CS233389B1 - Process for producing phthalic esters - Google Patents

Abstract

The invention provides a method for producing phthalic acid esters by esterification of phthalic anhydride with aliphatic alcohols C_ to C-, in the presence of a catalyst based on Tidg, or possibly carborafin and diatomaceous earth. The essence is that for esterification, a mixed catalyst based on activated TiO2.HgO gel, promoted by the addition of 0.1 to 50% by mass of aluminum sulfate octadecahydrate, based on dry matter TiO2, is used in an amount of 0.001 to 0.5, preferably 0.05 to 0.2% by mass, based on the total esterification batch. In this case, the heat input during the actual esterification process is interrupted when the acid number drops to the range of 3.0 to 0.1 mg KOH/g of the esterification mixture, after which the excess esterification component is removed by vacuum distillation and steam stripping, the ester is drained off under vacuum and the mixed catalyst and any auxiliary additives used are separated by filtration. During ζ-stripping, it is advantageous to use an addition of NaOH in an amount of up to 0.5% by weight, based on the total amount of ester, preferably in the form of a 40% aqueous solution.

Description

The invention solves a process for the production of phthalic acid esters by phthalic anhydride by aliphatic alcohols C? only in the presence of a catalyst based on TiO 2 .xH 2 O, optionally carboraffin and diatomaceous earth.

The production of organic plasticizers, the main group of which consists of esters of phthalic acid and alcohols of 7 to 11 carbon atoms in the molecule, consists in catalytic esterification and isolation of the ester from the reaction mixture. A number of technological processes are used for this production. The extended processes include esterification in the presence of an alkaline aluminate catalyst, since the catalyst can be easily separated from the crude ester and used repeatedly for esterification in the next production cycle. Progress has been made with the use of organotitanate catalysts of various types, for example, according to U.S. Pat. Nos. 5,404,242, 3, 047,515, or 3, 209,021. the catalysts are considerably higher and only one-time use of the catalyst is possible, since the catalyst has to be separated from the finished ester as waste by complicated and costly processes. The use of an organotitanate catalyst promoted by aluminum chloride addition The re-use of the esterification catalyst allows the process for the preparation of phthalate plasticizers according to the Czechoslovak invention No. 214 216. This process uses TiOg-based active gel catalyst. xHgO, whose separation by filtration from the finished ester can be operated without po233 389

The disadvantage is still the relatively high cost of the catalyst and the fact that production still remains energy intensive, since the esterification time, which is considerably shorter than when using, for example, an alkaline aluminate catalyst, still remains relatively long. * *

These disadvantages can be further mitigated when the process for preparing phthalic acid esters according to the invention is used. It is based on the fact that it is used in an amount of 0.001 to 0.5, preferably 0.05 to 0.2% by weight, based on the esterification the total esterification batch of the activated gel catalyst TiOg.x HgO promoted by the addition of 0.1 to 50% by weight of aluminum sulphate octadecahydrate, based on the TiOg dry matter. At the same time, the heat input of the esterification process itself is interrupted 0 to 0.1 mg KOH / g of esterification mixture, after which excess esterification component is removed by vacuum distillation and steam stripping, the ester is dewatered under vacuum and the mixed catalyst and any auxiliaries used are separated by filtration. in an amount of up to 0.5% by weight, based on the total amount of ester, preferably in the form of a 40% aqueous solution.

The advantage of the process for producing the phthalic acid esters according to the invention is, above all, a reduction in the cost of production, both as a catalyst, by replacing a portion of the titanate gel with a more costly aluminum sulfate octadecahydrate. for the same reasons, it significantly increases the capacity of the production facility.

The following examples illustrate the practice of the plasticizer production process according to the present invention, as well as the comparison with the prior art.

*

Example 1

5,400 kg of phthalic anhydride were introduced into the esterification boiler,

200 kg of 2-ethylhexanol, 200 kg of catalyst-based suspension

TiCl 4 x 23 (23.1 kg of dry matter), 25 kg of carboraffin and 25 kg of diatomaceous earth.

The esterification with a final temperature of 220 ° C was carried out in 6 hours to an acid number of 0.83 mg KOH / g esterification mixture.

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The 2-ethylhexanol was distilled off in vacuo and the acid number dropped to 0.52 mg KOH / g. Residues of 2-ethylhexanol were glued with water vapor at 180 ° C for 1 hour and 15 kg of an aqueous NaOH solution were added to the ester during stripping. After 15 minutes _in vacuum drying, the finished product had an acid value of 0.07 mg KOH / g. .

Example 2

After the dosing of the components of Example 1, 0.231 kg of AlgiSO4 / H2 O dissolved in 10 l of water was added to the mixture. The final esterification at 220 ° C was completed in 5 hours at an acid number of 0.78 mg KOH / g. The ethylhexanol was distilled off under vacuum, reducing the acid number during the distillation to 0.34 mg KOH / g. Under the stripping conditions with NaOH as in Example 1, and drying for 15 minutes, the acid number was 0.06 mg KOH / g.

Example 3

To 160 kg of the same TiOg · xHgO catalyst slurry as used in Example 1 was added 4.62 kg of Alg (SO 4) 4 · 18 HgO dissolved in 10 L of water. The pH of the slurry was adjusted to pH 9 with a 40% aqueous NaOH solution. The catalyst thus prepared was added to 5,400 kg of phthalic anhydride and 15,200 kg of 2-ethylhexanol. The esterification with the same temperature regime as in Example 1 took 4 hours and 15 minutes. it was 0.81 mg KOH / g and further decreased to 0.29 mg KOH / g during 2-ethylhexanol distillation. After 1 hour stripping with 15 kg of a 40% aqueous NaOH solution and 15 minutes of vacuum drying, the acid number was determined to be 0.07 mg KOH / g.

Example 4

The esterification boiler was charged with 5,100 kg of phthalic anhydride, 00 kg of a C? The esterification was terminated at 220 ° C after 4 hours 15 minutes with an acid number of 0.83 mg KOH / g. The unreacted alcohol mixture was subsequently distilled off under vacuum, the number of The acid value dropped to 0.34 mg KOH / g. During steam stripping at 180 ° C, 15 kg of a 40% NaOH solution was added to the boiler, after 15 minutes of drying the acid value was 0.08 mg KOH / g.

Claims (2)

Process for the preparation of phthalic acid esters by esterification of phthalic anhydride with aliphatic alcohols C? to Cj in the presence of a TiOg.xHgO catalyst or carboraffin and diatomaceous earth, characterized in that 0.001 to 0.5% by weight, preferably 0.05 to 0.20% by weight, of activated gel based TiOg.xHgO based on the total esterification handpiece-promoted addition of 0.1 to 50% by weight oktadekahydrótu aluminum sulfate based on dry weight of TiO _2, that the input of heat in the actual esterification process stopped when an acid number decrease in values of 3, 0 to 0.1 mg KOH / g of esterification mixture, after which excess esterification component is removed by vacuum distillation and steam stripping, the ester is dewatered under vacuum and the catalyst is removed by filtration. 2. A process for preparing phthalic acid esters according to claim 1, characterized in that, during steam stripping, up to 0.5% by weight of NaOH, based on the amount of ester to be treated, is preferably added in the form of a 40% aqueous solution.