Figure 5

(A) Illustration of a switchable mixed/counter flow setup to test a T-shaped catalyst bed (yellow: carbon monoxide, blue: oxygen, green: mix); gas flow as indicated by the green arrows gives a feed of mixed carbon monoxide and oxygen; the yellow and blue arrows, respectively, indicate carbon monoxide and oxygen flowing from different sides into the catalyst bed, resulting in an interface between the two gases within the catalyst bed, (B) Conversion efficiency of CO₂ measured via mass spectrometry at the outlet of the reactor as a function of time during the switches between the two flow modes. Counter flow of oxygen and carbon monoxide creates a transition zone, thereby increasing the amount of the highly active intermediate phase and, thus, activity, and (C) illustration how a counter flow of oxygen and carbon monoxide in the T-shaped reactor maximizes the region where multiple phases are present in the reactor, enhancing the fraction of most active catalyst boosting the conversion.