High yield of ethyl valerate from the esterification of renewable valeric acid catalyzed by amino acid ionic liquids
作者:Lin-Lin Dong、Ling He、Guo-Hong Tao、Changwei Hu
DOI:10.1039/c3ra23034a
日期:——
Ethyl valerate (EV) as a promising fuel additive was produced by esterification of valeric acid with ethanol over Brønsted acidic amino acid ionic liquids. Hammett method and density functional theory (DFT) calculations were preformed to evaluate the acidities of the catalysts. The composition of catalyst, reaction temperature, reaction time, molar ratio of reactants, amount of catalyst, and recycling ability of the catalyst were investigated. Proline bisulfate (ProHSO4) ionic liquid has the highest catalytic activity and the best recyclability under the optimized esterification conditions. A high conversion of valeric acid (>99.9%) was obtained for 7 h at 80 °C, with 100% selectivity of EV. The density, viscosity, melting point, boiling point, elemental analysis and heat of combustion of the EV product were measured. The density of EV is 0.896 g cm−3. The viscosity of EV was 1.7 cP at room temperature. The heating values of EV are 4158.1 kJ mol−1 and 31.9 kJ g−1. EV obtained from esterification has higher energy density than methanol, ethanol, γ-valerolactone, and valeric acid, which illustrates that EV is a promising biofuel candidate.
乙酸乙酯(EV)作为一种有前景的燃料添加剂,通过在Brønsted酸性氨基酸离子液体中将戊酸与乙醇酯化反应制得。采用Hammett方法和密度泛函理论(DFT)计算评估了催化剂的酸性。研究了催化剂的组成、反应温度、反应时间、反应物的摩尔比、催化剂的用量以及催化剂的回收能力。经过优化的酯化条件下,脯氨酸双硫酸盐(ProHSO4)离子液体具有最高的催化活性和最佳的回收性。在80 °C下,7小时内戊酸的转化率超过99.9%,EV的选择性达到100%。测量了EV产品的密度、粘度、熔点、沸点、元素分析和燃烧热。EV的密度为0.896 g cm−3,室温下的粘度为1.7 cP。EV的热值为4158.1 kJ mol−1和31.9 kJ g−1。由酯化反应得到的EV的能量密度高于甲醇、乙醇、γ-戊内酯和戊酸,表明EV是一个有前景的生物燃料候选者。