MXPA00004886A - Method of preparing phosphate catalysts for triethylenediamine production - Google Patents

Abstract

A new method of making phosphate-based catalysts by mixing phosphoric acid with a substantially water insoluble alkaline earth metal salt such that the phosphorus to alkaline earth metal molar ratio is less than 1. The product, containing alkaline earth metal hydrogen phosphate and the starting alkaline earth metal salt, is filtered and dried. The product can be used as a catalyst in the production of triethylenediamine from, for example, mono- and di-substituted piperazines, such as hydroxyethylpiperazine and aminoethylpiperazine, ethanolamines and substituted ethanolamines, and crude hydroxyethylpiperazine containing piperazine, hydroxyethylpiperazine, bis-hydroxyethylpiperazine, and water

Description

METHOD OF PREPARATION OF PHOSPHATE CATALYSTS FOR THE PRODUCTION OF TRIETILENDIAMINE BACKGROUND OF THE INVENTION Organic synthesis by condensation reactions that result in the loss of a molecule of water or ammonia is well known in the art. Certain of such reactions are generally carried out in the presence of acid catalysts. An important area in which such acid catalysts are used is in the cyclization reactions as in the synthesis of triethylenediamine and its C-substituted counterparts. -Catalysts are normally solid products of the Lewis acid type. A group of catalysts which have been found effective for acid catalyzed organic condensation reactions such as those used to produce triethylenediamine (also referred to herein as TEDA) are phosphate catalysts. The following patents provide examples of such phosphate catalysts. U.S. Patent 3,297,701 (Brader et al., 1967) describes the use of metal phosphate catalysts such as aluminum phosphate, calcium phosphate and cobalt phosphate, for the synthesis of C-substituted TEDA and TEDA from piperazines or alkanolamines.

U.S. Patent Nos. 4,405,784, 4,514,567 and 4,521,600 (Wells et al, 1983-1985) disclose the use of strontium monohydrogen phosphate (SrHP04), strontium pyrophosphate (Sr2P207), strontium dihydrogen phosphate (Sr (H2P04) 2), the pyrophosphate, monohydrogen phosphate and dihydrogen phosphate of copper, magnesium, calcium, barium, zinc, aluminum, lanthanum, cobalt, nickel, cerium and neodymium and mixtures thereof, as effective catalysts for organic condensation reactions especially the reaction for The catalysts are prepared by reacting a soluble salt of one of the metals with the mono- or diphosphate of an alkali metal or ammonium.The pH of the reaction mixture is adjusted to 5 ± 3 in order to precipitate the mono- or dihydrogen phosphate of the metal U.S. Patent 4,757,143 (Vanderpool et al, 1988) describes the conversion of cyclic and acyclic hydroxyethyl ethylene polyamines to TEDA using a catalyst composed of zirconia or titania to which from 0.5 to about 7% by weight of phosphorus has been chemically linked by thermal means in the form of phosphate linkage. U.S. Patent 5,037,838 (Zimmerman et al, 1991) discloses the conversion of N-hydroxyethyl piperazine to TEDA using a tungstoprophosphate catalyst supported on titania.

BRIEF DESCRIPTION OF THE INVENTION This invention is concerned with a new methods of making phosphate-based catalysts that are useful for the production of triethylenediamine (TEDA). The catalysts are prepared by mixing phosphoric acid with an alkaline earth metal salt substantially insoluble in water such that the molar ratio of phosphorus to alkaline earth metal is less than 1. An aqueous suspension of the salt, such as strontium carbonate, carbonate of Calcium, barium carbonate, is mixed with an aqueous solution of phosphoric acid to form an alkaline earth hydrogen phosphate. Since less than the stoichiometric amounts of alkaline earth metal salt and acid is used, some of the alkaline earth salt remains unreacted and is present in the precipitated product. The product, which contains alkaline earth metal hydrogen phosphate and the starting alkaline earth metal salt is filtered and dried. The mixture can be used as a catalyst in the production of TEDA from, for example, mono- and di-substituted piperazines, such as hydroxyethylpiperazine and aminoethylpiperazine, ethanolamines and substituted ethanolamines and hydroxyethylpiperazine containing piperazine, hydroxyethylpiperazine, bis-hydroxyethylpiperazine and water. There are several advantages to this method of making alkaline earth metal hydrogen phosphate compared to the known method of reacting an alkaline earth metal nitrate with sodium hydrogen phosphate both of which are in solution: the alkaline earth metal salt does not need to be placed in solution before reacting with phosphoric acid; The catalyst does not need to be washed to remove unwanted metals such as sodium and the cost of raw materials is much lower. It has also been found that the product made by the method of this invention has a much better activity and selectivity in the manufacture of TEDA from hydroxyethylpiperazine than the catalysts formed from a known method.

