Carbon Promoted ZrO2 Catalysts for Aqueous-Phase Ketonization of Acetic Acid

The present study reports aqueous-phase ketonization of acetic acid over different ZrO2/C catalysts and promotion of carbon in ketonization activity. Highly carbonized ZrO2 catalysts are synthesized via a sol-gel and Zr-based metal organic framework carbonization method, which possess high acetone production of 62.09 and 34.13 mmol/gZrO(2), respectively. ZrO2 catalysts with little carbon are synthesized via hydrothermal precipitation and a hydrolysis method, which possess acetone production of 13.54 and 15.51 mmol/gZrO(2), respectively. ZrO2 supported on carbon nano tubes (CNTs) exhibits increased acetone production with high CNT content but lower activity than carbonized ZrO2. Carbon release, accompanied by crystal phase transformation, leads to activity loss. Carbon species in carbonized catalysts significantly reduce crystallite size of t-ZrO2 and enhance surface properties, resulting in high activity. Small particle size also benefits aqueous-phase ketonization. Larger nanoparticles of supported ZrO(2)cover on CNT supports, and carbon and ZrO2 show much weaker interaction, resulting in lower activity than carbonized catalysts. For carbonized catalysts, acetic acid is enriched on the catalyst surface and water adsorption is weakened, enhancing ketonization reaction over active ZrO2 species.