Investigation of spatially patterned catalytic reactors
The theme of this work is to enhance the performance of a primary reaction system by introducing dual-functionality into a packed-bed reactor via a spatial pattern. This paper focuses on a generic system in which the primary reaction is equilibrium-limited and an auxiliary reaction is incorporated to act as a drain-off mechanism alleviating the equilibrium constraint. It is found that patterns in which the two catalysts are spatially layered (and maintained at different temperatures) or well-mixed (and operated at a common temperature) can both offer significant improvements over an unpatterned reactor. Operating the well-mixed pattern at high temperature is generally superior to switching between high- and low-temperature layers in the segmented configuration. The exception to this rule occurs when the mixed bed is punished for being hot as either the equilibrium ceiling on the primary reaction drops sharply or a competitive reaction dominates at high temperature. The extent to which the layered pattern’s improvements are compromised by axial heat dispersion between zones is examined in terms of a backflow mixing cell model.
Spatiotemporal Catalytic Patterns Due to Local Nonuniformities
Nonuniformities of properties, like activity and transport coefficients, are common to catalytic systems and were evident in studies of spatiotemporal patterns. Under such conditions it is usually difficult to conclusively differentiate between the effects of spontaneous symmetry breaking and those due to nonuniformity. We analyze the dynamics of one-dimensional systems with single-variable or two-variable kinetics and space-dependent properties and show that these systems may admit stable stationary fronts, oscillatory fronts, source points, and unidirectional pulses. Uniform systems, with similar properties, admit traveling front and pulse solutions. Patterns in nonuniform systems are quite similar to those in systems with a global interaction that induces symmetry breaking, and both can be classified by the sequence of phase plane spanned by the system. We also analyze the impact of global interaction that preserves the symmetry and show that it may destroy the inhomogeneity due to nonuniform propertie...
An experimental study of mixing and segregation in a stirred tank reactor
The second order, homogeneous reaction between sodium thiosulphate and hydrogen peroxide was used to study the mixing in a 2.5-liter, continuous flow stirred tank reactor and in a 50-gallon pilot unit. The residence time distribution was measured with deionized water and pulse injection of a tracer. 
 
 
 
At low speeds the agitation was related to a “segregation” model. The region of “maximum mixedness” and the onset of “perfect mixing” were correlated with both horsepower input and recirculation rate within the reactor. 
 
 
 
On utilise la reaction homogene de second ordre entre le thiosulfate de sodium et le peroxyde d'hydrogene pour etudier le malaxage dans un reacteur continu, avec agitation, do capacite de 2.5 litres et 50 gallons. Le temps de residence est mesure avec de L'eau deionisee et L'injection pulsatoire d'un traceur. 
 
 
 
On presente une correlation pour la region de melange maximum et le debut de melange parfait en tenant compte de la puissance d'agitation et du taux de recirculation dans le reacteur.