Al-MCM-41 modified with carbonaceous deposits: characterisation by nitrogen adsorption measurements

Aluminosilicate MCM-41 samples in the as-prepared form and modified by depo sition of carbonaceous compounds formed during conversion of cyclohexene we re investigated by nitrogen adsorption. The amount of the deposits decrease s with the reaction temperature and increases with the quantity of aluminiu m incorporated into the materials. The formation of coke occurs primarily i n the aluminium-rich pores. The modification leads to a lowering of adsorpt ion capacity, surface area, pore volume and relative pressure corresponding to the adsorption isotherm step that reflects the capillary condensation. The nitrogen adsorption measurements appeared to be a useful tool for chara cterisation of structural and surface properties of both the original and t he novel surface-modified porous materials.