Sorption and elution of asphaltenes from porous silica surfaces

Adsorption of asphaltene from toluene on silica sorbents of various porosit ies and on montmorillonite pillared with Al2O3 was studied. Asphaltene is a dsorbed on the surface of pillared montmorillonite in relatively large amou nts; however, the extent of adsorption is decreased by preliminary hydropho bization of the surface of the adsorbents. Asphaltene elution experiments w ere carried out in a flow system at high temperature (T = 50, 90 degreesC) and pressure (p = 10, 40, 80 bar). Eluents used were pure toluene and tolue ne containing 2.5, 5.0 or 10% N-methyl-pyrrolidone (1-methyl-2-pyrrolidone) . Elution experiments carried out at high pressure and at various temperatu res show that the desorption of asphaltene from silica gel is strongly depe ndent on pressure and on the concentration of the additive included as a pe ptizator, N-methyl-pyrrolidone. Structural changes in the surface brought a bout by the adsorption and desorption of asphaltene were monitored by N-2-a dsorption, small-angle X-ray diffraction and FT-IR spectroscopy. (C) 2001 E lsevier Science B.V. All rights reserved.