Brnsted双核磺酸功能化离子液体催化制备生物柴油

Preparation of biodiesel catalyzed by Brnsted dicationic SO_3H-functionalized ionic liquid

以吗啡啉、1,3-丙烷磺内酯、1,4-二溴丁烷和浓硫酸为原料,通过三步法合成了双-(4-(3-磺丙基)吗啡啉)亚丁基双硫酸氢盐(Bi-[C_3SO_3Hnhm]H_SO_4)双核磺酸功能化离子液体。分别采用FT-IR和TG对合成的离子液体的结构和热稳定性进行表征;同时测定了该离子液体的溶解性、酸性及对奥氏体型不锈钢316的腐蚀性。此外,考察了该离子液体催化大豆油和甲醇反应制备生物柴油的工艺条件中。结果表明,合成的离子液体与目标产物一致,具有较高的热稳定性,能够溶解于极性溶剂,且具有较强的酸性,98%浓硫酸对钢样的腐蚀速率为离子液体的近8倍。当醇油摩尔比为14∶1、离子液体加入量为大豆油和甲醇总质量的5%、反应时间为8 h、反应温度为60℃时,生物柴油的收率为95.4%,且该离子液体经回收、真空干燥,重复使用6次后生物柴油的收率仍然能够达到91.2%。

With morphine,1,3- propanesultone,1,4- dibromobutane and concentrated sulfuric acid as raw materials,the dicationic SO3H- functionalized ionic liquid Bi- [C_3SO_3Hnhm]HSO_4 was synthesized by three- step method. The structure and thermal stability of the ionic liquid were characterized by FT- IR and TG. At the same time,the acidity,solubility and the corrosion to austenite stainless steel316 of the ionic liquid were also determined. In addition,the preparation conditions of biodiesel through transesterification of soybean oil with methanol catalyzed by the ionic liquid were investigated. The results showed that the ionic liquid synthesized was consistent with the target product and had high thermal stability and strong acidity,soluble in polar solvent. The corrosion rate of 98% concentrated sulfuric acid to steel sample was nearly seven times higher than that of the ionic liquid. Under the conditions of molar ratio of methanol to soybean oil 14∶ 1,dosage of ionic liquid 5% of the total mass of soybean oil and methanol,reaction temperature 60 ℃ and reaction time 8 h,the yield of biodiesel was 95. 4%. After the ionic liquid was recycled,dried under vacuum and reused for six times,the yield of biodiesel still could reach91. 2%.