Abstract The effects of catalyst supports (γ-Al2O3 and α-Al2O3) on hydrogen yield and carbon nanotubes formation were studied during steam reforming of toluene over Ni-based catalysts. Hydrogen yield and CNTs quality over Ni/γ-Al2O3 were better than those over Ni/α-Al2O3 at S/C ratio of 1 due to the high Ni dispersion of Ni/γ-Al2O3. With the increasing of steam addition, CNTs production remarkably increased over Ni/α-Al2O3, while it decreased over Ni/γ-Al2O3. The CNTs on Ni/γ-Al2O3 were corroded at S/C ratio of 3 by excess steam. Toluene conversion and hydrogen yield over Ni/α-Al2O3 were significantly larger than those over Ni/γ-Al2O3, which was attributed to the different effects of CNTs on catalytic activity. The strong interaction between Ni particle and γ-Al2O3 led to the base-growth mechanism of CNTs on Ni/γ-Al2O3 in which Ni particles located at the bottom of CNTs, thus the growth of CNTs covered Ni active sites and decreased catalytic activity of Ni/γ-Al2O3. By contrast, owing to weak interaction, CNTs grown on Ni/α-Al2O3 followed tip-growth mechanism that would increase Ni dispersion and promote reforming reaction.

中文翻译：

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Ni/Al 2 O 3 催化剂上碳纳米管的形成及其对甲苯蒸汽重整的影响：催化剂载体的作用

摘要 研究了催化剂载体（γ-Al2O3 和α-Al2O3）在Ni 基催化剂上甲苯蒸汽重整过程中对氢气产率和碳纳米管形成的影响。由于 Ni/γ-Al2O3 的高 Ni 分散性，在 S/C 比为 1 时，Ni/γ-Al2O3 上的氢产率和碳纳米管质量优于 Ni/α-Al2O3 上的那些。随着蒸汽添加量的增加，碳纳米管的产量在 Ni/α-Al2O3 上显着增加，而在 Ni/γ-Al2O3 上则下降。Ni/γ-Al2O3 上的碳纳米管在 S/C 比为 3 时被过量蒸汽腐蚀。Ni/α-Al2O3 上的甲苯转化率和氢气产率显着高于 Ni/γ-Al2O3 上的，这归因于 CNT 对催化活性的不同影响。Ni粒子与γ-Al2O3之间的强相互作用导致了CNTs在Ni/γ-Al2O3上的碱生长机制，其中Ni粒子位于CNTs的底部，因此CNTs的生长覆盖了Ni活性位点，降低了对碳纳米管的催化活性。 Ni/γ-Al2O3。相比之下，由于相互作用较弱，在 Ni/α-Al2O3 上生长的 CNT 遵循尖端生长机制，这将增加 Ni 分散并促进重整反应。