Ecologically friendly and catalytic process "Research and Development of catalysts for selective synthesis of ethylenediamine"

研究了在酸性沸石催化剂上，以乙醇胺为原料，以氨气为催化剂合成乙二胺的反应。在本研究测试的沸石中，H-EDTA-MOR （H_4EDTA脱铝h型丝光沸石）是最好的催化剂。结果表明，该反应对EDA的选择性比H-EDTA-MOR高，副反应产物为少量的亚胺和哌嗪衍生物。随着NH_3分压的增加，EDA合成的催化活性提高。反应初始产物为El，随后生成EDA。结果表明，EDA的形成需要丝光沸石通道中较强的酸性位点和过量的NH_3。丝光沸石通道可以延缓较大的哌嗪衍生物和其他多胺的形成。通过H-EDTA-MOR质子的加入，EA的反应通过氨离子进行；然后EA的氨离子发生分子内缩合，在催化剂的活性位点上生成El中间体。乙烯亚胺被较强的酸性位点和过量的NH_3质子化生成EDA。采用IR（吡啶吸附）、XRD、XRF、MAS NMR等研究了H_4EDTA和不同浓度盐酸对丝光沸石脱铝的影响。采用GO-MS对各催化剂的催化活性进行测试，并对产物进行分析。吸附吡啶的量（从红外光谱计算）随着脱铝的进行而增加。在Si/Al（体积）=5时达到最大值，随后减小。催化活性随吡啶用量的增加而增加，随结晶度和吡啶用量的减少而降低。也就是说，催化反应曲线与酸的用量，特别是与Bronsted酸的用量密切相关。除铝过程中酸量增加的原因正在调查中。

The synthesis of EDA (ethylenediamine) from EA (ehtanolamine) with NH_3 over acidic types of zeofite catalyst was investigated. Among the zeolites tested in this study, H-EDTA-MOR (H-type mordenite dealuminated with H_4EDTA) was the best catalyst. The reaction proved to be highly selective for EDA over H-EDTA-MOR, with small amounts of ethyleneimine and piperazine derivatives as the side products. The catalytic activity for EDA synthesis rises with increasing partial pressure of NH_3. The initial product of reaction was El, and the formation of EDA followed. The results suggest that the formation of EDA required stronger acidic sites in the mordenite channels with excess amounts of NH_3. The mordenite channels may retard the formation of bulkier piperazine derivatives and other polyamines. The reactions of EA proceed through ammonio-ions by the addition of protons of H-EDTA-MOR ; then intramolecular condensation of ammonioions of EA occurred to produce an El intermediate over the active sites of the catalyst. ethyleneimine is protonated by the stronger acidic sites with excess amounts of NH_3 to produce EDA.Dealuminated mordenites by H_4EDTA and hydrochloric acid of different concentration were investigated with IR (pyridine adsorption), XRD, XRF, MAS NMR.Each catalyst was used to test the catalytic activity and the produsts were analyzed with GO-MS.The amount of adsorbed pyridine (calculated from IR spectra) increased as the dealumination proceeds. It reached its maximum around Si/Al (bulk) =5, and then decreased. The catalytic activity increased as the amount of pyridine increased, and it decreased as the crystallinity and the pyridine amount decreased. That is, the curve of catalytic reaction strongly relates to the acid amount, especially Bronsted acid. It is under investigation the reason the acid amount increased with dealumination.