JP3629952B2 - Method for producing cyclohexanedimethanol - Google Patents

Description

【００４５】

【００４６】
実施例１〜４及び比較例１、２を比較すると、本発明の触媒を用いることによって、高い活性が長期間維持でき、未反応のシクロヘキサンジカルボン酸ジアルキルやヒドロキシメチルシクロヘキサンカルボン酸メチルの副生を抑えることが可能となり、又、高沸点物の生成量を抑えることが可能となった。更に、３ヶ月使用後の触媒の圧壊強度もアルミナ（比較例１）やジルコニア（比較例２）を用いた銅−亜鉛成型触媒と比して強い。
【００４７】
【発明の効果】
本発明の方法を適用することにより、シクロヘキサンジカルボン酸ジアルキルの水素化反応に用いる銅−亜鉛系成型触媒の耐久性が大幅に改善され、且つ環境面でも安全な触媒を用いて実施することができ、目的とするシクロヘキサンジメタノールを収率良く、しかも高い生産性で工業的に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing cyclohexanedimethanol (hereinafter abbreviated as “CHDM”). By applying CHDM as a diol component such as a polyester resin, a polyurethane resin, and a polycarbonate resin, CHDM is effective in improving the heat resistance, transparency, weather resistance, and moldability of these resins. In particular, it has recently attracted attention as a compound useful for modifying PET.
[0002]
[Prior art]
As a method for producing CHDM, a process in which a dialkyl phthalate is used as a starting material and a nuclear hydrogenation of an aromatic ring is performed in the first stage to form a cyclohexanedicarboxylic acid dialkyl ester (hereinafter referred to as “pre-stage reaction”), followed by an ester moiety In general, the method is produced by two steps of a hydrogenation reduction of an alcohol to an alcohol (hereinafter referred to as “rear reaction”).
[0003]
A technique of using a copper-zinc-based molded catalyst as a catalyst for the subsequent reaction in the production of CHDM has been known. For example, in JP-A-10-45645, a dialkyl 1,4-cyclohexanedicarboxylate obtained by the previous reaction is used. 1,4-CHDM is produced by performing a hydrogenation reaction in the presence of a copper-zinc-alumina molding catalyst under conditions of 160 to 300 ° C. and 50 to 300 kg / cm ² G.
[0004]
In addition, a dialkyl 1,4-cyclohexanedicarboxylate is used under a condition of 150 to 350 ° C. and 204 bar or less using a copper-zinc-based molded catalyst containing an oxide of aluminum, magnesium, zirconium, or a mixture thereof as a third component. A method for obtaining 1,4-CHDM by performing a hydrogenation reaction is also disclosed (US Pat. No. 5,334,795).
[0005]
However, the above-described method has disadvantages such as the catalyst life is short because the copper-zinc-based molded catalyst used has a very low crushing strength retention rate and poor catalytic activity. Therefore, unsteady operation of extracting the spent catalyst from the reaction apparatus or filling with a new catalyst is required in a short period of time, which reduces the productivity of CHDM and is industrially disadvantageous.
[0006]
On the other hand, other than the copper-zinc catalyst, there is also known a technique in which a dicarboxylic acid ester is hydroreduced to a corresponding diol (including CHDM) using a copper-chromium molded catalyst (US Pat. No. 5,030,771) Example 4 ). In the ester hydrogenation reduction reaction using a copper-chromium-based catalyst, the catalyst is said to have high activity and good sustainability. However, it contains highly toxic chromium, and waste treatment after use This is a problem.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to establish an industrially practical CHDM production process that is excellent in productivity and environmentally safe by improving the durability of a copper-zinc catalyst. .
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the inventors of the present invention hydrogenated dialkylcyclohexanedicarboxylate to produce cyclohexanedimethanol, and selected a copper-zinc-silica molded catalyst as a catalyst. It has been found that the strength and activity retention of the catalyst can be drastically improved compared to the copper-zinc-based catalyst or the copper-zinc-alumina molded catalyst, and it is also effective in suppressing by-products during hydrogenation. And the present invention has been completed based on such findings.
[0009]
That is, the method for producing CHDM according to the present invention is characterized in that when hydrogenating a dialkylcyclohexanedicarboxylate to obtain cyclohexanedimethanol, the hydrogenation is carried out in the presence of a copper-zinc-silica shaped catalyst.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The reaction apparatus used in the present invention is a fixed bed continuous reaction apparatus, which may be a single tube reaction tower, or a multi-tube reaction tower in which a plurality of reaction towers are set in parallel. Also good.
[0011]
The dialkyl cyclohexanedicarboxylate used as a raw material in the present invention is usually obtained by nuclear hydrogenation of a dialkyl phthalate, but the production method is not particularly limited, and any of the production methods can be used as the raw material of the present invention. It is. Examples of such a production method include, for example, JP-A-54-163554, JP-A-6-192146, JP-A-7-149694, JP-A-8-187432, JP-A-10-45645, WO9429261, WO9800383. US Pat. No. 3,334,149, US Pat. No. 5,319,129, US Pat. No. 5,286,898, US Pat. No. 5,399,742 and the like are known.
[0012]
For example, in the method of WO9800383, a reaction temperature of 120 to 180 ° C., a pressure of 30 to 100 kg / cm ² G, a ruthenium / alumina catalyst in the presence of a dialkyl aromatic dicarboxylate concentration adjusted to 30% by weight or more is used as a raw material. , Liquid feed rate F / V = 0.1 to 5 h ⁻¹ (F represents the substrate feed rate, V represents the capacity of the reactor), and hydrogen feed rate is 1 to 40 cm as a superficial gas linear velocity. Dialkyl cyclohexanedicarboxylate is obtained by performing hydrogenation in the range of / s.
[0013]
