Effect Of Ambient Gas On Sulfidation Performance Of Iron-Manganese Based Sorbent At Mid-Temperature

Medium and high temperature desulfurization was regarded as one of the key techniques in efficient and clean conversion of coal. By means of performance difference of various active components, the two step desulfurization of bulk removal and polish removal was put forward. The deep removal of sulfur will reduce the burden of polish removal stage and save preparation cost. Iron oxide with the high sulfur capacity, the high reactivity, extensive sources and low price is considered as one of the most favorable sorbents for bulk removal of H2S. The modification of iron based sorbent and investigation of performance can provide necessary basic data and theoretical basis for industrialization.The sulfidation performance of iron oxide prepared from various precursors was investigated,and the ferric nitrate with better sulfidation performance was chosen as precursor of active component. The manganese nitrate was chosen as precursor of side active component. A series of iron - manganese based sorbents with different molar ratio of Fe/Mn were prepared. The sulfidation performance of these sorbents were studied. The sulfidation behavior of sorbents pretreated by 7F3M750 was also studied in different gas steam. COS was found in outlet gas during H2S removal process. So the performance of iron and manganese active component with different valence were investigated in COS / N2 and H2 / COS / N2 gas stream. The following conclusions can be drawn:1) The sequence of sulfidation activity of various iron oxides prepared from ferric nitrate, ferrous sulfate and analytic pure iron oxide is:NF > F > SF. The ferric nitrate was optimal as precursor of desulfurizer based on comprehensive consideration.2) The manganese can be favour of the sulfidation performance of the iron based sorbents, while the sorbents of 7F3M750 has the best sulfidation behavior.3) The H2 can improve the sulfidation performance of iron - manganese based sorbent, which depends on degree of reduction and existing form of active component.4) CO2 can repress the sulfidation performance of sorbent due to its bigger molecular volume. The carbon deposition from CO disproportionation has adverse effect on structure stability of sorbent. These effects can be relieved greatly when CO and CO2 coexist. CO can improve the unfavorable effect of CO2 on sulfidation performance of sorbent and CO2 can relieve the carbon deposition from CO.5) As product of sulfidation reaction, H2O has the most significant negative effect on sulfidation performance of sorbent. This effect can be weakened by water gas shift reaction in mixed gases, and enhanced by reversed water gas shift reaction.6) The H2S removal ability of Fe is smaller than that of Fe2O3 and Fe3O4. The removal abilities of them are stronger than that of Mn2O3 and MnO.7) The removal abilities of Fe2O3,Fe3O4 and Fe for COS are related to temperature, and obviously weaker than that of Mn2O3 and MnO.8) Iron sulfide and manganese sulfide both have catalysis on COS hydrogenolysis in different degree.