A series of well-mixed Ce-containing MgAlCe rare earth catalysts derived from layered double hydroxides were synthesized and tested for H₂S selective catalytic oxidation. Particularly, no chemisorption O-vacancies but intrinsic defect sites were present on catalyst surface. Significantly, the catalysts exhibited excellent catalytic activity, reasonable durability, and outstanding sulfur selectivity (100%) at relatively low temperatures. Furthermore, the catalyst followed a step-wise mechanism, and the catalyst deactivation was due mainly to the slower oxidation rate of Ce³⁺ to Ce⁴⁺ by O₂ as compared to the reduction rate of Ce⁴⁺ to Ce³⁺ by H₂S. Particularly, the added water, a Lewis base, can compete with inefficient S₈ catalyst for the occupation of Lewis acid sites and active sites. Meanwhile, it can change the characteristics of catalyst surface, resulting in sulfur existing form transforming from inefficient S₈ catalyst to inactive S₃. Thus, lead to a decrease of deposited inefficient S₈ catalyst content. Consequently, decrease the catalytic activity.

中文翻译：

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MgAlCe层状双金属氢氧化物在混合良好的含Ce稀土催化剂上H ₂ S选择性催化氧化性能的见解

合成了一系列得自层状双氢氧化物的充分混合的含Ce的MgAlCe稀土催化剂，并进行了H ₂ S选择性催化氧化的测试。特别地，在催化剂表面上不存在化学吸附的O空位，而是固有的缺陷位点。值得注意的是，该催化剂在相对较低的温度下表现出优异的催化活性，合理的耐久性和出色的硫选择性（100％）。此外，催化剂遵循逐步机理，并且催化剂失活主要是由于与H将Ce ⁴⁺还原为Ce ³⁺的速率相比，O ₂将Ce ³⁺氧化为Ce ⁴⁺的速率较慢。_2个特别是，添加的水，路易斯碱，可以与效率低下的S ₈催化剂竞争，占据路易斯酸位和活性位。同时，它可以改变催化剂表面的特性，导致存在的硫形式从无效的S ₈催化剂转变为惰性S ₃。因此，导致沉积的无效S ₈催化剂含量的降低。因此，降低了催化活性。