NANO-IRON CARBIDE-CATALYZED FISCHER-TROPSCH SYNTHESIS IN SLURRY REACTORS: NEW DEVELOPMENTS

摘要

Nano-iron carbides (NFeC), produced by a plasma spray technique, are used in Fischer-TropschSynthesis (FTS) 3-Φ continuously-stirred slurry tank reactors. The NFeC particles are initially encapsulated in acarbon matrix which protects the highly-sensitive carbides from air-borne oxidation. This matrix is partially removedunder reductive conditions as a pre-treatment of subsequent FTS reactions. The reactants simulate the composition ofsynthesis gas produced by urban biomass gasification. At-line gas chromatography (GC) of the more volatileproducts and global liquid product analyses by micro-distillation provide the necessary data for mass balance,conversion and selectivity estimations. Also, an appropriate algorithm successfully estimates the ratio of FTS extentsover Water Gas Shift reactions. The results show that this nano-powder, characterized by very low internal porosity,produces a liquid fuel that is lighter than other commercial catalysts under similar reaction severities but at a muchlower catalyst load. Increased catalyst loading in the slurry above a critical limit leads to higher product water holdupand, consequently, higher rates of catalyst deactivation. Conversion, selectivity and the Anderson-Schulz-FloryDistribution probability of chain growth “α” were compiled and reported. The attempt to link “α” and liquid productselectivity with the phenomenological model severity factor is reported and discussed.