DETAILED DESCRIPTION OF THE INVENTION The preparation of alkaline earth metal hydrogen phosphates can be carried out by first forming an aqueous suspension of an alkaline earth metal salt which is substantially insoluble in water such as strontium carbonate, barium carbonate or calcium carbonate. . "Substantially insoluble in water" means that the solubility in water at room temperature (that is, about 25 ° C) is less than 1 part per 100 parts of water. An aqueous solution of phosphoric acid, for example, an 85% aqueous solution, is added to the alkaline earth metal salt solution, with stirring, in an amount such that the molar ratio of the phosphoric acid to the alkaline earth metal salt is less than 1; preferably less than 0.8. The reaction can be brought to cairo at room temperature, this is about 25 ° C and atmospheric pressure. The precipitate of the product is a mixture of the alkaline earth metal hydrogen phosphate salt and the unreacted alkaline earth metal salt. The molar ratio of phosphorus to alkaline earth metal of the product is less than 1; preferably less than 0.8. The precipitate is filtered and can then be washed, for example with water, although washing is not required. Then the filtered precipitate can be dried. For use as a catalyst, the product may be employed in the form of irregular particles of a desired size range by breaking the retort of the washed and dried filter or in the form of irregularly shaped pellets obtained by known methods of molding, pelletizing or extrusion. The product can also be deposited or otherwise impregnated into the pores of a microporous substrate such as alumina, silica, silica-alumina and the like.

In service, the catalyst of the present invention to catalyze organic condensation reactions, substantially the same conditions can be employed as when using the known catalysts. However, for optimal results, some adjustments of temperature, diluent and / or space velocity can be found beneficial. A continuous process is commonly used in the production of triethylene diamine. The temperature range is about 285 to 420 ° C, preferably 300 to 390 ° C, the pressure range is about 0.1 to 1.5 atmospheres (101.4 to 152.03 KPa), preferably 0.2 to 1.0 atmospheres (30.3 to 101.4 KPa) ) and the space velocity per hour of liquid (LHSV) of organic raw material per volume of catalyst is in the range of about 0.05 to 1.5, preferably 0.1 to 0.3. The reaction can be carried out in the presence of an inert gas such as nitrogen, argon or helium. In the preparation of TEDA, the organic raw material includes mono- and di-substituted piperazines selected from the group consisting of hydroxyethylpiperazine, aminoethylpiperazine, ethanolamines and substituted ethanolamines. The catalysts of this invention are relatively unaffected by the purity of the raw material. For example, high conversion and good yields can be obtained from crude hydroxyethylpiperazine which contains, in addition to hydroxyethylpiperazine, piperazine, bis-hydroxyethylpiperazine, and water. The invention will be further clarified by a configuration of the following examples which are intended to be only exemplary of the invention.

EXAMPLE 1 PREPARATION OF THE CATALYST A slurry (or suspension) was prepared by adding 30.1 g of SrC03 (supplied by CPC) to 40.02 g of deionized water. To this suspension, 11.6 g of 85% phosphoric acid are added with stirring. Carbon dioxide is released during the reaction. The solid was filtered, washed with deionized water and dried at 110 ° C. The solid contained a mixture of SrHP0 and SrC03. The chemical analysis shows that the solid had a P / Sr ratio of 0.54. The surface area of BET was 6 m2 / g.

EXAMPLE 2 PREPARATION OF TEDA FROM HYDROXYETHYL PIPERAZINE USING A CATALYST PREPARED FROM CARBONATE STRESS The reactions were carried out in a continuous flow tubular reactor under atmospheric pressure. The catalyst of Example 1 agglomerated to 18-35 mesh particles was charged to the reactor and heated to 340 ° C under a flow of anhydrous nitrogen. An aqueous solution of 25% hydroxyethylpiperazine (HEP) was pumped into the reactor at 1.5 ml / minute. Nitrogen is co-charged to the reactor at a rate of 22 ml / min. The reaction effluent was collected and analyzed by gas chromatography. The results are shown in the table below in the present.

