Recycling Sulfur-Poisoned Pd Catalysts via Thermal Atomization for Semi-Hydrogenation of Acetylene.

Palladium catalysts are highly efficient for a variety of chemical industrial processes but are prone to being affected by poisons during practical application. Sulfur is one of the major poisons in Pd-based catalysts. The recycling of deeply poisoned Pd species like Pd sulfides is challenging due to the strong Pd-S bond. Herein, we proposed a top-down strategy to degrade Pd sulfides and create Pd single-atom sites simultaneously by one-step thermal atomization. Pd ₄ S model nanoparticles were successfully converted to Pd single-atom sites supported on nitrogen and sulfur-codoped carbon (Pd ₁ /N, S-C) after loading them on ZIF-8 and thermal treatment. PdZn intermediates were formed during the atomization process. Density functional theory revealed that the formation of PdZn helped the generation of vacancies adjacent to metal nanoparticles, which prompted the atomization process. This strategy can be facilely applied to the atomization of sulfur-poisoned commercial Pd/C, which shows the potential for recycling commercial catalysts. The optimal Pd ₁ /N, S-C catalyst showed good activity and much enhanced selectivity than Pd ₄ S for the semi-hydrogenation of acetylene.