This paper reports the preparation, evaluation, and comparison of alkaline and acidic heterogeneous carbon-based catalysts in the transesterification of safflower oil with methanol to obtain biodiesel. These catalysts were obtained from the pyrolysis of flamboyant pods and their functionalization and activation with potassium hydroxide, citric acid, tartaric acid, sulfuric acid, and calcium nitrate. Different routes for the preparation of these catalysts were tested and analyzed where the FAME formation was the target variable to be improved. Results showed that the catalyst prepared with potassium hydroxide and calcium nitrate achieved the highest FAME formation (i.e., 95%) and outperformed the catalysts prepared with calcium nitrate and other acids even after four regeneration-reaction cycles. The best properties of an alkaline catalyst could be associated with its specific surface area and contents of potassium and calcium moieties, which were higher than those observed for acidic catalysts. Transesterification rates for biodiesel production were better estimated with the pseudo-order kinetic model, which ranged from 0.0004 to 0.038 L/mol⋅min for alkaline and acidic catalysts.

中文翻译：

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碱性和酸性多相碳基催化剂的制备、表征及其在植物油酯交换制取生物柴油中的应用

本文报道了碱性和酸性非均相碳基催化剂在红花油与甲醇酯交换制取生物柴油中的制备、评价和比较。这些催化剂是通过热解华丽的豆荚以及用氢氧化钾、柠檬酸、酒石酸、硫酸和硝酸钙对其进行功能化和活化而获得的。测试和分析了制备这些催化剂的不同途径，其中 FAME 的形成是要改进的目标变量。结果表明，用氢氧化钾和硝酸钙制备的催化剂达到了最高的 FAME 形成率（即 95%），甚至在四个再生反应循环后也优于用硝酸钙和其他酸制备的催化剂。碱性催化剂的最佳性能可能与其比表面积以及钾和钙部分的含量有关，这些都高于酸性催化剂所观察到的。使用伪级动力学模型可以更好地估计生物柴油生产的酯交换速率，碱性和酸性催化剂的范围为 0.0004 到 0.038 L/mol·min。