AN EXPERIMENTAL STUDY OF MULTIPLE STEADY STATES IN A POROUS CATALYST DUE TO PHASE TRANSITION

Abstract

Up to four multiple steady states were experimentally observed by hydrogenating cyclohexene on a Pt/Al₂O₃ catalyst having bimodal distribution. The catalyst, in the form of 3/16-in. by 3/16-in. cylindrical pellet containing 5.6 wt% platinum on γ-alumina support, was imbedded in a bed of inert α-alumina pellets of similar size to isolate the effect of individual catalyst pellet, and was surrounded by reacting mixture containing saturated cyclohexene vapor. The reaction was run at four different temperatures, i.e. 15, 22, 30 and 40°C, and as a means of changing reaction condition at a given reaction temperature the hydrogen partial pressure was varied. From experimental evidence, two of these multiple steady states were interpreted as the rates in vaporfilled and liquid-filled catalyst pores and the other two steady states as those of pores with different degrees of liquid filling. The transition of phase was apparent from sharp change in observed reaction rate.