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首页> 外文期刊>ACS catalysis >Rh/ZrP2O7 as an Efficient Automotive Catalyst for NOx Reduction under Slightly Lean Conditions
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Rh/ZrP2O7 as an Efficient Automotive Catalyst for NOx Reduction under Slightly Lean Conditions

机译：Rh / ZrP2O7是在轻度稀薄条件下有效还原NOx的汽车催化剂

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摘要

The three-way catalyst performances of honeycomb-coated Rh catalysts were studied on several metal phosphate supports (AlPO4, YPO4, ZrP2O7, and LaPO4) using various simulated exhausts with different air-to-fuel ratios (A/F). These supports significantly improved the NO purification (deNO(x)) efficiency under slightly lean conditions (14.6 < A/F <= 153) as compared with conventional Rh/ZrO, catalysts. The deNO(x) activity exhibited the following sequence of increasing the mean electronegativity of the supports: ZrO2 < YPO4 < LaPO4 < AlPO4 < ZrP2O7. Although both NO-CO and NO-C3H6 reactions contributed to the deNO(x) process, the latter reaction was more favored on Rh/ZrP2O7 than on Rh/ZrO2. Partially oxidized C3H6 was adsorbed on Rh/ZrP2O7 in the form of reactive aldehyde species, in contrast to the less reactive carboxylate species adsorbed on Rh/ZrO2. Furthermore, Rh oxide was more easily reduced to the active metallic state on ZrP2O7 compared with Rh/ZrO, when the atmosphere was changed from lean (A/F > 14.6) to rich (A/F < 14.6). Metallic Rh formed on ZrP2O7 was only slowly oxidized on exposure to excess O-2, whereas Rh on ZrO, was readily oxidized to less active Rh2O3. The high activity of Rh/ZrP2O7 toward C3H6 oxidation via aldehyde species as well as the resistance of metallic Rh against reoxidation are considered to be possible reasons for the enhanced deNO(x) performance of this catalyst in a slightly lean region.
机译：使用具有不同空燃比（A / F）的各种模拟排气，研究了在几种金属磷酸盐载体（AlPO4，YPO4，ZrP2O7和LaPO4）上蜂窝涂层Rh催化剂的三元催化性能。与传统的Rh / ZrO催化剂相比，这些载体在稍微稀薄的条件（14.6 14.6）变为浓（A / F <14.6）时，与Rh / ZrO相比，Rh氧化物在ZrP2O7上更容易还原为活性金属态。 ZrP2O7上形成的金属Rh仅在暴露于过量的O-2时才缓慢氧化，而ZrO上的Rh容易被氧化为活性较低的Rh2O3。 Rh / ZrP2O7对经由醛类物质进行的C3H6氧化的高活性以及金属Rh对再氧化的抗性被认为是这种催化剂在稀薄区域中提高deNO（x）性能的可能原因。

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