Understanding the impact of reactive holdup on process intensification in the design of reactive distillation column

•Alternative design based on wider diameter to expand the applicability of reactive distillation.•Intensified RD process: exploring the vital role of reactive holdup in design.•Large catalyst holdup reduces the reboiler's heat load and overcomes hydraulic limitations.•Tradeoff between the capital investment and energy cost of RD relative to reactive holdup.•Impact optimal reactive holdup on economics and design of RD columns. The commercial viability of reactive distillation as a front-runner industrial process intensification technique is limited by slow reactions. It is because the diameter established by the vapor-loading method restricts large holdup volumes (or catalyst amount) to accomplish the essential conversion. However, placing a large amount of catalyst on column trays necessitates either a high tray weir height (limited to excessive column pressure drop) or a large column diameter. This study aims to investigate an alternative design approach by increasing the column diameter beyond that required for vapor loading to retain a large holdup volume. Several combinations of tray weir heights and column diameters were studied and demonstrated through case studies for three industrial processes, and their optimal designs have been reported. High catalyst holdup volume enhanced energy efficiency and overcame hydraulic limitations despite requiring large diameter vessels. These design configurations with optimized catalyst holdup also resulted in improved process economics. Fabricating a wide column diameter is a good conservative engineering procedure considering safety aspects and better design control. [Display omitted]