Best practice for scale-down of gas-liquid reactions requires control of the volumetric mass transfer coefficient, kLa. It is demonstrated that the use of small bubble columns can provide well-controlled kLa and catalyst dispersion down to a scale of 3 cm3. This scale is several times less than has been previously demonstrated for heterogeneously catalysed reduction using gaseous hydrogen and is more easily reproduced than small scale stirred vessels. Measurements have been made at a fixed total gas flow, with the effective mass transfer rate being adjustable by dilution of the hydrogen flow with either helium or nitrogen.
Atherton, J. H., Elmekawy, A., Hall, A., & Williams, H. (2015). Scale-down of Heterogeneous Catalytic Reduction Using a Bubble Column: Controlled Mass Transfer down to 3 cm3 Working Volume. Organic Process Research and Development, 19(9), 1159-1163. https://doi.org/10.1021/acs.oprd.5b00034