JPH0338532A - Production of dimethylnaphthalene rich in 2,6-isomer - Google Patents

Abstract

PURPOSE:To inexpensively obtain the high-quality subject compound for polyester raw material, etc., by separating and recovering dimethylnaphthalene rich in 2,6-isomer from a fraction containing dimethylnaphthalenes and then subjecting the residue to reforming reaction. CONSTITUTION:Dimehtylnaphthalenes rich in 2,6-isomer are separated and recovered from a fraction containing dimethylnaphthalenes and residue after the separation and recovery is subjected to reforming reaction using a catalytic reforming method which is a general method for obtaining a gasoline of high octane value from a naphtha fraction to provide the objective compound. the reaction is carried out using a catalyst in which platinum or platinum and rhenium, germanium, tin, etc.,, are carried on an alumina support at 400-550 deg.C and 1-50kg/cm<2> in 0.1-3h<-1> liquid space velocity and 0.5-20 hydrogen/oil molar ratio. Furthermore, the above-mentioned fraction preferably contains mixture of each dimethylnaphthalene isomer and preferably contains >=70wt.% dimethylnaphthalenes.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to extracting 2,6
The present invention relates to a method for producing monolithically enriched dimethylnaphthalene. [Prior art] Among dimethylnaphthalenes, 2,6-1 and 2,7-
Dimethylnaphthalene can be oxidized to 2,6-1
and 2,7-naphthalene dicarboxylic acid, which is used as a raw material for polyesters such as polyethylene naphthalate. This polyester can be formed into synthetic fibers, films, etc. with excellent properties, but 2,6-1 and 2,
An inexpensive industrial production method for 7-dimethylnaphthalene has not yet been established. In view of the current situation, the present inventor conducted intensive research and found that a considerable amount of dimethylnaphthalenes were present in the product oil obtained by reforming kerosene fractions.
By separating and recovering ,6-dimethylnaphthalene,
We discovered that high-quality dimethylnaphthalenes containing almost no nitrogen and sulfur compounds could be recovered, and proposed a method for producing dimethylnaphthalenes (patent application 1983-
No. 236331). [Problems to be Solved by the Invention] As a result of further research on this subject, the present inventor recovered 2,6-dimethylnaphthalene from dimethylnaphthalenes, and subjected this residual oil to a reforming reaction again. Surprisingly, it was discovered that another isomer of dimethylnaphthalene undergoes an isomerization reaction to produce 2,6-dimethylnaphthalene. The present invention was made based on this knowledge, and an object of the present invention is to extract 2,6
- To provide a method for efficiently producing distylnaphthalene. [Means for Solving the Problems] The present invention provides a method for extracting 2,6
This method consists of separating and recovering distylnaphthalene, which is enriched in monomers, and subjecting the residual liquid after separation and recovery to a reforming reaction. The fraction containing dimethylnaphthalenes referred to in the present invention is a fraction containing a mixture of various isomers of dimethylnaphthalene,
A fraction having a boiling point range of 255 to 270°C and containing 70% by weight or more of dimethylnaphthalenes is preferred. As this fraction, coal tar or a fraction obtained by distilling cycle oil of a fluid catalytic cracking process can be used (see Japanese Patent Application Laid-Open No. 60-69042). It contains a high concentration of nitrogen and sulfur compounds that significantly shorten the life of zeolite used to adsorb and separate dimethylnaphthalene rich in 2,6 monomers, and of catalysts used in reforming reactions. Therefore, when using these, it is necessary to perform a reduction treatment for nitrogen and sulfur compounds before these treatments. Furthermore, the heavy fraction of reformate obtained by subjecting the naphtha fraction to a reforming reaction also contains dimethylnaphthalenes, and the fraction obtained by distilling and separating this reformate can also be used. This fraction is preferable because it has a low content of nitrogen compounds and sulfur compounds. Furthermore, the reformed oil obtained by reforming kerosene fraction contains a large amount of dimethylnaphthalenes.
By using this, dimethylnaphthalenes can be efficiently recovered from the fraction obtained from the naphtha,
Moreover, the content of nitrogen compounds and sulfur compounds is small, which is particularly preferable.

