Monolithic Carbon Molecular Sieves from activated bituminous coal impregnated with a slurry of coal tar pitch

A very simple preparation process was designed to successfully prepare monolithic Carbon Molecular Sieves (CMS) from very cheap precursors (an activated carbon (AC), obtained from a low rank coal, and coal tar pitch). This process consists of using a slurry of AC, coal tar pitch and toluene, which permits the monoliths to be moulded at room temperature. The AC/coal tar pitch ratio and the final pyrolysis temperature have been the main parameters analysed. The porosity blockage occurring during preparation of monoliths has been studied based on the results obtained by gas adsorption (i.e. N2 at −196°C and CO2 at 0°C) and thermal analysis. An important aspect of this method is that a previous oxidation step of the binder is not necessary before the carbonisation of the monolith. The obtained results show that the proposed method is effective for the CMS preparation from the selected precursors. In this method, the use of coal tar pitch as binder is adequate since it plays a multiple role: (i) it confers an important mechanical stability to the monoliths and; (ii) it modifies the final porosity of the AC leading to the molecular sieving properties. ► A very simple preparation process to prepare monolithic Carbon Molecular Sieves. ► Previous oxidation step is not necessary before the carbonization of the monolith. ► Coal tar pitch confers mechanical stability and modifies the porosity.