No dead-zones, no bed packing & distribution effects. The catalyst packing is straightforward and does not require special procedures. A single string of catalyst particles is loaded in the reactors with an internal diameter (ID) that closely matches the particle average diameter. This applies to single catalyst systems, as well as stacked-bed systems. The use of a narrow reactor avoids any maldistribution of gas and liquid over the catalyst bed, thereby eliminating catalyst-bed channeling and incomplete wetting of the catalyst.