1. General

1.1 Different feed modes

Under the usual operating conditions for fixed-bed gas-liquid catalytic reactors, both phases are fed at cocurrent downflow. The liquid then trickles onto the catalyst in the form of discontinuous films and threads, while the gas forms a continuous phase that flows into the remaining pore volume. This is the operating mode referred to by the technology's English term, trickle bed. However, even in this feed mode, the liquid can become the continuous phase at high flow rates. The gas is then dispersed in the form of bubbles, and the reactor is said to be flooded.

Gas and liquid can be fed in co-current. In this case, the reactor is flooded, even at low gas and liquid flow rates. The main disadvantages of this operating mode are the existence...