Gas-limited hydrogenation of 1-Octene in a fixed bed : upflow versus downflow

16 Feb 2012

Two downflow operational modes with different hydrodynamic states were compared to upflow operation. Various gas limited conditions (γ = 15 - 60) were employed. The downflow mode with the higher wetting efficiency consistently outperformed the downflow mode with the lower wetting efficiency. Both the downflow modes outperformed the upflow mode at high gas mass fluxes and underachieved against upflow at lower gas mass fluxes. The results stand in contradiction to the theory on direct gas-solid mass transfer under trickle flow conditions. The switching behavior of the upflow mode performance was attributed to hydrodynamic regime shifts, hinting that the perceived ‘poor’ performance of upflow reactors under gas limited conditions might be linked to slugging in laboratory scale reactors.