Phosphoric acid membranes

Currently, there are two major types of PEFC operated at elevated temperatures one with polysulfonic acid (Nafion)-based membranes and the other with polybenzimidazole (PBl)-phosphoric acid-based membranes. For Nafion-type membrane PEFCs with a typical operating temperature of about 110-120°C, already existing models can be readily used. A detailed discussion of these models tcan be found in review articles in the literature [9-12]. This chapter focuses on the HT-PEFC type based on PBl-phosphoric acid membranes, which type can be referred to as a phosphoric acid fuel ceU (PAFC) with a polymer membrane. The classical PAFC... 

Sousa, T., Mamlouk, M., and Scott, K. (2010) An isothermal model of a laboratory intermediate temperature fuel cell using PBI doped phosphoric acid membranes. Chem. Eng. Sci., 65, 2513. 

Overture The Early History of PBI/Phosphoric Acid Membranes... 

Subianto S (2014) Recent advances in polybenzi-midazole/phosphoric acid membranes for high temperature fuel cells. Polym Int 63 1134—1144... 

Modeling polybenzimidazole/phosphoric acid membrane behaviour in a HTPEM fuel cell. In ... 

Thermal and structural transformations of phosphoric acid membranes... 

The pore architecture observed by SEM following heat treatment is shown in Fig. 19. On heating sulphuric acid-derived PAA membranes to 800 °C, the pore shape and size remain virtually unchanged. No overall shrinkage was observed at temperatures up to 1000 °C despite the weight loss and crystallisation processes. The basal face (Fig. 19, right) retains its open pore structure, in contrast to the pore closure observed in phosphoric acid membranes (Fig. 11, right). 

Phospholipids. Phospholipids, components of every cell membrane, are active determinants of membrane permeabiUty. They are sources of energy, components of certain enzyme systems, and involved in Hpid transport in plasma. Because of their polar nature, phosphoUpids can act as emulsifying agents (42). The stmcture of most phosphoUpids resembles that of triglycerides except that one fatty acid radical has been replaced by a radical derived from phosphoric acid and a nitrogen base, eg, choline or serine. 

MEMBRANE EXTRACTION AND SEPARATION OF COPPER(II) FROM PLATINUM(IV) BY DI(2-ETHYLHEXYL)PHOSPHORIC ACID DURING ELECTRODIALYSIS... 

Crystal surface specificity of the potential of zero charge, 152 Current-potential curves for bipolar membranes, 228 of iron dissolution in phosphoric acid,... 

In a simple version of a fuel cell, a fuel such as hydrogen gas is passed over a platinum electrode, oxygen is passed over the other, similar electrode, and the electrolyte is aqueous potassium hydroxide. A porous membrane separates the two electrode compartments. Many varieties of fuel cells are possible, and in some the electrolyte is a solid polymer membrane or a ceramic (see Section 14.22). Three of the most promising fuel cells are the alkali fuel cell, the phosphoric acid fuel cell, and the methanol fuel cell. 

Reforming 573 K Shift-Conversion Phosphoric Acid, 473 K or Proton Exchange Membrane Fuel Cells, 363 K... 

PAFC, phosphoric acid fuei ceii MCFC, moiten carbonate fuei ceii SOFC, soiid oxide fuei ceii PEMFC, proton exchange membrane fuei ceii DMFC, direct methanoi fuei ceii AFC, alkaiine fuel cell. 

The intracellular and plasma membranes have a complex structure. The main components of a membrane are lipids (or phospholipids) and different proteins. Lipids are fatlike substances representing the esters of one di- or trivalent alcohol and two aliphatic fatty acid molecules (with 14 to 24 carbon atoms). In phospholipids, phosphoric acid residues, -0-P0(0 )-O-, are located close to the ester links, -C0-0-. The lipid or phospholipid molecules have the form of a compact polar head (the ester and phosphate groups) and two parallel, long nonpolar tails (the hydrocarbon chains of the fatty acids). The polar head is hydrophihc and readily interacts with water the hydrocarbon tails to the... 

Among cations, potassium, acetylcholine, some cationic surfactants (where the ion-exchanger ion is the / -chlorotetraphenylborate or tetra-phenylborate), calcium (long-chain alkyl esters of phosphoric acid as ion-exchanger ions), among anions, nitrate, perchlorate and tetrafluoro-borate (long-chain tetraalkylammonium cations in the membrane), etc., are determined with this type of ion-selective electrodes. 

There are six different types of fuel cells (Table 1.6) (1) alkaline fuel cell (AFC), (2) direct methanol fuel cell (DMFC), (3) molten carbonate fuel cell (MCFC), (4) phosphoric acid fuel cell (PAFC), (5) proton exchange membrane fuel cell (PEMFC), and (6) the solid oxide fuel cell (SOFC). They all differ in applications, operating temperatures, cost, and efficiency. 

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