Manufacture of activated carbon

Western Europe has seven manufacturers of activated carbon. The two largest, Norit and Chemviron (a subsidiary of Calgon), account for 70% of West European production capacity, and Ceca accounts for 13% (42). Japan is the third largest producer of activated carbon, having 18 manufacturers, but four companies share over 50% of the total Japanese capacity (43). Six Pacific Rim countries account for the balance of the world production capacity of activated carbon, 90% of which is in the Philippines and Sri Lanka (42). As is the case with other businesses, regional markets for activated carbon products have become international, lea ding to consoHdation of manufacturers. Calgon, Norit, Ceca, and Sutcliffe-Speakman are examples of multinational companies. 

Source references for frequentiy used test procedures for determining properties of activated carbon are shown in Table 4. A primary source is the Jinnual Book ofyimerican Societyfor Testing and Materials (ASTM) Standards (61). Other usehil sources of standards and test procedures include manufacturers of activated carbon products, the American Water Works Association (AWWA) (33,34), and the Department of Defense (54). 

Based upon raw material and intended application, the manufacturing of activated carbon falls into two mam categories thermal activation and chermcal activation. In general, thermal activation involves the heating/gasification of carbon at high ternperamres [13], while chemical activation is characterized by the chermcal dehydration of the raw material at significantly lower temperatures [11,14]. 

Applications of activated carbons are discussed in Chapters 8-10, including their use in the automotive arena as evaporative loss emission traps (Chapter 8), and in vehicle natural gas storage tanks (Chapter 9). The use of evaporative loss emission traps has been federally mandated in the U.S. and Europe. Consequently, a significant effort has been expended to develop a carbon adsorbent properly optimized for evaporative loss control, and to design the on board vapor collection and disposal system. The manufacture of activated carbons, and their preferred characteristics for fuel emissions control are discussed in Chapter 8, along with the essential features of a vehicle evaporative loss emission control system. 

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. 

Coconut-shell-based GACs These have a high portion of micropores and present surface areas generally over 1000 m2/g and apparent densities of about 0.50 g/cm3. Being manufactured mainly from vegetative material, they do not exhibit the fully developed pore structure of coal-based carbons. They are used in both vapor- and liquid-phase applications. Coconut shell-based carbon is slightly more expensive to produce than coal-based GAC, since about only 2% of the raw material is recoverable as GAC, versus 8-9% for coal-based carbons. In Table 4.1, the basic properties of common materials used in the manufacture of activated carbon ate presented. 

Basic properties of common materials used in the manufacture of activated carbon (Dabrowski et al., 2005 Streat el al., 1995)... 

In conclusion, we can assert that the pyrolysis and activation process applied for the manufacture of activated carbons from nutshells resulted in good quality adsorbents. We have demonstrated the influence of both processes on the speed of the benzene adsorption from water solutions. The hypothesis that the effective surface diffusion is the slowest step of the global process was used and the estimation of the effective diffusion coefficient resulted in values ranging between 2 and 6 X 10-10 m /s. 

Activation is the process of enhancing a particular characteristic. Carbon whose adsorption characteristic is enhanced is called activated carbon. The activation techniques used in the manufacture of activated carbons are dependent on the nature and type of raw material available. The activation techniqnes that are principally used by commercial production operations are chemical activation and steam activation. As the name snggests, chemical activation nses chemicals in the process and... 

Although there has been a rapid decline in commercial destructive distillation of wood, manufacture of activated carbon by the pyrolysis of cellulosic materials still constitutes a major commercial operation. Finally, the possibility of developing new processes for production of special chemicals by the pyrolysis of cellulose, or the adaptation of the old process to the economy of developing nations blessed with rich forest resources, cannot be overlooked. Controlled pyrolysis of cellulose and cellulosic materials to provide a totally impermeable carbon and other industrial products is an example of the former possibilities. 

Temperature Carbonisation of the Biomass for Manufacturing of Activated Carbon... 

A wide range of organic products is suitable as feed.stocks for the manufacture of activated carbon. Wood, sawdust, peat, coconut shells and even olive stones are the preferred uncarbonized feedstocks. Of the (already) carbonized feedstocks coal, low temperature lignite coke, charcoal and coke from acid sludges (e.g. from the manufacture of lubricants) are utilized. The properties of activated carbon are very much influenced by the type of feedstock utilized. 

Fig. 5.7-1. Flow Chart for the Manufacture of Activated Carbon from uncarbonized feedstocks by Chemical and Gas-pha.se Activation...

The heating value of a typical biomass is sufficient to produce steam in excess of that required by the activated process if the system has been designed for maximum thermal efficiency. This can be especially important to developing countries who have large supplies of biomass such as rice hulls or coconut shells and who are currently contemplating the manufacture of activated carbon for export or local water treatment. 

The feasibility of using the char generated by tyre pyrolysis as a precursor in the manufacture of activated carbon has been studied by various authors.119,131 Merchant and Petrich131 have obtained carbons with surface areas above 500 m2 g 1 from tyre pyrolysis in batch reactors and subsequent activation of the chars by treatment with superheated steam at temperatures in the range 800-900 °C. Teng et a/.119 have obtained activated carbons with surface areas above 800 m2 g 1 by pyrolysis of tyres up to 900 °C, followed by activation of the resulting chars in C02 at the same temperature. These surface areas are... 

In discussing the manufacture of activated carbon it is important to keep in mind that the term activated carbon comprises a family of substances. None of the mpmtw nf the.family is characterized by a definite structural formula nor can any be separately identified by chemical analysis. Our only basis for differentiating is by adsorptive and catalytic properties. As is well known, carbons from such... 

It is perhaps meaningful that the latest entry in recent years into the manufacture of activated carbon in America developed a type and form of carbon that furnishes a utility not previously available. From this we might deduce that opportunities await new types of carbon. The catch here is that the new types must not only provide new forms of usefulness but also serve a new market of sufficient size to support the undertaking. Few are given the crystal ball for this. 

Pore size distribution is tangible, and it is moreover one of the more controllable properties in the manufacture of activated carbon in fact, some report an ability to tailor-make a desired pore size distribution. No one can gainsay that an understanding of this feature has contributed to the manufacturing art, and if pore diameter were the sole decisive factor in usefulness of carbon the task of the manufacturer would be greatly simplified. 

Agreement is also necessary as to the amount of tolerance to be allowed, and this in turn will depend on the magnitude of the experimental errors inherent in the test procedure, plus provision for deviations in quality that normally occur in the manufacture of activated carbon. For this the manufacturers experience is the best guide in the case of established tests. With new and untried tests, it is well to base specifications on experimental data covering at least a dozen different batches of the grade of carbon selected. 

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