Experiment On Recover And Reuse Of Titanium Dioxide In Spent Selective Catalytic Reduction Catalyst

With the selective catalytic reduction(SCR) becoming the major technology of power denitration, the catalyst of V2O5-WO3/TiO2 has been widely used as the core part of the SCR system. However, the SCR catalyst need to be replaced regularly after deactivation, and will be disposed as waste if it can’t be regenerated. The purpose of this study was to recover the Ti O2 from spent SCR catalyst by the most simple and convenient method, and the recovered Ti O2 was used as the carrier to re-prepare new catalysts for SCR and catalytic combustion reaction.The TiO2 was recovered from spent SCR catalysts by simple hydrothermal treatment in the alkali solution. The influence of alkali concentration, reaction temperature and reaction time were investigated. The results show that recovered sample with more 97% content of TiO2 could be obtained when the concentration of alkali solution was 30wt%, reaction temperature was 100℃ and reaction time was 3h,which has similar content to commercial TiO2; The properties of TiO2 were characterized with SEM, XRD and BET. The results indicated that the specific surface area of recovered TiO2 was larger than that of the commercial Ti O2; The crystal structures of two types TiO2 have similar crystal phase of anatase and uniform pore distribution.The V2O5-WO3/TiO2 catalysts with different V loadings were prepared by recovered TiO2(R-TiO2) and commercial Ti O2(C-TiO2) as carrier. According to the results, the temperature window of catalyst made by R-TiO2 was 300~440 °C at which the NOx conversion could reach above 95%, that has similar activity with the commercial SCR catalyst; Chemical and physical characterizations of the catalyst samples were also characterized by means of SEM, XRF, BET and XRD. It was found that, appropriate amount of V ions could form the active center which played a major role to enhanced the rate of SCR reaction. The catalysts with V 1wt% loading exhibited optimal DeNOx performance with NOx conversion above 95% at 280 °C~440 °C,which were consistent with the curve of commercial SCR catalyst, and almost no difference between the crystal structure, element content and pore distribution of the two catalysts.The combustion catalyst had been prepared by R-TiO2 and C-TiO2 with the 10wt% loadings and n(Ni)/n(V)=1:1 for Dichaloromethane(DCM)catalytic combustion, the activity of combustion catalyst made by R-TiO2 was slightly lower than the one made by commercial TiO2, because the wolfram remained in recovered Ti O2.