Abstract <p>This study was focused on the problem of removing trace amounts of oxygen from hydrocarbon gas mixtures using a Ni-based solid sorbent supported on γ-Al₂O₃. The studied sorbents were synthesized by the incipient wetness impregnation of alumina supports with a solution containing nickel precursor compounds. The parameters varied during the study were the following: the active component content in the samples (4–8 wt %), the nature of the support (γ-Al₂O₃ extruded with the addition of CH₃COOH or aqueous ammonia), and the nature of the nickel salt used for impregnation (nickel nitrate and a hydroxonickel(II) carbonate–ammonia complex). The synthesized sorbents were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and pulsed chemisorption of CO and O₂. Transmission electron microscopy microphotos of the surface show that nickel particles have similar sizes (~2–3 nm) in the sorbents synthesized from both nitrate and a hydroxonickel(II) carbonate–ammonia complex. However, the CO pulsed chemisorption results revealed a significant difference in the average Ni particle size: 1.5–2.5 and 5.9–7.9 nm for the nitrate and ammonia complex, respectively. This difference in experimental data was attributed to the more significant tendency of the ammonia complex to forming a more inert nickel–aluminum spinel, which is reduced at extremely high temperatures and, therefore, is not detected by pulse chemisorption. In addition, it should be noted that the O₂ pulsed chemisorption results indicate that the main factor that affects the apparent capacity of the sorbents is the active and accessible surface area of the nickel particles. No clear effect of the used support on sorption activity has been revealed. In addition, a process flow diagram for oxygen capture from a hydrocarbon mixture on Ni/γ-Al₂O₃ with subsequent sorbent regeneration in a hydrogen stream is proposed.</p>