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.
Spatially patterned catalytic reactors. Feasibility issues
Abstract The basic idea of spatially patterned catalytic reactors in this paper is to integrate auxiliary catalysts into a system in order to steer a desired reaction around a performance obstacle and toward enhanced selective conversion. While a traditional multi-functional catalytic reactor is limited to coupling reactions that can effectively operate in a common environment, a spatially layered pattern provides the unique opportunity to tune operating conditions in order to mitigate potential incompatibilities while optimizing performance. The power of the layered pattern approach is demonstrated through modelling studies on a by-product-inhibited reaction system that suffers from temperature and/or chemical species incompatibilities. Because multiple steady states — with dramatically varying levels of performance — often exist for these complex reaction networks, operation on an appropriate steady state has been shown to be critical to the realization of performance enhancements. The potential for multiplicity to undo the anticipated benefits of patterned operation is explored.
Some further observations on tubular reactor stability
A necessary and sufficient condition for stability of the empty adiabatic tubular reactor with axial mixing is derived which depends upon steady state information alone. The stability conditions require the solution of a linear ordinary differential equation and the character of this solution determines the stability or instability of the system without the use of transient calculation. The lumped constant reactor is always stable. The method of computation requires a minimum amount of memory capacity in a digital computer and could be carried out on an analogue computer with ease. 
 
 
 
La condition necessaire et suffisante de stabilite d'un reacteur tubulaire adiabatique avec diffusion axiale seulement est derivee. L'utilisation de cette condition de stabilite ne requiert la solution que d'une equation differentielle lineaire ordinaire, les proprietes de cette solution determinent le caractere de stabilite ou d'instabilite du systeme sans qu'il soit necessaire d'effectuer des calculs relatifs a l'etat transitoire. On a decouvert ainsi qu'un reacteur dans Iequel il n'y aurait pas de diffusion selon la direction axiale serait toujours stable. La methode de calcul ne requiert qu'un minimum de memoire de la part d'une calculatrice numerique et pourrait facilement etre realisee a l'aide d'une calculatrice de type analogique.