This paper describes the application of chromium(III) terephthalate (Cr-Tp) and cobalt(II) terephthalate (Co-Tp) metal organic frameworks, as heterogeneous acid catalysts to avoid the yield reduction caused by saponification during the process of biodiesel production using Calophyllum inophyllum oil. The catalysts were mainly characterized using spectroscopic (FTIR), microscopic (SEM, energy-dispersive X-ray spectroscopy) and X-ray diffractive techniques. The surface acidity and the thermal stability of the catalysts were determined using Hammett indicator and thermo-gravimetric methods, respectively. The catalysts were employed for the pre-esterification of free fatty acid content of the oil before subjecting the oil for the transesterification of its triglyceraldehyde content. The pre-esterification was performed through a couple of successive catalytic cycles under milder conditions [25°, 1 atm, and 2/1 MeOH/oil (w/w) ratio] than the conditions reported so far. The study revealed that the successful pre-esterification required these catalysts in very small amount (< 2.5% by oil weight) and occurred within very short time (2 h for the 1st cycle and 2–4 h for the 2nd cycle), reducing the acid value of C. inophyllum oil significantly (88%) from 56.91 to ~ 6.5 mg KOH g⁻¹. The catalytic activity of these catalysts remained unchanged even after the 10th cycle of catalyst reuse. More importantly, the yield of biodiesel obtained from C. inophyllum oil in this way was significantly high (~ 93%) and free from saponification.

中文翻译：

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铬和对苯二甲酸钴金属有机骨架作为催化剂在轻度条件下以高产Calophyllum inophyllum油生产生物柴油的应用

本文介绍了将对苯二甲酸铬（III）和对苯二甲酸钴（II）（Co-Tp）金属有机骨架作为非均相酸催化剂的应用，以避免在使用生物柴油生产过程中皂化引起的收率降低茶树油。催化剂的主要特征是使用光谱（FTIR），显微技术（SEM，能量色散X射线光谱法）和X射线衍射技术。分别使用哈米特指示剂和热重法测定催化剂的表面酸度和热稳定性。在使油进行甘油三醛含量的酯交换反应之前，将催化剂用于油中游离脂肪酸含量的预酯化。通过比目前报道的条件更温和的条件[25°，1 atm和2/1 MeOH /油（w / w）比率]在几个连续的催化循环中进行预酯化反应。研究表明，成功的预酯化需要这些催化剂的量非常少（<2。C.inophyllum油从56.91到〜6.5 mg KOH g ^-1显着（88％）。这些催化剂的催化活性甚至在催化剂再利用的第10个循环后仍保持不变。更重要的是，以这种方式从茶树油中获得的生物柴油的收率非常高（〜93％），并且没有皂化作用。