Method of selectively synthesizing triethylenediamine

#The present invention relates to a selective process for the preparation of triethylenediamine (TEDA) from piperazine (PIP), in which a zeolite of a specific composition is used as a catalyst.

#TEDA (IUPAC name: 1,4-diazabicyclo[2.2.2]octane) is an important intermediate and end product in the chemical industry, which is used mainly as such as a catalyst in the preparation of polyurethanes. A large number of different syntheses which differ mainly in the choice of the starting materials and of the catalysts used are available for the preparation of TEDA.

#On the one hand, it is possible to use a range of different starting materials which contain a C2 building block and/or a nitrogen building block and may be cyclic or acyclic. Examples of suitable starting materials include ethylenediamine, diethylenetriamine, ethanolamine, aminoethylethanolamine, piperazine, aminoethylpiperazine and hydroxyethylpiperazine. A single starting material is frequently used, but mixtures of two or more suitable starting materials may also advantageously be used. Usually, water is also added to the reaction mixture. The composition of the product mixture is decisively influenced by the choice of the starting materials, the avoidance of the formation of byproducts, in addition to the availability of the starting materials, being an important aspect with regard to the specification to be achieved in the working-up. In most cases, in order to increase the selectivity with respect to the desired product TEDA, the synthesis is carried out so that only a partial conversion of the starting material or starting materials used occurs. The disadvantage of the low yield is accepted because of the small amounts of undesired byproducts which could be achieved.

#A Catalyst Preparation

#The zeolite powder (from ALSIPENTA, aluminosilicate of the type Na-ZSM-5, modulus 1 000) was subjected to an exchange three times with a 20% strength NH4Cl solution, washed, and calcined at 500° C. for 5 hours. Thereafter, the powder was subjected to an acid treatment (5% strength HCl, room temperature) three times for 8 hours, washed neutral each time with water and calcined at 500° C. for 3 hours. Finally, the zeolite powder was extruded with 20% by weight of SiO2 (based on the total mass of the prepared 2 mm extrudates) and was calcined at 500° C. for 5 hours.

#B Carrying Out the Process