Novel Cobalt Carbide Catalyst Wall-Coating Method for FeCrAlloy Microchannels Exemplified on Direct Production of Lower Olefins from Syngas

Wall-coating is an attractive approach for immobilizing catalyst into microchannels due to potential enhancement in heat and mass transfer and a small pressure drop. A novel hybrid method was thus developed for efficiently wall-coating special cobalt carbide catalyst into FeCrAlloy microchannels on the direct production of lower olefins from syngas. The effect of pretreatment was investigated to form a uniform Al2O3 layer on the surface of FeCrAlloy substrate. The small loss of coated catalyst layer in the mechanical adherence test by exposing the FeCrAlloy substrate to a fast nitrogen flow indicated its outstanding stability in the immobilization of cobalt carbide catalyst. The coating catalyst exhibited a stable and good activity after reaching the steady state. Additionally, calculations revealed that the wall-coated and fixed-bed microreactors had comparable mass transfer factor jD, but the former provided a five times larger heat transfer factor jH and 100 times lower pressure drop per unit length, confirming in detail the advantages of wall-coating. The proposed wall-coating strategy can be applied for immobilizing other catalyst within metallic microchannels, providing a practical technical solution for industrial implementation of microreactors.