Studies on stability and coking resistance of Ni/BaTiO3–Al2O3 catalysts for lower temperature dry reforming of methane (LTDRM)
Studies on stability and coking resistance of Ni/BaTiO3–Al2O3 catalysts for lower temperature dry reforming of methane (LTDRM)
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DOI：
10.1016/j.apcata.2011.11.004
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发表时间：
2012-01
影响因子：
5.5
通讯作者：
Xiancai Li;Q. Hu;Yifeng Yang;Yan Wang;F. He
中科院分区：
文献类型：
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作者：
Xiancai Li;Q. Hu;Yifeng Yang;Yan Wang;F. He
重量% BaTiO3-Al2O3（wt.%）采用溶胶-（干）凝胶法，通过改变BaTiO_3的含量，合成了BaTiO_3 =0-100%的复合载体。Ni/wt.%采用等体积浸渍法制备了BaTiO 3-Al 2 O 3镍基催化剂，并在690°C ~ 800°C进行了甲烷干重整反应。采用XRD、IR、N2吸附-脱附、H2-TPR、SEM和XPS等手段对复合材料的结构和性能进行了表征。BaTiO 3-Al 2 O3复合载体以及Ni/wt.% BaTiO 3-Al 2 O3催化剂结果表明，BaTiO 3颗粒在γ-Al_2O_3表面呈不连续分散状态，其分散状态为单个孤立颗粒BaTiO 3-Al 2 O3复合载体。同时，γ-Al_2O_3表面BaAl_2O_4尖晶石相和BaTiO_3相的共存可能抑制了Ni/wt.% BaTiO 3-Al 2 O3催化剂由NiAl 2 O 4尖晶石相形成，提高了催化剂的催化性能。Ni/BaTiO 3催化剂在690°C下甲烷干重整反应中表现出较低的稳定性和严重的积炭现象，这主要是由于Ni/BaTiO 3催化剂的电子给体强度过大，导致CO还原反应。与Ni/BaTiO 3催化剂相比，Ni/wt.% BaTiO 3的加入使活性镍的分散度提高，降低了NiOx物种的电子给体强度。结果表明，所制备的Ni/32.4%BaTiO3-Al 2 O3催化剂对甲烷低温干重整反应具有较高的催化活性、良好的稳定性和抗积炭性能。
Wt.%BaTiO3–Al2O3(wt.%BaTiO3=0–100%) composite supports were synthesized through varying the BaTiO3content by the “sol–(xero)gel” method. Ni/wt.%BaTiO3–Al2O3nickel-based catalysts prepared by incipient wetness method were evaluated for dry reforming of methane carried out between 690°C and 800°C. Characterizations using XRD, IR, N2adsorption–desorption, H2-TPR, SEM, and XPS were conducted to investigate the structure or properties of the wt.%BaTiO3–Al2O3composite supports as well as the Ni/wt.%BaTiO3–Al2O3catalysts. The results demonstrate that BaTiO3particles are discontinuously dispersed on the surface of γ-Al2O3in the form of individual isolated particles for the wt.%BaTiO3–Al2O3composite supports. Meanwhile, it is probably that the coexistence of BaAl2O4spinel phase with the BaTiO3phase on the surface of γ-Al2O3inhibits the Ni/wt.%BaTiO3–Al2O3catalysts from the formation of NiAl2O4spinel phase, improving the catalytic performance of the catalysts. The Ni/BaTiO3catalyst showed poor stability and severe coke formation in the dry reforming of methane tested at 690°C, which was thought to be mainly originated from the excessive strong electronic donor intensity of Ni/BaTiO3catalyst as well as the resulted CO disproportionation reaction. Compared with the Ni/BaTiO3catalyst, the Ni/wt.%BaTiO3–Al2O3catalysts with the addition of BaTiO3had a higher dispersion of active nickel and a weakened electronic donor intensity of the NiOxspecies. As a result, the synthesized Ni/32.4%BaTiO3–Al2O3catalyst exhibited a high catalytic activity, excellent stability as well as coking resistance for lower temperature dry reforming of methane.