Adsorption of native resins on asphaltene particles:: A correlation between adsorption and activity

Adsorption isotherms of two native resins on two different asphaltene surfaces were obtained using the UV spectrophotometric technique. The shape of the curves obtained can be attributed both to multilayer adsorption and to penetration of resins in the microporous structure of the asphaltenes. The relationship between adsorption behavior and activity of the native resins as asphaltene stabilizers indicates that their effectiveness is related to their adsorbed amount on asphaltene particles and also to their capacity to dissolve asphaltenes. The results obtained support a model for asphaltene stabilization where the resins are incorporated into the bulk asphaltenes helping them to diffuse in the solvent. Significant differences in the behavior of native resins and alkylbenzene-derived amphiphiles as asphaltene stabilizers were observed. At the same equilibrium concentration, the adsorbed amount of native resins is lower than the adsorbed amount of amphiphiles. However, the native resins exhibit a higher asphaltene dissolution power than amphiphiles and a comparable effectiveness as asphaltene stabilizers.