We have previously demonstrated the influence of the niobium species over the glycerol dehydration reaction and how the catalyst regeneration by thermal treatment modified the catalytic performance due to the transformation of superficial niobium species. This experimental conclusion encouraged us to find a way to maintain and even improve the catalytic behavior of these Nb-based catalysts. Thus, herein, it is reported the influence of phosphoric acid treatment on 8 wt% Nb₂O₅ supported on zirconium doped mesoporous silica (Si/Zr 5 molar ratio) catalyst varying the Nb/P molar ratio between 0.1 and 1. Catalysts were full characterized and tested in the glycerol dehydration at 325 °C. This acid treatment modifies the nature of species present on the catalyst surface, as inferred from ³¹P NMR data, where the presence of zirconium hydrogenphosphate was detected. A comprehensive study of the influence of acid properties on the catalytic activity has been carried out. Thus, the selectivity to acrolein was improved, which was attributed to this hydrogenphosphate phase and the catalyst stability was associated to the existence of acid sites of low and moderate strength. The best catalyst was studied at higher reaction temperatures, showing the highest glycerol conversion and achieving acrolein selectivity of 74%, at 350 °C. This catalyst was also regenerated, maintaining its catalytic activity.

中文翻译：

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H ₃ PO _4处理对掺Zr介孔二氧化硅催化剂上负载的Nb ₂ O ₅催化活性的影响。案例研究：甘油脱水

先前我们已经证明了铌物种对甘油脱水反应的影响，以及由于表面铌物种的转化，通过热处理的催化剂再生如何改变了催化性能。这个实验结论鼓励我们找到一种方法来维持甚至改善这些基于Nb的催化剂的催化性能。因此，在本文中，据报道磷酸处理对负载在锆掺杂的介孔二氧化硅（Si / Zr 5摩尔比）催化剂上的8wt％Nb ₂ O ₅催化剂的影响，Nb / P摩尔比在0.1和1之间变化。在325°C的甘油脱水条件下进行了充分表征和测试。由酸推断，这种酸处理改变了存在于催化剂表面的物质的性质。³¹ P NMR数据，其中检测到磷酸氢锆的存在。已对酸性质对催化活性的影响进行了全面研究。因此，提高了对丙烯醛的选择性，这归因于该磷酸氢盐相，并且催化剂稳定性与存在低强度和中等强度的酸位有关。在较高的反应温度下研究了最好的催化剂，该催化剂在350°C时显示出最高的甘油转化率和74％的丙烯醛选择性。该催化剂也被再生，保持其催化活性。