We recently reported that polymer chains with phenylene sulfide moieties can efficiently modify the Pd catalyst surface, enabling selective partial hydrogenation of acetylene under ethylene-rich conditions. In the present study, we synthesized oligomeric and polymeric phenylene sulfides with tailored molecular sizes to systematically investigate the catalytic effect of chain length of organic modifiers. The results showed that the increased chain length of the modifiers is beneficial for improving the acetylene partial hydrogenation selectivity by inhibiting adsorption and full hydrogenation of ethylene. This was attributed to the fact that modifiers with a greater number of sulfide groups per molecule can bind more efficiently to the Pd surface for entropic reasons (chelate effect) and thus better inhibit ethylene adsorption. In contrast, the adsorption of acetylene to Pd was nearly unaffected by the presence and size of the modifiers owing to its stronger binding ability and small kinetic diameter. Modifiers with larger chain lengths were also advantageous in improving long-term catalyst stability because of their higher thermochemical stability and greater ability to inhibit the formation of carbonaceous deposits. The present results showed that polymers can act as more efficient and long-lasting selectivity modifiers than commonly used small organic molecules.

我们最近报道了具有苯硫醚部分的聚合物链可以有效地修饰 Pd 催化剂表面，从而能够在富含乙烯的条件下选择性地部分氢化乙炔。在本研究中，我们合成了具有定制分子大小的低聚和聚合苯硫醚，以系统地研究有机改性剂链长的催化作用。结果表明，改性剂链长的增加有利于通过抑制乙烯的吸附和完全加氢来提高乙炔部分加氢的选择性。这归因于这样一个事实，即由于熵的原因（螯合效应），每分子具有更多硫化物基团的改性剂可以更有效地结合到 Pd 表面，从而更好地抑制乙烯吸附。相比之下，由于其更强的结合能力和小的动力学直径，乙炔对 Pd 的吸附几乎不受改性剂的存在和大小的影响。具有较大链​​长的改性剂也有利于提高催化剂的长期稳定性，因为它们具有更高的热化学稳定性和更强的抑制碳质沉积物形成的能力。目前的结果表明，与常用的有机小分子相比，聚合物可以作为更有效、更持久的选择性改性剂。具有较大链​​长的改性剂也有利于提高催化剂的长期稳定性，因为它们具有更高的热化学稳定性和更强的抑制碳质沉积物形成的能力。目前的结果表明，与常用的有机小分子相比，聚合物可以作为更有效、更持久的选择性改性剂。具有较大链​​长的改性剂也有利于提高催化剂的长期稳定性，因为它们具有更高的热化学稳定性和更强的抑制碳质沉积物形成的能力。目前的结果表明，与常用的有机小分子相比，聚合物可以作为更有效、更持久的选择性改性剂。