Study On The Application Of Plasma-catalytic Method For DeNO_x In Flue Gas

As a major source of air pollution, nitrogen oxides NOx mainly emitted from mobile and stationary sources. They are main contributors to a series of environmental issues. Nowadays, the nonthermal plasma (NTP) technology has been researched widely for NOx removal because NTP can activate molecules even at room temperature. The present work is focused on the study of a combined adsorption-discharge plasma process for NOx removal. The efficiency of this new process for NOx removal could achieve95%at ambient temperature. The main contents and results are as follows:(1) A combined adsorption-discharge plasma process was proposed for DeNOx in simulated flue gas at room temperature. The efficiency of this new process for NOx removal could achieve95%under the condition of simulated flue gas. The energy efficiency of the new process proposed was improved. Thus we believe that this new deNOx technology has broad application prospects.(2) Natural mordenite (NMOR), modified by acid treatment and ion-exchange, was employed for NO adsorption in the present study. The NO storage capacity of modified NMOR was greatly improved compared with its original correspondents, mainly due to the preservation of crystalline structure and the improvement of surface area of NMOR. Among all the modified NMOR, Ni-NMOR exhibited the highest adsorption capacity for NOx (1.20mmol/g). The influence of the main ingredients in flue gas on the storage capacity of NMOR for NO had also been investigated. H2O, CO2and SO2all displayed negative impact on NO adsorption due to their competitive adsorption on the surface of NMOR with NO, while the presence of02greatly improved the adsorption of NO because of the formation of NO2. Moreover, Ni-NMOR exhibited high efficiency for NOx removal through the NOx adsorption-plasma discharge process.(3) NOx storage and reduction with CH4by a plasma process was proposed for (4) NOx removal at ambient temperature. H-ZSM-5acted as an adsorbent for NOx at the adsorption stage and a catalyst at the discharge stage. The influence factors including the discharge power, flow rate, O2concentration and CH4concentration were investigated. High energy density is beneficial to NOX conversion. Obviously, CH4enhanced the total NOx conversion. On one hand, a suitable amount of CH4could play a role as a reducing agent in NSR; on the other hand, CH4oxidation consumed O2to restrain the reverse reaction of NOX decomposition. NOx removal via cyclic operation has also been investigated, maintaining efficieniency above90%.(5) The effect of water vapor on NOx storage and reduction in combination with non-thermal plasma was investigated. H2O could lower NOX adsorption capacity of H-ZSM-5at the adsorption stage, due to the competitive adsorption between H2O and NOx on HZSM-5. Ni-ZSM-5exhibited better resistance to H2O than H-ZSM-5. At the discharge stage, the introduction of H2O decreased the total NOx conversion. When increasing the CH4concentration and the discharge power, the conversion of adsorbed NOx to N2moved up to97.4%.(6) NOx storage and reduction with NH3by a plasma process was proposed for NOx removal in simulated flue gas. The influence factors including the discharge power, flow rate, O2concentration and NH3concentration were investigated. The introduction of NH3is able to reduce the energy consumption for the discharge process, while raising the total NOx conversion. Moreover, H2O did not affect the NOx conversion in this process. NOx removal via cyclic operation has also been investigated, maintaining efficieniency above90%.