Effect of modification method for Ni/MgAl2O4 catalysts in dry reforming of methane
| Autor: | Yang-Lin Lu, 呂彥霖 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 Dry reforming of methane is an attractive route to utilize two types of greenhouse gases (methane and CO2) to produce valuable syngas (H2+CO) that can be further applied in Fischer-Tropsch synthesis for the production of liquid fuels. Dry reforming of methane is a highly endothermic reaction and requires high reaction temperatures to achieve the desired conversion. The use of catalysts could accelerate dry reforming of methane because of the high reaction rate of reactants and the fast yield rate of products. However, catalyst deactivation caused by coke deposition and metal sintering during dry reforming of methane. Methane cracking and Boudouard reactions are the main contributors to the coke deposition on the active sites of catalysts and plug the pores of catalysts during dry reforming of methane reaction. Alumina (Al2O3) is a common material used as a support for catalytic reactions; however, carbon formation occurs on the acidic sites of the alumina. In this study, high purity magnesium aluminate (MgAl2O4) with basic sites, prepared by solution combustion, were used as supports during the preparation of nickel catalysts by the impregnation method. The effects of modification methods (species of metal addition, the amount of metal addition, and the preparation method of metal active phase) on the modification of MgAl2O4-supported Ni catalysts were investigated. The effects of modification methods on the Ni/MgAl2O4 catalysts were characterized by X-ray diffraction(XRD), Brunauer-Emmett-Teller (BET), field-emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), temperature-programmed reduction with H2 (H2-TPR), and Raman spectra analysis. The modifications of 10Ni/MgAl2O4 through the addition of different metals (Ca, Fe, Ce) were used, the 10Ni5Fe/MgAl2O4 catalyst shows higher activity values than 10Ni5Ca/MgAl2O4 and 10Ni5Ce/MgAl2O4 catalysts due to the reduction of Ni oxides with strong interaction with the support and metal particles being well dispersed on the MgAl2O4 supports. The catalytic activity of the Ni-Fe/MgAl2O4 catalysts with different iron loading follows the order 10Ni5Fe/MA7 > 10Ni10Fe/MA7 > 10Ni1Fe/MA7. Fe incorporation into MgAl2O4 supported Ni catalyst significantly stabilized nickel particles during activity test. The catalyst with 5 wt.% of Fe showed the best catalytic activity due to the good dispersion of particles. Experimental results indicated that Ni/MgAl2O4 catalyst which prepared by polyol method and the microwave heated polyol process performed good catalytic activity and stabilization on dry reforming of methane. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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