(155a) Compaction of Powders to Produce Catalyst Support Tablets: The Effect of Moisture Content and Drying on Mechanical Properties

Compaction of powders to produce tablets is a common industrial process for the manufacture of catalyst supports. The advantage of the compaction process is that tablets can be mass produced to make honeycomb shapes and supports with holes. In addition, the process wastes very little material. Aluminum oxide, commonly referred to as "alumina," is one of the most widely used materials for catalyst supports to facilitate efficient chemical processes. Alumina tablets are engineered to meet specific mechanical properties, including hardness, tensile strength, Young’s modulus, and porosity. To optimize the manufacturing process, various parameters must be carefully controlled in each step, such as particle size, pore volume, compaction load, binder content, and drying temperature.

This study investigates the effects of moisture content and drying conditions on different types of alumina tablets. The moisture content of alumina powders can vary due to ambient humidity, storage conditions, and processing parameters. Tablets were compacted under varying moisture content and compaction loads, followed by mechanical testing 24 hours post-ejection. Increasing the moisture content up to 20% w/w led to a significant enhancement in both tensile strength and Young’s modulus. However, tablets with high moisture content also require proper drying, as excessive moisture combined with inadequate drying conditions can lead to microcrack formation. Experimental results indicate that drying at 120°C for 24 hours effectively removes most of the residual water; however, microcracks were observe using MicroCT. These microcracks propagate internally and undermine the mechanical integrity of the tablets. A comparative analysis of different drying methods revealed that each approach has distinct advantages and limitations. Milder drying techniques effectively reduce the risk of microcrack formation and preserve the strength of the tablets. Notably, to the best of the authors’ knowledge, there is a lack of studies examining the combined effects of moisture content and drying conditions on catalyst support tablets. The findings of this study highlight the critical importance of controlling moisture content and drying parameters to enhance the mechanical strength and durability of the tablets.