Study of the Solvent-Free Process of Enzymatic Synthesis of Pentyl Esters in a Packed Bed Reactor (PBR) Using the Lipozyme435 Heterogeneous Biocatalyst

Abstract

This article describes a solvent-free enzymatic esterification process for the production of pentyl acetate or pentyl propanoate from pentanol and the corresponding acetic or propanoic acids. Both reactions were carried out in a continuous packed bed reactor (PBR) using the immobilized lipase Lipozyme435 as the catalyst. The effect of several variables was analyzed to determine the most suitable conditions: temperature, proportion of reactants, and flow rate of the products in the reactor. High conversions of the acid substrate (above 80%) were obtained at all working temperatures for an alcohol-to-acid molar ratio of 2 and flow rates up 1 mL/ min, demonstrating the technical feasibility of the reactor configuration for this type of synthesis. However, it was observed that the enzyme lost activity due to the synergistic effect of high temperatures (>70 °C) and an equimolar alcohol-to-acid ratio, exhibiting a behavior similar to that observed when using a batch stirring reactor (BSTR). In contrast to observations in a batch stirring reactor (BSTR) under the same conditions, the synthesis process in the PBR at 70 and 80 °C with a 2:1 alcohol-to-acid molar ratio showed no signs of enzymatic deactivation. This behavior suggests that scaling up the process for continuous industrial production is more advantageous than using small-scale batch processes. The economic indicators of the biocatalytic processes calculated here also indicated that PBR reactors are preferable for large-scale production.