Dipcoating, carbon monoliths

Table 3 shows the textural characteristics of three carbon monoliths, two of which were produced by dipcoating a cordierite monolith with a solution of sucrose or PFA and one of which was produced by a CVD process resulting in a CNF coating. These are referred to as Cord-SUC, Cord-PFA, and Cord-CNF, respectively. From a texture analysis, it was concluded that the sucrose-derived carbon is highly porous, with pore diameters in a favorable range (t)q5ically, 11 nm). The PFA-derived carbon was microporous and, as a consequence, not suitable for adsorption of large species, such as enzymes. 

Different carbon monoliths were prepared from a sucrose coating [8,43], a polyfurfuryl coating [9], a furan coating [44] via the dipcoating method, and from methane [14,35] via the CVD method over deposited Ni. Ruthenium was loaded on furan-based monoliths by impregnation from [RuCls H20] in diluted hydrochloric acid, and lipase was loaded on the other monoliths by physical adsorption from a phosphate buffer (pH 7). 

Dipcoating a liquid polymer or a solution of a carbon precursor is introduced into the monolith channels by dipcoating, and then it is converted into carbon by heating in an inert atmosphere sometimes, the polymer is preoxidized to induce cross-linking to avoid mobility during heating. 

The most widely applied method is dipcoating (81). The monoliths are dipped in a precursor solution and subsequently dried, carbonized, and (if necessary) activated. Many different carbon precursors have been used, such as saccharides (56,82,83), polyfurfuryl alcohol (84), phenolic resins, and furanic resins (85,86). 

CNF on cordierite monoliths were prepared as reported elsewhere [6]. In brief, first cordierite monoliths were coated with Y-alumina by dipcoating with a sol. Subsequently, Ni was dispersed by ion exchange. Finally, the monolithic catalyst was reduced in a H2 flow at 823 K and CNF growth was carried out at 873 K using C2H6 as the carbon source. 

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