The hydrogenation catalyst used in the present invention is a copper-zinc-silica molding catalyst, and its components are 5 parts by weight to 1000 parts by weight of zinc oxide and 0.5 parts by weight of silica to 100 parts by weight of copper oxide. Examples are 500 parts by weight, preferably 10 to 800 parts by weight of zinc oxide and 1 to 300 parts by weight of silica. When zinc oxide is less than 5 parts by weight or more than 1000 parts by weight, the catalyst strength and activity are lowered, and more by-products are generated. On the other hand, if the silica content is less than 0.5 parts by weight, the catalyst strength tends to decrease. If the silica content exceeds 500 parts by weight, the catalyst activity tends to decrease, and more by-products tend to increase.
[0014]
Further, it may be molded by adding various binders to maintain the catalyst strength. Examples of the binder to be used include polyvinyl acetate, polymethyl methacrylate, bentonite, zeolite, graphite, molecular sieves and the like.
[0015]
The catalyst is prepared by preparing an aqueous solution of copper and zinc metal salts (eg, sulfate, nitrate, hydrochloride, etc.) and mixing this with an aqueous solution of silicate (eg, sodium silicate, potassium silicate, etc.). To obtain a suspension. Alternatively, a silicon hydroxide solution obtained by hydrolyzing a solution of a silicon alkoxide compound (eg, tetramethoxysilane, tetraethoxysilane, etc.) or a halogen compound (eg, tetrachlorosilane, tetrabromosilane, etc.) An aqueous metal salt solution of copper and zinc is mixed to obtain a suspension. An alkaline aqueous solution such as ammonia, sodium hydroxide, potassium hydroxide or the like is further added as a precipitating agent to the suspension prepared by either of these methods. The resulting precipitate is filtered, washed with water, dried and fired. The powder thus obtained is tableted by a tablet machine to obtain a fixed bed catalyst.
[0016]
On the other hand, in order to control the rapid exotherm at the start of the reaction or to effectively exhibit the catalytic activity, it is effective to subject the copper-zinc-silica shaped catalyst to a pre-reduction treatment according to a conventional method. is there.
[0017]
Copper used in the present invention - Zinc - The surface area of the silica molded catalyst is exemplified ^{10m 2} / ^g~200m 2 / g, preferably ^{20m 2} / ^g~100m 2 / g. If it is less than 10 m ² / g, the reaction rate is slow, and if it exceeds 200 m ² / g, the effect of promoting the reaction rate is reduced, the crushing strength is low, and the strength retention during the reaction tends to decrease.
[0018]
The shape of the copper-zinc-silica shaped catalyst is not particularly limited, but a cylindrical one that is industrially easily available is recommended. The size is determined by the inner diameter of the reaction tower to be used, but is preferably cylindrical and has a diameter of 2 to 6 mm and a height of 2 to 6 mm.
[0019]
The reaction conditions for hydrogenation can be appropriately selected depending on the type of dialkyl cyclohexanedicarboxylate used as a raw material, but generally the following conditions can be presented.
[0020]
As reaction temperature, the range of 200-280 degreeC is illustrated, and the range of 230-260 degreeC is especially preferable. If it is less than 200 ° C., the reaction rate is slow, and if it exceeds 280 ° C., a by-product is produced, and in any case, it is not practical.
[0021]
The reaction pressure in the range of 160~300kg / cm ² G and the like, in particular in the range of 200~250kg / cm ² G are preferred. If it is less than 160 kg / cm ² G, the reaction rate is slow, and if it exceeds 300 kg / m ² G, the reaction rate does not increase, and it is not economical in terms of equipment.
[0022]
Specific examples of the dialkyl cyclohexanedicarboxylate include dimethyl 1,2-cyclohexanedicarboxylate, diethyl 1,2-cyclohexanedicarboxylate, dipropyl 1,2-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylate, Examples include diethyl cyclohexanedicarboxylate, dipropyl 1,3-cyclohexanedicarboxylate, dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate and dipropyl 1,4-cyclohexanedicarboxylate.
[0023]
Although a reaction solvent is not usually required, alcohols may be used in combination when the starting material is a dialkyl cyclohexanedicarboxylate having a high melting point and is difficult to handle or when it is easy to remove reaction heat.
[0024]
Examples of alcohols include linear, branched and cyclic alcohols having 1 to 8 carbon atoms, specifically, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, hexanol, cyclohexanol, octanol, Examples include 2-ethylhexanol. In particular, when the raw material for the subsequent reaction is dimethyl cyclohexanedicarboxylate, methanol is preferable as the reaction solvent.
[0025]
Furthermore, cyclohexanedimethanol, which is a product of the hydrogenation reaction, or crude cyclohexanedimethanol containing a high boiling point substance may be used as the reaction solvent.
[0026]
The amount of reaction solvent used is appropriately selected, and the concentration of dialkyl cyclohexanedicarboxylate in the system is recommended to be in the range of 5 to 80% by weight, and in particular, adjusted to be in the range of 10 to 50% by weight. preferable. If it is less than 5% by weight, the productivity is not improved, and if it is 80% by weight or more, the melting point does not decrease so much, and in any case, there is no effect of using the reaction solvent.
[0027]
As a form of the fixed bed hydrogenation reaction relating to the latter stage reaction, any of a flow-down method in which a raw material is supplied together with hydrogen gas from the upper part or the lower part of the fixed bed reactor filled with the shaped catalyst, or an ascending method may be used.
[0028]
The feed rate of the raw material of the cyclohexanedicarboxylic acid dialkyl (F / V), the range of 0.1～5.0H ^-1 is recommended, in particular in the range of 0.1～2.0H ^-1 it is preferred.
