Catalysis to produce hydrogen

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Copyright: Assanee, Natthakich
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Abstract
The present study is focused on two studies. The kinetics 0: methane steam reforming over a Ni/MgO catalyst at high pressure is reported in the first study. The second study is focused on the steam iron process over promoted Fe-oxide based catalyst using four different reductants; H2, H2 /CO mixture, CH4 and CH4 /C02 mixture. A kinetic study of methane steam reforming over a Ni/MgO catalyst at high pressure was carried out. The kinetic orders of methane and steam at 40 bars and 600 QC were found to be 0.82 and 0.62 respectively. 1~he estimation of energy of activation of the process was found to be 106 KJ/mol. T11e reaction rate data was explained by a Langmuir - Hinshelwood - Hougen - Wastson model. Four differe11t reductants (H2, H2 /CO mixture, CI-4 and CH4 /C02 mixture) , were applied for the study of the steam iron process. A study of the steam iron process using H2 as reductant focused on the first reduction of 4%Cr203 - 96% Fe203 with H2. The first reduction was found to be composed of a two step reduction up to 550 QC. The estimation of energy of activation for the process was found to be 92.4 KJ/mol and 68.2 KJ/mol respectively. The study of the steam iron process using H2 ICO mixture as reductant over 4%Cr203 - 96% Fe2O3 found that FeO was an intermediate for the reduction of Fe203 with H2ICO mixture to Fe metal. The application of methane as reductant for the steam iron process gave the worst results. As a result, NiO was added to Cr203 -Fe203 to increase the activity. Carbon formation on NiO also was found to be a serious problem. In order to minimize carbon formation on NiO, CO2 was introduced in a mix with CI-4 for the oxidation of deposited carbon during the reduction step. Although the introduction of CO2 can suppress carbon formation, the strong oxidation of reduced iron oxide by water formed during the reduction process coupled to the l1igher favorable reaction of the water gas shift reaction adversely affects the complete reduction of iron oxide to iron metal.
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Assanee, Natthakich
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Publication Year
2008
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Thesis
Degree Type
Masters Thesis
UNSW Faculty
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download Assanee-014183560.pdf 8.52 MB Adobe Portable Document Format
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