Seon-Ju Park

Enhanced Catalytic Performance by Zirconium Phosphate‐Modified SiO2‐Supported RuCo Catalyst for Fischer–Tropsch Synthesis

Our zirconium phosphate (ZrP)‐promoted Ru/Co/ZrP/SiO2 catalyst reveals a high catalytic activity and stability during Fischer–Tropsch synthesis. Surface modification with ZrP on SiO2 support with an appropriate amount of phosphorous component prevents cobalt particle aggregation and enhances its stability. These positive effects of ZrP are mainly induced by the spatial confinement of cobalt particles in a thermally stable ZrP matrix, and the catalytic performance was greatly improved when the P/(Zr+P) molar ratio was 0.134 on the CoZrP(0.5) catalyst.

Phosphorus Modified Co/Al 2 O 3 Fischer-Tropsch Catalyst for a Slurry Phase CSTR with Enhanced Hydrothermal and Mechanical Stability

− Phosphorus was incorporated into Co/Al 2 O 3 catalyst for FTS by impregnating an acidic precursor, phosphoric acid, in γ-Al 2 O 3 support to improve the mechanical strength, the hydrothermal stability of the catalyst particle, and the catalytic performance as well. Surface characterization techniques such as FT-IR revealed that AlPO 4 phase was generated on the surface of the P-modified catalyst. The addition of phosphorus was found to alleviate the interaction between cobalt and alumina surface, and to increase reducibility of catalyst. The catalytic activity such as C 5+ productivity and turnover frequency (TOF) was calculated to evaluate catalytic performance. The influence of calcination temperature of the Al 2 O 3 containing 2 wt.% P on the catalytic performance was also investigated. Through hydrothermal stability test and XRD analysis, the P-modified catalyst had strong resistant to the pressurized and hot H 2 O. The mechanical strength of the P-modified catalyst was also examined through an in-house fluidized-bed vessel, and it was found that the catalyst fragmentation could be successfully suppressed with P. Taken as a whole, the best performance was shown to be at 1~2 wt.% P in alumina and at the calcination temperature of 500 C.

Effects of CO2 on the deactivation behaviors of Co/Al2O3 and Co/SiO2 in CO hydrogenation to hydrocarbons

Different deactivation behaviors of the prototype Co/γ-Al2O3 (CoAl) and Co/SiO2 (CoSi) catalysts under an excess CO2 environment were investigated in terms of the surface oxidation and aggregation of cobalt crystallites for the Fischer–Tropsch synthesis (FTS) reaction. The presence of excess CO2 in the syngas feed largely altered the catalytic activity and product distribution, especially on the CoAl catalyst. A relatively faster deactivation and lower C5+ selectivity under an excess CO2 environment were observed on CoAl compared with the CoSi, which also were fairly stable under the same reaction conditions. From measurements of the reduction–oxidation behaviors of the cobalt crystallites, it could be seen that CO2 molecules acted as a mild oxidant by partially oxidizing the exposed metallic cobalt surfaces. The dramatic decrease in CO conversion and an increase in CH4 selectivity under the CO2 environment over CoAl were mainly attributed to the irreducible oxidation of the metallic cobalt surfaces through strong interactions with the Al2O3 support. Meanwhile, the marginal deactivation rate and lower changes of selectivity on CoSi were mainly attributed to the reversible oxidation–reduction property of the metallic cobalt crystallites by forming larger cobalt crystallites with relatively weak interactions with the SiO2 support. An excess exposure to the mild oxidant of CO2 on the FTS catalysts generally decreased the catalytic activity irreversibly by forming strongly interacted large cobalt crystallites, which was more predominantly seen on the acidic Co/Al2O3 than on the Co/SiO2 catalyst. The easy reversibility of the oxidation–reduction of the surface metallic cobalt crystallites on SiO2 even in the presence of excess CO2 could prevent catalyst deactivation during the FTS reaction.