DETERMINATION OF WETTING EFFICIENCY IN TRICKLE-BED REACTORS BY A REACTION METHOD

External wetting efficiencies were determined in a trickle-bed reactor by employing conversion data from the hydrogenation of the anthracene contained in an anthracene oil. Reactions were carried out at 573 K a nd 9.8 MPa on a sulfided Ni-Mo/gamma-Al2O3 catalyst. The results were compared with the total wetted area determined from the correlations b ased on the tracer method and developed by other authors. The discrepa ncy between both sets of data was attributed to the existence of a cer tain surface wetted by stagnant fluid whose fraction, f(s), was estima ted from the comparison between tracer and reaction data. The correlat ions of Ring and Missen (1991) and Al-Dahhan and Dudukovic (1995), dev eloped for high pressure trickle-beds, were employed to estimate f(s). A geometrical model has been employed to relate the static holdup wit h the fraction of surface covered by stagnant liquid which yielded an estimation of the mean distance between particles. The product of effe ctiveness factor and intrinsic rate constant were obtained for liquid- and gas-covered surfaces. Individual and overall effectiveness factor s were estimated from a liquid phase intrinsic kinetic constant obtain ed in a previous work, showing that reaction took place preferably on the wetted surface.