Sabatier Optimal of Mn-N4 Single Atom Catalysts for Selective Oxidative Desulfurization.

Understanding the relationship of competitive adsorption between reactants is the prerequisite for high activity and selectivity in heterogeneous catalysis, especially the difference between the adsorption energies (Eads) of two reactive intermediates in Langmuir-Hinshelwood (L-H) models. Using oxidative dehydrogenation of hydrogen sulfide (H2S-ODH) as a probe, we develop various metal single atoms on nitrogen-doped carbon (M-NDC) catalysts for controlling Eads-H2S, Eads-O2 and investigating the difference in activity and selectivity. Combining theoretical and experimental results, a Sabatier relationship between the catalytic performance and Eads-O2/Eads-H2S emerges. Mn-NDC as the optimal catalyst shows excellent H2S conversion (>90 %) and sulfur selectivity (>90 %) in a wide range of O2 concentrations over 100 h. Such a high-efficiency performance is attributed to appropriate Eads-H2S and Eads-O2 on Mn-N4 sites, boosting redox cycle between Mn2+ and Mn3+, as well as preferential formation of sulfur. This work provides a fundamental guidance for designing Sabatier optimal catalysts in L-H models.