Investigation On The Catalytic Removal Of NO Process By Liquid Petroleum Gas Based On Adsorption-Reduction Decoupling

Currently the most widely applied and mature NO.control technology is selective catalytic reduction of NO.by ammonia（NH₃-SCR）.However,the ammonia slipping and ammonia tail emissions during NH₃-SCR process cause a series of problems due to the corrosivity of NH₃.As an alternative technology,catalytic removal by hydrocarbon（HC-deNO_x）prove to be a potential and efficient process for elimination of NO_x emissions.Due to the consumption of hydrocarbons by oxygen,the NO+HC reaction is significantly inhibited in the presence of excess oxygen.However,oxygen in flue is inevitable.To overcome the inhibition effect of oxygen,we proposed a rotary reactor.The nature of the reductant has an important impact on nitrogen oxides reduction by hydrocarbons.As a widely-used fuel,liquid petroleum gas are mixtures of propane,butane and other alkanes.Since propane and butane were reported to have better performance with more C atoms,liquid petroleum gas have potential application for HC-deNO_x as a reductant.Liquid petroleum gas was used for elimination of nitrogen oxides as a reductant.The catalysts used were Co-Ce-Ti mixed oxide catalysts synthesized by a sol-gel method and characterized by SEM,BET,XRD and XPS.In a fixed bed reactor,catalysts exhibited better NO conversion efficiency at higher temperature without oxygen addition.But catalysts are highly susceptible to oxygen.Catalysts achieved nearly full removal of NO_x from gas at 300 ℃:in a simulated rotary reactor.Catalysts exhibited better NO conversion efficiency at higher temperature without oxygen addition and 300 ℃ is considered to be the most optimum temperature with lower energy consumption and excellent flue gas purification performance.To investigate the mechanism of the HC+NO reaction over Co-Ce-Ti catalysts,in situ DRIFT spectra of the HC+NO co-adsorption and dynamic process of NO_x adsorption-reduction were recorded.The in situ DRIFT showed that the introduction of excess oxygen at adsorption stage could contribute to a greater variety of adsorbed NO_x species.Organic nitro and nitrito compounds are the main active intermediates,which reacted with nitrate and formed the desired product,N2,CO₂ and H₂O.In order to determine the effect of Co and Ce oxides dopants on catalytic performance on the fixed bed reactor and the simulated rotary reactor.The catalytic activity was investigated by varying the molar ratio of loaded metal oxides.The result suggested that interaction between Ce and Co have a synergistic effect on catalytic activity via the redox cycle,Ce³⁺+Co³⁺<->Ce⁴⁺+Co2+,which changed the pore structure of catalysts,increased the dispersion of cobalt oxide on the surface of catalysts and improve the catalytic performance during the adsorption and reduction process of NO in a rotary reactor.Meanwhile,the addition of Cu,Fe and Mn has an important impact on properties of catalysts in varying degrees.These catalysts exhibited limited catalytic activity on a fixed bed reactor,but with higher NO_x removal efficiency during the NO_x adsorption and reduction decoupling process.Decoupling removal process of NO_x could overcome the inhibition effect of oxygen,and achieve excellent NO removal efficiency,which prove to be a potential and efficient process for elimination of NO_x emissions.