Features of Fluidized Catalyst Beds for Proper Design and Operation of Catalytic Reactions

Abstract

Fluidized catalyst beds have been used in chemical and refinery processes and studied extensively for more than 50 years. However, the features of this reactor are still not understood perfectly. There is still much more to learn about the fluidized catalyst beds. It is important to elucidate the bubble behavior and the contact between catalyst particles and reactant components in the reactors. Understanding the features of the reactors contributes to the proper catalyst design together with the appropriate design and operation of the reactors. In this paper, the influence of gas properties on the bubble behavior is described, and pseudo-3-dimensional images of bubbles are shown. The important effects of direct and successive contact in the bed are discussed regarding conversion and selectivity. The reaction analysis showed that the selectivity could be improved by the effective use of the direct contact catalyst particles. The synergy effect of the three factors, i.e., catalyst activity, contacting feature between gas and particles, and transport/ mixing properties in the bed, plays a salient effect in raising selectivity of consecutive reactions.

Effect of volume decrease on fluidization quality of fluidized catalyst beds

“…The minimum fluidizing velocity, measured by air under ambient conditions, was 1.9 mm s −1 . Not only were the catalyst particles “A group” particles,20 but they were also classified as the “AA group.”21 The settled bed height was around 350 mm. The superficial gas velocity was 50 mm s −1 .…”

Four Ways To Introduce Structure in Fluidized Bed Reactors

“…Despite their good heat transfer and short diffusion lengths, traditional (i.e., unstructured) fluidized beds have serious drawbacks, the two most important ones being their difficult scale-up − and their inefficient use of reactant gas as a result of the formation of bubbles. , The rather small particles (diameters on the order of 100 μm) used in fluidized beds almost always ensure the absence of mass transfer limitations inside the particles. At larger scales, however, mass transfer limitations are present in many fluidized bed processes, especially in the bubbling but also in the turbulent regime.…”

Observation of 3-D Structure of Bubbles in a Fluidized Catalyst Bed

“…Investigating the physical properties of catalyst particles used in the industrial fl uidized-bed process, Ikeda (Miyauchi et al, 1981) summarized the suitable particle properties for a fl uidized catalyst bed. These particles have the typical features of the group A solids and are called group AA (Kai et al, 2004). The range of group AA is 40-70 µm in mean particle size and 800-2000 kg m -3 in particle density.…”