The effect of loading alkaline earth metal oxides on sulfated alumina-zirconia (S/AZ), as a nanocatalyst in esterification of oleic acid (OA) and transesterification of waste cooking oil (WCO) was experimentally investigated. S/AZ modified by calcium (S/Ca–AZ), magnesium (S/Mg–AZ), strontium (S/Sr–AZ) and barium oxides (S/Ba–AZ) were synthesized by solvent-free method and characterized by various methods. Based on the results, zirconia (Z) and S/AZ exhibited less activity in biodiesel production due to their low acidity and basicity while their activities were clearly increased by loading alkaline earth metal oxides. Among the samples, S/Ba–AZ shows the highest activity in both esterification and transesterification reactions, followed by S/Mg–AZ, S/Ca–AZ, and S/Sr–AZ, respectively. However, evaluating the activity of catalysts in second uses as an important factor for industrial application of a catalyst shows that, although the activity of all samples decreases, S/Ca–AZ has the least deterioration in activity. This can be related to its small particle size (below 15 nm), and well bonding of the calcium oxides with other metal oxides and sulfate groups which eliminates the leaching of active phases. Results confirm that S/Ca–AZ can be chosen as the most appropriate nanocatalyst with high activity and stability for biodiesel production from low-cost feedstock.

中文翻译：

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SO 4 2− / MO–Al 2 O 3 –ZrO 2（M = Ca，Mg，Sr，Ba）作为固体酸碱纳米催化剂的制备，用于反式/酯化反应

实验研究了负载碱土金属氧化物对硫酸化氧化铝-氧化锆（S / AZ）作为油酸（OA）酯化和废食用油（WCO）酯交换中的纳米催化剂的影响。通过无溶剂法合成了钙（S / Ca–AZ），镁（S / Mg–AZ），锶（S / Sr–AZ）和氧化钡（S / Ba–AZ）改性的S / AZ，并对其进行了表征通过各种方法。根据这些结果，氧化锆（Z）和S / AZ由于其低酸度和碱性而在生物柴油生产中表现出较少的活性，而通过添加碱土金属氧化物则其活性明显增加。在样品中，S / Ba-AZ在酯化和酯交换反应中均表现出最高的活性，其次分别是S / Mg-AZ，S / Ca-AZ和S / Sr-AZ。然而，评估第二次使用的催化剂的活性是催化剂工业应用的重要因素，结果表明，尽管所有样品的活性均降低，但S / Ca-AZ的活性下降最少。这可能与它的小粒径（低于15 nm）以及氧化钙与其他金属氧化物和硫酸盐基团的良好键合有关，从而消除了活性相的浸出。结果证实，S / Ca-AZ可以被选为最合适的纳米催化剂，具有高活性和稳定性，可用于从低成本原料生产生物柴油。以及氧化钙与其他金属氧化物和硫酸盐基团的良好键合，从而消除了活性相的浸出。结果证实，S / Ca-AZ可以被选为最合适的纳米催化剂，具有高活性和稳定性，可用于从低成本原料生产生物柴油。以及氧化钙与其他金属氧化物和硫酸盐基团的良好键合，从而消除了活性相的浸出。结果证实，S / Ca-AZ可以被选为最合适的纳米催化剂，具有高活性和稳定性，可用于从低成本原料生产生物柴油。