Tuning Oxygen Vacancies in Ag/Ceria-Zirconia for Selective Trace Oxygen Removal from Olefin-Rich Streams with High Hydrogen-to-Carbon Ratios

Abstract

The selective removal of trace oxygen remains challenging in olefin-rich gas streams with high hydrogen-to-carbon ratios, particularly in the efficient utilization of refinery dry gas (RDG) resources. In this contribution, a highly selective and durable silver-based catalyst supported on ceria–zirconia was rationally designed and synthesized for the selective removal of trace oxygen under olefin-rich conditions with high hydrogen-to-carbon ratios. Among the prepared catalysts, the Ag/Ce_0.75Zr_0.25O₂–CC catalyst synthesized via the complexation–precipitation method selectively reduces oxygen to 0.2 ppm at 150 °C while maintaining a low 1,3-butadiene loss of 4.2% under simulated RDG conditions. Detailed physicochemical characterizations revealed that the catalyst’s outstanding performance is attributed to the highly dispersed Ag species and a moderate concentration of oxygen vacancies, which synergistically promote selective oxygen activation and removal. Furthermore, the balanced oxygen vacancy concentration and weak surface acidity of the support effectively suppress the undesired hydrogenation of 1,3-butadiene. The catalyst also demonstrated long-term stability over 100 h of continuous operation, highlighting its potential for industrial application. These findings offer valuable insights into industrial deoxygenation strategies, particularly for olefin-rich process streams.