| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 107 === Methane direct conversion to methanol or formaldehyde is important for the application of natural gas. Methanol (formaldehyde) is a valuable fuel and is also a raw material for synthesizing various hydrocarbon products. The present production of methanol (formaldehyde) in the industry is a two-step method, involving methane reforming into and methanol synthesis from syngas of which methane reforming. Therefore, methane direct conversion to methanol or formaldehyde is a cost-effective reaction. In this study, Cu/ZSM-5, a commonly used catalyst for the partial oxidation of methane. NaZSM-5, NH4ZSM-5 and HZSM-5, are prepared by ion-exchanged method and tested. Cu/HZSM-5 appears to be the best catalyst, attributable to its highest Cu loading. The total oxidation of methane occurs at low temperature, while the partial oxidation products like CO, H2 and HCHO are observed at high temperature. This is confirmed that from total oxidation participate in the methane conversion via oxidative steam reforming. The ratios of S/M, M/O and WHSV are varied for optimizing the yield of partial oxidation products. The results showed that the yield of partial oxidation products is the highest when M/O = 7 and S/M = 1. In addition, at high WHSV when the conversion is low, only CO2 and H2O are observed, but when the conversion is high the yield of CO, H2, HCHO increase. The last part compares the partial oxidation of methane with different metals (Cu, Fe and Ni) supported on HZSM-5. The results show that Cu/HZSM-5 has the highest yield of CO, H2 and HCHO. The next is Fe/HZSM-5, but only CO2, H2O are observed on Ni/HZSM-5.
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