The selectivity of 3-nitrostyrene (NS) hydrogenation over 0.5 wt-% Pt catalysts supported on carbon materials can be switched simply by changing reduction temperature. When the reduction temperature was 150 °C, 1-ethyl-3-nitrobenzene (ENB) was mainly produced in a selectivity of 93% at a conversion of 95% (at 100 °C). When the reduction was conducted at a higher temperature of 450 °C, in contrast, the main product was switched to 3-aminostyrene (AS) in a selectivity of 96% at a conversion of 91%. That is, the Pt/C catalysts reduced at low and high temperatures could preferentially catalyze the hydrogenation of vinyl and nitro groups of NS, respectively. This switching of the product selectivity may be ascribed to actions of surface oxygen-containing functional groups and surface hetero P species. The quantity and nature of these surface species were examined in detail by a few different methods. For the low-temperature reduced catalyst, surface acidic groups present close to Pt nanoparticles (∼2 nm) would interact with the nitro group of a NS molecule and make its vinyl group more likely to interact with the surface active metal species of Pt nanoparticles; this facilitates the hydrogenation of the latter and produces ENB selectively. For the high-temperature reduced catalyst, however, P species would interact with Pt and form Pt-PO_x complex, on which a NS molecule is likely to be adsorbed with its nitro group, facilitating the selective production of AS via its hydrogenation. It is demonstrated that surface functional groups and surface hetero atoms (like P), in addition to main active metal species (like Pt), should have direct actions in the catalysis for such a catalyst that exposes a larger quantity of surface functional groups and/or hetero atoms compared to the number of supported metal nanoparticles.

通过改变还原温度，可以简单地切换在碳材料上负载的0.5 wt％Pt催化剂上3-硝基苯乙烯（NS）加氢的选择性。当还原温度为150℃时，主要以93％的选择性和95％的转化率（在100℃下）产生1-乙基-3-硝基苯（ENB）。相反，当在450℃的较高温度下进行还原时，将主产物以96％的选择性转换为3-氨基苯乙烯（AS），转化率为91％。即，在低温和高温下还原的Pt / C催化剂可以分别优先催化NS的乙烯基和硝基的氢化。产物选择性的这种转换可以归因于表面含氧官能团和表面杂P物质的作用。这些表面物质的数量和性质通过几种不同的方法进行了详细检查。对于低温还原催化剂，靠近Pt纳米颗粒（〜2 nm）存在的表面酸性基团将与NS分子的硝基相互作用，并使其乙烯基更可能与Pt纳米颗粒的表面活性金属物质相互作用。这有利于后者的氢化并选择性地产生ENB。但是，对于高温还原催化剂，P物种会与Pt相互作用并形成Pt-PO 存在于Pt纳米颗粒附近（约2 nm）的表面酸性基团将与NS分子的硝基相互作用，并使其乙烯基更可能与Pt纳米颗粒的表面活性金属物质相互作用。这有利于后者的氢化并选择性地产生ENB。但是，对于高温还原催化剂，P物种会与Pt相互作用并形成Pt-PO 存在于Pt纳米颗粒附近（约2 nm）的表面酸性基团将与NS分子的硝基相互作用，并使其乙烯基更可能与Pt纳米颗粒的表面活性金属物质相互作用。这有利于后者的氢化并选择性地产生ENB。但是，对于高温还原催化剂，P物种会与Pt相互作用并形成Pt-PO_x络合物，一个NS分子很可能会被其硝基吸附，从而有助于通过氢化作用选择性地生产AS。结果表明，表面活性基团和表面杂原子（如P），除主要的活性金属物质（如Pt）外，还应在催化中发挥直接作用，使这种催化剂暴露出大量的表面官能团和/或杂原子与负载的金属纳米粒子的数量相比。