| dc.description.abstract | CH4 reforming of CO2 reaction could transform the greenhouse gas (CH4 and CO2) to synthesis gas (CO and H2). The synthesis gas could be used to produce methanol, liquid fuel and so on. To enhance the activity and stability of the LaNiO3 catalyst used in this reforming reaction, the catalyst was substituted by Ce and Cu elements. The activities of LaNiO3, La1-xCexNiO3 and La0.9Ce0.1Ni1-yCuyO3 for CO2/CH4 reforming are then experimentally compared.
The results show that conversions of CH4 and CO2 over LaNiO3 catalyst are 95% and 93%, and the selectivites of H2 and CO achieved are 57% and 49%, respectively, at 800 oC. La of LaNiO3 catalyst was partially substituted by Ce to form La1-xCexNiO3 (x = 0.1) catalyst, the conversions of CH4 and CO2 are both also more than 90%, which are not much different from LaNiO3 catalysts, however, the selectivity of H2 is increased to 62%. Ni of LaNiO3 catalyst was partially substituted by Cu to form La0.9Ce0.1Ni1-yCuyO3 (y ≤ 0.5) catalyst. The conversions of CH4 and CO2 and the selectivities of H2 are not much different from LaNiO3 and La1-xCexNiO3 catalysts, however, the selectivity of CO increases slightly with increasing Cu (y = 0.1, 0.3, 0.5). The selectivities of CO with three catalysts (y = 0.1, 0.3, 0.5) are 49%, 50%, 51%, respectively, at 800 oC.
The H2-TPR result shows that La1-xCexNiO3 (x = 0.1) catalyst provides the lattice oxygen vacancies, which activate C-H bond, and increase the selectivity of H2. The H2-TPR result also confirms that Cu metals are of the capability for storage and provision of the oxygen and can be reduced easily, experimental results also prove the good activity of La0.9Ce0.1Ni1-yCuyO3 (y ≤ 0. 5) catalyst. The oxygen atoms of La0.9Ce0.1Ni1-yCuyO not only activate C-H bond but also react with carbon which form on catalyst surface to form CO. Therefore, La0.9Ce0.1Ni0.7Cu0.3O3 catalyst has the best stability and the reaction time can be extended up to 84 hours. Additionally, the ESCA results show that adding Ce or Cu into LaNiO3 catalyst is beneficial to suppress carbon deposition. | en_US |