Room Temperature Desulfurizers And Regeneration Characteristics Of Metal Doped ZnO Desulfurizer

Coal plays a leading role in China’s energy structure.In the process of coal utilization,a large number of pollutants will be produced,among which H₂S is the main sulfide pollutant.It is very important to use coal resources efficiently and cleanly.Dry desulfurization has been widely used in deep or fine removal of various forms of sulfide,of which the most attractive way is adsorbing H₂S by metal oxide desulfurizer.ZnO is a very important and widely used desulfurizer at medium temperature in industrial application.However,the activity of traditional ZnO desulfurizer at room temperature is very low.Some literatures show that the activity of ZnO at room temperature can be improved by dopping other metals has been,but there is no deep discussion about this result,and there is no reasonable comparison of the effects of different metal elements.In this paper,the effects of Fe,Co,Ni and Cu doping on the desulfurization and regeneration performance of ZnO were investigated.The mechnism of metal doping on oxygen regeneration process was also studied by DFT.The main research results are as follows:（1）Use metal doping to modify the ZnO desulfurizer.On the one hand,metal doping can increase the specific surface area and pore volume of ZnO desulfurizer.On the other hand,it can improve the surface alkalinity of the desulfurizer,and provide sufficient HS^-or S^2-for sulfidation reaction.The breakthrough sulfur capacity of ZnO desulfurizer with 3%Co doping at room temperature is as high as 143 mg/g,which is 2.7 times that of undoped ZnO desulfurizer.（2）The effects of metal doping on regeneration are mainly reflected in the regeneration temperature,sulfur release rate,and the formation and decomposition of sulfate.The doping of Fe,Co,Ni and Cu can reduce the regeneration temperature,whereas sulfate is also easy to be formed.（3）The regeneration rate of desulfurizer is related to the decomposition temperature of each sulfate.Sulfate with high decomposition temperature is not easy to regenerate completely,while it with low decomposition temperature is easy to regenerate completely.The regeneration temperature of desulfurizer should be lower than the temperature of sulfate formation as far as possible,therefore the decomposition temperature of sulfate should be considered when choosing the doped metal.（4）The adsorption energies of O₂ and O atoms on the surfaces of ZnS（110）and metal-doped ZnS（110）were calculated.Studies have found that doping metal can improve the adsorption ability O₂ and O atoms on ZnS（110）,especially after Co doping.The adsorption energy can reach-235.48 k J·mol^-1 and-586.21 k J·mol^-1,respectively,which is higher than that of other metal doped and undoped ZnS（110）,indicating that Co doping is more instrumental in the adsorption of oxygen on ZnO surface during regeneration.（5）DFT calculation shows that,the rank of the transition state energy for O₂ dissociation reaction from low to high is Co doped,undoped,Ni doped,Cu doped and Fe doped.The transition state energies of S-O substitution reaction from low to high are Cu doped,Co doped,Fe doped,undoped and Ni doped.These results indicate that Co doping is beneficial to the reaction between oxygen and ZnS,which is consistent with the results obtained by the thermogravimetric experiment.