微波裂解硬脂酸钠脱羧成烃机理研究

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.

Mechanism of Hydrocarbon Generation from Sodium Stearate Decarboxylation by Microwave Assisted Pyrolysis

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.