-extracted, ordinary crystallization method or pressure crystallization method [Chemical Engineering, 51, (6), 428-433 (1987)] Etc. For the recovery, a method by atmospheric distillation is economically preferable, and a high-concentration methylnaphthalene compound can be obtained by collecting a fraction at 230 to 250 ° C.

[Examples] (Examples 1 and 2, Comparative Examples 1 and 2) Desulfurized kerosene fractions 1 and 2 and desulfurized kerosene fraction having the properties shown in Table 1 obtained by hydrodesulfurizing kerosene fractions under different conditions Using a catalytic reforming catalyst that uses 0.2% by weight of platinum on an alumina carrier as a raw material, a raffinate obtained by recovering 90% by weight of normal paraffin using zeolite from 2 is used, pressure is 25 kg / cm ² , temperature is 490 ° C., and LHSV is LHSV. Of 0.8 h ⁻¹ and hydrogen / oil in a molar ratio of 6 were subjected to a reforming reaction. The properties of this produced oil and the content of methylnaphthalene are shown in Table 2. Further, the above reforming reaction was carried out for 5 days, and changes in the yield of methylnaphthalene relative to the feedstock at this time are shown in Table 3. As a result of distilling this produced oil under atmospheric pressure and collecting a fraction at 230 to 250 ° C., the purity of methylnaphthalene was 92%.

As is clear from these results, by reforming the kerosene fraction containing sulfur and nitrogen at 1 ppm or less, the yield of methylnaphthalene can be improved and the catalyst methylnaphthalene can be improved. It can be seen that the deterioration of the production activity of can be suppressed.

EFFECTS OF THE INVENTION The present invention is designed to recover methylnaphthalene compounds from a kerosene fraction having a sulfur content and a nitrogen content of 1 ppm or less or a raffinate obtained by reforming a normal paraffin from the kerosene fraction and subjecting the produced oil to a reforming reaction. In addition, it has a remarkable effect that it is possible to produce methylnaphthalene having a high yield, a long catalyst life, and an extremely low sulfur and nitrogen contents.

Claims (2)

(57) [Claims] Claims: 1. A kerosene fraction is hydrotreated to reform a hydrotreated oil having a sulfur content and a nitrogen content of 1 ppm or less, and then methylnaphthalene is recovered from the produced oil. A method for producing methylnaphthalene, which is characterized. 2. A raffinate after reforming reaction after recovering normal paraffins from a hydrotreated oil having a sulfur content and a nitrogen content of 1 ppm or less each by hydrotreating a kerosene fraction, and then producing the resulting oil. A method for producing methylnaphthalene, characterized in that methylnaphthalene is recovered from the product.