Comparative economic analysis of batch vs. continuous manufacturing in catalytic heterogeneous processes: impact of catalyst activity maintenance and materials costs on total costs of manufacturing in the production of fine chemicals and pharmaceuticals

To evaluate the feasibility of transforming batch manufacturing processes in the fine chemicals and pharmaceutical industries to continuous synthesis, Capex, Opex and the total cost of manufacturing are estimated for production facilities for the hydrogenation of a nitro compound to its final amino counterpart. Two cases are evaluated: First, a high annual production dedicated plant, designed on the basis of processing 100,000 kg of the principal raw material per year, where raw materials cost, catalyst cost, and catalyst activity maintenance are varied over a broad range for typical industrial cases. Second, a “short campaign” model for a small volume production trial setup designed for the manufacture of only 100 kg of the final product, as a way to evaluate relevant industrial scenarios of scale-up and process development. A comparison is made between slurry batch, catalyst basket batch reactor and fixed bed continuous reactor manufacturing facilities. The hydrogenation of 2,4-dinitrotoluene was chosen as a probe reaction for the development of the manufacturing processes, with costs of the key raw material varying between $5 and $100 per kilogram, costs of catalyst varying between $100 and $1,500 per kilogram, and catalyst activity maintenances varying between 1,000 and 2,000,000 total turnovers before a change in catalyst load is necessary. For low catalyst activity maintenance, the total manufacturing costs for the fixed bed reactor process were always found to be higher than those of the two other alternatives. As catalyst activity maintenance increases, the manufacturing costs for the continuous alternative rapidly fall, reaching savings between 37 and 75% compared to the base batch reactor case, depending on the combination of costs of the key raw material and catalyst used.

Graphical Abstract