Catalyzed gas‐liquid reactions in trickling‐bed reactors

Kinetic studies were made in a differential flow reactor of the hydogenation of α‐methyl‐styrene with the liquid trickling over a bed of catalyst pellets countercurrent to a stream of hydrogen. The catalysts consisted of palladium, platinum, rhodium, ruthenium, and nickel supported on the external surfaces of aluminal pellets. With palladium at pressures above 3 atm. the apparent rate‐controlling step was a surface reaction between dissociated hydrogen and α‐methylstyrene both adsorbed on different type of active sites. Below 3 atm. pressure the reactants competed for similar active sites. With platinum the apparent rate‐controlling step was a surface reaction between dissociated hydrogen and α‐methylstyrene on similar active sites. Rhodium and nickel catalyzed the polymerization α‐methylstyrene together with slow hydrogenation. Ruthenium had negligible activity for catalyzing the hydrogenation under the moderate conditions used in this work. In all cases mass transfer resistances were negligible.