An Experimental Investigation of the Urea-water Decomposition and Selective Catalytic Reduction (SCR) of Nitric Oxides with Urea Using V2O5-WO3-TiO2 Catalyst
An Experimental Investigation of the Urea-water Decomposition and Selective Catalytic Reduction (SCR) of Nitric Oxides with Urea Using V2O5-WO3-TiO2 Catalyst

Author: Jasmeet Singh Johar

Publisher:

Published: 2005

Total Pages:

ISBN-13:

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Two flow reactor studies, using an electrically heated laminar flow reactor over Vanadia based (V2O5-WO3/TiO2) honeycomb catalyst, were performed at 1 atm pressure and various temperatures. The experiments were conducted using simulated exhaust gas compositions for different exhaust gases. A quartz tube was used in order to establish inert conditions inside the reactor. The experiments utilized a Fourier transform infrared (FTIR) spectrometer in order to perform both qualitative and quantitative analysis of the reaction products. Urea-water solution decomposition was investigated over V2O5-WO3/TiO2 catalyst over the entire SCR temperature range using the temperature controlled flow reactor. The solution was preheated and then injected into pure nitrogen (N2) stream. The decomposition experiments were conducted with a number of oxygen (O2) compositions (0,1, 10, and 15%) over the temperature range of 227°C to 477°C. The study showed ammonia (NH3), carbon-dioxide (CO2) and nitric oxide (NO) as the major products of decomposition along with other products such as nitrous oxide (N2O) and nitrogen dioxide(NO2). The selective catalytic reduction (SCR) of nitric oxide (NO) with urea-water solution over V2O5-WO3/TiO2 catalyst using a laboratory laminar-flow reactor was investigated. Urea-water solution was injected at a temperature higher than the vaporization temperature of water and the flow reactor temperature was varied from 127°C to 477°C. A FTIR spectrometer was used to determine the concentrations of the product species. The major products of SCR reduction were NH3, NO and CO2 along with the presenceof other minor products NO2 and N2O. NO removal of up to 87% was observed. The aim of the urea-water decomposition experiments was to study the decomposition process as close to the SCR configuration as possible. The aim of the SCR experiments was to delineate the effect of various parameters including reaction temperature and O2 concentration on the reduction process. The SCR investigation showed that changing parameter values significantly affected the NO removal, the residual NH3 concentration, the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. In the presence of O2, the reaction temperature for maximum NO reduction was 377°C for [Beta] ratio of 1.0.

Selective Catalytic Reduction of NOx
Selective Catalytic Reduction of NOx

Author: Oliver Kröcher

Publisher: MDPI

Published: 2018-12-14

Total Pages: 281

ISBN-13: 3038973645

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This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NOx" that was published in Catalysts

Selective Catalytic Reduction (SCR) of Nitric Oxide (NO) with Ammonia Over Vanadia-based and Pillared Interlayer Clay-based Catalysts
Selective Catalytic Reduction (SCR) of Nitric Oxide (NO) with Ammonia Over Vanadia-based and Pillared Interlayer Clay-based Catalysts

Author: Hyuk Jin Oh

Publisher:

Published: 2004

Total Pages:

ISBN-13:

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The selective catalytic reduction (SCR) of nitric oxide (NO) with ammonia over vanadia-based (V2O5-WO3/TiO2) and pillared interlayer clay-based (V2O5/Ti-PILC) monolithic honeycomb catalysts using a laboratory laminar-flow reactor was investigated. The experiments used a number of gas compositions to simulate different combustion gases. A Fourier transform infrared (FTIR) spectrometer was used to determine the concentrations of the product species. The major products were nitric oxide (NO), ammonia (NH3), nitrous oxide (N2O), and nitrogen dioxide (NO2). The aim was to delineate the effect of various parameters including reaction temperature, oxygen concentration, NH3-to-NO ratio, space velocity, heating area, catalyst arrangement, and vanadium coating on the removal of nitric oxide. The investigation showed that the change of the parameters significantly affected the removals of NO and NH3 species, the residual NH3 concentration (or NH3 slip), the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. The reaction temperature was increased from the ambient temperature (25°C) to 450°C. For both catalysts, high NO and NH3 removals were obtained in the presence of a small amount of oxygen, but no significant influence was observed from 0.1 to 3.0% O2. An increase in NH3-to-NO ratio increased NO reduction but decreased NH3 conversions. For V2O5-WO3/TiO2, the decrease of space velocity increased NO and NH3 removals and broadened the active temperature window (based on NO> 88% and NH3> 87%) about 50°C. An increase in heating area decreased the reaction temperature of the maximum NO reduction from 350 to 300 ʻC, and caused the active reaction temperature window (between 250 and 400 ʻC) to shift toward 50 ʻC lower reaction temperatures (between 200 and 350°C). The change of catalyst arrangements resulted slight improvement for NO and NH3 removals, therefore, the change might contribute to more gas removals. The catalyst with extra vanadium coating showed higher NO reductions and NH3 conversions than the catalyst without the extra vanadium coating.

Masters Theses in the Pure and Applied Sciences
Masters Theses in the Pure and Applied Sciences

Author: Wade H. Shafer

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 411

ISBN-13: 1461305993

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Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1 957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 32 (thesis year 1987) a total of 12,483 theses titles from 22 Canadian and 176 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 32 reports theses submitted in 1987, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.

Selective Catalytic Reduction (SCR) of Nitric Oxide with Ammonia Using Cu-ZSM-5 and Va-based Honeycomb Monolith Catalysts
Selective Catalytic Reduction (SCR) of Nitric Oxide with Ammonia Using Cu-ZSM-5 and Va-based Honeycomb Monolith Catalysts

Author: Saurabh Gupta

Publisher:

Published: 2003

Total Pages:

ISBN-13:

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In this work, the steady-state performance of zeolite-based (Cu-ZSM-5) and vanadium-based honeycomb monolith catalysts was investigated in the selective catalytic reduction process (SCR) for NO removal using NH3. The aim was to delineate the effect of various parameters including pretreatment of the catalyst sample with H2, NH3-to-NO ratio, inlet oxygen concentration, and space velocity. The concentrations of the species (e.g. NO, NH3, and others) were determined using a Fourier Transform Infrared (FTIR) spectrometer. The temperature was varied from ambient (25 C) to 500 C. The investigation showed that all of the above parameters (except pre-treatment with H2) significantly affected the peak NO reduction, the temperature at which peak NO reduction occurred, and residual ammonia left at higher temperatures (also known as 'NH3 slip'). Depending upon the particular values of the parameters, a peak NO reduction of around 90% was obtained for both the catalysts. However, an accompanied generation of N2O and NO2 species was observed as well, being much higher for the vanadium-based catalyst than for the Cu-ZSM-5 catalyst. For both catalysts, the peak NO reduction decreased with an increase in space velocity, and did not change significantly with an increase in oxygen concentration. The temperatures at which peak NO reduction and complete NH3 removal occurred increased with an increase in space velocity but decreased with an increase in oxygen concentration. The presence of more ammonia at the inlet (i.e. higher NH3-to-NO ratio) improved the peak NO reduction but simultaneously resulted in an increase in residual ammonia. Pretreatment of the catalyst sample with H2 (performed only for the Cu-ZSM-5 catalyst) did not produce any perceivable difference in any of the results for the conditions of these experiments.