Regeneration Behavior Of CeO₂ High Temperature Coal Gas Desulfurization Sorbent In SO₂-O₂ Atmophere

As a main form of energy supply, the clean conversion and utilization of coal resources is very necessary. So far the research and development of clean coal conversion and utilization technologies such as integrated gasification combined cycle (IGCC) power generation, fuel cell (FC) power generation, coal polygeneration (CPG), etc. has become a century’s most advanced technology due to the high thermal efficiency, and low pollution. The conversion and utilization of sulfur removal and effective resource utilization in desulfurization process is very important The sorbent regeneration process is a key step in desulfurization/regeneration cycles for sulfur resource use and recycling. Therefor, the good desulfurization and regeneration performance are need in order to ensure desulfurization/regeneration cycle stability. The operation conditions and atmosphere in the regeneration process have a direct impact for regeneration of sorbent and sulfur recovery resources.Selection of high-temperature gas desulfurization CeO2 as research subjects in a fixed bed differential and integral fixed bed, respectively, under an atmosphere of O2, SO2 and SO2-O2 mixed atmosphere, the influences of temperature, concentration, space velocity on the sorbent regeneration behavior were researched. The phase composition of sorbents before and after regeneration, microstructure changes in the surface distribution of elements and desulfurizer, were characterized by XRD, XPS, SEM and other characterization methods, And regeneration mechanism were proposed under different atmospheres desulfurizer.The experimental results show that the major regeneration products for CeO2 sorbent are CeO2、SO2 and elemental sulfur in O2 atmosphere. The weight of sorbent after regeneration decrease as the temperature rises, and the content of elemental sulfur in outlet gas and the regeneration conversion increase. No obvious changes of desulfurization activity are found when change the concentration of O2 in the differential bed. But in the integral fixed-bed reactor, the rate of regeneration and the content of the elemental sulfur in outlet gas increases as the O2 concentration in inlet gas is increased, and it has the maximum when the O2 concentration is 8%; the increase of space velocity enhances the course of reaction, the time of regeneration becomes shorter and Selectivity of elemental sulfur increases, the best space velocity is 6000h-1. Both the surface area and the number of large pore are increased after regeneration. It still has a better desulfurization activity after the four times sulfuration/regeneration cycles by regeneration in the integral fixed-bed reactor.In SO2 atmosphere the major regeneration products for CeO2 sorbent are CeO2 and elemental sulfur. The maximum Selectivity of elemental sulfur was achieved at 800℃ in the fixed-bed. No obvious changes of sulfuration activity are found when change the concentration of SO2 in the differential bed. But in the integral fixed-bed reactor, the increase of the concentration of SO2 can shorten the time of regeneration and the content of elemental sulfur in outlet gas increased. The maximum Selectivity of elemental sulfur was achieved when the SO2 concentration is 4.5% at 6000h-1.In SO2-O2 atmosphere the major regeneration products for CeO2 sorbent are CeO2、SO2 and elemental sulfur. In a mixed atmosphere, the existence of O2 to promote the formation of sulfate, but it can decomposed at 800℃ to increase the regeneration conversion. In the differential bed, the concentration of regeneration gas has little impact on regeneration activity. The increases of temperature、the ratio of SO2/O2 and space velocity can enhance Selectivity of elemental sulfur, so it can benefits the sulfur recovery.