Co-production Of Piperazine And N-ethylpiperazine

Piperazine and N-ethylpiperazine are important chemical intermediates to antibiotics drugs industries. Besides, they are also widely used in electronic products and steel manufacture industries, and their industrial usage increases year by year. Meanwhile, piperazine derivatives have already been used into CO2 absorption industry, and piperazine derivatives shows an excellent performance which made a large market protencial of piperazine derivatives.A system study for co-production of piperazine and N-ethylpiperazing has been carried on in this thesis. The hydroxyethylethylenediamine （AEEA） and ehanol were used as raw material, and a series of catalysts were employed for this reaction in a fixed-bed reactor. Cu₃₀Cr₁₀/γ-Al₂O₃ shows a good coversion and selectivity. The reaction mechanism was put forward, which was identified by GC-MS.Moreover, the reaction parameters including temperature, H2 pressure, AEEA concentration, feed rate and preparation method of catalyst were optimized:the temperature is 200℃, the H2 pressure is 3.0Mpa, the AEEA concentration is 40%, the feed rate is 0.5mL/min. The conversion of AEEA is 99.2%, and the selectivity of piperazine and N-ethylpiperazine is 70.7% and 27.4%, respectively. Finally, the lifetime of the catalyst was evaluated and the reaction could continuously proceed over 60 days.The reaction mixture was separated by rectification. The azeotropic composition of N,N-diethylpiperazine and water was taken away from the mixture. Then 620g piperazine was separated at 145～148℃, and 257g N-ethylpiperazine was obtained from the mixture at 154～156℃. The purities of piperazine and N-ethylpiperazine can be improved to 99.5% by controlling efflux ratio.At last, a scale-up experiment was carried on in a plant. A fix bad with a diameter of 100cm,150cm high,500L reactor and a rectifying column with a diameter of 300mm were employed.31.78 tons AEEA and 10.8 ton ethanol were added into reaction and 21.332 ton 99.9% N-ethylpiperazine was obtained.The lifetime of catalyst canbe used for more than 1 year,and the catalyst’s cost was low. During the process, the obtained piperazine can be sold as a product and it also can be used to produce N-ethylpiperazine. The residual liquid after rectification can be used as a material to produce DABCO （triethylene diamine）.