Improving the performances of a simulated-moving-bed reactor for the synthesis of methyl acetate ester by using partial port-closing strategies

Abstract

Simulated-moving-bed reactor (SMBR) is one of the trustworthy processes to achieve high levels of conversion, yield, and throughput for an equilibrium-limited reversible reaction. As one way of finding a practical method to significantly improve the performances of an SMBR, the applicability of a partial port-closing strategy and its potential impact on the SMBR performances were investigated for the first time in this study. To facilitate this work, the synthesis of methyl acetate (MeOAc) ester was employed as a model reaction system. There are two applicable modes for implementing the aforementioned strategy in the SMBR for MeOAc synthesis. The first one is a partial extract-closing (PEC) mode, in which an extract port (non-product port) remains closed during the time that MeOAc passes through two zones adjacent to the extract port. Such action occurs mostly during the beginning of each step. By contrast, the second one is a partial raffinate-closing (PRC) mode, in which a raffinate port (product port) remains closed during the time that unreacted and side-product components pass through two zones adjacent to the raffinate port, which happens mostly during the end of each step. A series of comprehensive optimizations for the considered SMBR revealed that both the PEC and PRC strategies were effective in making a significant improvement in reaction yield, throughput, and solvent usage. It was also found that the higher the required throughput, the more advantageous it was to use PEC rather than PRC mode. Finally, it was confirmed that the merit of PEC over PRC mode in the economic feasibility of the SMBR became greater as the target levels of reaction yield and throughput were set higher.