Abstract For biodiesel production from waste cooking oils with high acid values, an inefficient esterification pretreatment is always conducted to convert free fatty acids (FFAs) before alkali-catalysed transesterification process. In this paper, phosphotungstic acid based poly(ionic liquid) was prepared to catalyse the esterification of palmitic acid with methanol while the required catalyst dosage was much lower than commercial Amberlyst-15. And the catalyst was characterized by 31P CP-MAS NMR, FTIR, SEM, XRF and TG. Among the three poly(ionic liquid)s prepared in this paper, phosphotungstic acid based poly(ionic liquid) was selected to be the most suitable catalyst for esterification because the catalyst could be reused for more than 5 times without significant deactivation. According to single factor analyses, the esterification yield could reach 91.6% after 8 h while the reaction temperature, methanol to acid molar ratio and catalyst dosage were 65 °C, 6 and 3% wt, respectively. Afterwards, palmitic acid was proposed to be first adsorbed on the catalyst before reacting with methanol. Finally, a palmitic acid adsorbed Eley-Rideal model was employed to analyse the reaction and the adsorption mechanism was assumed as well.

中文翻译：

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磷钨酸基聚离子液体的制备及其在棕榈酸酯化反应中的应用

摘要 对于从高酸值废弃食用油生产生物柴油，在碱催化酯交换过程之前总是进行低效的酯化预处理以转化游离脂肪酸（FFA）。在本文中，制备了磷钨酸基聚（离子液体）以催化棕榈酸与甲醇的酯化，同时所需的催化剂用量远低于商业 Amberlyst-15。并对催化剂进行了31P CP-MAS NMR、FTIR、SEM、XRF和TG表征。在本文制备的三种聚（离子液体）中，磷钨酸基聚（离子液体）被选为最适合酯化反应的催化剂，因为该催化剂可以重复使用 5 次以上而不会显着失活。根据单因素分析，反应温度、甲醇酸摩尔比和催化剂用量分别为65℃、6%和3%wt，8h后酯化产率可达91.6%。之后，有人提议先将棕榈酸吸附在催化剂上，然后再与甲醇反应。最后，采用吸附棕榈酸的 Eley-Rideal 模型来分析反应，并假设吸附机理。