CS214550B1 - Catalyst for the preparation of organic esters - Google Patents

Abstract

The invention relates to a catalyst for the preparation of organic esters, especially phthalate and other plasticizers. Its essence is that it is formed by an activated filterable gel based on TiO2.xH2O, which is prepared by hydrolysis of an acidic aqueous solution of titanyl sulfate, preferably from the production of titanium white, under boiling. The precipitated hydrolyzate is filtered off, washed with water, after which its activation is carried out by boiling in an alkaline solution of a concentration of at least 35% by weight for at least two hours, preferably 10 hours. The invention finds application in the industrial production of organic esters.

Description

The invention relates to a catalyst for the preparation of three organic esters, in particular phthalate and other plasticizers.

For the catalysis of esterification reactions, an alkali aluminum catalyst is used, which is disadvantageous mainly due to the very long esterification time and a wide range of titanium-containing compounds. These are, for example, compounds of the MX type wherein M is titanium and X is a hydroxy-, alkoxy-, oxialkoxy- or aminalkoxy group or halogen (U.S. Pat. No. 540,242J). Another extended group of titanium catalysts are Ti (OR) 4 catalysts where R is alkyl residue (U.S. Pat. No. 3,209,021, Germany Patent No. 1,593,503J), and the most widely used industrial catalysts of this type are tetra (2-ethylhexyl) titanate and tetrabutyl titanate. It is interesting from a technical point of view that the catalytic effects for the esterification reactions also have the products of hydrolysis of the titanium catalysts used, which are basically gels of the TiO2 * xH2O type. is expensive, arose Gels are usually very difficult to filter, and their activity in 0pakovaném application decreases rapidly; this form of titanium catalysts is therefore not used industrially.

These disadvantages are overcome by the esterification catalyst of the invention. Its essence is that it consists of an activated filterable gel based on TiO2 .XH2O which is prepared by hydrolyzing an acidic aqueous solution of titanyl sulfate, preferably from the production of titanium dioxide, at boiling. The precipitated hydrolyzate is filtered off, washed with water, and then activated by boiling in a solution of at least 35% by weight alkaline solution for at least two hours, preferably 10 hours.

The esterification catalyst according to the invention offers considerable advantages over the catalysts used hitherto. This is primarily the shortening of the esterification time and the reduction of the molar excess of alcohol in the esterification compared to the use of an alkaline aluminum catalyst. Compared to the titanium catalysts used, the catalyst gel of the present invention is completely removed from the ester by filtration after completion of esterification,

Claims (1)

Catalyst for the preparation of organic esters, in particular phthalate and other plasticizers, characterized in that it consists of an activated filterable gel based on ΊΊΟ2.ΧΗ2Ο, which is prepared by hydrolyzing an acidic aqueous solution of titanyl sulphate, preferably from 223 SO; strength, as is the case with organotitanate catalysts. The main advantage of the catalyst according to the invention, in comparison with other titanium catalysts, is that it can be introduced into the process 20 or more times during industrial esterifications, while its activity is practically not reduced. The economic advantage of the catalyst according to the invention is increased by the continuity of its preparation to the production of titanium dioxide, since part of the preparation of the catalyst according to the invention is part of the technology of this production. The practical properties of the catalyst according to the invention depending on the conditions for its preparation are evident from the following examples. Example 1 Weigh 40 g of an aqueous alkaline titanate suspension from titanium dioxide production containing 4.4 g of TiO2 and 42 g of solid NaOH into a distillation flask. The alkaline titanate is obtained by hydrolyzing the solution of titanyl sulfate while boiling, filtering and washing the hydrolyzate and subsequent boiling with sodium hydroxide. The batch was refluxed in the distillation flask for 6 hours. Then 4 g of carboraffin, 4 g of diatomaceous earth were added to the white, and after mixing the mixture was stirred for 4 hours. the catalyst was filtered and washed with water to a final pH = 9.5. The resulting filter cake was used as a catalyst to esterify 370 g phthalic anhydride and 813.2 g 2-ethylhexanol, the esterification was terminated at 215 ° C and an acid number of 0.30 mg KOH / g esterification mixture in 3 h 15 min. Example 2 In the same apparatus, the same TiO2 and NaOH batch as in Example 1 was boiled for 9 h, after which the catalyst was treated as in Example 1. 1. When the phthalic anhydride was esterified with 2-ethylhexanol under exactly the same conditions as in Example 1, the esterification was completed in 2 h 50 min. Example 3 The same batch of T102 and NaOH as in Example 1 was kept boiling for 12 'in the same apparatus and the catalyst was treated as in Example 1. The obtained catalyst was used to esterify phthalic anhydride with 2-ethylhexanol, under exactly the same conditions as in Example 1, esterification was complete in 2 h 45 min. According to the invention, the precipitated hydrolyzate is filtered off, washed with water and activated by boiling to a solution of at least 35% by weight of alkaline solution for at least two hours, preferably for 10 hours.