Hydrogen Production from Water using Non-Stoichiometric Oxide

使用非化学计量氧化物从水中制氢

• 批准号: 07805071
• 负责人: OMATA Kohji
• 金额: $ 1.28万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07805071/
• 关键词: Hydrodegen Production; Non-Stoichiometric Oxide; Water Decomposition; Oxygen Desorption; Methane; Ethylene; Tin Oxide; K_2NiF_4 Type Mixed Oxide

It is well known that under low oxygen pressure and at high temperature, dioxygen is evolved from some special mixed oxide, such as perovskite type and spinel type, and from oxide of Co, Mn, Pr, Tb. On the other hand some oxide at low oxidation number (metal was excluded in this study) can reduce water to produce dihydrogen. From thermodynamical consideration, oxide of Ce, Nb, V,Ti, Fe and Sn can have such special low oxidation number. If mixed metal consisted from metals of these two groups are synthesized, it is possible that dioxygen is evolved at high temperature and water is reduced at low temperature to produce hydrogen with regenerating the original oxide. Totally water should be decomposed with thermal cycle.In this study variety of oxides were tested by periodic reaction where inert gas (Ar) and water/Ar were alternately supplied for oxygen evolution and re-oxidation, respectively. From Co_3, O_4, PrO_<22>, MnO_2 and mixed oxide containing Fe, Co, Mn, Pr or Ag, dioxygen was ev … More olved in Ar at high temperature. From oxide of Sn or Ce and mixed oxide containing Sn, Ce or Nb, hydrogen was generated in water/Ar atmosphere. The behavior of simple oxide could be predicted from thermodynamical calculation. It is revealed that such calculation is a useful guideline for a search of oxides. Because cerium oxide was assumed to be most suitable site for water reduction among the oxide mentioned above, mixed cerium oxide was mainly surveyed. When it is mixed with Ag or Rh, oxygen was evolved from cerium oxide. However, hydrogen was not produced by the successive water feed.The purpose of this study is to develop a process to produce hydrogen without waste product. If lattice oxygen of oxide is not used for combustion but is used to produce useful chemicals, usage of a reducing agent doesn't degrade the merit of this process. In this study methane was used for the reducing agent to produce ethylene by partial oxidation. From the thermodynamical calculation only oxide of Sn or Fe can produce ethylene from methane and can reduce water in normal reaction temperature range. The latter showed high activity for methane oxidation but selectivity was quite low. Tin oxide showed high selectivity when it was mixed with alkaline earth metal oxide. Especially K_2NiF_4 type oxide showed high activity for C2 hydrocarbon production. Preparation procedure and additives were investigated and the activity was successfully increased without deterioration of selectivity. Less

众所周知，在低氧气压力和高温下，二氧化物是从一些特殊的混合氧化物（例如钙钛矿类型和尖晶石）中进化而来的，以及CO，MN，MN，PR，TB的氧化物。另一方面，一些在低氧化物数（本研究中排除了金属）的氧化物可以减少产生二氢的水。从热力学考虑，CE，NB，V，Ti，Fe和SN的氧化物可以具有如此特殊的低氧化物数。如果将这两组的金属组成的混合金属合成，则可能在高温下进化二氧化物，并在低温下降低水，以产生氢，并带有原始氧化物的再生。在这项研究中，应通过周期性反应测试各种氧化物，在这项研究中，惰性气体（AR）和水/AR分别用于氧气进化和再氧化。从co_3，o_4，pro_ <22>，mno_2和含有Fe，Co，Mn，Pro或Ag的混合氧化物，二恶英在高温下在AR中更加元素。从SN或CE的氧化物以及含有SN，CE或NB的混合氧化物中，在水/AR大气中产生氢。可以通过热力学计算来预测简单氧化物的行为。据表明，这种计算是搜索氧化物的有用指南。由于认为氧化铜是上述氧化物中最适合减少水的部位，因此主要调查了氧化含量。当它与Ag或Rh混合时，氧气从氧化岩岩中进化出来。但是，氢不是由成功的水饲料产生的。本研究的目的是开发一个没有废物的氢的过程。如果不使用氧化物的格子氧，而是用于生产有用的化学物质，则还原剂的使用不会降低该过程的优点。在这项研究中，甲烷用于还原剂通过部分氧化产生乙烯。从热力学计算中，只有SN或Fe的氧化物可以从甲烷中产生乙烯，并可以减少正常反应温度范围内的水。后来的甲烷氧化活性很高，但选择性很低。当氧化锡与碱性土金属氧化物混合时，氧化锡的选择性很高。特别是K_2NIF_4型氧化物对C2碳氢化合物产生的活性很高。研究了制备程序和添加剂，并成功增加了活性，而无需延迟选择性。较少的

项目成果

K.Omata: "Methane-water redox reaction on A_2SnO_4 (A=Mg, Ca, Sr, Ba) oxide to produce C2 hydrocarbons" Catalysis Letters. 45. 245-248 (1997)

K.Omata：“A_2SnO_4（A=Mg、Ca、Sr、Ba）氧化物上的甲烷-水氧化还原反应生成 C2 碳氢化合物”催化快报。