(304e) Study of Ni/CaO-?-Al2O3 Catalyst Using for Gasification Tar Removal

Nickel-based catalysts have been extensively researched for their low cost and good activity in the catalytic reforming of tar in raw syngas from gasification. However, their industrial application is limited due to their propensity to foul with carbon and deactivate during the catalytic reforming of tar. In this study, Ni/γ-Al₂O₃ catalysts with various CaO contents were prepared using the impregnation method, with toluene as a model compound for tar, to investigate the performance of the CaO-doped Ni/γ-Al₂O₃ catalyst in the catalytic cracking of tar. The results showed that, compared to Ni/γ-Al₂O₃, the Ni/CaO-γ-Al₂O₃ catalyst with a 15% mass fraction of CaO doping exhibited higher stability and better activity. At 550°C, the initial toluene conversion rate reached 100%, and after two hours of reaction, the toluene conversion rate could still reach 94%. A series of characterizations including XRD, SEM, BET, and TG were employed, and it was found that calcination of CaO with γ-Al₂O₃ resulted in the formation of CaAl₂O₄ spinel, which effectively inhibited the phase change of NiAl₂O₄. Additionally, calculations using the Scherrer formula revealed that the addition of CaO reduced the particle size of the catalyst after reduction, and the particle size of the Ni/15CaO-γ-Al₂O₃ catalyst after reaction was smaller than before. The addition of CaO suppressed the sintering and aggregation of the Ni-based catalyst, endowing the catalyst with good stability.