Synthesis And Kinetics Of Piperazine And Triethylenediamine

Piperazine and triethylenediamine are widely used as material for the synthesis ofantibacterial agents, hypotensor, hypoglycemic agents, antalgesic, antihistamine, anthelminticagents, as well as the production of surfactants, antiseptics, stabilizers, corrosion inhibitors,defoamers, curing agents, coatings and other fine chemical products.Piperazine and triethylenediamine synthesized from monoethanolamine has beenreported, but there are some problems, such as lower selectivity of catalyst that results invarious productions and hard separation. So it is important to do research on catalyst,technological conditions and their intrinsic kinetics. Piperazine and triethylenediamine weresynthesized from monoethanolamine and ammonia in this paper, and modified HZSM-5zeolite served as the catalyst. The influence of components of catalyst and impregnation,desiccation, calcination in the process of catalyst making on catalyst performance wereinvestigated. Through single-factor experiment, effects of space velocity, temperature, themolar ratio of ammonia to monoethanolamine and pressure on conversion and selectivitywere researched, preferred process operation parameters of preparing piperazine andtriethylenediamine were put forward when modified HZSM-5zeolite served as the catalyst.Qualitative and quantitative analysis of products by gas chromatography and gaschromatography-mass spectrography, combined with intrinsic kinetics’ experiment, reavaledkinetics characteristic of the reaction that synthesis of piperazine and triethylenediamine frommonoethanolamine.The main results are included as follows:（1）The suitable conditions for catalyst preparation: HZSM-5zeolite was modified bymetal nitrate C, the mass ratio of C to zeolite is0.04, the impregnating temperature is60℃,the impregnating time is6h, the drying temperature is140℃, the drying time is1h, thecalcining temperature is450℃, the calcining time is6h.（2）Modified HZSM-5zeolite was used for100h, the conversion and selectivity werestable. It indicated that the stability of catalyst is well.（3）The suitable technological conditions for this reaction: Space velocity is4h^-1,temperature is330℃, the molar ratio of ammonia to monoethanolamine is15, pressure is1Mpa.（4）Kinetics’ equations of piperazine and triethylenediamine synthesized from monoethanolamine and ammonia by modified HZSM-5zeolite as catalyst are shown asfollows:r_PIP=2.62×10¹⁶exp（-163610/RT）(y_MEA)^1.40r_TEDA=9.17×10²⁶exp（-268810/RT）(y_MEA)^2.30Among them: R is ideal gas constant, T is temperature. y_MEAis the mole fraction ofethanolamine.