Effect of H₂O on Slurry‐Phase Fischer–Tropsch Synthesis over Alumina‐supported Cobalt Catalysts

Abstract

In this article, the hydrothermal stability and change in the physicochemical properties of supported cobalt catalysts modified with Zn, P, and Zr have been studied for slurry‐phase Fischer–Tropsch synthesis (FTS) at 230°C and 2.0 MPa. The Co/P/γ‐Al2O3 exhibited weaker interactions between cobalt oxides and alumina support than other catalysts. The support of all the Co catalysts underwent phase transformation of γ‐Al2O3 into boehmite (AlO(OH)) during hydrothermal treatment at 250°C for 12 h, except Co/P/γ‐Al2O3, which was hydrothermally stable in the presence of H2O. The initial CO conversion increased with increasing number of Co surface sites during FTS. However, CO conversion decreased when H2O was cofed, causing a shift in product distribution from C2–C4 to C5+ hydrocarbons. The CO conversion and product distribution were partially reversible at 0–42.7% H2O in the feed stream. The lower adsorption capacity of H2O on the catalysts caused higher CO conversions under H2O‐rich condition. The catalytic activity of Co/P/γ‐Al2O3 was least affected by the co‐fed H2O, while that of Co/Zr/γ‐Al2O3 was strongly influenced by H2O concentration in the feed stream. The Co/P/γ‐Al2O3 did not exhibit phase transformation of γ‐Al2O3 to AlO(OH) during slurry‐phase FTS.

Comparative Study of Strategies for Enhancing the Performance of Co3O4/Al2O3 Catalysts for Lean Methane Combustion

“…In this sense, Liotta et al [19] reported that adding Ba during the sol-gel synthesis of Al 2 O 3 decreased diffusion of the Co 2+ ions into the structure of the alumina after Co deposition. Similarly, Park et al [20] and Park et al [21], on different studies, observed that adding phosphorus to Al 2 O 3 resulted in the formation of a mixed AlPO 4 phase that partially suppressed the formation of CoAl 2 O 4 . On the other hand, Cheng et al [22] found out that the addition of Mn or Fe during the synthesis of a Cu-Co/Al 2 O 3 catalyst improved the redox properties of both active metals.…”