Flame-Made Titania/Silica Epoxidation Catalysts: Toward Large-Scale Production

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• 作者：Wendelin J. Stark ; Hendrik K. Kammler ; Reto Strobel ; Detlef G&uuml ; nther ; Alfons Baiker ; and Sotiris E. Pratsinis
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2002
• 出版时间：October 2, 2002
• 年：2002
• 卷：41
• 期：20
• 页码：4921 - 4927
• 全文大小：155K
• 年卷期：v.41,no.20(October 2, 2002)
• ISSN：1520-5045

文摘

Titania/silica catalysts were made continuously in flame reactors and evaluated for thedemanding epoxidation of 2-cyclohexenol with tert-butylhydroperoxide. Silica- and titania-precursors were evaporated separately and mixed prior to feeding into a hydrogen-air diffusionflame. Upon reaction, the corresponding oxides formed highly agglomerated nanoparticles withtitania confined to the surface of silica particles. The epoxidation activity was strongly dependenton the titania content of the catalyst. Scaling-up the production rate of these catalysts (6-500g/h) in the flame did not affect their exceptionally high catalytic performance. Sample compositionand homogeneity were determined by local analysis using laser ablation inductively coupledplasma mass spectroscopy. Large-scale flame-made catalysts (100-500 g/h) were compared tosimilar catalysts made in a laboratory flame microreactor (6 g/h) and to conventional onesprepared by wet-phase chemistry. Compared to classical catalysts (65-80% selectivity), the flame-made titania/silica showed excellent selectivity (up to 90%) at 80% conversion.