| Nitrogen oxides emitted from flue gas are one of the most important pollutants in air pollution,and it have a great impact on human society and the ecological environment.In/H-Beta catalyst has high catalytic performance in the absence of sulfur dioxide and water vapor,but the catalyst is deactivated under sulfur water conditions.The sulfur and water resistance of the catalyst after doping Co3O4 in In/H-Beta certainly improved,however,the reaction mechanism of the In/H-Beta catalyst lacks systematic research.In this paper,the surface adsorption of catalysts is mainly carried out by means of temperature-programmed surface reaction?TPSR?,temperature programmed desorption?TPD?,X-ray photoelectron spectroscopy?XPS?and in situ diffuse reflectance Fourier transform infrared spectroscopy?DRIFTS?.The reaction characteristics and the catalytic mechanism of In/H-Beta catalyst were analyzed.The poisoning mechanism of In/H-Beta catalyst and the poisoning mechanism of In-Co3O4/H-Beta catalyst were studied.The catalytic mechanism of In/H-Beta was studied under oxygen-rich conditions,mainly by investigating different gas components such as NO,NO+CH4,NO+O2,NO+CH4+O2 at different temperatures in In/H-Beta catalyst.The adsorption and reaction characteristics of the surface were used to analyze the catalytic mechanism.The results show that the CH4-SCR active sites of In/H-Beta catalysts are ZO-H+,ZO-In+and ZO-In+-O,and NO can be oxidized to NO2,NO on the surface of H-Beta or In/H-Beta catalysts.ZO-H-ON+is formed at the ZO-H+position on the Bronsted acid site,and NO and CH4 can react with ZO-H-ON+to form a nitromethane species after adsorption and activation at the ZO-In+-O active site.It rapidly transforms to CO2,H2O and N2.The poisoning mechanism of In/H-Beta was studied under the conditions of SO2 and H2O.The adsorption and reaction of NO,NO+CH4,NO+O2,NO+CH4+O2 and other gas components on the surface of In/H-Beta molecular sieve were investigated.Characteristics to analyze its poisoning.The results show that SO2 can interact with ZO-H+and ZO-?InO?+active sites,inhibit the adsorption of NO on H-Beta molecular sieves,reduce the NO+species produced,and interact with ZO-?InO?+active sites.Sulfite is formed and a sulfate of indium is formed at a high temperature.H2O inhibits the conversion of NO to NO2,and competes with NO at the ZO-H+position.H2O also interacts with ZO-?InO?+to form In?OH?2+,which reduces In/H-Beta catalyst reactivity.The anti-poisoning mechanism of In-Co3O4/H-Beta with optimal anti-poisoning under SO2 and H2O conditions was studied.The main gas components such as NO,NO+O2,NO+CH4,NO+CH4+O2 were investigated.The adsorption and reaction characteristics of the surface of In-Co3O4/H-Beta catalyst were analyzed for its anti-toxicity.The results show that the incorporation of Co3O4 improves the sulfur and water resistance of the catalyst,changes the adsorption characteristics of the catalyst to NO,and enhances the adsorption of NO at lower temperatures.The adsorption of the catalyst with CH4 is enhanced,which is more conducive to the activation of CH4 and promotes the oxidation of CH4. |
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