【摘要】 植物油由于运动黏度较大、凝点高,限制了其在油浸绝缘高电压设备中作为绝缘油的使用。植物油通过酯交换反应,能够大大降低其黏度,提高散热性能。为探究经酯交换得到甲酯的热稳定性,以NaOH为催化剂,棕榈油为原料油,通过酯交换反应(醇油摩尔比9∶1、反应温度65℃、催化剂用量1%、反应时间30 min)制备得到棕榈油甲酯。通过热重分析平台分别在10、20、30、40℃/min升温速率条件下考察棕榈油甲酯与棕榈油热稳定性,并基于等转化率法采用非预置模型FlynnWall-Ozawa计算两者的热解活化能,利用Avrami理论计算热解反应级数。结果表明,棕榈油经酯交换后起始分解温度大大降低,棕榈油和棕榈油甲酯的热解活化能平均值分别为195. 57 kJ/mol和57. 14 kJ/mol,反应级数分别为0. 315～0. 383和1. 402～1. 580。更多还原

【Abstract】 The application of vegetable oil used in oil insulated high voltage equipments was restricted due to its high kinematic viscosity and solidifying point. The viscosity of vegetable oil could be reduced greatly through transesterification,thus enhancing the heat dispersion. In order to investigate the thermal stability of methyl ester,NaOH was employed as catalyst for transesterification of palm oil and methanol( molar ratio of methanol to oil 9∶ 1,catalyst amount 1%,reaction temperature 65 ℃ and reaction time 30 min) to produce methyl ester. Thereafter,the palm oil and methyl ester were evaluated by thermogravimetry at four heating rates of 10,20,30,40 ℃/min. Based on the iso-conversional method,Flynn-Wall-Ozawa method and Avrami theory were adopted to calculate activation energy of thermodecomposition and reaction order,respectively. The results showed that the initial decomposition temperature was reduced after palm oil was transesterified. The average activation energy of thermodecomposition for palm oil and methyl ester were 195. 57 kJ/mol and 57. 14 kJ/mol,and the corresponding reaction order were 0. 315-0. 383 and 1. 402-1. 580,respectively.更多还原