Dehydrogenation of 2,3-Butanediol to Acetoin Using Copper Catalysts
Zahraa Al-Auda, Xu Li, Keith L. Hohn
Abstract
2,3-Butanediol (2,3-BDO) was converted to 3-hydroxy-2-butanone (acetoin) using a heterogeneous catalyst having dehydrogenation activity. Copper-supported alumina (Cu-Al2O3) and zirconia (Cu-ZrO2) were investigated in the catalytic gas-phase reaction of 2,3-BDO in a fixed bed reactor. The results showed that these catalysts can convert 2,3-BDO to acetoin with selectivity reaching 96% at 170 °C at a conversion of 63% over Cu-Al2O3. The effects of copper loading, reaction temperature, and H2 on product selectivity were studied. Increasing copper loading led to higher acetoin selectivity on Cu-Al2O3. Increasing the temperature decreased acetoin selectivity on both catalysts due to increased production of 2,3-butanedione through dehydrogenation of acetoin. The presence of hydrogen is generally detrimental to acetoin production because it slows dehydrogenation of 2,3-BDO, although it also slows the rate at which acetoin is dehydrogenated to 2,3-butanedione. The number and strength of acid sites appear to be the likely explanation for why Cu-ZrO2 generally gives higher acetoin selectivity compared to Cu-Al2O3.