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Study on Hydrogen Production from Steam Reforming of Ethanol on Nickel-Based Catalyst Prepared from FC Structured Precursor

Author: LiuShuo
Tutor: LiYongDan；LinYueSheng
School: Tianjin University
Course: Industrial Catalysis
Keywords: Ethanol Steam reforming Hydrogen Production Nickel-based catalyst Thermodynamics Coprecipitation Reverse Microemulsion
CLC: TQ116.2
Type: PhD thesis
Year: 2008
Downloads: 170
Quote: 0
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Abstract

Currently, the majority of the world's energy comes from fossil fuels. Fossil fuel reserves are limited, and awareness to the oil, gas and coal to provide energy for mankind's time is limited. Relative to fossil fuels, burning hydrogen does not pollute the environment emissions, while based on fuel cell technology, using hydrogen as fuel can constitute an energy system. Therefore hydrogen is considered to be the future energy carrier. Most of the hydrogen produced by steam reforming of fossil fuels. Greenhouse gas emissions from fossil fuels, hydrogen production will cause air pollution. Although there are many different raw materials can be used to produce hydrogen. However, in many of the liquid raw material, ethanol has a lot of advantages, such as renewable and easily transported, biodegradable, low toxicity. Therefore, the the ethanol hydrogen production research has important implications. The use of the Gibbs free energy minimum principle of the steam reforming of ethanol oxidation thermodynamic analysis. The results show that the oxygen added to effectively reduce the reaction of the endothermic. In this paper, the conditions of the system to achieve a self-heating. Found the the autothermal reaction temperature is a function of the molar ratio of the feed H2O/EtOH and O2/EtOH. At 700 K and below can be achieved in broad feed mole ratio, of H2O/EtOH and O2/EtOH autothermal, but under such a low temperature activity of the catalyst is hard to find. 900 K, the system can be achieved in the the certain of H2O/EtOH and O2/EtOH molar ratio within self-heating. 1100 K, lt in O2/EtOH; within 0.9 does not exist can be achieved H2O/EtOH than self-heating. The number of moles of the balance of hydrogen under autothermal conditions in the 900 K maximum, so that the 900 K is considered to be suitable for working conditions. For non self-heating conditions, the emphasis on the 700,900 and 1100 K, H2O/EtOH O2/EtOH respectively in 1.0-10.0,0.0-0.90 conditions the number of moles of hydrogen, methane, carbon monoxide, and carbon balance. Increase hydrogen yield and lower methane yield and to avoid soot formation conditions. Prepared by the Feitknecht compound precursor having a different load of the nickel-based catalyst, the ethanol steam reforming reaction activity, stability and resistance to coking performance. The results showed that the degree of dispersion of the nickel can be controlled by changing the load. Found that the addition of magnesium can change the acidity of the carrier. Best performance when the catalyst composition NiMgAl-0.5 activity, selectivity for hydrogen and Carbon Deposition. No deactivation in the catalyst after 100 hours of reaction, but the surface of the catalyst there is carbon fiber formation, also slightly sintered nickel particles. Successfully prepared using inverse microemulsion method Feitknecht compound precursor, and the precursor obtained after roasting, after applied to the ethanol steam reforming reaction. Coprecipitation and prepared by impregnation with the same amount of metal loading of the catalyst compared to the results show that the catalyst obtained by the reverse microemulsion has a larger surface area, and high nickel dispersity. The catalyst showed the best activity and stability, a small amount of coke. The lanthanum and cerium doped nickel magnesia catalyst was prepared by the the Feitknecht compound precursor starting. Applied to ethanol steam reforming reaction. BET results showed that lanthanum and cerium doped nickel magnesia catalyst specific surface area with respect to the undoped nickel-magnesia catalyst has increased significantly, but the doped amount of lanthanum and cerium optimum value exists. Oxide XRD results indicate that a small portion of the lanthanum into the nickel-magnesium solid solution. While cerium aggregation and distribution of the outer surface. The TPR results lanthanum and cerium doped improve the reducing ability of the catalyst, wherein lanthanum is more obvious. XPS data indicate that in contrast to the catalyst doped with cerium, lanthanum-doped catalyst is reduced to the amount of the zero-valent nickel. After the reaction, the catalyst XRD results indicate that the smallest diameter of the nickel grains in the lanthanum-doped catalyst described Lanthanum better able to inhibit the sintering of the nickel crystallites. The active data showed that lanthanum and cerium doped catalyst to improve the catalytic activity and stability.

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