【摘要】 采用过量浸渍法制备了Ni-Co/La2O3-γ-Al2O3双金属催化剂,并使用固定床石英反应器在850oC,0.1 MPa和空速为6000mL gcat1h 1的条件下考察了预处理对催化剂性能的影响.运用X射线衍射、热重-差示扫描量热、透射电子显微镜、扫描电镜和X射线能谱分析等手段对催化剂进行了表征.结果表明,与传统氢气还原预处理相比,经氢气和二氧化碳预处理后,催化剂性能明显提高,且能基本消除该催化剂上沼气重整反应的诱导期.511 h的稳定性实验结果表明,催化剂经氢气和二氧化碳预处理后具有很好的稳定性和抗积碳性,平均积碳速率仅为0.2 mg gcat1h 1.表征结果显示,经氢气和二氧化碳预处理后,催化剂具有更好的抗烧结和抗积碳性能,反应后金属颗粒较小,分布较均匀,粒径分布范围较窄,从而增强了催化剂的稳定性.更多还原

【Abstract】 Ni-Co bimetallic catalysts supported on -Al2 O3 pellets for biogas reforming to hydrogen were successfully prepared using the excessive impregnation method.The effects of pretreatment on the catalytic performance were investigated in a fixed-bed vertical quartz reactor under conditions of 850℃,0.1 MPa,and a gas hourly space velocity of 6000 mL gcat 1 h 1(4 g of catalyst,2.5–3.5 mm). The samples were characterized using X-ray diffraction,transmission electron microscopy,thermogravimetry coupled to differential scanning calorimetry, and emission scanning electron microscopy with energy-dispersive X-ray spectroscopy.The results showed that the catalyst pretreated with both H2 and CO2 showed higher activity,and basically eliminated the long induction period of the biogas reforming reaction,compared with the catalyst pretreated with only H2.In a 511 h stability test,the catalyst pretreated with both H2 and CO2 exhibited excellent stability,with a very low carbon deposition rate,ca.0.2 mg gcat–1 h–1.The average conversion of CH4 and CO2,selectivity for H2 and CO,and ratio of H2/CO were 96%,97%,98%,99%,and 0.98,respectively.The characterization results showed that the catalyst pretreated with both H2 and CO2 exhibited higher carbon formation resistance and better anti-sintering performance during reactions;this resulted in smaller metal particles and thus enhanced the stability of the catalyst.This new pretreatment route is very promising for enhancing the performance of biogas reforming catalysts.更多还原