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Development of the segregated multiphase flow catalytic tubular reactor
Abstract
A new type of multiphase reactor, referred to as the segregated multiphase flow catalytic tubular reactor, was developed in this study. The reactor consists of a hollow, macroporous ceramic tube coated on the inside or the outside with a thin film of microporous ceramic material that is impregnated with a catalytic component. Gas containing the volatile reactant flows on the side of the tube that is coated and the liquid flows on the other side. Liquid penetrates the tube pores by capillarity. A liquid phase catalytic reaction occurs between the dissolved volatile and nonvolatile reactants in the catalytically impregnated tube. Direct contact of the gas with the nonwetted, liquid-filled, microporous film enables an efficient supply of the volatile reactant. The catalyst support was prepared by washcoating the inside of $\alpha$-Al$\sb2$O$\sb3$ tubes with a thin layer of $\gamma$-Al$\sb2$O$\sb3$. In order to obtain thick washcoats (50 $\mu$m or more) that adhere well to the substrate, it was showed that it is best to use a boehmite sol that has a low viscosity and a high alumina content, and to perform several short dippings. The results also suggest that the relative sizes of the pores of the substrate and of the boehmite particles have an impact on the quality of the adhesion. Experiments performed on a prototype single tube reactor that operated well showed that most of the hydrogen that reacted was directly supplied from the gas phase; the contribution of the hydrogen predissolved in the liquid feed was negligible. A detailed modeling study of the prototype tubular reactor confirmed that transport limitations were negligible below 40$\sp\circ$C. Above that temperature pore emptying may occur, leading to a catalytic gas phase reaction. The benefit gained from the partial wetting of the tubular reactor was quantified by comparing its overall rate to that of a fully wetted, surface shell impregnated pellet, considered a prototype trickle-bed. It was observed that for the presaturated liquid feed, the tubular reactor performed 5 to 7 times better than the fully wetted single tube reactor, and up to 20 times for the unsaturated liquid feed.
Subject Area
Chemical engineering
Recommended Citation
Cini, Philippe, "Development of the segregated multiphase flow catalytic tubular reactor" (1991). Doctoral Dissertations Available from Proquest. AAI9207374.
https://scholarworks.umass.edu/dissertations/AAI9207374