Several catalysts containing metals such as Al, Zr, Ti and Nb were incorporated in SBA-15 with Si/M ratio = 20 using the hydrothermal process. These catalysts were evaluated for their reactivity during acid-catalyzed condensation of glycerol with acetone to yield a mixture of branched compounds, namely (2,2-dimethyl- [1,3] dioxane-4-yl)-methanol (solketal) and 2,2-dimethyl- [1,3] dioxane-5-ol, which are being used as fuel additives. The synthesised catalyst samples were characterized by ICP-AES analysis, N₂ adsorption–desorption measurements, X-ray diffraction, FT-IR, SEM–EDX, UV–visible diffuse reflectance spectroscopy, TPD of ammonia and ex situ pyridine-adsorbed FT-IR spectroscopy. The various characterization results confirm that metal oxides were incorporated in the pore wall of the SBA-15 matrices. The results of NH₃-TPD and ex situ adsorbed pyridine FT-IR analyses showed that the acidity of the samples increased after incorporation of metal into the pure SBA-15 samples. Among various metals incorporated into the SBA-15, the Nb–SBA-15 (Si/Nb = 20) showed higher catalytic activity toward the acetalization of glycerol in liquid phase compared to that of other samples investigated. Under the optimal reaction conditions, the Nb–SBA-15 (Si/Nb = 20) exhibited 95% glycerol conversion with 100% solketal selectivity. The catalyst reusability studies indicated that the Nb–SBA-15 sample is regenerable and highly stable in the acetalization of glycerol.

中文翻译：

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在各种金属改性的SBA-15催化剂上用丙酮对甘油进行酯化

使用水热法将几种含金属的催化剂（例如Al，Zr，Ti和Nb）以Si / M比= 20的方式掺入SBA-15中。在甘油与丙酮的酸催化缩合反应过程中，评估了这些催化剂的反应性，得到了支化化合物的混合物，即（2,2-二甲基-[1,3]二恶烷-4-基）-甲醇（缩酮）和2 ，2-二甲基-[1,3]二恶烷-5-醇，正用作燃料添加剂。合成的催化剂样品通过ICP-AES分析表征，N ₂吸附-解吸测量，X射线衍射，FT-IR，SEM-EDX，紫外-可见漫反射光谱，氨的TPD和非原位吡啶吸附的FT-IR光谱。各种表征结果证实，金属氧化物已掺入SBA-15基质的孔壁中。NH ₃的结果-TPD和异位吸附吡啶的FT-IR分析表明，将金属掺入纯SBA-15样品后，样品的酸度增加。与其他研究样品相比，在SBA-15中掺入的各种金属中，Nb-SBA-15（Si / Nb = 20）在液相中对甘油的缩醛化具有更高的催化活性。在最佳反应条件下，Nb-SBA-15（Si / Nb = 20）表现出95％的甘油转化率和100％的溶胶脂选择性。催化剂可重复使用性研究表明，Nb–SBA-15样品在甘油的缩醛化过程中可再生且高度稳定。