The Study On Ni/Ce-M-O (M=Zr Or Ti) For Partial Oxidation Of Methane

Partial oxidation of methane is an important process in the use of natural gas. The catalyst is the most important factor. Ni-based catalysts show many advantages such high activity and low cost. However, stability is so poor as the result of carbon deposition. Ce-Ti and Ce-Zr mixed oxide as support are studied in this paper. We explored new access to prepare Ni-based catalyst with high stability for methane partial oxidation. The NiO/Ce-Zr-O catalysts were prepared by modified citrate route and the results are compared with catalysts made by co-precipitation-impregnation route. Different precipitator and cerium resources are used in the preparation by two ways. In the process of preparation, many factors were studied such as the addition of H₂O₂ or K2O, kind of cerium resources, different ways of preparation, the content of active component, impregnation processes, the molar ratio of Ce/Ti, and the calcination temperature in order to know the effect of these factors on the structure of Ce-Ti mixed oxides for methane patial oxidation. XRD, N2-BET adsorption and TPR have been used to investigate the structure, surface area and reduction behavior of the samples. The main results are as follows: (1) For NiO/Ce_0.5Zr_0.5O₂: get better result by citric method way than by co-precipitation and impregnation method. (2) The catalyst performance of NiO/Ce-Ti-O by co-precipitation and impregnation method is better than that of NiO/TiO₂ by same method. The level of addition of CeO₂ is less than 0.5 to 0.5 of cerium and titanium whose best rate is 0.15 to 0.85. (3) The catalyst performance of NiO/Ce-Ti-O by citric method is better than those of NiO/TiO₂ by the same method. The best rate of CeO₂ and TiO₂ is 0.5 to 0.5. (4) To add CeO₂ elevates the catalyst nature, anti carbon deposit, and stabilities. The CeO₂ and TiO₂ can be into solid solution with certain kind. (5) The result of XRD indicates that NiO reacts more easily with Anatase TiO₂ than with Rutile TiO₂. The addition of CeO₂ improves the distribution of TiO₂ and NiO, block the reaction between NiO and TiO₂. (6) The result of TPR and XRD indicates that NiO appeared on the surface of catalyst with the addition of CeO2 .In addition, NiO distributed well finely and interacted with support.