摘要:
Disclosed herein are embodiments of a patterned electrode comprising regions of catalyst and segregating regions that separate the regions of catalyst. The segregating regions may be regions of non-catalytic material. The catalyst regions may correspond to the channels of a flow field. The electrode provides improved fuel cell performance, particularly at high current densities. The electrode may be for all suitable applications, such as in a membrane electrode assembly and/or a fuel cell. Also disclosed is a method for making the patterned electrode. The method may comprise using masks to apply the catalyst and non-catalyst material to a substrate.
摘要:
There is provided a method and apparatus for treatment of a hydrogen-rich gas to reduce the carbon monoxide content thereof by reacting the carbon monoxide in the gas with an amount of oxygen sufficient to oxidize at least a portion of the carbon monoxide in the presence of a catalyst in a desired temperature range without substantial reaction of hydrogen. The catalyst is an iridium-based catalyst dispersed on, and supported on, a carrier. In the presence of the catalyst, carbon monoxide in a hydrogen-rich feed gas is selectively oxidized such that a product stream is produced with a very low carbon monoxide content.
摘要:
A preferential oxidation reactor is provided including a plurality of reactor sections. The reactor sections are individually optimized for operating at a preferred reaction temperature. In one embodiment, each reactor subsection includes a respective coolant flow for manipulating the operating temperature of the respective subsection. In another embodiment, a first section includes a lower temperature catalyst substrate, a second reactor section includes a higher temperature (i.e. normal) catalyst substrate and a third reactor section includes a lower temperature catalyst substrate. Yet another embodiment includes modifying the catalyst substrates of the respective subsections through the inclusion of promoters. Still another embodiment includes varying a density of the catalyst substrate across the reactor sections. Each of the embodiments enable quick light-off of the reactor, while limiting a reverse water-gas shift reaction.
摘要:
In one aspect, the present invention provides a method for operating a fuel cell system. The system comprises a reactor having one or more catalytic beds and is fed a hydrocarbon fuel along with air and steam. Where more than one catalytic bed is present, such catalytic beds are preferably arranged sequentially such that the outlet from one bed enters the inlet of the next bed. The catalytic beds are the regions where reactions among the hydrocarbon, air, and steam are catalyzed within the reactor. The method comprises supplying a stream of a fuel and air mixture to the reactor which is lean. The mixture is lean in that it has an excess amount of oxygen relative to the stoichiometric amount required for reaction with the fuel. The reactions occurring with the lean mixture heat the reactor. When there is more than one catalytic bed, the hot gases generated from one catalytic bed can be used to heat other catalytic beds. After sufficient heating of the reactor by the lean mixture, a fuel-rich stream is fed to the reactor. This fuel-rich mixture comprises fuel, air, and water in the form of steam. The mixture is rich in that fuel is fed in an excess amount relative to the amount of oxygen for a stoichiometric reaction. The reactions of the fuel-rich stream produce a product comprising hydrogen (H2).
摘要:
A compact autothermal (partial oxidation and steam reforming) fuel reactor is provided for implementation with a fuel cell system. The reactor includes a premixing chamber for premixing a volume of air, steam and fuel into an effluent, a thermal POX reactor, a first stage reforming segment, a post-premix chamber, and a second stage reforming segment. Further provided are a water/fuel vaporizer for supplying steam and fuel as a gas to the premix chamber and an airflow cavity disposed about the reactor for pre-heating air supplied to the premix chamber. The thermal POX segment operates during an initial start-up period for pre-heating the other components of the reactor. Once the other components achieve an operation temperature, the first and second stage reforming segments catalytically reform the effluent. The premix and post-premix chambers enable variance in the O/C and S/C ratios to be achieved as the effluent is reformed through the multiple stages.