微波裂解硬脂酸钠脱羧成烃机理研究

摘要

可再生烃类燃料相对于脂肪酸甲酯（生物柴油）有显著优势.本研究以硬脂酸钠为研究对象,采用微波裂解技术开展脂肪酸盐脱羧成烃机理的研究,通过气质联用等手段对裂解产物进行分析,研究结果表明微波能选择性作用于硬脂酸钠羧基端,导致其在微波场中发生偶极转向极化和界面极化.离子或极性分子的Lorentz力按照电磁波作用的方式运动,有助于碳负离子的形成,有效推动了脱羧反应的进行;添加于反应体系中的甘油具有很高的介电常数,在微波场中形成＂高热位点＂,降低了脱羧反应活化能并为硬脂酸钠脱羧起到了供氢体的作用.液体产物中端烯烃和正构烷烃系列从C8～C20有规律的分布,符合烃类裂解的规律.研究结果证实了由脂肪酸盐在微波作用和甘油做为供氢体的条件下,脱羧裂解生产优质替代性烃类燃料和绿色化学品的可行性.%Renewable hydrocarbon fuel have significant advantage to biodiesel（fatty acid methyl ester）.The purpose of present study was to explore decarboxylation mechanism of fatty acid sodium salt with mi-crowave radiation.Sodium stearate（C18） was chosen as a model compound,the carboxy-terminal of this di-polar molecular was further polarized with microwave radiation.The Lorentz force of ions or dipolar mole-cules were moved in accordance with the way of electromagnetic waves,contributing to the formation of carbanion,which effectively promote the decarboxylation reaction.Glycerol possessing high dielectric con-stant were added which formed a ＂high-temperature locus＂ that lowed the activation energy of decarboxyla-tion reaction and played a role as the hydrogen donor.The liquid products were analysed and the results showed C8～C20 n-alkanes and n-alk-1-enes were arranged regularly which complied with the law of hydro-carbon pyrolysis.All the work proved the feasibility of deriving renewable hydrocarbon fuel from fatty acid sodium salt by microwave pyrolysis.