甘油与异丁烯、叔丁醇共醚化强化反应机制研究

tert-Butyl glycerol ethers obtained from etherification of biodiesel based glycerol with isobutene or tert-butyl alcohol are excellent fuel additives. Etherification of glycerol with isobutene has high glycerol conversion and yield to the desired high ethers, while liquid-liquid mass transfer rate or liquid-liquid equilibrium concentration restricts the reaction rate. Glycerol etherification with tert-butyl alcohol proceeds quickly, while its glycerol conversion and high ether yield are low due to the limits of chemical equilibrium and inhibition of the produced water. This work thus combines these two etherification systems, i.e., etherifying glycerol with isobutene and tert-butyl alcohol simultaneously. In the co-etherification, tert-butyl alcohol promotes the mutual solvation and mass transfer of glycerol and isobutene, which increases the etherification rate. Isobutene is introduced to enhance the glycerol conversion and yield of high ethers, via driving the chemical equilibrium of glycerol etherification with tert-butyl alcohol and decreasing the adsorption inhibition of the produced water on the catalyst surface. With the aids of simulation and experimental investigation, the chemical equilibrium coupling of co-etherification under multi-phase condition is explored. The synergy and matching between the rates of liquid-liquid-solid mass transfer and surface reaction under different conditions are studied. The effects of phase separation and homogenization of the reaction mixture on the mass transfer and surface reaction are also discussed. And thus, the enhancement mechanism of co-etherification is uncovered. A new strategy for the intensification of glycerol etherification are developed, which provide an effective path for bio-energy utilization.

生物柴油副产甘油与异丁烯或叔丁醇醚化得到的叔丁基醚是性能优良的燃料添加组分。甘油-异丁烯醚化的甘油转化率及目的产物高醚收率高，但受液-液传质速率或反应物液-液平衡浓度的制约，反应过程速率较低；甘油-叔丁醇醚化反应速率高，但因化学平衡的限制或产物水的阻碍，其甘油转化率及高醚收率较低。本项目将两个单一醚化反应耦合，即同时使用叔丁醇和异丁烯对甘油进行共醚化，叔丁醇促进甘油和异丁烯的溶合及相间传质，以提高反应速率；异丁烯推动甘油-叔丁醇反应的化学平衡移动、减小产物水在催化剂表面的吸附阻碍作用，从而提高甘油转化率和高醚收率。结合模拟计算和实验研究，探索多相条件下共醚化复杂反应化学平衡耦合规律，考察不同条件下共醚化反应中液-液-固相间传质与表面催化反应速率的协同匹配及反应液分相/溶合对它们的影响，进而揭示共醚化强化反应过程的微观机制，形成甘油醚化反应强化的新策略，为生物能源的高效利用提供新途径。

生物柴油副产甘油与叔丁醇或异丁烯醚化得到的叔丁基甘油醚是性能优良的燃料添加剂。甘油-异丁烯醚化的甘油转化率及目的产物高醚收率高，但受液-液传质速率或反应物液-液平衡浓度的制约，反应速率较低；甘油-叔丁醇醚化在均一液相中进行，但因化学平衡的限制或产物水的阻碍，其甘油转化率及高醚收率较低。基于甘油-异丁烯、甘油-叔丁醇醚化反应在动力学、热力学上的优劣特点及互补性，本项目将两单一醚化反应耦合，即同时使用叔丁醇和异丁烯对甘油进行共醚化，以强化反应速率、甘油转化率和高醚收率。.建模分析了甘油-异丁烯醚化反应中的相间传质规律及液-液相平衡特征，明确了该过程中液-液-固传质速率远大于催化反应速率，液-液两相主体浓度接近相平衡浓度，反应速率受限于反应相中较低的异丁烯浓度；实验研究了甘油-异丁烯连续醚化中各步反应的动力学行为，考虑反应液分相的影响，建立了液-液-固多相反应动力学模型，发现各个反应通过反应物的竞争性吸附相互作用，证实了一醚通过促进甘油、异丁烯溶合而促使反应加速；详细计算了多相条件下甘油与异丁烯、叔丁醇共醚化的化学平衡规律，共醚化通过热力学耦合可获得介于两个独立醚化反应之间的平衡转化率及高醚收率；在商业树脂NKC-9上开展了共醚化实验，证实了共醚化可获得更高的反应速率、甘油转化率及高醚收率，结合热力学模拟发现共醚化可以改善反应相中反应物的浓度分布，从而提高反应速率。.本项目研究揭示了共醚化强化反应过程的内在机制，形成甘油醚化反应强化的新策略，为生物能源的高效利用提供新途径；同时完善了液-液-固多相反应动力学、热力学及过程强化的研究方法。