Parametric analysis of Fischer-Tropsch synthesis in a catalytic microchannel reactor

Abstract

Fischer-Tropsch synthesis (FTS) is the catalytic conversion of synthesis gas, which is a mixture of carbon monoxide and hydrogen, to a wide range of synthetic fuels that can replace their petroleum-driven counterparts. FTS requires effective temperature control since the product distribution strongly depends on temperature. Integration of FTS with microchannel reactor technology can turn into a promising process, since sub-millimeter dimensions of this technology lead to significant intensification of the process that inherently minimizes transport resistances and allows excellent temperature control and efficient use of the catalyst. The aim of this study is to analyze FTS in catalytic microchannels through a parametric analysis employing computer-based techniques and to explore the effects of reactor geometry and operating parameters on FTS temperature. For this purpose, FTS is to run at high temperature (623 K) and pressure (20 atm) over a Fe-Cu-K catalyst in a microchannel network composed of horizontal arrays of reaction and cooling channels. The two dimensional geometry is simulated by COMSOL MultiphysicsTM using finite element method. Analysis is based on exploring the effects of material type and thickness of the separating wall, side length of the cooling channel, the type and flow rate of cooling fluid, molar H2/CO ratio in the feed and channel wall texture on the FTS temperature.The results indicate that, using thicker walls with high thermal conductance properties and micro-baffles on the catalytic wall can lead to near-isothermal conditions during FT operation. In contrast with the type and flow rate of the coolant, cooling channel side length is found to have negligible effect on the reaction temperature. It is observed that increasing H2/CO ratio leads to a decrease in average temperature.