生物柴油抗氧化剂没食子酸异戊酯制备及其抗氧化性能研究

Preparation of biodiesel antioxidant iso-amyl gallate and its antioxidant activity

首先以吗啡啉和溴代正丁烷作为反应物,制成正丁基吗啡啉硫酸氢盐离子液体。采用离子液体作为催化剂催化没食子酸与异戊醇酯化合成没食子酸异戊酯。通过单因素试验和正交试验对合成没食子酸异戊酯的反应条件进行优化。结果表明:影响酯化产率的因素主次顺序为反应温度>反应时间>醇酸摩尔比>催化剂用量;最佳反应条件为反应温度80℃,醇酸摩尔比30∶1,反应时间50 min,催化剂用量6%;最佳条件下酯化产率为97.45%。在此基础上进行酯化反应动力学分析,得出反应活化能为4.91 k J/mol,动力学模型为-dC_A/dt=5.22e-^(4.91/RT)C_A^(0.843)。分析了没食子酸异戊酯对8种生物柴油的抗氧化效果,其抗氧化性能极佳,在添加量为600 mg/kg时能使小桐子油生物柴油氧化稳定性能达到国家标准要求。

With morphine and 1 -bromobutane as reactants, the n -butyl morpholinium hydrogen sulfate （ [ Hnhm ] HSO4 ） ionic liquid was prepared firstly. The esterification of gallic acid and isoamyl alcohol to synthesize iso - amyl gallate was catalyzed by the ionic liquid. The reaction conditions of synthesis of iso - amyl gallate were optimized by single factor experiment and orthogonal experiment. The resuhs showed that the sequence of the factors influencing the esterification yield from high to low was：reaction temperature, reaction time, molar ratio of isoamyl alcohol to gallic acid, dosage of catalyst. The optimal reaction conditions were obtained as follows： reaction temperature 80 ℃, molar ratio of isoamyl alcohol to gallic acid 30： 1, reaction time 50 min and dosage of catalyst 6%. Under these conditions, the esterification yield was 97.45%. The kinetics of esterification was analyzed and the activation energy and kinetic model were 4. 91 kJ/mol and -dCA/dt=5.22e^-4.91/RT CA^0.843 respectively. The antioxidant effects of iso -amyl gallate on eight kinds of biodiesels were excellent. The oxidative stability of Jatropha biodiesel could meet the national standard requirment when the dosage of iso - amyl gallate was 600 mg/kg.