Many researchers reported that a sigmoid kinetic curve was obtained in oil transesterification with methanol catalyzed by CaO and gave different explanations for this formation. In this paper, heterogeneously catalyzed transesterification of soybean oil with methanol using CaO has been investigated. The solid catalyst and the liquid reaction mixture under different reaction time periods were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and high-performance liquid chromatography (HPLC) to reveal the formation of an S-shape kinetic curve. The appearance of calcium hydroxide, calcium methoxide, calcium glyceroxide, fatty acid calcium, diglycerides, and monoglycerides and their contributions to the kinetic curve have been discussed. The low reaction rate in the induction period can be attributed to mass transfer in this three-phase system. However, the formation of surfactants, diglycerides and monoglycerides, promotes the emulsification of the reaction mixture and numerous emulsion reactors are generated. These emulsion reactors can improve the contact of the solid catalyst with the reactants and thus accelerate the reaction.
Ying Zeng,Hao Chen,Guangjin Hu,Rui Cai,Yujie ChenYang,Zhixing Huang,Benyong Han
Eight novel amino acid (AA)–based trifluoromethanesulfonate ionic liquids (ILs; named [AAH][CF 3 SO 3 ]-ILs) were synthesized via neutralization reactions from natural AAs and trifluoromethanesulfonate (CF 3 SO 3 H). The catalytic performance of [AAH][CF 3 SO 3 ]-ILs in biodiesel preparation was evaluated with oleic acid and methanol as substrates. Among the eight [AAH][CF 3 SO 3 ]-ILs, the proline trifluoromethanesulfonate ([ProH][CF 3 SO 3 ]) catalyst displayed the best catalytic activity. The optimal process conditions for the response surface methodology (RSM) were as follows: [ProH][CF 3 SO 3 ] loading = 14.99 wt%, MeOH-to-oleic acid molar ratio = 17.94:1, reaction time = 1.95 h, and temperature = 71°C, and an oleic acid conversion rate of 98.97% was obtained. A first-order reaction kinetics of [ProH][CF 3 SO 3 ]–catalyzed oleic acid esterification showed an activation energy of 18.25 kJ·mol −1 and a frequency factor of 14.04 min −1 . ΔH, ΔS, and ΔG of oleic acid esterification reaction were 15.42 kJ·mol −1 , −0.232 kJ·mol −1 ·K −1 , and 97.32 kJ·mol −1 , respectively. The catalytic activity of [ProH][CF 3 SO 3 ] did not considerably change after eight reuse cycles, demonstrating its excellent stability and reusability. When applied as a catalyst, [ProH][CF 3 SO 3 ] dissolved in the reaction medium during the esterification reaction, enabling efficient homogeneous catalysis . After the reaction, phase separation automatically occurred between biodiesel (methyl oleate) and the catalyst, minimizing the product separation and purification process. The application of [ProH][CF 3 SO 3 ] in this study provides an environmentally friendly technique for biodiesel production . [ProH][CF 3 SO 3 ] is a promising renewable catalyst that it can be used to catalyze fatty acid esterification for biodiesel preparation instead of traditional catalysts.
Yang Wang,Ding Wang,Minghui Tan,Bo Jiang,Jingtang Zheng,Noritatsu Tsubaki,Mingbo Wu
SO3H-functionalized monodispersed hollow carbon/silica spheres (HS/C-SO3H) with primary mesopores were prepared with polystyrene as a template and p-toluenesulfonic acid (TsOH) as a carbon precursor and −SO3H source simultaneously. The physical and chemical properties of HS/C-SO3H were characterized by N2 adsorption, TEM, SEM, XPS, XRD, Raman spectrum, NH3-TPD, element analysis and acid–base titration techniques. As a solid acid catalyst, HS/C-SO3H shows excellent performance in the esterification of oleic acid with methanol, which is a crucial reaction in biodiesel production. The well-defined hollow architecture and enhanced active sites accessibility of HS/C-SO3H guarantee the highest catalytic performance compared with the catalysts prepared by activation of TsOH deposited on the ordered mesoporous silicas SBA-15 and MCM-41. At the optimized conditions, high conversion (96.9%) was achieved and no distinct activity drop was observed after 5 recycles. This synthesis strategy will provide a highly effective solid acid catalyst for green chemical processes.
危险品化学品经营许可证（带存储）