We have studied the catalytic behavior of different Ni/Al₂O₃ catalysts for the dry reforming of methane which originate from different Ni metal sources: NiO and also non-stoichiometric and stoichiometric NiAl₂O₄. After complete reduction of the stoichiometric NiAl₂O₄ precursor at high temperatures, the resulting Ni/Al₂O₃ catalyst had more dispersed Ni particles of smaller size and with stronger interactions with alumina. Accordingly, this catalyst was more active and stable, developing only a moderate amount of carbon deposits which were less graphitized. On the other hand, the catalyst formed from NiO showed low initial activity and notable deactivation resulting from the encapsulation and separation of Ni metal particles from the support by more graphitic carbons, which was facilitated by the weaker metal-support interactions. In contrast to what is frequently reported, here we provide evidence which suggests that the NiAl₂O₄ species should be considered the most beneficial precursor for Ni metal in a Ni/Al₂O₃ catalyst for the dry reforming of methane even though a high reduction temperature (>950 °C) is needed to activate it.

我们研究了不同 Ni/Al ₂ O ₃催化剂对甲烷干重整的催化行为，这些催化剂来源于不同的 Ni 金属源：NiO 以及非化学计量和化学计量的 NiAl ₂ O ₄。化学计量的 NiAl ₂ O ₄前驱体在高温下完全还原后，生成的 Ni/Al ₂ O ₃催化剂具有更分散的更小尺寸的Ni颗粒并且与氧化铝具有更强的相互作用。因此，这种催化剂更活泼、更稳定，仅产生少量石墨化程度较低的碳沉积物。另一方面，由 NiO 形成的催化剂显示出较低的初始活性和显着的失活，这是由于更多的石墨碳将 Ni 金属颗粒从载体上包裹和分离而导致的，这得益于较弱的金属-载体相互作用。与经常报道的情况相反，我们在此提供的证据表明 NiAl ₂ O _{4物种应被认为是 Ni/Al 2} O ₃中镍金属最有益的前体即使需要高还原温度（> 950°C）来活化甲烷，也可以作为甲烷干重整的催化剂。