[0029]
The hydrogen supply rate is recommended to be in the range of 1 to 40 cm / s in terms of the superficial gas linear velocity under the reaction conditions, and particularly preferably in the range of 2 to 20 cm / s.
[0030]
The CHDM thus obtained can be purified by a conventionally known method such as distillation.
[0031]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. The surface area in each example was measured by the BET method. Moreover, the crushing strength in the lateral direction of the catalyst was measured using a digital hardness meter (KHT-20 type) manufactured by Kiyama Seisakusho.
[0032]
Production Example 1
A cylindrical (3.2 mmφ × 3.2 mm) 0.5% ruthenium / alumina supported catalyst 360 g was charged into a fixed bed reactor (0.314 L) having an inner diameter of 20 mm and a column length of 1 m. A solution prepared in 30% by weight of dimethyl terephthalate and 70% by weight of dimethyl 1,4-cyclohexanedicarboxylate in this apparatus was subjected to 500 mL / h (F / V = F / V = reaction conditions at a temperature of 160 ° C. and a pressure of 50 kg / cm ² G). 0.48 h ⁻¹ ) was fed together with hydrogen gas 1.4 Nm ³ / h (cylinder gas linear velocity 4 cm / s) from the upper part of the reaction tower to continuously carry out the nuclear hydrogenation reaction. The composition of the reaction crude liquid obtained after 10 hours in this fixed bed continuous nuclear hydrogenation reaction was measured by gas chromatography. The obtained results are shown below.
[0033]
Dimethyl 1,4-cyclohexanedicarboxylate 94.5% by weight
Low boiling point 2.4
Methyl 4-hydroxymethylcyclohexanecarboxylate 2.7
Dimethyl terephthalate 0.4
[0034]
[Preliminary reduction treatment] In the same reaction apparatus as in Production Example 1, a cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-silica molding catalyst (copper oxide 39 wt%, zinc oxide 49 wt%, silica 12 wt%) , Surface area 36.6 m ² / g) was charged with 499 g, and a prereduction treatment was performed under conditions of a temperature of 100 to 200 ° C., a normal pressure of 100 kg / cm ² G, and a hydrogen concentration of 1 to 100%.
[0035]
Example 1
After the preliminary reduction treatment, the reaction crude liquid obtained in Production Example 1 was fed at 245 mL / h (F / V = 1.10 h ⁻¹ ) under the reaction conditions of a temperature of 245 ° C. and a pressure of 205 kg / cm ² G. Hydrogen solution was continuously supplied from the upper part of the reaction tower with hydrogen gas 7.3 Nm ³ / h (cylinder gas linear velocity 6 cm / s) at a liquid speed.
[0036]
The composition of the raw material obtained by this fixed bed continuous hydrogenation reaction after 10 hours, 1.5 months, and 3 months, methyl hydroxymethylcyclohexanecarboxylate, CHDM, low boilers and high boilers obtained as by-products. Measured by gas chromatography. Furthermore, the time-dependent change of the copper-zinc-silica molded catalyst strength used was also measured. The results obtained are shown in Table 1.
[0037]
Example 2
Liquid feed rate of the reaction crude liquid obtained in Production Example 1 440 mL / h (F / V = 1.4 h ⁻¹ ), reaction temperature 265 ° C., hydrogen gas 7.1 Nm ³ / h (cylinder gas linear velocity 6 cm / h) s) and a cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-silica molding catalyst (copper oxide 43 wt%, zinc oxide 53 wt%, silica 4 wt%, surface area 59.7 m ² / g) 484 g The hydrogenation reaction was continuously carried out in the same manner as in the subsequent reaction of Example 1 except that was charged. The results obtained are shown in Table 1.
[0038]
Production Example 2
[Preliminary reaction] A cylindrical (3.2 mmφ × 3.2 mm) 0.5% ruthenium / alumina supported catalyst (378 g) was used as a raw material from 50% by weight of dimethyl isophthalate and 50% by weight of dimethyl 1,3-cyclohexanedicarboxylate. A nuclear hydrogen reaction was carried out in the same manner as in Production Example 1 except that the resulting solution was used. The composition of the reaction crude obtained after 10 hours in this fixed bed continuous nuclear hydrogenation reaction was measured by gas chromatography. The obtained results are shown below.
[0039]
95.9% by weight of dimethyl 1,3-cyclohexanedicarboxylate
Low boiling point 1.7
Methyl 3-hydroxymethylcyclohexanecarboxylate 2.1
Dimethyl isophthalate 0.3
[0040]
Example 3
Filled with 454 g of a cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-silica molding catalyst (copper oxide 41 wt%, zinc oxide 51 wt%, silica 8 wt%, surface area 57.3 m ² / g), The hydrogenation reaction was carried out continuously in the same manner as in Example 1 except that the reaction crude liquid obtained in Production Example 2 was fed at a rate of 370 mL / h (F / V = 1.18 h ⁻¹ ). The results obtained are shown in Table 1.
[0041]
Example 4
Except for filling 507 g of a cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-silica molding catalyst (copper oxide 30 wt%, zinc oxide 35 wt%, silica 35 wt%, surface area 27.0 m ² / g). The hydrogenation reaction was carried out continuously in the same manner as in Example 1. The results obtained are shown in Table 1.
[0042]
Comparative Example 1
Except for filling 455 g of cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-alumina molding catalyst (copper oxide 47 wt%, zinc oxide 50 wt%, alumina 3 wt%, surface area 60.0 m ² / g) The hydrogenation reaction was carried out continuously in the same manner as in Example 1. The results obtained are shown in Table 2.
[0043]
Comparative Example 2
Except for filling 507 g of cylindrical (3.2 mmφ × 3.2 mm) copper-zinc-zirconia molding catalyst (copper oxide 41 wt%, zinc oxide 44 wt%, zirconia 15 wt%, surface area 26.3 m ² / g) The hydrogenation reaction was carried out continuously in the same manner as in Example 1. The results obtained are shown in Table 2.
[0044]

