| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 97 === In this study, simple method for confined synthesis of NiO nanoparticles in the pore channels of SBA-15 has been developed by the modified hydrophobic encapsulation route. The developed route greatly shortens the process time which longer time is required for the hydrophobic encapsulation route. Further, the fact of blockage-free nature in the pore channels with the confined small NiO nanoparticles is almost identical to that obtained from the original hydrophobic encapsulation route.The formed NiO nanoparticles are highly uniform and well distributed in the confined space without blocking the pore channels until 20 wt% of Ni loading. The average grain size of NiO slightly increases from 1.54 nm (5 wt%) to 2.51 nm (20 wt%)).
After reduction, the synthesized NiO/SBA15 shows excellent ability to steam reforming of ethanol reaction (SRE) for hydrogen production. It shows that Ni10/SBA-15 possesses the best catalytic performance: with 0.1 g of Ni10/SBA-15 and 9.6 h-1 of WHSV, 100 % ethanol conversion is achieved at 500 oC with H2 selectivity of 86.4 % and CO2 selectivity of 46.3 %.
To further improve the hydrogen production efficiency, the role of Cu is studied with NiCu/SBA15 catalysts. To avoid the possible blockage, Ni5/SBA15 (5 wt% Ni) is employed for modification of Cu. It is found that incorporation of Cu improves the dispersity of Ni. It should be noticed that addition of Cu seems to weaken the interaction between Ni and SiO2. Among the NiCu/SBA-15 catalysts, NiCu55/SBA15 shows the best catalytic performance on SRE: with 0.1 g of NiCu55/SBA15 and 9.6 h-1 of WHSV, 100 % conversion of ethanol is achieved at 500 oC with 71.8 % of H2 selectivity, 56.8% of CO2 selectivity, 8.6% of CO selectivity and 34% of CH4 selectivity. Coking rate can also be hindered with addition of Cu. (Ni5/SBA15:1.14 mol C/unit time; NiCu55/SBA15: 0.192 mol C/unit time)
In order to promote the efficiency of hydrogen production and inhibitation of coke formation resistance, CeO2 is further incorporated since the lattice oxygen can be stored and released from CeO2. It is found that coking problem can be effectively solved by CeO2. SRE can be improved as well. With 10 wt% of CeO2 (NiCu55/ CeO2-10/ SBA15), the highest catalytic activity is shown. (100% conversion of ethanol at 600 oC, 100% of H2 selectivity, 61.4% of CO2, 24% of CO, 5.8% of CH4)
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