EXAMPLE 3 PREPARATION OF TEDA FROM HYDROXYETHYL PIPERAZINE USING A CATALYST PREPARED FROM CARBONATE OF STRONTIUM The catalyst was prepared as in Example 1, except that SrC03 was supplied by Aldrich. The TEDA was prepared according to the procedure of example 2.-The results are shown in the table below in the present.

EXAMPLE 4 PREPARATION OF TEDA FROM HYDROXYETHYL PIPERAZINE USING A CATALYST PREPARED FROM CARBONATE OF CALCIUM The catalyst was prepared according to the procedure of Example 1, except that calcium carbonate was used in place of strontium carbonate. The TEDA was prepared according to the procedure of example 2. The results are shown in the table below in the present.

COMPARATIVE EXAMPLE 5 PREPARATION OF STRONTIUM HYDROGEN PHOSPHATE BY A PROCEDURE OF PREVIOUS TECHNIQUE AND USE OF THE CATALYST IN THE SYNTHESIS OF TEDA A strontium hydrogen phosphate catalyst was "prepared according to the procedure of U.S. Patent 4,405,784 in which a solution of strontium nitrate (Sr (N03) 2) was reacted with sodium hydrogen phosphate (Na2HP0) and the pH of the reaction mixture was adjusted to about 5.5.The product was separated by filtration, washed with water and dried. The catalyst was used in the production of TEDA according to the procedure of example 2. The results are shown in the table below.

Reaction conditions: 1.0 cc of catalyst (18-35 mesh), temperature = 340 ° C, pressure = 1 atmosphere; feeding = 1.5 ml / h of HEP at 25% by weight; nitrogen flow = 22 cc / min. The data was used for examples 2, 3 and 4 in which a mixture of a hydrogen phosphate of alkaline earth metal and carbonate, compared to example 5, in which pure hydrogen strontium phosphate was used demonstrate that the use of the catalyst of this invention unexpectedly results in a higher conversion of hydroxyethylpiperazine to TEDA and a higher selectivity to TEDA. In addition, the highest conversion and the highest selectivity of the catalyst of this invention was obtained with lower amounts of strontium or calcium hydrogen phosphate. The data of Examples 2, 3 and 4 also demonstrate that there are improved conversions and selectivity over a wide range of surface area of the catalyst; that is, 6 m2 / g to 17 m2 / g.

Claims (10)

1. CLAIMS 1. A method for the preparation of a catalyst comprising an alkaline earth metal hydrogen phosphate and an alkaline earth metal salt characterized in that it comprises: combining an aqueous phosphoric acid solution with an aqueous suspension of an alkaline earth metal salt substantially soluble in water such that the molar ratio of the phosphoric acid to the alkaline earth metal salt is less than 1, to form a precipitate of the alkaline earth metal hydrogen phosphate containing residual alkaline earth metal salt; filter the precipitate of the alkaline earth metal hydrogen phosphate containing residual alkaline earth metal salt and dry the precipitate.
2. 2. The method of compliance with the claim 1, characterized in that the alkaline earth metal salt is selected from the group consisting of strontium carbonate, calcium carbonate and barium carbonate.
3. 3. The method of compliance with the claim 2, characterized in that the alkaline earth metal salt is strontium carbonate.
4. 4. The method according to claim 2, characterized in that the alkaline earth metal salt is calcium carbonate.
5. 5. The method according to claim 2, characterized in that the molar ratio of phosphoric acid to alkaline earth metal salt is less than 0.8.
6. 6. A method for the preparation of triethylenediamine characterized in that it comprises contacting a compound selected from the group consisting of hydroxyethylpiperazine, crude hydroxyethylpiperazine, N-aminoethyl piperazine, ethanolamines and ethanolamines substituted with a catalyst comprising a combination of a metal hydrogen phosphate alkaline earth and an alkaline earth metal salt wherein the molar ratio of phosphorus to alkaline earth metal in the combination is less than 1.
7. 7. The method according to claim 6, characterized in that the molar ratio of the phosphorus to alkaline earth metal in the combination is less than 0.8.
8. 8. The method of compliance with the claim 7, characterized in that the alkaline earth metal is strontium, calcium or barium and the salt is carbonate. -
9. 9. The method according to the claim 8, characterized in that the compound is crude hydroxyethylpiperazine or hydroxyethylpiperazine.
10. 10. The method according to claim 8, characterized in that the compound is crude hydroxyethylpiperazine.