Fuel cell carbon monoxide

The ideal performance of a fuel cell depends on the electrochemical reactions that occur with different fuels and oxygen as summarized in Table 2-1. Low-temperature fuel cells (PEFC, AFC, and PAFC) require noble metal electrocatalysts to achieve practical reaction rates at the anode and cathode, and H2 is the only acceptable fuel. With high-temperature fuel cells (MCFC, ITSOFC, and SOFC), the requirements for catalysis are relaxed, and the number of potential fuels expands. Carbon monoxide "poisons" a noble metal anode catalyst such as platinum (Pt) in low-temperature... 

Nuvera will design, build, test, and deliver a 15 kilowatt electrical (kWe ) direct current (DC) fuel cell power module that will be specifically designed for stationary power operation using ethanol as a primary fuel. Two PEM fuel cell stacks in parallel will produce 250 amps and 60 volts at rated power. The power module will consist of a fuel processor, carbon monoxide (CO) clean-up, fuel cell, air, fuel, water, and anode exhaust gas management subsystems. A state-of-the-art control system will interface with the power system controller and will control the fuel cell power module under start-up, steady-state, transient, and shutdown operation. Temperature, pressure, and flow sensors will be incorporated in the power module to monitor and control the key system variables under these various operating modes. The power module subsystem will be tested at Nuvera and subsequently be delivered to the Williams Bio-Energy Pekin, Illinois site. 

Some of the high-temperature fuel cells described in Chapter 7 can use this carbon monoxide as a fuel. However, fuel cells using platinum as a catalyst most certainly cannot. Even very small amounts of carbon monoxide have a very great effect on the anode. If a reformed hydrocarbon is to be used as a fuel, the carbon monoxide must be shifted to carbon dioxide using more steam... 

The desulfurized natural gas is mixed with the recycled depleted fuel stream containing steam formed in the fuel cell. About 75 percent of the methane is converted to hvdrogen and carbon monoxide in the prereformer. The hvdrogen-rich fuel is then passed over the fuel cell anode, where 85 percent is converted to electricity. The balance is burned with depleted air in the combustion zone. 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

One leading prototype of a high-temperature fuel cell is the solid oxide fuel cell, or SOFC. The basic principle of the SOFC, like the PEM, is to use an electrolyte layer with high ionic conductivity but very small electronic conductivity. Figure B shows a schematic illustration of a SOFC fuel cell using carbon monoxide as fuel. 

Sol-gel technique has also been applied to modify the anode/electrolyte interface for SOFC running on hydrocarbon fuel [16]. ANiA SZ cermet anode was modified by coating with SDC sol within the pores of the anode. The surface modification of Ni/YSZ anode resulted in an increase of structural stability and enlargement of the TPB area, which can serve as a catalytic reaction site for oxidation of carbon or carbon monoxide. Consequently, the SDC coating on the pores of anode leads to higher stability of the cell in long-term operation due to the reduction of carbon deposition and nickel sintering. 

Methanol can be considered as a hydrogen carrier in a fuel cell. Conventionally, methanol has been reformed/shift converted to produce hydrogen. A low concentration of carbon monoxide formed during this process leads to a strong poisoning of the anode, and even after cleaning of the... 

This reaction serves for removal of carbon monoxide from gas mixtures and is usually carried out over supported metal catalysts. In reforming techniques, carbon monoxide, poisonous for the catalyst in fuel cells, is removed in such a way. It is also applied in automobiles for reducing the exhaust gas carbon monoxide to an environmentally acceptable level. 

Formates and carbon monoxide are products of a shallow reduction of carbon dioxide (two electrons per one CO2 molecule). In the last few years, much attention has been paid the problem of obtaining products of deeper reduction (e.g., methanol or methane) which may be used as fuels in engines or in fuel cells. 

The Pt-Rn catalysts have another important property. In contrast to pure platinum, they are almost insensitive to poisoning by carbon monoxide CO. They can be used, therefore, in the hydrogen electrodes of hydrogen-oxygen fuel cells operated with technical hydrogen containing marked amonnts of CO. 

PEMFC)/direct methanol fuel cell (DMFC) cathode limit the available sites for reduction of molecular oxygen. Alternatively, at the anode of a PEMFC or DMFC, the oxidation of water is necessary to produce hydroxyl or oxygen species that participate in oxidation of strongly bound carbon monoxide species. Taylor and co-workers [Taylor et ah, 2007b] have recently reported on a systematic study that examined the potential dependence of water redox reactions over a series of different metal electrode surfaces. For comparison purposes, we will start with a brief discussion of electronic structure studies of water activity with consideration of UHV model systems. 

However, the Pt anode is seriously poisoned by trace amounts of carbon monoxide in reformates (fuel gas reformed from hydrocarbon), because CO molecules strongly adsorb on the active sites and block the HOR [Lemons, 1990 Igarashi et ah, 1993]. Therefore, extensive efforts have been made to develop CO-tolerant anode catalysts and cell operating strategies to suppress CO poisoning, such as anode air-bleeding or pulsed discharging. 

Rice C, Tong YY, Oldfield E, Wieckowski A, Hahn F, Gloaguen F, Leger J-M, Lamy C. 2000. In situ infrared study of carbon monoxide adsorbed onto commercial fuel-cell-grade carbon-supported platinum nanoparticles correlation with C NMR results. J Phys Chem B 104 5803-5807. 

Carbon Monoxide. Carbon monoxide, a fuel in high-temperature cells (MCFC and SOFC), is preferentially absorbed on noble metal catalysts that are used in low-temperature cells (PAFC and PEFC) in proportion to the hydrogen-to-CO partial pressure ratio. A particular level of carbon monoxide yields a stable performance loss. The coverage percentage is a function of temperature, and that is the sole difference between PEFC and PAFC. PEFC cell limits are < 50 ppm into the anode major U.S. PAFC manufacturers set tolerant limits as < 1.0% into the anode MCFC cell limits for CO and H20 shift to H2 and C02 in the cell as the H2 is consumed by the cell reaction due to a favorable temperature level and catalyst. 

Phosphoric acid-based systems, for cellulosics, 11 488 Phosphoric acid esters, 24 159 Phosphoric acid fuel cells (PAFC), 13 858— 860 12 203-204, 216-219 19 626 effects of carbon monoxide and sulfur in, 12 219... 

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