Iron-Based Catalysts Derived from Iron-Containing Sludge for Enhanced Catalytic Performance of H₂S Selective...

In this work, iron-containing sludge is used to prepare iron-based catalysts for efficient H₂S selective catalytic oxidation. First, the effect of calcination temperatures on the catalytic activities of H₂S selective oxidation is carried out and it can be found that S-500 calcined at 500 °C performs excellent catalytic activity. Then, the catalytic performance of the S-500 catalyst is further optimized using alkaline treatment with different concentrations of NaOH solution. The results indicate that S-500(2.0) treated with 2 M NaOH solution has the highest catalytic activity of H₂S selective oxidation. Next, various characterization methods are used to analyze the structure and physical-chemical of the sludge-based catalysts. N₂-Brunauer-Emmett-Teller (N₂-BET) and X-ray photoelectron spectroscopy analyses show that the S-500(2.0) catalyst has the smallest average particle (11.17 nm), the biggest ratio of S _ext/S _micro(17.98) with bigger external specific surface area (49.09 m²·g^-1), a higher proportion of Fe³⁺ species (50.88%), and surface adsorbed oxygen species (48.07%). Meanwhile, O₂-TPD and CO₂-TPD analysis indicates that the S-500(2.0) catalyst has a bigger value of the O_ads/O_Total ratio (50.56%) and (CO₂)_{(weak+moderate)} /(CO₂)_Total ratio of (31.41%), indicating that there are much more oxygen vacancies and weak alkaline sites. As a result, the excellent catalytic performance of H₂S selective oxidation can be attributed to its outstanding physical-chemical properties.