Fuel Reforming and CO Removal for Transportable Hydrogen Production Systems

燃料电池是以氢为燃料的高效率设备，因为电池可以直接将化学能转化为电子能量。特别值得一提的是，聚合物电解质燃料电池结构紧凑，便于运输，因此可用于汽车和住宅。在可运输系统中，氢气必须在现场生产。本研究以甲醇和碳氢化合物为原料，采用负载型铜催化剂对甲醇制氢进行了研究。对于低负载量催化剂，催化剂活性严格依赖于载体。以高比表面积的锌铝氧化物为载体的铜催化剂具有较高的催化活性。它们有两种活性部位。一种是高TOF的X射线衍射峰，另一种是低TOF的X射线衍射峰。甲烷的下一步部分氧化反应是在六铝酸混合氧化物负载的镍催化剂上进行的。在800℃时，混合氧化物的还原支持了Ni物种的存在。该催化剂在高温下仍表现出高活性和高稳定性。在少量氧气存在的条件下，对重整甲醇和烃类气体中的CO进行了脱除。氧气促进了CO的脱除，特别是在150℃的低温下，氧对CO的脱除有明显的促进作用。在Ni-YSZ金属陶瓷中添加CaO、SRO和CeO_2降低了结碳速率。CaO的加入抑制了水蒸气重整的失活。含钙Ni-YSZ电极催化剂的性能略低于母体Ni-YSZ，表现出稳定的活性。

Fuel Cells are highly efficiency devices, which use hydrogen as fuel, since the cells can directly convert chemical energy to electronic energy. In particular, polymer electrolyte fuel cells are compact and transportable ; therefore, they can beused in cars and houses. In transportable system, hydrogen must be produced on site. In this study, hydrogen productions form methanol and hydrocarbons were investigated.For hydrogen synthesis from methanol, supported Cu catalyst was used. For low loading catalyst, catalyst activity strictly depended on the support. The Cu catalyst supported on ZnAl_2O_4 with high surface area showed high activity. They had two kinds of active sites. One was an XRD-detectable species which showed high TOF and, the other was an XRD undetectable species which showed low TOF.Next partial oxidation of methane was conducted on Ni catalysts supported on hexaaluninate mixed oxide. Ni species was supported by the reduction of the mixed oxide at 800℃. It showed high activity and high stability even at high temperature range.CO removals from reformed methanol and hydrocarbon gasses were conducted on Cu-Al_2O_3-ZnO catalyst in the presence of small amount of oxygen. Oxygen promoted the CO removal, and enhanced CO removal in particular at low temperature of 150℃.Generation experiment was conducted on solid oxide fuel cell, inside of which methane was reformed with steam. CaO, SrO, and CeO_2 addition to Ni-YSZ cermet reduced the carbon formation rate. Deactivation for steam reforming was suppressed by the CaO addition. Performance of Ca-containing Ni-YSZ for Electrode catalyst was slightly lower than parent Ni-YSZ and showed stable activity.