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Phosphoric Acid Fuel Cells (PAFCs)
Published in Xianguo Li, Principles of Fuel Cells, 2005
The phosphoric acid fuel cell is just one type of the acid-electrolyte fuel cells, therefore, its basic cell structure as well as the half-cell and total-cell overall reaction has already been described in Sections 1.3.2 and 3.2. As the name implies, the PAFC uses the phosphoric acid (H3PO4) as its electrolyte. The phosphoric acid is usually in highly concentrated form (95% or higher, hence in the form of pyrophosphoric acid, or H4P2O7), with a high ionic conductivity of more than 0.6 S/cm. The electrolyte is often immobilized in a porous silicon carbide (SiC) matrix by capillary action. Pure hydrogen or hydrogen-rich gases can be used as fuel and air is almost invariably used as oxidant. Because the acid electrolyte is tolerant to the presence of CO2 in the reactant gas streams, as mentioned earlier, hydrogen produced by steam reforming of organic fuels, such as hydrocarbons (typically natural gas or methane) and alcohols (mainly methanol or ethanol), is often used as the anodic reactant.
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Chemical/Physical. Tetraethyl pyrophosphate is quickly hydrolyzed by water, forming pyrophosphoric acid (NIOSH, 1997). The reported hydrolysis half-life at 25°C and pH 7 is 7.5 h (Ketelaar and Bloksma, 1948; Coates, 1949).
Preparation and properties of ammonium polyphosphate microcapsules for coal spontaneous combustion prevention
Published in International Journal of Coal Preparation and Utilization, 2022
Yan-Ni Zhang, Pan Shu, Jun Deng, Shao-Kang Chen, Xin-Nan Li
Figure 4 shows the TG and DTG curves of APP. According to the law of mass change, the thermal decomposition process of APP in air can be categorized into two stages: at 100–440°C and 440–600°C. In the first stage, the mass begins to decrease at approximately 100°C, and the rate of mass decline is initially relatively moderate. This is possibly because the APP is damp during storage and water is evaporated. The maximum weight loss rate is achieved at 185°C. At this instance, the APP decomposes to produce gaseous ammonia, water vapor, pyrophosphoric acid, and phosphoric acid (Liu, Li, and Yong 2010). With the generation of considerable amounts of gases, the quality of samples rapidly deteriorates; the weight loss at this point is approximately 46%. In the second stage, the main APP chain is broken. Moreover, the products decomposed from the hard shell in the previous stage are further dehydrated and condensed to form phosphorus oxide and water vapor, which could not only dilute the oxygen concentration but also reduce the effective contact area with oxygen. At 600°C, the weight loss is approximately 7%. At this temperature, the TG curve exhibits a downward trend, indicating that the second stage of decomposition reaction has not been completed.
Recycling of spent lithium-iron phosphate batteries: toward closing the loop
Published in Materials and Manufacturing Processes, 2023
Srishti Kumawat, Dalip Singh, Ajay Saini
Acids including phosphoric acid (H3PO4), sulfuric acid (H2SO4), pyrophosphoric acid (H4P2O7), acetic acid (CH3COOH), formic acid (HCOOH), ascorbic acid (C6H8O6), and reducing agents such as H2O2, Na2S2O8 are all needed in considerable quantities for leaching of black mass in hydrometallurgy. It is possible to prioritize the extraction of lithium and accomplish effective metal leaching without the use of reducing agents in the water/acid leaching stage, which bodes well for industrial applications.