“…Scale-up, however, is complicated by the fact that basic design parameters such as free area for vapor flow, catalyst holdup, and specific area differ between laboratory and industrial versions of catalytic packing. In applications where a certain conversion or selectivity must be guaranteed, even pilot plant experiments may be imperative to ensure safe scale-up [30]. Catalyst holdup in commercial packings ranges from 25% to 40%, and hydraulic capacity is therefore lower than in distillation.…”