Modelling of Three Phase Catalytic Upflow Reactor: a Significant Chemical Determination of Liquid-solid and Gas-liquid

INTRODUCTION Muhiphase reactors with fixed beds of catalyst particles contacted by either cocurrent downflow (Trickle-Bed Reactors) or cocurrent upflow (Packed Bed Column) of gas and liquid, are widely used in petroleum, petrochemical and chemical industries, environmental, biochemical and electrochemical processing, etc In many cases the gaseous reactant is sparingly soluble in the liquid phase and the reactor performance depends mainly on mass transfer characteristics. So far, empirical correlations available in literature are based primarily on studies performed in academic systems as air-water-glass beads at low temperature and atmospheric pressure Prediction of reliable gasliquid and liquid-solid mass transfer coefficients for modelling and design purpose of industrial processes is still a very hazardous task Obviously, mass transfer parameters measured in fixed bed reactors at typical reaction conditions differ from those obtained in packed absorption columns as pointed out by Turek and Lange ( 1981 ) and Mazzarino et al (1988) In this paper gas-liquid and liquid-solid mass transfers are investigated at reaction conditions by an original chemical method, then these data, along with measurements of reactor hydrodynamics and heat transfer parameters, are used to predict axial profiles of concentration and temperature of a complex reaction system the selective hydrogenation of 1,5,9-Cyclododecatriene (CDT) to Cyctododecene (CDE) in a continuous catalytic fixed bed reactor with upflow mode CHEMICAL DETERMINATION OF G-L AND L-S MASS TRANSFER COEFFICIENTS I';X1'ERIMIiNII4L I'RO('Iil)UIU'; The chemical method selected here is based on rate measurements of global hydrogen conversion (RH2) using the same reaction and reactor but with differential operation Differential mode refers to isothermal operation and small global hydrogen conversions (~QH2 < 2-8%) For these conversions, the assumption of linear initial kinetics with respect to hydrogen has been experimentally verified (Stttber, 1995) Isothermal behaviour of the reactor U-IK) was conveniently achieved by means of an external cooling jacket A schematic drawing of the differential fixed bed reactor can be seen in figure t: the whole experimental set-up is given m Stuber (1995)