This paper introduces a novel structured metallic catalyst that improves mass transfer performance of a monolith reactor for highly exothermic gas–solid reactions. The monolith channels are designed to have metallic substrates that consist of two layers with one of the layers being the metallic support and another layer being a foam metal annular that is tightly deposited onto the support surface by some means. Parametrical studies based on a 2D monolith reactor model showed that the present design yields an enhanced mass transfer between the bulk fluid and the catalyst layer due to a decrease in external film resistance, and an enhanced mass transfer within the solid phase mainly due to the viscous flow effect within the porous catalyst layer.

This paper presents new experimental results on the separation of an o-dichlorobenzene/p-dichlorobenzene mixture in a continuous moving crystal bed crystallization column under the top-fed operation mode. Local concentration distributions of the binary eutectic mixture were investigated as a function of the feed composition, reflux ratio, crystal bed height, and internal stirring speed. It is demonstrated that the key factor that is decisive to the separation capability of column crystallization is the reflux ratio. The experiments showed that product purities can easily exceed 99.0% over a wide range of feed compositions, 68-94 wt%, reflux ratios, 1.0-4.7, and crystal bed heights, 200-900 mm within a column of 50 cm i.d.

Two-phase flow hydrodynamics in vertical capillaries of circular and square cross sections were experimentally studied, using air as the gas phase and water, ethanol, or an oil mixture as the liquid phase. The capillary hydraulic diameters ranged from 0.9 mm to 3 mm, with the superficial gas and liquid velocities covering a span of 0.008-1 m/s, which is typical of that obtained in monolith reactors. Using a high-speed video camera, four distinct flow regimes were observed within the range at which experiments were conducted: bubbly, slug-bubbly, Taylor, and churn flows. Annular flow was observed at excessively high gas and low liquid flow rates, well beyond those of interest to this study. Based on the definition of a two-class flow regime, the combination of two parameterssthe slip ratio (S) and the ratio of the superficial gas velocity to two-phase superficial velocity (UG/UTP)-was observed to be suitable for determining the transition from homogeneous flow to nonhomogeneous flow. The influence of capillary geometry, capillary hydraulic diameter, and fluid properties on bubble rise velocity (Vb) were investigated and determined to be of little significance. Furthermore, a new and simplified correlation for predicting Vb and, by implication, the gas holdup (∈G) was proposed. Liquid slug lengths were also experimentally studied, using a correlation that was developed to estimate them. Pressure drop experiments were also performed, and the peculiar phenomenon of negative frictional pressure drops was observed at very low liquid velocities. By defining a new dimensionless quantitysthe pressure factor, FE-a flow-regime-dependent method for estimating the total pressure drop in two-phase vertical capillary flows was developed.

Gas–liquid mass transfer from Taylor bubbles rising in 1, 2 and 3mm diameter capillaries of circular and square cross-sections was investigated for air–water system. The liquid-phase volumetric mass transfer coefficient kLa was obtained from experimental oxygen absorption dynamics. The experimental kLa values are in good agreement with the model developed by van Baten and Krishna (2004.Chemical Engineering Science 59, 2535–2545), with the additional assumption that the