Preparation And Evaluation Of Cerium Oxide As Hot Gas Desulfurizer

Coal is the most abundant fossil energy in the world. The Integrated Gasification Combined Cycle(IGCC) is considered to be one of the most promising way for high efficiency and clean utilization of coal in the 21th century. The high temperature coal gas desulfurization is regarded as a key technique in the whole IGCC process. Up to now, the one of main problem of high temperature gas desulfurization technology is the regeneration of desulfurization sorbents, which is considered to be a obstacle for industrial development. Cerium oxide sorbent has been studied as a candidate second-generation sorbent for high temperature gas desulfurization. It has been widely noticed in recent years due to the primary advantage of producing element sulfur during the regeneration phase of the process.In this paper, Cerium oxide and Cerium oxide added redmud sorbents were prepared from cereous nitrate and redmud, bentonite was chosen as the additive. An attempt was made to investigate the effects of preparing condition of Cerium oxide on pore volume, strength and desulfurization performance. The Cerium oxide sorbent was subjected reduction/sulffidation experiment in a fixed-bed, simulated Texaco coal-derived was utilized for the experiment; the cerium oxide adding redmud sorbents was subjected sulffidation and regeneration experiment; the fresh and sulfided sorbent having representation were characterized by means of several techniques, such as BET andXRD. It was found that:Cerium oxide sorbents is suitable to removal most of sulfur at high temperature, specially in a strong reducing gas.In the range of 500C to 800C, the BET was rapid enlarge, the pore volume was wide-range increment and the mechanical robustness was augmentation with the heighten of temperature.The activity of desulfurization exhibited pretty well by addition of pore-forming agent in proper quantities, but effects mechanical robustness due to excess.The desulfurization efficiency could be increased by curium oxide reduction, and the longer the time and the higher the temperature became, the higher the desulfurization efficiency reached.The presence of water vapor always inhibited reduction and sulfidation process.The grain size of cerium oxide sorbent had greatly effects on desulfurization performance. The performance of the smaller grain size sorbent was obviously better than the larger grain size ones.Cerium oxide sorbent added redmud improved sulfur capacity and had no primary effects on curium oxide sorbent structure.The regeneration of added redmud sorbent was complete in the temperature of 500C and in the gas having 95% N2 and 5% O2, but had low element sulfur recovery ratio.The reduced valence of cerium oxide sorbents is +3, which combine with Si contained in bentonite and form Ce4.667(SiO4)O. It has low removal H2S ability compared with CeOn(1.5