In this work, a novel supported catalyst was prepared starting from calcium chloride and chitosan flakes using a very mild approach in an aqueous medium without final calcination at high temperatures. The as-prepared catalyst was fully characterized by thermogravimetric analysis (TGA), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and X-ray photoelectron (XPS) spectroscopies, transmission and scanning electron microscopies (TEM, SEM), Energy Dispersive X-ray Spectroscopy (EDS), demonstrating that it consists of calcium hydroxide particles of about 200 nm supported on chitosan micrometric structures. The most crucial parameters in the transesterification process were investigated. A methanol/oil ratio of 6:1, a reaction time of 6 h, and a temperature of 60 °C were found to lead to complete conversion. A reaction on a gram scale using waste oil as a starting material was also tested, and excellent results were achieved. Moreover, the catalyst proved to be very robust, since even after the 10th recycle, the conversion rate remained at around 90 %. Spectroscopic analyses showed minimal leaching of material without modification of chemical composition. The kinetic behavior (activation energy, E) of the catalyst was also studied, which resulted in similar outcomes to Ca-based systems present in the literature, but without the need for costly preparations and with superior recycling resistance. An E value of 63.25 kJ·mol was found, which agrees with data reported in the literature.

中文翻译：

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壳聚糖负载氢氧化钙杂化材料作为新型、高效、可回收的生物柴油生产催化剂

在这项工作中，以氯化钙和壳聚糖薄片为原料，采用非常温和的方法在水介质中制备了一种新型负载型催化剂，无需在高温下进行最终煅烧。通过热重分析 (TGA)、衰减全反射傅里叶变换红外 (ATR-FTIR) 和 X 射线光电子 (XPS) 光谱、透射和扫描电子显微镜 (TEM、SEM)、能量色散光谱对所制备的催化剂进行了全面表征。 X 射线光谱 (EDS)，证明它由负载在壳聚糖微米结构上的约 200 nm 的氢氧化钙颗粒组成。研究了酯交换过程中最关键的参数。发现甲醇/油比例为 6:1、反应时间为 6 小时、温度为 60 °C 可实现完全转化。还测试了以废油为起始原料的克级反应，并取得了优异的结果。此外，事实证明该催化剂非常坚固，即使在第10次循环后，转化率仍保持在90%左右。光谱分析显示，在不改变化学成分的情况下，材料的浸出量最小。还研究了催化剂的动力学行为（活化能，E），其结果与文献中存在的基于钙的系统相似，但不需要昂贵的制备，并且具有优异的耐回收性。发现E值为63.25 kJ·mol，这与文献报道的数据一致。