Molten carbonate fuel cells using carbon monoxide

In the molten carbonate fuel cell, methane is used as the fuel. This cell runs at high temperatures and uses a molten mixture of lithium and potassium carbonates as electrolyte. In most such cells, the methane is reformed into hydrogen and carbon monoxide before reacting in the cell ... 

Second, molten carbonate fuel cells have electric efficiencies of 47 to 50 percent or more, which significantly reduces their fuel costs for stationary applications compared with both phosphoric acid and pem fuel cells, whose overall efficiency when running on natural gas might not exceed 35 to 40 percent. Third, high temperatures allow relatively inexpensive nickel to be used as a catalyst rather than pricey platinum, which is required by the lower-temperature fuel cells. Fourth, these fuel cells are far more tolerant of carbon monoxide, which can poison the electrochemical reaction of pem... 

Molten carbonate (MCFC). The cell operates at 650°C and uses hydrogen or carbon monoxide as anode fuel, which reacts with carbonate... 

Carbon monoxide, trace metals, and sulfur compounds, such as HjS, COS, mercaptans, and thiophenes, exist in hydrogen produced from coal gasification and used in molten carbonate Hj/Oj fuel cells. In addition, nitrogen compounds from coal, such as HCN and HCNS can be present or they might oxidize to corrosive NO. While carbon monoxide is reactive in these cells, the rest impurities can either poison the Ni anode or they can attack chemically cell and electrodes 249), for example, HjS sulfidizes nickel and stainless steel. HjS could also undergo oxidation to deposit sulfur 250) ... 

From the very outset of molten carbonate fuel cell development, research workers were attracted by the fact that not only hydrogen but also carbon monoxide could be used as a reactant fuel (reducing agent). Carbon monoxide (the so-called water gas, a mixture of CO and H2) is readily obtained by the steam gasification of coal ... 

Molten carbonate fuel cells operate at temperatures around 650 °C and are tolerant to unlimited amounts of carbon monoxide. In most instances mixtures of lithium carbonate and potassium carbonate act as the electrolyte. The electrolyte is suspended in an insulating and chemically inert lithium aluminate ceramic. Nickel or nickel-chromium alloys serve as the anode catalysts, while nickel oxide is used as the cathode catalysts. 

Molten carbonate fuel cells can use hydrogen, carbon monoxide, natural gas, propane, landfill gas, marine diesel, and coal gasification products as the fuel. MCFCs producing 10 kW to 2 MW MCFCs have been tested with a variety of fuels and are primarily targeted to electric utility applications. MCFCs for stationary applications have been successfully demonstrated in several locations throughout the world. 

The electrolyte used by the fuel cell is a solid gas—impermeable zirconia known as zirconium oxide (ZrOj). This ZrOj is doped with calcium oxide (CaO) to supply enough oxide ions to carry the cell current. The oxidant air or oxygen is bubbled through the molten silver cathode, which is held inside the zirconia cup. At the fuel electrode or the carbon-based anode electrode, the oxide ions are combined with carbon monoxide (CO) and give up their electrons to an external circuit. The cell by-products CO and hydrogen, which are formed in the initial fuel decomposition, are burned outside the cell to keep the fuel cell at operating temperature. The hydrogen is not involved in the electrochemical cell reaction. 

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