Effect Of Zirconium Additive On Regeneration Behavior Of Iron Cerium Mixed Based High Temperature Coal Gas Desulfurization Sorbent

Coal occupies an important position in China's primary energy consumption.But at present,the utilization of coal still exist many problems,the low utilization rate of coal directly,causing serious pollution problems,so it is important to the clean use of coal.At present,integrated gasification combined cycle?IGCC?and fuel cell power generation?FC?are the advanced and efficient coal conversion technology,and the removal of sulfur compounds is a very important issue in this processes.In order to utilize the sensible heat in the coal gas,the high temperature coal gas desulfurization sorbents has been widely concerned.High temperature coal gas desulfurization sorbent are not only efficient desulfurization under high temperature and reducing atmosphere,but also can be regeneration,which can suffer multiple on recycling.However,single metal is difficult to meet the requirements of desulfurization,and the complex metal oxide desulfurizer has a great potential in high temperature desulfurization.Therefore,it is of great significance to study the regeneration of composite metal oxide desulfurizer.The iron cerium composite desulfurization sorbent has the phenomenon of thermal effect compensation during the regeneration process.In order to give full play to the advantage,we put forward the effect of zirconium additive on regeneration behavior of iron cerium composite desulfurization sorbent.In this paper,we prepared iron cerium zirconium composite high temperature desulfurization sorbent and studied the regeneration behavior of iron cerium zirconium omposite desulfurization sorbent in SO₂ atmosphere.The effects of different regeneration temperature,inlet SO₂ concentration and regeneration space velocity on the regeneration rate and regeneration ratio of iron cerium zirconium omposite desulfurization sorbent were studied.And the effect of zirconia on the regeneration of iron cerium based composite desulfurization sorbent was discussed.The reduction performance and structure of before and after regeneration of desulfurization sorbent by XPS and TPR were studied.The main conclusions are as follows:?1?When iron cerium zirconium composite sorbent regeneration reaction took place at SO₂ atmosphere,the regeneration product were Fe₃O₄,Fe₂O₃ Ce_0.8Zr_0.22 and elemental sulfur.With the increase of regeneration temperature,regeneration velocity and the concentration of regeneration gas can improve the regeneration reaction rate of iron cerium zirconium composite desulfurization sorbent.And the effect of the three regeneration conditions is the regeneration temperature>regeneration concentration>regeneration velocity.High regenerati--on temperature can improve the regeneration ratio of desulfurizing sorbent.And when regeneration temperature is 750 oC,the regeneration ratio reached more than 98%.?2?In the regeneration process of cerium oxidede sulfurization sorbent,surface oxygen and bulk oxygen of cerium oxide changed,and this caused the surface of Ce⁴⁺ increased and the bulk of Ce⁴⁺ decrease of cerium oxide.The presence of oxygen vacancies in the zirconium zirconium composite desulfurization sorbent after regeneration is beneficial to the migration of the bulk phase oxygen,which can make the cerium zirconium desulfurizer better reduction at low temperature.The temperature of the reducing peak of the iron cerium zirconium compound desulfurization sorbnet was reduced after regeneration,which was beneficial to secondary sulfuration of iron cerium zirconium compound desulfurization sorbent.?3?When the regeneration temperature is higher than 650 oC,sulfuration breakthrough sulfur capacity after regeneration was not significantly reduced,but also slightly higher than the fresh sample.But when the regeneration temperature is 650 oC,breakthrough sulfur capacity of sorbents after regeneration exceeded breakthrough sulfur capacity of fresh samples.Iron cerium zirconium composite desulfurizer was conducted on 5 continuous sulfuration regeneration cycles.Iron cerium zirconium composite desulfurization sorbent performed high reactivity and sulfur capacity at two sulfurization,after the four cycle,the sulfur content of desulfurization sorbent tends to be stable.?4?Regeneration performance of FeZr_0.2 and Ce₉0.8)Zr₉0.20 composite desulfurization sorbent was better than iron oxide and cerium oxide desulfurization sorbent.But with the increase of Zr content,the rate of regeneration of FeZr composite desulfurization sorbent,sulfur yield and regeneration rate increased.And zirconium improves the dispersion of iron oxide.But with the increase of zirconium content,the regeneration performance of cerium zirconium desulfurizer first increase then decrease.Different zirconium content with different cerium zirconium solid solution structure,and the cubic crystal formed by zirconium content of 0.2 can promote the regeneration of cerium zirconium composite desulfurization sorbent.?5?With the increase of zirconium content in the regeneration of iron cerium zirconium composite desulfurization sorbent,regeneration rate first increase then decrease.And FeCe₉0.8)Zr-90.20 composite desulfurization sorbent regeneration rate is the fastest.And the addition of different amounts of zirconium oxide with different cerium zirconium solid solution structure,and in the FeCe₉0.8)Zr-90.20 composite desulfurization sorbent,ceria zirconia solid solutions of cubic crystal structure can be formed.The cubic structure of ceria zirconia solid solution can promote the regeneration of cerium zirconium composite desulfurization sorbent.