Modification of activated carbon porosity by pyrolysis under pressure of organic compounds
- PDF / 510,884 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 5 Downloads / 215 Views
Modification of activated carbon porosity by pyrolysis under pressure of organic compounds Juan Alcañiz-Monge · M. José Illán-Gómez
Received: 14 September 2006 / Revised: 31 July 2007 / Accepted: 17 September 2007 / Published online: 5 October 2007 © Springer Science+Business Media, LLC 2007
Abstract Co-pyrolysis at relatively low temperature (673 K) and high pressure (10 MPa), using three organic compounds, was used to modify the porosity of the two ACs. The co-pyrolysis is effective for the modification of the porosity of an AC, and the efficiency depends on the organic compound used. The differences found are consequence of the chemical composition of the organic precursor. High pressure pyrolysis produces beneficial results when an organic compound that volatilizes during the preparation is used. Conducting pyrolysis at low temperature permits improved control of the porosity because the rate of gasification can be more tightly controlled. Keywords Activated carbon · Microporosity
1 Introduction Activated carbons (ACs) are porous solids with interesting properties such as high thermal stability, high hydrophobic character and high chemical resistance. One of the most relevant characteristics of these materials is its versatile pore size distribution (Bansal et al. 1988). The pore size distribution is a function of several parameters, of which the most relevant are: the carbon precursor (Foley 1995), the pretreatment and carbonization process (Mackay and Roberts 1982; Vyas et al. 1993), and the activation process (LozanoCastelló et al. 2002; Patrick and Arnold 1995). In general, all materials that after pyrolysis yielding a high carbon J. Alcañiz-Monge () · M.J. Illán-Gómez Departamento de Química Inorgánica, Universidad de Alicante, Apto 99, Alicante 03080, Spain e-mail: [email protected]
content carbonized could be used as ACs precursor. Thus, coals, pitches, agricultural by-products, polymeric materials (phenol-formaldehyde resins, PAN, PVC), tires, sucrose, etc. have been used as ACs precursor, being coals and agricultural by-products the most widely used by industry. Usually, the ACs obtained from these precursors show a high pore volume but, also, a wide pore size distribution (containing micropores, meso and macropores). In order to obtain ACs with a narrow pore size distribution, different post-treatments have been developed (Armor 1991; Cabrera et al. 1993; Chihara and Suzuki 1979; David et al. 2004; Freitas and Figueiredo 2001; Hu and Vansant 1995; Jüntgen et al. 1981; Kawabuchi et al. 1998; Miura et al. 1991; Mochida et al. 1995; Moreira et al. 2001; Orfanoudaki et al. 2003; Prasetyo and Do 1999; Toda et al. 1972; Verma and Walker 1990, 1992; Verma 1991; Walker et al. 1966): heat treatment, carbon deposition—from gas or from pyrolysis of impregnated organic substances—, controlled gasification and plasma. However, most of these methods need microporous materials with low meso and macroporosity (Armor 1991; Verma 1991) as precursors. In the industry, the most used method is the carbon deposition during
Data Loading...
