Gas–liquid catalytic hydrogenation reaction in small catalyst channel



A study is presented on the performance potential of gas–liquid–solid multiphase catalytic reactions in small-size structured catalyst/reactor channels. A hydrogenation reaction is performed over the Ni/alumina monolith catalyst module with a model feed consisting of styrene, 1-octene, and toluene. The gas/liquid feed stream is directly delivered into a single, representative channel of the multichannel monolith catalyst module to eliminate any flow distribution problem. The reaction tests are conducted with different channel sizes, wall structures, and feed compositions. The cocurrent downflow operation is compared to the cocurrent upflow. The olefin hydrogenation reaction is found to be severely limited by mass-transfer rates. Because of intensified mass transfer inside the small catalyst channel, substantial olefin conversion (>50%) is achieved even at unconventionally high LHSV (∼2000 v/v/h). Liquid and gas superficial linear velocities were varied over a wide range (UL = 1–50 cm/s, UG = 1–2000 cm/s) to elucidate effects of possibly different flow regimes on the reaction performance. The mass-transfer rate constant of liquid reactant from bulk fluid onto the channel surface in a 1-mm reaction channel is found to be related to the flow conditions by a simple equation, akLS (1/s) = 0.094(UL + 0.1UG)0.788. The mass-transfer equation is useful for selection of suitable flow conditions for a given catalytic reaction rate. © 2005 American Institute of Chemical Engineers AIChE J, 2005