Flying droplets as model system for spray drying—An in situ synchrotron X-ray scattering study on complex oxides catalyst precursors

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• 作者：Jork Leiterer ; Franziska Emmerling ; Jö ; rg Radnik ; Ursula Bentrup ; Angelika Brü ; ckner
• 关键词：Acoustic levitation ; Spray drying ; Molybdate catalysts ; X-ray scattering
• 刊名：Catalysis Today
• 出版年：2010
• 出版时间：15 October 2010
• 年：2010
• 卷：155
• 期：3-4
• 页码：326-330
• 全文大小：432 K

文摘

As a model for spray drying the early stages of crystallization of complex molybdate catalyst precursors were monitored online in droplets levitated acoustically. Synchron X-ray scattering techniques were applied to study the drying process of a typical molybdate catalysts precursor prepared from Ni-,Fe-,Bi-nitrate, ammonium heptamolybdate and H₃PO₄. Comparison with diffraction patterns obtained from sessile droplets shows significant differences in the crystal growth, whereas the final crystal structure – including a Keggin-type anion – is identical in both cases. The levitated samples exhibit a decelerated growth with a large number of small crystallites at the beginning of the crystallization, whereas in case of the sessile droplets a small number of large crystallites were observed after a few minutes. The acoustic levitation using an ultrasonic trap proves to be an elegant tool to mimic spray drying and offers new possibilities in relation to the understanding of the drying process.