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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of Oxygen Concentration and Promoters on the Performance of Copper Catalysts During Catalytic Reduction of Nitrogen Monoxide

Liu, Kai-Chung 14 September 2001 (has links)
This study utilized Cu-catalysts to catalyze a NO reduction reaction using CH4 as a reductant. Due to CH4 being a weak reductant and is easily affected by O2 concentration, we undertook a series experiments with O2 concentration and promoters, so that we could better understand their influence. The experiment conditions were as follows : reaction temperature between 150¢J- 800¢J¡Fa catalysts weight of 0.5 g¡F total gas flow rate of 1000 ml/min¡Frelative humidity at 0.9 %¡Fan O2 concentration between 0 - 6%¡Fand CH4 concentration between 1000 - 10000 ppm. First, we sorted out the best metal carriers and calcining temperature, from this we decide to use £^-Al2O3 as a carrier with a calcining temperature under 500¢Jto produce our catalysts. During the O2 concentration experiment, when the inflow O2 concentration was below 1% (including 0% O2), Cu-catalysts reduce NO above 550¢J.The conversion reached a rate of 95 % at a temperature of 750¢J¡Fwhen the oxygen concentration was between 3% and 6% O2, catalysts reacted within 300 - 500¢J with NO converting to NO2¡Fat a concentration between 1.5% and 2% O2, NOx underwent reduction at 750¢J,and NOx conversion raised from 0 % to above 90%. Therefore in analyzing the experiment results, it shows that NOx will reduce violently when the O2 concentration is below 0.7% and while using CH4 as a reductant. This result was also apparent in O2 concentrations between 1.5 % and 2%. In the experiments of M/O ratio (the ratio of CH4 and O2 inflow), we found M/O ratio was not a deciding factor within the reaction mechanics, furthermore the limiting factor of O2 concentration decreases under 0.7%¡Fin addition it was also found that adding large amounts of CH4 could quicken the reduction process. Lastly, a mass balance was performed, which had a result over 70 %. In the experiments where Y¡BLa¡BSr¡BCo were added as promoters to the Cu-catalysts, we found that Cu-La/£^-Al2O3¡BCu-Sr/£^-Al2O3 and Cu-Co/£^-Al2O3 can accelerate O2 depletion. Henceforth, it is possible to deduce promoters will be a useful method in solving O2 limiting. In the comparison of metals loading methods, we found no difference in activity using separate-impregnation and co-impregnation methods, whereas in the BET and SEM co-impregnation experiments, there was a larger surface-area and dispersion.

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