微波辅助酸化蒙脱土催化合成乳酸正丁酯的研究

采用微波辐照法对钠基蒙脱土进行了酸化改性,制备出了酸化蒙脱土(H-MMT)固体酸催化剂,并利用X射线衍射、低温物理吸附等技术对催化剂性质进行了表征,结果表明,经微波辐照酸改性的催化剂层状结构没有被破坏,层间距略有下降,结晶度降低;比表面积和孔径都增大,形成了较好的介孔结构;表面酸量增加.这些特性使得催化剂表现出良好的催化活性.而后,以H-MMT为催化剂,系统研究了乳酸正丁酯的微波辅助合成方法,考查了催化剂用量、微波功率以及微波辐照时间对酯化率的影响.结果表明,微波功率200W、辐照15min、催化剂用量6.0%(占乳酸和正丁醇总质量)为最优的酯化条件,在此条件下,酯化率可达72.4%.最后,探讨了微波辅助H-MMT催化合成乳酸正丁酯的机制,发现H-MMT与微波具有协同作用.微波辅助H-MMT催化合成乳酸正丁酯是一种高效、节能、环境友好的方法,具有市场推广前景.

Microwave assisted synthesis of n-butyl lactate catalyzed by acid-activatedmont morillonite clay

Acidic montmorillonite (H-MMT) was managed to be prepared by treating Na-montmorillonite with H₂SO₄ under microwave irradiation.The structure and characters of H-MMT were studied by X-ray diffraction(XRD) and nitrogen adsorption/desorption techniques.The results revealed that acid activation did not affect the layer structure,the surface area and pore volume was larger,and the acid amount was increased.Thus,H-MMT exhibits high catalytic activity in the microwave assisted esterification of lactic acid and n-butyl alcohol.After that,the synthesis of n-butyl lactate was performed by the esterification of lactic acid and n-butyl alcohol in the presence of H-MMT as catalyst under microwave irradiation.The synthesis conditions were systematically investigated and the optimum conditions are as follows:the microwave power is 200W,the reaction time is 15min and the catalyst amount is 6.0%.Under the above conditions,the ester yield could reach 72.4%.Compared to conventional heating and sulfuric canalization,microwave and H-MMT have a synergistic effect on the ester yield of n-butyl lactate.Microwave assisted synthesis of n-butyl lactate catalyzed by H-MMT was proved to be high-efficient,economical and eco-friendly.