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Study of NTP Assisted Catalytic Oxidation on Mn/ZSM-5for NO

Author: WangChuan
Tutor: TangXiaoLong
School: Kunming University of Science and Technology
Course:
Keywords: Non-thermal plasma NOx Mn/ZSM-5 Synergetic catalytic oxidation
CLC: X701
Type: Master's thesis
Year: 2013
Downloads: 31
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Abstract

The problem of environmental pollution caused by nitrogen oxides is more and more serious. Strengthen emission Limitation for industrial emissions of NOx in China, then, flue gas denitrification become essential issue of air pollution control after desulfurization pollution control. The technology of Non-thermal plasma assisted catalytic is becoming one of the hot topics of intensive interest. A superior effective technology for flue gas denitrification was presented in this work, and the "one-stage" method feasibility was studied. In this thesis, catalyst preparation conditions(loading amount、calcination temperature、precursor)were investigated. The optimum operation parameters of reactor were identified with adjusting parameters conditions. According to the particularity of this reaction, the effects of the particle size and volume of catalysts, SO2, H2O, the inlet concentration of NO and O2were studied. The purpose of this paper is denitrification with low energy consumption in Low temperature. The research results in this paper were summarized as follows.1. An excessive dipping method was used to prepare catalyst composed of difference carrier and Mn as the active component. We investigated the effect of preparation conditions on reactive activity. The optimal preparation conditions were as follows: manganese acetate as the precursor, ZSM-5zeolite carrier, Mn loading10%, calcination temperature for catalyst400℃, ultrasound-assisted impregnation. The synergetic catalytic oxidation efficiency of NO reached73%. The catalysts characterized by BET、XPS to obtain its structure and morphology, then, discussed the effects of the preparation method on reactive reactivity. The results showed that:catalyst used of manganese acetate as the precursor was better than manganese nitrate as its large specific surface area and more micropore distribution. Moreover, the catalyst surface has more Mn3+which is conducive to catalytic oxidation of NO in low temperature. In addition, calcination temperature leads to the various Mn content on catalyst surface. Catalyst which prepared by400℃has good performance is that the surface of catalyst contain more Mn3+2. In order to optimize the NTP reactor parameters, the influencing factors (e.g. discharge voltage, dielectric material, discharge gap and electrode material) on synergetic catalytic oxidation of NO were investigated. Results show that:In the experimental system, when the discharge voltage is applied to5kV, the discharge is relatively slight, but the concentration of NO and NO2changed greatly. The starting voltage of Dielectric Barrier Discharge (DBD) reactor voltage is5kV. In the discharge voltage5.5kV and6kV, the NTP synergistic function was promotion. When the discharge voltage reached6.5kV the reactive activity declined. Experimental results indicated that:using of quartz tube has better effect than ordinary glass. The synergetic catalytic oxidation of NO increased with the discharge gap reducing to2.0mm. The reactivity of the copper electrode is slightly higher than the stainless steel electrode.3. The particle size of catalyst not only impacts on the reaction diffusion and contact area of gas-solid phase, but also affects the capacitance in the DBD reactor. The appropriate catalyst particle size in our experimental system was20-40mesh(0.38-0.83mm). The optimum volume of catalysts is1.2g.4. Influences of the inlet concentration on NO oxidation have been studied in. It was found that:in a certain range, the activity reaction had little change. However, when the inlet NO concentration increased to1340mg/m3(1000ppm) the synergetic catalytic oxidation of NO was significantly decreased. Oxygen is the active species of synergistic catalytic oxidation of NO in the catalyst surface. The effect of the oxygen concentration (0,3,5,7and10%) was investigated. NO mainly decomposed in the N2/NO system. The reactive activity was improved by the increasing of oxygen content and maintained a high performance in a certain range. When the oxygen concentration was too high occurred side reactions, that is, inhibit the oxidation of NO and increase the concentration of NO. The testing results indicated that the experimental system has performance of resistance the SO2and H2O. The NO2concentration was improved greatly in addition of water vapor. The result showed that H2O could promote NTP assisted catalytic oxidation of NO.

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