Time-resolved in-situ x-ray diffraction study of CaO and CaO:Ca 3 Al 2 O 6 composite catalysts for biodiesel production
Time-resolved in-situ x-ray diffraction study of CaO and CaO:Ca 3 Al 2 O 6 composite catalysts for biodiesel production
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用于生物柴油生产的CaO和CaO:Ca 3 Al 2 O 6 复合催化剂的时间分辨原位X射线衍射研究
DOI：
10.1088/2515-7655/ac0413
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发表时间：
2021
期刊：
影响因子：
9
通讯作者：
Bonaccorso A
中科院分区：
文献类型：
--
作者：
Bonaccorso A
替代性和可持续废物来源正受到越来越多的关注，因为它们可用于生产低碳足迹的生物燃料。废鱼油就是一个这样的例子，可以被认为是生产生物柴油的丰富且可持续的废物来源。最终，这可能导致渔业社区拥有自己的船只和车辆的“离网”燃料来源。在工业层面，目前生物柴油采用均相催化法生产，因为催化剂活性和选择性较高。相比之下，多相催化具有多种优点，例如提高可重复使用性、减少浪费和降低加工成本。在这里，我们研究了两种多相催化剂 CaO 和 Ca 3 Al 2 O 6: CaO ('C3A: CaO') 复合材料在原位条件下从鱼油生产生物柴油的相演化。设计了一种新反应器，利用同步加速器粉末 X 射线衍射监测反应过程中晶体催化剂的演变。大约 30 分钟后，两种催化剂的二甘油氧化钙 (CaDG) 量开始迅速增加。 CaDG 的这种快速增加可能与异位核磁共振研究有关，该研究表明鱼油向生物柴油的转化在 30 分钟后迅速增加。两种催化剂活性差异的关键似乎是 Ca 3 Al 2 O 6: CaO 复合材料比 CaO 更长时间地保持高 CaDG 形成速率，尽管初始形成速率和反应动力学相似。 CaDG 中的 Ca 主要来自 CaO 相。此外，在使用 CaO 催化剂的第二次测试快结束时（120 分钟后），CaDG 快速下降，Ca (OH) 2 快速增加。对于 Ca 3 Al 2 O 6: CaO 催化剂没有观察到这种情况，这是由于 Ca 3 Al 2 O 6 稳定了复合材料中的 CaO。在我们的原位实验期间没有观察到额外的含钙中间结晶相。总体而言，这种专门的原位装置已被证明适合监测甘油三酯酯交换反应过程中多相结晶催化剂的相演化，提供了将结晶相与活性、失活和稳定性相关联的机会。
Alternative and sustainable waste sources are receiving increasing attention as they can be used to produce biofuels with a low carbon footprint. Waste fish oil is one such example and can be considered an abundant and sustainable waste source to produce biodiesel. Ultimately this could lead to fishing communities having their own'off-grid'source of fuel for boats and vehicles. At the industrial level, biodiesel is currently produced by homogeneous catalysis because of the high catalyst activity and selectivity. In contrast, heterogeneous catalysis offers several advantages such as improved reusability, reduced waste and lower processing costs. Here we investigate the phase evolution of two heterogeneous catalysts, CaO and a Ca 3 Al 2 O 6: CaO ('C3A: CaO') composite, under in-situ conditions for biodiesel production from fish oil. A new reactor was designed to monitor the evolution of the crystalline catalyst during the reaction using synchrotron powder x-ray diffraction. The amount of calcium diglyceroxide (CaDG) began to increase rapidly after approximately 30 min, for both catalysts. This rapid increase in CaDG could be linked to ex-situ nuclear magnetic resonance studies which showed that the conversion of fish oil to biodiesel rapidly increased after 30 min. The key to the difference in activity of the two catalysts appears to be that the Ca 3 Al 2 O 6: CaO composite maintains a high rate of CaDG formation for longer than CaO, although the initial formation rates and reaction kinetics are similar. The Ca for the CaDG mainly comes from the CaO phase. In addition, towards the end of the second test utilising the CaO catalyst (after 120 min), there is a rapid decrease in CaDG and a rapid increase in Ca (OH) 2. This was not observed for the Ca 3 Al 2 O 6: CaO catalyst and this is due to Ca 3 Al 2 O 6 stabilising the CaO in the composite material. No additional calcium containing intermediate crystalline phases were observed during our in-situ experiment. Overall this specialised in-situ set-up has been shown to be suitable to monitor the phase evolution of heterogeneous crystalline catalysts during the triglycerides transesterification reaction, offering the opportunity to correlate the crystalline phases to activity, deactivation and stability.