EXPERIMENTAL-STUDY OF THE TUBULAR MULTIPHASE CATALYST

A new type of multiphase catalyst is developed for transport-controlled, volatile-reactant-limited reactions: the tubular-supported ceramic membrane. A microporous, catalytically-impregnated gamma-Al2O3 film (permeable membrane) coats the inside wall of a hollow, macroporous alpha-Al2O3 tube. The gas containing the volatile reactant flows through the tube core, and the liquid containing the nonvolatile and dissolved volatile reactants flows on the shell side. Reaction occurs in the film. Results using the hydrogenation of alpha-methylstyrene to cumene on Pd/Al2O3 reveal that the tubular catalyst compares favorably to conventional catalyst designs. The results demonstrate that the main benefit is the more efficient supply of the volatile reactant. Apparent activation energy analyses reveal that for catalyst temperatures below 40-degrees-C, the rate is kinetically-controlled and catalyst utilization nearly complete. A reduction in the activation energy above 45-degrees-C indicates the onset of transport limitations or heat effects. A comparison between the tubular catalyst and a fully-wetted pellet reveals rate increases by up to a factor of 20.