Effect of Ni addition on the catalytic performance of Cu/γ-Al2O3 in the combustion of lean methane containing SO2
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摘要: 采用共浸渍法制备了不同Ni含量的Cu/γ-Al2O3催化剂,在固定床反应器上考察了该催化剂在含硫(SO2,0.01%,体积分数)气氛中对低浓度甲烷(3%)的催化燃烧活性及抗硫中毒稳定性。结果表明,SO2会使Cu/γ-Al2O3催化剂发生硫中毒,Ni的加入可增强其抗硫性能,而且随着Ni含量的增加,其抗硫性改善效果越明显。在Ni含量为10%的Cu/γ-Al2O3催化剂上反应10 h后,甲烷转化率仍可保持在96%以上。SEM、XRD和TPD表征结果显示,Ni的加入促使Cu/γ-Al2O3催化剂表面生成NiAl2O4尖晶石相,提高了催化剂的稳定性。随着Ni含量的增加,催化剂表面Lewis酸性降低,吸附SO2的能力减弱,可延缓催化剂硫中毒,同时也缩短了CO2分子在催化剂表面的停留时间,从而提高了甲烷催化燃烧效率。Abstract: The Cu/γ-Al2O3 catalyst promoted with Ni was prepared by incipient wetness impregnation and used in the catalytic combustion of lean methane (3%) containing SO2 (0.01%) in a fixed bed reactor; the effect of Ni addition on the catalytic activity of Cu/γ-Al2O3 and stability against sulfur poisoning in lean methane combustion was investigated. The results showed that Cu/γ-Al2O3 catalyst is facilely poisoned by SO2 in the feed gas and its resistance against sulfur poisoning can be effectively improved through the addition of Ni as a promoter. The stability of Cu/γ-Al2O3 catalyst is increased with the increase of Ni content; over the Cu/γ-Al2O3 catalyst promoted by 10% Ni, the conversion of CH4 remains above 96% after reaction at 650 ℃ for 10 h. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and NH3 temperature-programmed desorption (NH3-TPD); the results illustrated that NiAl2O4 spinel is formed on the Ni-promoted Cu/γ-Al2O3 catalyst. Upon the formation of NiAl2O4 spinel, the surface Lewis acidity is reduced, and meanwhile, the adsorption of SO2 is weakened and the retention time of CO2 on the surface is reduced, all these may contribute to the high activity and stability against sulfur poisoning of the Ni-promoted Cu/γ-Al2O3 catalyst in lean methane combustion.
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Key words:
- Cu/& /
- gamma /
- -Al2O3 /
- Ni promoter /
- lean methane /
- catalytic combustion /
- sulfur poisoning
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