(693b) Automated Platform for Experimental Execution and Model Regression of Volumetric Mass Transfer Coefficient and Vessel Characterization

Authors: 
Mattern, K. A. - Presenter, Merck & Co. Inc.
Grosser, S. T., Merck & Co. Inc.
Mass transfer is an important parameter when considering the scale up of aerobic oxidations or other reactions in which the delivery of gaseous reactants to a liquid phase impacts process performance. In the case of oxidations, the oxygen transfer rate from the gas phase to the liquid is dependent upon the volumetric mass transfer coefficient, kla, and the concentration driving force between the concentration of oxygen in the bulk liquid and the saturation concentration of oxygen at the gas-liquid bubble interface. For biocatalytic aerobic oxidations in particular, the reaction solvent is typically water, which is known to have a very low oxygen solubility relative to other solvent systems. As a result, the oxygen transfer rate can be dominated by the kinetics of mass transfer and is highly dependent on reactor geometry and process parameters. Proper characterization of kla under a given set of conditions becomes a critical activity in understanding and mitigating scale-up risks.

As an alternative to traditional pressurization/depressurization tests to determine kla, we have been refining experimental methods which leverage the dynamics of oxygen dissolution following a change in the equilibrium concentration of oxygen. These methods are often tedious to execute and require careful experimental planning and data capture and as a result, we sought to develop an automated platform for experimental execution, data stream integration and kla regression. Additionally, this automated platform was applied to characterize oxygen mass transfer in reactors of various geometries ranging in scale from 10 mL to 100 L to demonstrate the value of this platform for the scale up of aerobic oxidations.