Study of H2S selective oxidation on new model catalysts

Fe2O3 supported on hollow micro/mesospheres silica for the catalytic partial oxidation of H2S to sulfur

“…In the case of the Cab-10Fe, the selectivity towards elemental sulfur decrease, obtaining higher proportions of undesired SO2, since its selectivity is above 37% after 300 min of TOS at 180 ºC. This data is in agreement with the literature where previous authors have reported that the formation of bigger Fe2O3 crystals tends to give rise to SO2 as a majority product [20][21][22].…”

“…In this sense, previous research have reported that Fe-catalysts are highly active in the selective oxidation of H2S reaction, although the Fe2O3-phase tends to favor the formation of combustion product, i.e. SO2 [20,21]. The decrease of the Fe2O3-crystals causes an increases of the number of the available Fe-sites and favors the partial reduction of the Fe2O3-crystals at lower temperature under the reaction medium, forming MOSand then MS2species, as indicated the reactions 5 and 6 [15], and then the subsequent desorption of the sulfur species as elemental sulfur [23], which is in agreement with that reported in the present research since small Fe2O3 crystals are highly active in the selective oxidation of H2S to elemental sulfur.…”

“…However, the elemental sulfur obtained as product in this reaction can be condensed in the micropores, leading to difussional limitations as well as a decrease of the available active sites [8]. Therefore, it is necessary the use of higher reaction temperature to remove the chemisorbed sulfide, although this increase must be controlled since it can lead to the formation of undesired products such as SO2 [20,21]. Thus, a slight increase in the reaction temperature, from 170 ºC to 180 ºC, reports a greater resistance to the deactivation of catalyst, mainly for long reaction times, as shows Figure 10.…”

“…In the case of the partial oxidation of H2S to elemental sulfur, the Fe2O3-based catalysts are more inexpensive materials than V2O5-based catalysts, attaining high conversion values. However, the main drawback of the Fe2O3-based catalysts is related with its low selectivity towards elemental sulfur, resulting in high proportions of undesired SO2 (which is formed maunly by combustion of elemental sulfur) [20,21]. However, it has been reported that the selectivity to elemental sulfur can be improved if the size of the Fe2O3 crystals are small and these crystals are dispersed in an appropriate support [10,22].…”

Catalytic behaviors of combined oxides derived from Mg/AlxFe1−x–Cl layered double hydroxides for H2S selective oxidation

“…However, its sulfur selectivity is quite low due to the excess oxygen requirement. Recently, a number of methods have been established to modify iron oxide catalysts to obtain more selective and stable catalysts, particularly by incorporating a second metal element into the iron oxide structure [7][8][9][10][11] activity and stability at a relatively higher GHSV and a lower reaction temperature.…”