【Example】

Next, regarding one of the preferred embodiments of the present invention, a method for producing 2,6-enriched dimethylnaphthalene from this reformed oil by using a kerosene fraction as a starting material and carrying out a reforming reaction. Let me be more specific. In this case, the kerosene fraction is 15% by distillation separation operation.
Fractions distilled in a temperature range of 0 to 300°C can be used, and in addition to straight-run kerosene fractions obtained by atmospheric distillation of crude oil, various petroleum fractions, thermal decomposition of residues, etc. It goes without saying that fractions having the above-mentioned boiling point range obtained by contact table decomposition, hydrogenolysis, alkylation, other purification treatments, etc. can also be used. This kerosene fraction preferably has a sulfur content and a nitrogen content of 50 ppm or less,
This is a commonly used hydrodesulfurization treatment method that uses a catalyst supporting one or more of cobalt, nickel, molybdenum, tungsten, etc. on a support such as alumina or silica-alumina under normal desulfurization conditions. , 250
Temperature of ~430°C, pressure of lO ~200 kg/aII,
It is preferable to use a desulfurization section that is desulfurized under the conditions of a liquid hourly space velocity (LH8V) of 0.1 to 15 h and a hydrogen circulation rate of 50 to 140 ON/-. In addition to the above, the kerosene fraction may also be a raffinate obtained by recovering normal paraffins from the kerosene fraction. In this case, even if the reforming reaction conditions are mild, the amount of dimethylnaphthalenes produced is large. can do. This normal paraffin can be removed using an adsorption separation method using zeolite or a separation method using a urea adduct. It is sufficient that this raffinate is one in which normal paraffin is collected and removed at a recovery rate of about 50 to 95%. Further, for the reforming reaction of this kerosene fraction, a catalytic reforming method which is generally widely used as a method for producing high octane gasoline from naphtha fraction etc. can be adopted. In this case, for example, platinum is supported on alumina, or a catalyst in which rhenium, germanium, soot, iridium, ruthenium, etc. is supported in addition to platinum is used.
temperature of °C, pressure of 1 to 50 kg/cot, liquid hourly space velocity (
LH8V) 0.1~3h-1, hydrogen/oil molar ratio 0.5~
It can be carried out under 20 conditions. In addition, other modification reaction methods include zeolite or crystalline aluminosilicate, silica, alumina, zirconia, titania, and chromia. solid phosphoric acid, or indium, lanthanum, manganese,
Oxides such as cerium or tin, or two of these
Using an acidic refractory containing a mixture of more than one species, or a catalyst containing or supporting metals such as platinum, palladium, rhenium, etc., at a temperature of 250 to 700°C, 1 to 100 kg/- Pressure, 0.1~20h-'
(7) It can also be carried out under the conditions of LH3V and hydrogen/oil/L/ratio of 0.5 to 20. Although a reactor in which part of the reforming reaction actor is a fixed bed may be used, it is preferable in terms of efficiency to use a reactor comprising a moving bed to which a continuous catalyst regeneration method is added. Distillation, solvent extraction, ordinary crystallization method or pressure crystallization method from the reformed oil of the kerosene fraction obtained in this way [Chemical Engineering, 51
．． (6), 428-433 (1987)), etc., a fraction containing a high concentration of dimethylnaphthalenes is recovered. Recovery is preferably performed by distillation as it is economical.
By collecting the fraction at 270°C, a fraction containing a high concentration of dimethylnaphthalenes can be obtained. From this fraction containing dimethylnaphthalenes, dimethylnaphthalene rich in 2,6 monomers is separated and recovered using known means such as adsorption separation using zeolite, crystallization, and separation by complex compound formation. Next, this recovered residual liquid is subjected to a reforming reaction. For the reforming reaction in this case, the catalyst and conditions described above can be applied as they are. In particular, it is preferable to mix this residual liquid with the kerosene fraction supplied as a raw material for the previous reforming reaction and use it for the reforming reaction, since this is convenient in terms of operation of the apparatus. Next, an experimental example will be shown in order to clarify the effects of the present invention. (Experiment example) A desulfurized kerosene fraction having the properties shown in Table 1 obtained by hydrodesulfurizing a kerosene fraction was used as a raw material, and 0.0% platinum was added to an alumina carrier.
Using a catalytic reforming catalyst supported at 2% by weight, the pressure was increased to 25k.
The reforming reaction was carried out under the following conditions: g/cd, temperature of 490° C., LH3V of 0.8 h', hydrogen/oil volume/L, and ratio of t'6. This reformed oil was distilled under atmospheric pressure and a fraction of 255 to 265°C was collected, resulting in a dimethylnaphthalene mixture having the composition shown in Table 2. This was cooled to a temperature of 1℃, and
, 6-enriched dimethylnaphthalene was crystallized and separated. The compositions of the crystallized product and the residual liquid after this separation are shown in Table 3. Next, this residual liquid was heated to 25% using the same catalyst as above.
As a result of the reforming reaction at the temperature shown in Table 4 under the conditions of kg/hang, LH3V of o, sh-', hydrogen/oil molar ratio of 6, a dimethylnaphthalene mixture having the composition shown in Table 4 was obtained. It was done. As is clear from these results, dimethylnaphthalene rich in 2,6 monomers can be obtained by subjecting the residual oil from recovered dimethylnaphthalene rich in 2,6 monomers to a reforming reaction. [Effects of the Invention] The present invention provides a special effect in that 2,6-dimethylnaphthalene can be produced extremely efficiently because the residual liquid after separating and collecting dimethylnaphthalene rich in 2,6 monomers is subjected to a reforming reaction. has.

Claims (1)

[Claims] Production of dimethylnaphthalene rich in 2,6-isomer, which is characterized by separating and recovering dimethylnaphthalene rich in 2,6-isomer from a fraction containing dimethyl and naphthalenes, and subjecting the residual liquid after separation and recovery to a reforming reaction. Method.