While numerous studies have been carried out using rare earth oxides as catalysts for the oxidative coupling of methane, there is substantial disagreement as to which catalyst is the best. More importantly, most of these prior evaluations were done under conditions that were not commercially viable. In the current work, 35 rare earth oxide catalysts were synthesized and tested under identical conditions (CH₄/O₂ = 7.4, no diluent, 5 ms residence time), and Sr-doped La₂O₃ was isolated as the optimum catalyst composition. However, the amount of Sr is important. As the bulk Sr/La ratio was increased, the activity of the catalyst decreased but the selectivity increased significantly. A bilayer catalyst structure is proposed comprising a thermally stable Sr-La₂O₃ base layer that controls activity covered at least in part by a layer of a partially amorphous mixture of SrO, Sr (OH)₂, SrO₂, and SrCO₃ that controls selectivity. The importance of this catalyst in adiabatic autothermal operation of an oxidative coupling of methane reactor is discussed.

中文翻译：

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甲烷氧化偶联的最佳催化剂和最佳操作条件的确定：碱土掺杂镧系元素的活性和选择性

尽管已经使用稀土氧化物作为甲烷的氧化偶联催化剂进行了许多研究，但是关于哪种催化剂是最好的却有很多分歧。更重要的是，大多数这些先前的评估都是在商业上不可行的条件下进行的。在当前工作中，合成了35种稀土氧化物催化剂，并在相同条件下（CH ₄ / O ₂ = 7.4，无稀释剂，停留时间为5 ms）和掺Sr的La ₂ O _{3进行了测试。}分离出最佳催化剂组合物。但是，Sr的量很重要。随着本体Sr / La比的增加，催化剂的活性降低，但选择性显着提高。提出了一种双层催化剂结构，其包括热稳定的Sr-的La ₂ ö ₃基底层，其控制活性通过的SrO的部分无定形混合物的层部分地覆盖至少，SR（OH）₂，的SrO ₂，和的SrCO ₃那控制选择性。讨论了该催化剂在甲烷反应器氧化偶合的绝热自热运行中的重要性。