Cuboid Packed-Beds as Chemical Reactors?

Raja Ghosh

doi:10.3390/pr6050044

Abstract

Columns are widely used as packed-bed or fixed-bed reactors in the chemical process industry. Packed columns are also used for carrying out chemical separation techniques such as adsorption, distillation, extraction and chromatography. A combination of the variability in flow path lengths, and the variability of velocity along these flow paths results in significant broadening in solute residence time distribution within columns, particularly in those having low bed height to diameter ratios. Therefore, wide packed-column reactors operate at low efficiencies. Also, for a column of a particular bed height, the ratio of heat transfer surface area to reactor volume varies inversely as the radius. Therefore, with wide columns, the available heat transfer area could become a limiting factor. In recent papers, box-shaped or cuboid packed-bed devices have been proposed as efficient alternatives to packed columns for carrying out chromatographic separations. In this paper, the use of cuboid packed-beds as reactors for carrying out chemical and biochemical reactions has been proposed. This proposition is primarily supported in terms of advantages resulting from superior system hydraulics and narrower residence time distributions. Other potential advantages, such as better heat transfer attributes, are speculated based on geometric considerations.

Highlights

Packed-bed or fixed-bed reactors are ubiquitous in the chemical process industry [1,2,3]
The HiTrap Capto S column was used as the surrogate packed-column reactor while a custom designed cuboid packed-bed device filled with Capto S resin particles served as the surrogate cuboid packed-bed reactor
The average heat transfer distance (AHTD) was greater with cuboid packed-bed device for (L/W) values lower than 2.4 but was lower are greater values of (L/W). These results suggest that a cuboid packed-bed reactor would have a significant advantage over a packed column for conducting endothermic and exothermic reactions

Summary

Introduction

Packed-bed or fixed-bed reactors are ubiquitous in the chemical process industry [1,2,3]. With the increasing popularity of flow chemistry-based synthesis, their use is likely to increase [4,5,6]. A column is the most common configuration for a packed-bed reactor. It is a cylindrical vessel within which a bed of particles is tightly held in place under compression (see Figure 1). In certain specialized forms of packed-beds, such as monoliths [7,8], the particles are fused together. Packed columns are used for chemical separation techniques such as adsorption, distillation, extraction and chromatography [9,10,11,12]

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Conclusion