Liquid–solid mass transfer in a tubular reactor with solid foam packings

• Liquid–solid mass transfer in solid foam packings was electrochemically studied in tubular reactors operated in co-current downflow.
• Mass transfer performance strongly depends on axial packing position.
• High superficial liquid velocity favors the mass transfer rate, while increasing foam pore density lowers the rate.
• Irrigation performance of the liquid distributor has a significant effect on the effective liquid–solid mass transfer coefficient.

Catalytically active open-cell solid foam packings are promising replacements for conventional randomly packed catalyst particles due to their low pressure drop and high specific surface area. The liquid–solid mass transfer was studied with a modified electrochemical limiting diffusion current method for different packings and flow rates. The effective liquid–solid mass transfer coefficients (ϕkLSϕkLS) were determined at two different axial packing positions. In particular, the effects of gas and liquid superficial velocities and the pre-wetting modes of the packing (LEVEC and KAN-LIQUID) were researched. The results reveal that higher liquid superficial velocity increases the liquid–solid mass transfer, while increasing foam pore density lowers the mass transfer rate. The strong multiplicity behavior known from the hydrodynamic study of Mohammed et al. (2013) was not obtained for the liquid–solid mass transfer. However, the type of liquid distributor providing the initial irrigation pattern had a significant effect on the effective liquid–solid mass transfer coefficient. A new correlation is proposed to predict the effective liquid–solid mass transfer coefficient.