Poisoning by carbon monoxide

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. 

Solid oxide fuel cellsoperateatvery high temperatures, around 1,000°C. High temperature operation removes the need for precious-metal catalyst, thereby reducing cost. It also allows SOFCs to reform fuels internally, which enables the use of a variety of fuels and reduces the cost associated with adding a reformer to the system. SOFCs are also the most sulphur-resistant fuel cell type they can tolerate several orders of magnitude more sulphur than other cell types. In addition, they are not poisoned by carbon monoxide (CO), which can even be used as fuel. This allows SOFCs to use gases made from coal. 

This type of N-doped soot catalyst is of particular interest for the development of advanced fuel cells. As this type of catalyst is not poisoned by carbon monoxide, it is a promising candidate for O2 cathodes in methanolconsuming fuel cells (132). In methanol-combusting cells, diffusive transport of methanol from the anode to the cathode cannot be avoided, with the consequence that the activity of Pt-activated cathodes becomes severely impaired by CO poisoning of the Pt catalyst therefore, a CO-insensitive cathodic electrocatalyst seems to be indispensible. Yet the longevity of this type of catalyst is still in dispute (133). 

The platinum catalyst used in the oxidation of hydrogen is poisoned by carbon monoxide. 

The high-cost of materials and efficiency limitations that chemical fuel cells currently have is a topic of primaiy concern. For a fuel cell to be effective, strong acidic or alkaline solutions, high temperatures and pressures are needed. Most fuel cells use platinum as catalyst, which is expensive, limited in availability, and easily poisoned by carbon monoxide (CO), a by-product of many hydrogen production reactions in the fuel cell anode chamber. In proton exchange membrane (PEM) fuel cells, the type of fuel used dictates the appropriate type of catalyst needed. Within this context, tolerance to CO is an important issue. It has been shown that the PEM fuel cell performance drops significantly with a CO con-... 

For catalase and peroxidase there is no direct evidence that a valency change of the iron atom occurs except when azide is added to catalase, and peroxidase is acting as an oxidase in the autoxidation of dihydroxy-maleic acid, when both systems can be poisoned by carbon monoxide. The normal absence of such poisoning cannot be taken as proof that the... 

Nitroglycerin is a heavy, colorless, oily liquid, which has a sweet taste and, as ordinarily prepared, a pale yellow color. It freezes at about 8°, melts at about 12°, and explodes when, heated to 180°. Small quantities burn in the open air without explosion. Nitroglycerin is very sensitive to shocks, and can readily be exploded by a sharp blow. It is a powerful poison, resembling strychnine somewhat in its physiological effects. It is used as a remedy in heart disease, and is injected into the blood in cases of poisoning by carbon monoxide or water-gas. 

The platinum-ruthenium combination has been of interest in fuel-cell technology, because ruthenium imparts some resistance to poisoning by carbon monoxide as with platinum-iridium, it is important to see whether joining metals of very different activities in hydrogenolysis creates binary centres having new properties. The few available studies ° ° all confirmed ruthenium s superior activity for hydrogenolysis (except for cyclopentane ) and its inability to do much else under normal circumstances. It does however induce other reactions characteristic of platinum at a temperature (493 K) well below that at which that metal would be active by itself. With Pt/AlaOs,X-ray absorption spectroscopy showed... 

Still another way of fighting hydrogen catalyst poisoning by carbon monoxide impurities is that of raising the operating temperature. 

In fuel cells, well known catalyst is produced from carbon black-supported Pt particles (Pt/C) for hydrogen and oxygen redox reactions which occurs at anode and cathode but conventional Pt/C catalyst has low durability and can be easily poisoned by carbon monoxide. Electrospun Pt/ruthenium, Pt/rhodium, and Pt nanowires have been produced and compared with Pt/C showing better performance in a proton exchange membrane fuel cell (PEMFC). 

Imagining the size or mass of an atom or an electron, or understanding the way they spin or traverse from one point to the next is humanly impossible. However, learning the ways and rules of atoms and molecules is not a pure academic exercise. You need to understand what is a blue color, how does microwave oven heats up your coffee, why is sunset red (and what is red ), or what your cell phone might be doing to your brains. You need to understand why household bleach removes stains or how you can help someone poisoned by carbon monoxide stay alive. You need to know the little molecules and atoms in order to understand the big world around you. 

MGFGs are also able to use carbon oxides as fuel. They are not poisoned by carbon monoxide or carbon dioxide, thus MGFGs are advanced to use gases from coal so that they can be integrated with coal gasification. 

Generally, the membranes need to be protected against rapid temperature and pressure changes and they are subject to poisoning by carbon monoxide, hydrogen... 

Suffocation victims usually look purple, but a person poisoned by carbon monoxide often has rosy cheeks. Explain. 

Hypeil aricoxyM (posiire has been used 10 treat poisoning by carbon monoxide, barbilurales, and cyanide. 

As with the platinum anode catalyst in the PEM fuel cell, the anode of the PAFC may be poisoned by carbon monoxide in the fuel gas. The CO occupies catalyst sites. Such CO is produced by steam reforming and for the PAFC the level that the anode can tolerate is dependent on the temperature of the cell. The higher the temperature, the greater is the tolerance for CO. The absorption of CO on the anode electrocatalyst is reversible and CO will be desorbed if the temperature is raised. Any CO has some effect on the PAFC performance, but the effect is not nearly so important as in Ihe PEMFC. At a working temperature above 190°C, a CO level of up to 1% is acceptable, but some quote a level of 0.5% as the target. The methods used to reduce the CO levels are discussed in the next chapter, especially in Section 8.4.9. 

MFCs use similar configurations as MFCs, with necessary modification due to the requirement for gas collection. The anode is usually made of carbon material for electron transfer and attachment of exoelectrogens. For the cathode, initial studies use a platinum (Pt)-coated material (Liu et al., 2005). However, Pt is expensive and Pt electrodes are easily poisoned by carbon monoxide or sulfur, so researchers started to search for Pt-free electrodes. One study compared Pt and Pt- ree electrodes, and found that once the applied voltage exceeds 700 mV, Pt does not have any additional effects on hydrogen evolution. In recent years, biocathodes have emerged as a promising alternative to Pt cathodes (Rozendal et al., 2008 Jafary et al., 2015). 

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