Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, the split exhaust engine system may include a first set of exhaust valves fluidly coupled to the exhaust passage, upstream of a turbocharger turbine, a first emission control device (ECD), and a second ECD disposed within the exhaust passage, the second ECD positioned downstream of the first ECD. The system may further include a second set of exhaust valves fluidly coupled to the intake passage and the exhaust passage, between the first ECD and the second ECD.