Countercurrent two-phase flow fixed bed catalytic reactors

Abstract While a very large number of publications have been devoted to fixed bed catalytic reactors with cocurrent two-phase flow, this cannot be said of fixed bed catalytic reactors in which the two fluid phases are in countercurrent flow. Very few publications have dealt with this type of reactor. In the following pages, we would like to point out the potential advantages of these countercurrent systems. These advantages can be especially important, for example in reversible reactions or those inhibited by one of the reaction products. The theoretical bases for making a detailed comparison of the two variants, for various reaction systems are first discussed. Then are presented a number of comparative examples of some typical cases: exothermic and non-exothermic reactions, reversible reaction, parallel reactions inhibited by one of the products. These reaction systems represent clearly-identified actual cases, such as the hydrogenation of aromatics, the hydrotreating of petroleum cuts, the synthesis of MTBE, etc.. The last part attempts to draw certain conclusions from the comparisons made, without ignoring the technological aspects and the practical constraints.