Hydrogenation of olefinic bonds in nitrile butadiene rubber on single-atom Pd₁/CeO_2−x catalysts with ultrahigh mass activity and stability

As pivotal high-performance elastomers, hydrogenated nitrile butadiene rubber (HNBR) was commonly manufactured by selective hydrogenation of nitrile butadiene rubber (NBR). Nevertheless, the high cost and poor stability of current noble metal-based catalysts seriously limit their large-scale applications. Herein, we report single-atom Pd supported by oxygen vacancies-rich CeO_2−x nanorods (Pd₁/CeO_2−x) as a novel catalyst for selectively hydrogenating the NBR. As a result of strong interaction between single-atom Pd and CeO_2−x support, the electrophilicity of Pd sites, and the nucleophilicity of olefinic bonds in NBR, the Pd₁/CeO_2−x show a very high hydrogenated degree of 97.6 %, an unprecedentedly high Pd mass activity of 93.9 g_NBR g_Pd⁻¹h⁻¹, and outstanding cycling stability, which considerably outperform those for previously reported catalysts. Therefore, this work will promote the low-cost manufacture of HNBR and the exploration of single-atom catalysts for selective hydrogenation.