کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
60883 | 47551 | 2015 | 8 صفحه PDF | دانلود رایگان |
• The use of Rh/heteropolyacid for ethanol carbonylation is studied.
• Fully exchanged heteropolyacids displayed highest selectivities toward propionates.
• In situ spectroscopy suggests a drop in oxidation state under reaction conditions.
• Broadly similar mechanism to soluble methanol carbonylation over Rh complexes.
Ethanol carbonylation is a potential route to valuable C3 products. Here, Rh supported on porous, Cs-exchanged heteropolyacid Cs3PW12O40, is demonstrated as an effective catalyst for vapor-phase ethanol carbonylation, with higher selectivity and conversion to propionates than existing catalysts. Residual acidity or a Mo polyatom was strongly detrimental to yields. Propionate selectivity was maximized at 96% at 170 °C and with added H2O. The catalyst displayed stable selectivity over 30 h on stream and up to 77% conversion. Ethyl iodide is a required co-catalyst but at levels as low as 2% relative to ethanol. XPS and in situ XANES indicate partial Rh reduction, consistent with the formation of low-valent reactive intermediates and slow deactivation through formation of Rh nanoparticles. With further optimization and understanding, these Rh/heteropolyacid catalysts may lead to stable and selective catalysts for the production of propionates through ethanol carbonylation.
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Journal: Journal of Catalysis - Volume 325, May 2015, Pages 1–8