Carbon, activated Carbonaceous material

Streat M, Malik DJ, Saha B (2004) Adsorption and ion-exchange properties of engineered activated carbons and carbonaceous materials. In SenGupta AK, Marcus Y, Marinsky JA (eds) Ion exchange and solvent extraction, chap 1. Dekker, New York... 

ADSORPTION AND ION-EXCHANGE PROPERTIES OF ENGINEERED ACTIVATED CARBONS AND CARBONACEOUS MATERIALS Michael Streat, Danish J. Malik, and Basudeb Saha... 

Several authors [4-S] have studied the effects of KOH on carbonization of carbonaceous materials. Marsh et al. indicated that the oxygen of alkali could remove cross-linking and stabilizing carbon atoms in crystallites at the activation temperature range of550 - 900 0. After activation reaction, a new structure of the microporosity of the activated carbon was created when potassium salts and carbon atoms fix>m the internal volume of the carbon were removed. Later, Otowa et al. also pointed out that high... 

It is manufactured either by carbonization of carbonaceous materials with simultaneous chemical activation or by gas treatment of already carbonized material (e. g., charcoal). Chemical treatment is carried out at 400-1000 °C with phosphoric acid or zinc chloride and gas activation at 800-1000 °C in the presence of water or carbon dioxide. Several types of kilns and furnaces are in use. A. is available as powder, granules and special shaped products. The absorbent property of a. is used in gas and water purification and in solvent recovery. Well known is its use for decoloration and purification in food, chemical and pharmaceutical industries. 

Adsorption. Adsorption involves the transfer of a component onto a solid surface. An example is the adsorption of organic vapors by activated carbon. Activated carbon is a highly porous form of carbon manufactured from a variety of carbonaceous raw materials such as coal or wood. The adsorbent may need to be... 

The process for the thermal activation of other carbonaceous materials is modified according to the precursor. For example, the production of activated carbon from coconut shell does not require the stages involving briquetting, oxidation, and devolatilization. To obtain a high activity product, however, it is important that the coconut shell is charred slowly prior to activation of the char. In some processes, the precursor or product is acid-washed to obtain a final product with a low ash content (23,25). 

One criterion for the anode material is that the chemical potential of lithium in the anode host should be close to that of lithium metal. Carbonaceous materials are therefore good candidates for replacing metallic lithium because of their low cost, low potential versus lithium, and wonderful cycling performance. Practical cells with LiCoOj and carbon electrodes are now commercially available. Finding the best carbon for the anode material in the lithium-ion battery remains an active research topic. 

Perhaps the first practical application of carbonaceous materials in batteries was demonstrated in 1868 by Georges Le-clanche in cells that bear his name [20]. Coarsely ground MnO, was mixed with an equal volume of retort carbon to form the positive electrode. Carbonaceous powdered materials such as acetylene black and graphite are commonly used to enhance the conductivity of electrodes in alkaline batteries. The particle morphology plays a significant role, particularly when carbon blacks are used in batteries as an electrode additive to enhance the electronic conductivity. One of the most common carbon blacks which is used as an additive to enhance the electronic conductivity of electrodes that contain metal oxides is acetylene black. A detailed discussion on the desirable properties of acetylene black in Leclanche cells is provided by Bregazzi [21], A suitable carbon for this application should have characteristics that include (i) low resistivity in the presence of the electrolyte and active electrode material, (ii) absorption and retention of a significant... 

There are two main varieties of carbon (i) crystalline (e.g., graphite and diamond), and (ii) amorphous. The amorphous variety consists of carbon blacks and charcoals. Carbon blacks are nonporous fine particles of carbon produced by the combustion of gaseous or liquid carbonaceous material (e.g., natural gas, acetylene, oils, resins, tar, etc.) in a limited supply of air. Charcoals are produced by the carbonization of solid carbonaceous material such as coal, wood, nut shells, sugar, synthetic resins, etc. at about 600 °C in the absence of air. The products thus formed have a low porosity, but when activated by air, chlorine, or steam, a highly porous material is produced this porous product is called activated charcoal. Chemically speaking carbon blacks and charcoals are similar, the difference being only in physical aspects. Carbon blacks find use in the rubber industry and in ink manufacture. An important use of charcoals is as adsorbents. 

