La_2O_3对Ni/α-Al_2O_3催化剂结构及沼气重整制氢性能的影响

Effect of La_2O_3 on the structure and performance of Ni/α-Al_2O_3 catalyst for biogas reforming to hydrogen

用浸渍法制备了不同La2O3含量的Ni/La2O3-α-Al2O3催化剂,考察了La2O3含量对沼气重整制氢Ni/α-Al2O3催化剂结构和性能的影响。反应在固定床反应器中进行,以V(CH4)/V(CO2)=1的混合气体模拟沼气。并运用XRD、H2-TPR、BET、TEM及TG-DSC对催化剂进行了表征。结果表明,La2O3的添加能增强金属Ni与载体之间的相互作用,并能抑制金属Ni颗粒在高温下的团聚和烧结。随着La2O3含量的升高,金属Ni的分散度和催化剂的还原性能更好。La2O3对Ni/α-Al2O3催化剂重整活性的影响取决于La2O3的添加量。催化剂w(La2O3)为6%时活性较好,掺杂过量的La2O3反而使催化剂活性下降。在100h的稳定性实验中,10Ni/6La2O3-α-Al2O3催化剂上甲烷和二氧化碳转化率保持较稳定,100h后分别只下降了2%和7%。

Biogas dry reforming was studied over La2O3 modified Ni/α-Al2O3 prepared by incipient wetness impregnation in a fixed-bed reactor with the simulated biogas stream （CH4/CO2 volume ratio of 1/1） as feed gas. The catalysts were characterized by XRD, H2-TPR, BET, TEM and TG-DSC techniques. The effects of La2O3 content on the structure and performance of Ni/La2O3/α-Al2O3 catalyst were investigated. The results showed that doping La2O3 into Ni/α-Al2O3 strengthened the interaction between metallic Ni and the support and suppressed the sintering of metallic Ni particles under high temperature. The reducibility of catalysts and the dispersity of metallic Ni on support were improved with the increase of La2O3 content. The effect of La2O3 on the activity of catalyst depended the content of La2O3. It was found that Ni/La2O3/α-Al2O3 with La2O3 mass fraction of 6% had better catalytic activity, however, excessive addition of La2O3 depressed the catalytic activity. During stability test, the conversions of CH4 and CO2 over 10Ni/ 6La2O3-α-Al2O3 catalyst decreased 2% and 7% after 100 hours on stream, respectively.