Checa Manuel, Montes Vicente, Hidalgo-Carrillo Jesús, Marinas Alberto, Urbano Francisco J
Departamento de Ingeniería Química y Química Física, Instituto Universitario de Investigación del Agua, Cambio Climático y Sostenibilidad, Universidad de Extremadura, E-06071 Badajoz, Spain.
Departamento de Química Orgánica, Instituto Universitario de Investigación en Química Fina y Nanoquímica (IUNAN), Universidad de Córdoba, E-14071 Córdoba, Spain.
Nanomaterials (Basel). 2019 Apr 2;9(4):509. doi: 10.3390/nano9040509.
The influence of boron, tungsten and molybdenum modifiers on zirconia-based Pt catalyst was studied for glycerol valorization. Zirconia modified supports were prepared by impregnation of ZrO₂ with either boric, silicontungstic or phosphomolybdic acids to obtain supports with enhanced Brönsted acidic properties. The modified supports were subsequently impregnated with chloroplatinic acid to obtain Pt-based catalysts. Pt incorporation resulted in the increase in Lewis acidity of the solids, being more significant for the Pt//W/ZrO₂ catalyst. Reduced Pt catalysts were tested for the liquid-phase glycerol hydrogenolysis, observing a synergistic effect between catalyst acid sites and metal function that proved to be crucial in glycerol hydrogenolysis. The Pt//W/ZrO₂ catalyst was the most active catalyst in this reaction, being the only leading to 1,3-PDO (45% sel., 160 °C) while Pt//Mo/ZrO₂ is the best option for 1,2-PDO (49% sel., 180 °C). Reusability studies carried out for Pt//W/ZrO₂ showed that catalytic activity dropped after the first use, remaining constant for the second and subsequent ones. Selectivity to reaction products also changes during reuses. Therefore, the selectivity to 1,2 PDO increases in the first reuse in detriment to the selectivity to n-propanol whereas the selectivity to 1,3-PDO remains constant along the uses. This behavior could be associated to the lixiviation of W species and/or catalyst fouling during reaction runs.
研究了硼、钨和钼改性剂对用于甘油增值的氧化锆基铂催化剂的影响。通过用硼酸、硅钨酸或磷钼酸浸渍ZrO₂来制备改性的氧化锆载体，以获得具有增强布朗斯台德酸性的载体。随后用氯铂酸浸渍改性载体以获得铂基催化剂。铂的引入导致固体路易斯酸度增加，这对Pt//W/ZrO₂催化剂更为显著。对还原后的铂催化剂进行了液相甘油氢解测试，观察到催化剂酸性位点和金属功能之间的协同效应，这在甘油氢解中被证明至关重要。Pt//W/ZrO₂催化剂是该反应中活性最高的催化剂，是唯一能生成1,3 - 丙二醇（选择性45%，160℃）的催化剂，而Pt//Mo/ZrO₂是生成1,2 - 丙二醇的最佳选择（选择性49%，180℃）。对Pt//W/ZrO₂进行的可重复使用性研究表明，首次使用后催化活性下降，第二次及后续使用时保持恒定。在重复使用过程中，对反应产物的选择性也会发生变化。因此，在第一次重复使用中对1,2 - 丙二醇的选择性增加，而对正丙醇的选择性降低，而对1,3 - 丙二醇的选择性在多次使用过程中保持恒定。这种行为可能与反应过程中钨物种的浸出和/或催化剂结垢有关。
