| According to the forecast of energy structure and energy consumption,coal will occupy the dominant position of energy consumption in China for a long time.However,the inefficient use and waste of coal have caused serious environmental and energy problems,and the clean and efficient coal conversion technology has become an effective way to solve these problems.Integrated Gasification and Combined Cycle(IGCC),Coal based polygeneration(CPG)and other power generation technologies,with high efficiency,low pollution and environmental friendly characteristics,have become the sustainable development strategy of clean coal technology with great potential in the future.However,H2 S produced in coal gasification process will cause serious harm to the pipeline equipment,environment and human health.Therefore,the research of high temperature gas desulfurization technology is of great significance.This paper summarized and analyzed the advantages and problems of iron-cerium based mixed desulfurization sorbents,chosen Zr as an additive and prepared iron-cerium-zirconium mixed high temperature coal gas sorbent to investigate the desulfurizaiton behavior of sorbents in a fixed bed reactor,andcombining with XRD,N2 adsorption,XPS,H2-TPR,SEM-EDS characterization methods to research the effect of zirconium additive on the structure,reduction properties and desulfurization properties of iron-cerium based mixed sorbents,which were connected with each other.The main conclusions are as follows:(1)The iron-cerium-zirconium mixed desulfurization sorbent which was prepared by co-precipitation method,has the form of Fe2O3-Ce1-xZrxO2.The optimum preparation conditions were: the molar ratio of Fe,Ce and Zr was1:0.8:0.2,and the calcination temperature was 700oC;the zirconium additive could increase the specific surface area and pore volume of iron oxide,cerium oxide and iron-cerium mixed desulfurization sorbents,which were more conducive to the adsorbing and desorbing of sulfur;the zirconium additive increased the oxygen vacancies of cerium oxide and iron-cerium mixed desulfurization sobents,which were more conducive to promoting the reduction of Ce4+?Ce3+?(2)The zirconium additive improved the reduction degree of Ce4+ of iron-cerium mixed sorbent,and the reduction temperature of bulk CeO2 was reduced,which is more beneficial to the active component of iron and cerium involving in the reduction and desulfurization reaction in isothermal zone.(3)Compared with single iron oxide and cerium oxide desulfurization sorbents,iron-cerium mixed sorbent showed the better desulfurization property at 600 oC,but it was with low reaction degree.At this temperature,it was known that the active component of cerium of Fe-Ce mixed sorbent was not fullyinvolved in the reaction.(4)Zirconium additive significantly improved the desulfurization precision,the utilization of desulfurization,breakthrough sulfur capacity,and the degree of desulfurizaiton of iron-cerium mixed sorbent and broaden the range of reaction temperature.For single particle desulfurization sorbent,both the reduction and the desulfurizaiton reaction are the layer reaction from external to internal.In the process of reduction,zirconium additive promoted Ce to gradually enrich to the outer layer or Fe migrate to the inner layer.In the process of desulfurizaion,zirconium additive promoted Ce to gradually migrate to the inner layer or Fe enrich to the outer layer.The migration of Fe,Ce element is more conducive to the participation of Ce in reduction and desulfurization reaction.The equation of desulfurizaiton reaction of Fe-Ce-Zr sorbent is as follows:Fe(7)(8)Zr2CesO(7)(8)(7)(8)3Hg2HsO(7)g(8)(7)(8)Ces2FeSSO(7)(8)5HsSZr(7)gO(8)222xx)2(1222Xx132(10)(10)(28)(10)(10)(10)--(5)Fe-Ce-Zr mixed sobent has good desulfurization-regeneration cycle stability. |
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