The catalytic reduction of nitrite in water with hydrogen has been studied using a new strategy to control selectivity. The catalysts used are based on size-controlled Pd-AOT nanoparticles, synthesized via sodium bis[2-ethylhexyl] sulfosuccinate (AOT)/isooctane reverse microemulsion, supported on activated carbon. The most remarkable feature of the catalysts is the negligible selectivity towards ammonium, which is attributed to shielding of Pd NPs by AOT and blockage of the active centers related to ammonium generation. The shielding by AOT also reduces the activity of Pd-AOT NPs, which can be overcome by immobilization on carbon and thermal treatment at mild conditions (473 K, N₂ atmosphere), although excessive removal of AOT results in higher ammonium production. Complete nitrite conversion with total selectivity to N₂ was achieved at room temperature for the Pd-AOT/C catalysts at controlled pH media using CO₂ as buffer agent. Moreover, the catalytic activity results at controlled pH show that the nitrite reduction reaction is not structure sensitive.

中文翻译：

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碳载Pd-AOT纳米粒子选择性地将亚硝酸盐还原为氮

已经使用一种控制选择性的新策略研究了用氢气催化还原水中亚硝酸盐的方法。所使用的催化剂基于尺寸控制的Pd-AOT纳米粒子，该粒子是通过负载在活性炭上的双[2-乙基己基]磺基琥珀酸钠（AOT）/异辛烷反向微乳液合成的。催化剂最显着的特点是对铵的选择性可忽略不计，这归因于AOT对Pd NP的屏蔽作用以及与铵生成有关的活性中心的堵塞。AOT的屏蔽作用还降低了Pd-AOT NP的活性，这可以通过固定在碳上并在温和的条件下进行热处理（473 K，N _2）来克服。大气），尽管过量去除AOT会导致更高的铵产量。在室温下，使用CO ₂作为缓冲剂，在受控pH值下，Pd-AOT / C催化剂在亚硝酸盐转化为N ₂时具有完全选择性。此外，在控制pH值下的催化活性结果表明，亚硝酸盐还原反应对结构不敏感。