Chemical Engineering Journal, Vol.349, 829-837, 2018
Intensifying heat transfer in Fischer-Tropsch tubular reactors through the adoption of conductive packed foams
The low-temperature Fischer-Tropsch synthesis is a strongly exothermic process wherein the temperature control is a crucial issue. In this work, we demonstrate experimentally for the first time the adoption of a Fischer-Tropsch tubular reactor (2.78 cm I.D.) loaded with a highly conducive open-cell aluminum foam packed with catalyst microspheres to enhance heat exchange. Accordingly, the performances of a highly active Co/Pt/Al2O3 catalyst packed into the metallic structure are assessed at industrially relevant operating conditions and compared with those obtained in a conventional randomly packed fixed-bed reactor. The structured catalyst reaches outstanding performances (duties in excess of 1300 kW/m(3) with CO conversions > 65%) with a remarkable temperature control. Almost flat axial temperature profiles are measured along the catalytic bed even under the most severe process conditions, showing the excellent ability of the "highly conducive packed-foam reactor" concept to manage the strong exothermicity of the reaction. In contrast, when the same experiment is carried out over the same Co/Pt/Al2O3 catalyst just randomly packed in the reactor, an abrupt increase of the catalyst temperature occurs already at low temperature, eventually leading to thermal runaway. The results herein collected prove the potential of conducive metal foams as enhanced reactor internals for the intensification of strongly exothermic processes in nonadiabatic tubular reactors. Furthermore, the "packed-foam" configuration also demonstrates the possibility to overcome the inherently limited catalyst inventory of the washcoated conducive structured reactors proposed so far, thus boosting the productivity per reactor volume.