Liquid-solid mass transfer in solid foam packed tubular reactors

Solid foams were found to be promising replacements of conventional fixed bed reactor catalysts due to their high specific surface area, high porosity and low pressure drop. Especially, high gas-liquid mass transfer rates were observed in solid foams (Stemmet et al., 2008). However, for liquid limited reactions, high liquid-solid mass transfer rates are required. The liquid-solid mass transfer is strongly affected by the wetting of the packing surface and thus, depends also on the pre-wetting mode. For example Joubert and Nicol (2012) found that solid-liquid mass transfer coefficients in trickle bed reactors exhibit significant multiplicity behavior due to different flow textures. However, to the best of our knowledge, studies on the liquid-solid mass transfer in down flow solid foam tubular reactors are not yet available. To determine liquid-solid mass transfer coefficient we applied the electrochemical diffusion current method (ferricyanide system with excess of NaOH) The method is based on the measurement of current (i.e. electron transfer from cathode to anode) at mass transfer diffusion limited condition, pure nickel foam (Alantum Europe) of same foam density was applied as cathode.
The aim of this study is to determine the effective liquid-solid mass transfer coefficient in tubular solid foam reactors at different axial positions in down-flow trickle mode taking “LEVEC” and “KAN-LIQUID” pre-wetting mode into account.