ABSTRACT
Mn-modified Ru/Al2O3 catalyst was investigated for catalytic activity, selectivity, and stability for Fischer-Tropsch synthesis in a continuous stirred tank reactor (CSTR) under pressurized conditions. Without Mn, the Ru/Al2O3 catalyst showed low CO conversion and the deactivation rate was clearly observed at low (493 K) reaction temperature. In contrast, a small amount of Mn addition (Mn/Al = 1/19) on Ru/Al2O3 enhanced both CO conversion and C5+ selectivity for Fischer-Tropsch synthesis. Under pressurized conditions (20 to 60 bar), high catalytic activity and high resistance to catalyst deactivation with time on stream were observed over Ru/Mn/Al2O3. At 60 bar, equilibrium CO conversion was estimated to be about 96%. Characterization results-BET surface area x-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS)—indicate that the addition of Mn increases the concentration of metallic Ru active species on the catalyst surface by removing chlorine atoms from RuCl3, thus increasing catalytic activity while inhibiting catalyst deactivation.