[0045]

[0046]
Comparing Examples 1 to 4 and Comparative Examples 1 and 2, by using the catalyst of the present invention, high activity can be maintained for a long period of time, and unreacted dialkyl cyclohexanedicarboxylate and methyl hydroxymethylcyclohexanecarboxylate are by-produced. It became possible to suppress, and it became possible to suppress the production amount of high-boiling substances. Furthermore, the crushing strength of the catalyst after three months of use is also stronger than that of a copper-zinc molded catalyst using alumina (Comparative Example 1) or zirconia (Comparative Example 2).
[0047]
【The invention's effect】
By applying the method of the present invention, the durability of the copper-zinc-based molded catalyst used in the hydrogenation reaction of the dialkyl cyclohexanedicarboxylate is greatly improved, and it can be carried out using an environmentally safe catalyst. The desired cyclohexanedimethanol can be industrially produced with good yield and high productivity.

Claims (3)

In the fixed bed continuous hydrogenation reaction, when hydrogenating dialkylcyclohexanedicarboxylate to obtain cyclohexanedimethanol in the presence of a copper-zinc-silica shaped catalyst, the surface area of the catalyst is 10 m. ² / G-200m ² / G production method of cyclohexanedimethanol. The method for producing cyclohexanedimethanol according to claim 1, wherein the composition of the catalyst is 10 to 800 parts by weight of zinc oxide and 1 to 300 parts by weight of silica with respect to 100 parts by weight of copper oxide. The surface area of the catalyst is 20 m ² / G-100m ² It is / g, The manufacturing method of the cyclohexane dimethanol of Claim 1 or Claim 2.