Improving the performances of a simulated-moving-bed process for separation of acetoin and 2,3-butanediol by the use of an adsorbent for minimizing the extent of 2,3-butanediol isomerism

The applicability of a simulated-moving-bed (SMB) method to the continuous-mode separation between acetoin and 2,3-butanediol (BD), which stemmed from related fermentative processes, has been previously verified. However, its process performances were restricted by the occurrence of a significant discrepancy between the adsorption behaviors of BD isomers (meso-BD and DL-BD) along the SMB columns. To address such concern, this study aimed to explore an effective adsorbent in preventing the problem of BD isomerism along a chromatographic bed, which was then attempted to be utilized in developing a substantially improved SMB for acetoin-BD separation. It was found first that an adsorbent with less pi bonds could be effective in minimizing the extent of BD isomerism and further in improving the performances of the acetoin-BD separation SMB to a marked degree. Using such a properly selected adsorbent, the adsorption parameters of acetoin and BD isomers were determined from multiple-frontal-analysis experimental data and the SMB experimental data respectively. On the basis of their resultant parameter values, the considered SMB was optimally designed and then experimentally tested, which revealed that the designed SMB could allow 44% higher throughput and 44% lower desorbent usage while keeping higher purities and lower losses, compared to the previous SMB. Furthermore, the developed SMB in this study was operated at room temperature, indicating its superiority over the previous SMB operated at 60 °C in energy efficiency.