Molten carbonate fuel cells catalysts

Molten carbonate fuel cells (MCFCs) are currently being developed for natural gas and coal-based power plants for electrical utility, industrial, and military applications. MCFCs are high-temperature fuel cells that use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic lithium aluminium oxide (LiAI02) matrix. Since they operate at extremely high temperatures of 650°C and above, non-precious metals can be used as catalysts at the anode and cathode, reducing costs. 

Molten carbonate fuel cell (MCFC)—Carbonate electrolyte with conventional metal catalyst. It can use coal gas and natural gas fuel, and is suited for 10 kW to 2 mW power plants. 

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... 

Deactivation Of Steam Reforming Catalysts For Molten Carbonate Fuel Cell Applications... 

The internal reforming molten carbonate fuel cell has a particular construction. In the anode chamber there is a catalyst for the reforming reaction of natural... 

Other fuels were also tried in the early stages of fuel cell development. Coal, the major fuel at that time, was considered as a candidate. Attempts to replace hydrogen with coal resulted in the invention of alkaline fuel cells (AFCs) and molten carbonate fuel cells (MCFCs). Mond used reformate gas from coal, which contained abundant hydrogen, as the fuel, with the intention of scaling up Grove s fuel cell to produce electric power. However, impurities poisoned the catalyst and made Mond s design impractical. 

Parmaliana, A. Frusteri, F. Tsiakaras, P. Giordano, N. Out of the cell performance of reforming catalysts for direct molten carbonate fuel cells (DMCFC). In Advances in Hydrogen Energy 5, 6th World Hydrogen Energy Conference, 1986 Vol. 3, 1252-1258. 

Electrochemical applications of a-BN include its use as carrier material for catalysts in fuel cells [297], as a constituent of electrodes in molten salt fuel cells [298, 299], as anticracking particles in the electrolyte for molten carbonate fuel cells [300, 301], and in seals for insulating terminals of Li/FeS batteries from the structural case [302], A BN-coated membrane is used in an electrolysis cell for the manufacture of high-purity rare earth metals from salt melts [381]. A porous boron nitride layer is applied to the upper outer surface of the electrolyte tube in sodium-sulfur batteries [303], and ceramic boron nitride separators are used in liquid fuel cells and batteries [304, 305]. Boron nitride powder may be included in the electrolyte of electrolytic capacitors for high-frequency utilization [306]. 

Heidebrecht, P. and Sundmacher, K. (2005) Optimization of reforming catalyst distribution in a cross-flow molten carbonate fuel cell with direct internal reforming. Ind. Eng. Chem. Res., 44 (10), 3522-3528. 

Fuel cells do not use a solid material to store their charge. Instead, low-temperature proton exchange membrane fuel cells use gases such as hydrogen and liquid ethanol (the same form of alcohol found in vodka) or methanol as fuels. These materials are pumped over the surface of the fuel cells, and in the presence of noble-metal catalysts, the protons in these fuels are broken away from the fuel molecule and transported through the electrolyte membrane to form water and heat in the presence of air. The liberated electrons can, just as in the case of batteries, be used to drive an electric motor. Other types of fuel cells, such as molten carbonate fuel cells and solid oxide fuel cells, can use fuels such as carbon in the form of coal, soot, or old rubber tires and operate at 800 degrees Celsius with a very high efficiency. 

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. 

Autothermal or steam reforming of methane was considered in thermodynamic calculations by Cavallaro and Freni for reformers, which were integrated into a molten carbonate fuel cell [43]. Direct or indirect internal reforming is possible within the molten carbonate fuel cell. The reforming may be performed either by the anode itself or by a dedicated catalyst in the anode compartment in analogy with the solid oxide fuel cell, as has been explained above. Direct reforming of alcohol fuels is also possible in molten carbonate fuel cells [44], whereas processing of liquid hydrocarbons requires a pre-reformer. 

Aicher et al. [72] developed an autothermal reformer for diesel fuel dedicated to supplying a molten carbonate fuel cell system from Ansaldo Fuel Cells S.p.A., Italy. The diesel fuel (which contained less than 10 ppm sulfur for the pilot plant application) was injected into the steam and air flows, which were pre-heated by a diesel burner to 3 50 °C. The reactor itself was operated at 4 bar, a S/C ratio of 1.5 and high O/C ratio of 0.98, which makes the reactor into a steam supported partial oxidation device. Consequently, the dry hydrogen content of the reformate was rather low with less than 35 vol.%. The operating temperature of the honeycomb had to be kept well above 800 °C to prevent coke formation and the presence of light hydrocarbons such as ethylene and propylene in the reformate. The reactor was operated for 300 h, which led to a slight deterioration in the catalyst performance. 

Zhang J, Zhang X, Liu W, Liu H, Qiu J, Yeung KL (2014) A new alkaU-resistant Ni/A1203-MSU-1 core-shell catalyst for methane steam reforming in a direct internal reforming molten carbonate fuel cell. J Power Sources 246 74—83... 

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