Effect of phosphorus modification on Cu-ZnO-Al₂O₃ for the removal of H₂S

Cu-Zn-Al oxides adsorbents with or without phosphorus modification have been investigated for their hydrogen sulfide removal efficiency. Cu_0.46 Zn_0.48/γ-Al₂O₃ was prepared by precipitating Cu and Zn nitrate precursors on unmodified and phosphorus-modified γ-Al₂O₃. For the preparation of Cu_0.46 Zn_0.48 /lP/γ-Al₂O₃, Cu_0.46 Zn_0.48/3P/γ- Al₂O₃, and Cu_0.46Zn_0.48/9P/γ-Al₂ O₃, the γ-Al₂O₃ was previously modified with different amounts of phosphorus (1, 3, and 9 wt %, taken in the form of phosphoric acid) and Cu and Zn precursors were precipitated in the slurry of it. The sorbents were characterized by X-ray diffraction (XRD), surface area, pore size distribution, temperature-programmed reduction (TPR), Cu surface area measurement, and X-ray photoelectron spectroscopy (XPS). The sorbent modified with 3 wt % P on γ-Al₂O₃ showed the maximum value for the sulfur removal capacity and a large surface area of Cu. This high value of Cu surface area mainly results from making a sorbent with large pore diameter. Reduction in the binding energy of Cu 2P of the well-dispersed Cu metal particles, as observed by XPS analysis, could be the reason for the high sulfur removal capacity.