The isotopic composition of carbon in carbonaceous organic material (kerogen) from ancient sedimentary rocks gives information on whether photosynthetic organisms were present during rock formation or not. It can also provide information on biological activities if cellular structures had already been destroyed. Sulphur can be used in a similar way (Schopf, 1999). 

The character of carbonaceous material s influence on performance of asymmetric EC systems (carbon - NiOx) is more complicated than that of carbon-carbon system. It is determined by the higher operating potential of NiOx electrode, due to which oxidation and volume changes in electrode active mass upon charge-discharge processes are taking place as the reaction of transformation of Ni(OH)2 into NiOOH is occurring. 

The Li-Ion system was developed to eliminate problems of lithium metal deposition. On charge, lithium metal electrodes deposit moss-like or dendrite-like metallic lithium on the surface of the metal anode. Once such metallic lithium is deposited, the battery is vulnerable to internal shorting, which may cause dangerous thermal run away. The use of carbonaceous material as the anode active material can completely prevent such dangerous phenomenon. Carbon materials can intercalate lithium into their structure (up to LiCe). The intercalation reaction is very reversible and the intercalated carbons have a potential about 50mV from the lithium metal potential. As a result, no lithium metal is found in the Li-Ion cell. The electrochemical reactions at the surface insert the lithium atoms formed at the electrode surface directly into the carbon anode matrix (Li insertion). There is no lithium metal, only lithium ions in the cell (this is the reason why Li-Ion batteries are named). Therefore, carbonaceous material is the key material for Li-Ion batteries. Carbonaceous anode materials are the key to their ever-increasing capacity. No other proposed anode material has proven to perform as well. The carbon materials have demonstrated lower initial irreversible capacities, higher cycle-ability and faster mobility of Li in the solid phase. 

The catalytic activation of carbon monoxide is a research area currently receiving major attention from academic, industrial, and government laboratories. There has been a long standing interest in this area however, the new attention obviously is stimulated by concerns with the present and future costs and availability of petroleum as a feedstock for the production of hydrocarbon fuels and of organic chemicals. One logical alternative source to be considered is synthesis gas, mixtures of carbon monoxide and hydrogen that can be produced from coal and other carbonaceous materials. 

This reaction is important in such processes as the decoking of catalysts, the manufacture of activated carbon for adsorption, and the gasification of carbonaceous materials for production of hydrogen or fuel gas. 

In some of the earliest recorded examples of adsorption, activated carbon was used as the adsorbent. Naturally occurring carbonaceous materials such as coal, wood, coconut shells or bones are decomposed in an inert atmosphere at a temperature of about 800 K. Because the product will not be porous, it needs additional treatment or activation to generate a system of fine pores. The carbon may be produced in the activated state by treating the raw material with chemicals, such as zinc chloride or phosphoric acid, before carbonising. Alternatively, the carbon from the carbonising stage may be selectively... 

Carbon blacks are promising electrode materials due to their relatively high activities and long lifetimes in contrast to the lower activity or rapid deactivation of the other carbonaceous materials [16-20]. These catalytic characteristics of carbon blacks are attributed to their microstructure that has many active sites consisting of edges and defects in nanosized graphitic layers [19-21]. 

Novel Manufacturing Processes. Different chemical activation processes have been used to produce carbons with enhanced adsorption characteristics. Activated carbons of exceptionally high surface area (>3000 m2/g) have been produced by the chemical activation of carbonaceous materials with potassium hydroxide (28,29). Activated carbons are also produced commercially in the form of cloths (30), fibers (31), and foams (32) generally by chemical activation of the precursor with a Lewis acid such as aluminum chloride, ferric chloride, or zinc chloride. 

---