Mass transfer limitations in a trickle‐bed reactor

Abstract

= dimensionless axial position o = frequency, rad./hr. 8 = time, hr. Su b r r i p t s g = gas phase in = gas phase inlet k 1 = liquid phase Coefficienh in Gas Phase Equations (17), (18). (191, and (23) 1 2 0 n ma = radial mesh point location = axial mesh point location A. -----2 0The hydrogenation of alpha-methylstyrene to cumene at 20 to 50°C. was studied experimentally with o trickle-bed reactor comprising a single vertical column of spherical porous palladium-on-alumina catalyst pellets. Other studies with powdered catalyst and studies in which catalyst pellets were swirled in a reactor allowed the intrinsic kinetics and effectiveness factor of the catalyst pellets to be determined. A t 50°C. the reaction rate in the trickle-bed was about one-half of that in the absence of mass transfer limitations in the outside liquid film. The effectiveness factor of the pellets alone at 50°C. was 0.0057, and the tortuosity factor was 7.5. Experimental results are compared with four theoreticol models for tricklebed reactors and criteria are presented for estimating whether mass transfer through the outside film is a significant resistance in an industrial trickle-bed reactor.A trickle-bed reactor consists of a fixed catalyst bed in the bulk gas phase and the liquid-gas interface, ( b ) mass which the liquid reactant flows over the catalyst pellets transfer through the liquid film surrounding the pellets, while the reacting gas, which fills the voids, flows either (c) diffusion and simultaneous reaction within the liquidin the same or opposite direction. The rate-controlling step filled catalyst pores, and ( d ) intrinsic kinetics of reaction can be one or a combination of the following processes: at the catalyst surface. The object of this study was to (a) mass transfer of reactants and/or products between determine the role played in the performance of a trickle-

Dynamic effects of vaporization with exothermic reaction in a porous catalytic pellet

“…This is evidenced by the large number of literature studies (Babcock et al, 1957;Satterfield et al, 1969;Germain et al, 1974;White et al, 1974;Morita and Smith, 1978;Herskowitz et al, 1979;Turek and Lange, 1981;El-Hisnawi et al, 1982;Funk et al, 1991;Cini and Harold, 1991;among others). These studies demonstrate that the liquid-phase/catalytic reaction is mass-transport-limited with respect to sparingly soluble hydrogen (in Cini and Harold (1991) showed that for a sufficiently low AMS concentration the rate is positiveorder in AMS.…”

Trickle‐bed root culture bioreactor design and scale‐up: Growth, fluid‐dynamics, and oxygen mass transfer

“…However, unlike conventional catalyst particles, roots have been shown to compensate for poor liquid distribution (McKelvey et al, 1993). Disproportionate liquid flow near the wall is typically not a problem if the column-to-particle diameter ratio is greater than 25 (Satterfield et al, 1969). By comparison, the column-to-particle diameters in the 2-and 14-L root reactors were 129 and 258, respectively.…”

“…In conventional trickle-bed reactors where reactions are known to be limited by gas species mass transfer through the liquid film, models and experiments (Satterfield et al, 1969) have verified a decrease in the mass transfer rate with increase in liquid flow at low flow rates (due to increased film thickness and diffusional resistance in the near-stagnant film) and increase in mass transfer with liquid flow rates at high liquid flow rates (due to convection). Maldistribution can also result in a flow-rate-dependent reaction rate (Satterfield, 1975).…”

Transparent silicon/glass microreactor for high-pressure and high-temperature reactions

“…Such small activation energies derived from the observed reaction rate indicate a mass transfer limited reaction. An interpretation of mass transfer limitations was done by applying trickle-bed reactor theory [41]. The ratio of observed reaction rate to the mass transfer rate through the film surrounding the catalyst particle was calculated in the range of 1-6.8.…”