| Coal is the most abundant fossil energy in the world. Integrated gasification combined cycle (IGCC) power generation process is an attractive option for using coal for electricity generation with a high efficiency and a low environmental pollution, and is regarded to be the most promising technology in this century. In IGCC system, removal of sulfur species (mainly H2S) is crucial for the efficient and economic coal utilization. Up to now, the main problem of high temperature coal gas desulfurization technology is the decrease of durability of desulfurization sorbents, which was considered to be a obstacle for industrial development. In order to solve this problems, it is very necessary to master the behaviors of desulfurization of the sorbents, the rules of texture changing in high temperature coal gas during cycles, and the effects of additives on the properties of desulfurizer.In this study, various clay were chosen as the additives of iron oxide sorbent made from redmud. First, the sorbents were each subjected to five sulfidation /regeneration cycles in a fixed-bed reactor, with simulated Texaco coal-derived gas as testing gas. The experimental results revealed a marked difference in the sulfur capacity of the sorbents, and progressive decay of sulfur capacity of all sorbents as the number of cycles increased for all sorbent. MS57802 exhibited the best in the respect of both sulfur capacity and durability. Sulfidation mostly took place in pores of radium larger than 2000A. Sulfur capacity increased with the increasing of pore volume larger than 2000A in radium. The change of texture of sorbents appeared as the main cause of the decline of sulfur capacity. It was shown that fixed-bed could be divided into sulfidation, transmitted and reduction zones, which converted to each other with the process of desulfurization.The mineral structures of redmud, fresh, sulfided and regenerated sorbnets were investigated by XRD. The results showed that the mineral structure of iron in sorbent changed with the calcination temperature increasing. From room temperature to 400 ℃, the main phases were Fe3O4 and FeO, 400-800 ℃ , v - Fe2O3, and the conversion of Y -Fe2O3 to alpha - Fe2O3 appeared during 700-800 ℃. In fresh sorbent gamma- Fe2O3 and a -Fe2O3 were the main phases. In the sulfided samples the most significant phases were Fe1-xS, Fe7S8 and FeS, the presence of Fe3O4 indicated the reduction of Fe2O3. CaCO3 was also detected in fresh sorbents, whereas the phase of CaO was not found indicating that CaO was highly dispersed in sorbents. Calcium sulfate formed during regeneration could react with H2S to produce sulfur in later sulfidation cycles, which means that calcium took part in every sulfidation/regeneration cycle. In all of the regenerated samples the same chemical species was detected indicating that mineral structural change was not the main cause for the decrease of sulfur capacity during multicycles.The microkinetics of reduction and sulfidation of the desulfurizer MS87802 in simulated Texaco coal-derived gas were studied by thermogravimetric analysis. Experiments were carried out with the powder of 180-200 mesh, at temperatures range of 400~550 ℃ , with H2S concentration 0.14-0.6%. It was found that in the overallsulfidation process, the rate of sulfidation was all faster than that of reduction. Improved shrinking core model can successfully describe the kinetics behavior of reduction and sulfidation. At the initial stage of reaction, sulfidation and reduction was all controlled by surface reaction rate, then the processes entered the diffusion rate controlled region at the middle and last stages. The surface reaction region of reduction was longer than that of sulfidation. It should be pointed out that diffusion activation energy was higher than the reaction energy in both reduction and sulfidation processes. Compared with literature, the activated energy of reduction was much higher, which indicating that further reduction of MS87802 could be avoided.Redmud, Clay and sorbents were characterized us...
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