Abstract Silicoaluminophosphate-34 (SAPO-34) molecular sieves have important applications in the petrochemical industry as a result of their shape selectivity and suitable acidity. In this work, nanoaggregate SAPO-34 with a large external surface area was obtained by dissolving pseudoboehmite and tetraethylorthosilicate in an aqueous solution of tetraethylammonium hydroxide and subsequently adding phosphoric acid. After hydrolysis in an alkaline solution, the aluminum and silicon precursors exist as Al(OH)4− and SiO2(OH)−, respectively; this is beneficial for rapid nucleation and the formation of nanoaggregates in the following crystallization process. Additionally, to study the effect of the external surface area and pore size on the catalytic performance of different SAPO-34 structures, the alcoholysis of furfuryl alcohol to ethyl levulinate (EL) was chosen as a model reaction. In a comparison with the traditional cube-like SAPO-34, nanoaggregate SAPO-34 generated a higher yield of 74.1% of EL, whereas that with cube-like SAPO-34 was only 19.9%. Moreover, the stability was remarkably enhanced for nanoaggregate SAPO-34. The greater external surface area and larger number of external surface acid sites are helpful in improving the catalytic performance and avoiding coke deposition.

中文翻译：

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纳米聚集体SAPO-34的低成本合成及其在糠醇催化醇解中的应用

摘要 磷酸硅铝34（SAPO-34）分子筛由于其形状选择性和适宜的酸度，在石油化工行业具有重要的应用。在这项工作中，通过将假勃姆石和原硅酸四乙酯溶解在四乙基氢氧化铵水溶液中，然后加入磷酸，获得了具有大外表面积的纳米聚集体 SAPO-34。在碱性溶液中水解后，铝和硅前驱体分别以 Al(OH)4- 和 SiO2(OH)- 存在；这有利于在随后的结晶过程中快速成核和形成纳米聚集体。此外，为了研究外表面积和孔径对不同 SAPO-34 结构催化性能的影响，选择糠醇醇解为乙酰丙酸乙酯 (EL) 作为模型反应。与传统的立方体状 SAPO-34 相比，纳米聚集体 SAPO-34 产生了更高的 EL 产率，为 74.1%，而立方体状 SAPO-34 的产率仅为 19.9%。此外，纳米聚集体 SAPO-34 的稳定性显着增强。更大的外表面积和更多的外表面酸位有助于提高催化性能和避免积炭。