UNIVERSAL BEHAVIOR OF ASPHALTENE AGGREGATION IN HYDROCARBON SOLUTIONS

• Published in: Petroleum science and technology 1998-03, Vol.16 (3-4), p.395-414
• Main Authors: YUDIN, I. K., NIKOLAENKO, G. L., GORODETSKII, E. E., MARKHASHOV, E. L., FROT, D., BRIOLANT, Y., AGAYAN, V. A., ANISIMOV, M. A.
• Format: Article
• Language: English
• ISSN: 1091-6466; 1532-2459
• DOI: 10.1080/10916469808949790

We have investigated the aggregation kinetics of asphaltenes of different origin and of different vanadium content in toluene+ n-heptane mixtures by dynamic light scattering (photon-correlation spectroscopy) adapted to opaque fluids. Two types of aggregation kinetics have been observed: diffusion-limited aggregation (DLA) and reaction-limited aggregation (RLA) Colloidal properties of asphaltenes have heen found to depend on the content of vanadium. At asphaltene concentrations in toluene below the critical micelle concentration of about 3 g L −1 the aggregation kinetics observed appears to be solely limited by diffusion. Far above the critical micelle concentration, the reaction-limited aggregation takes place at least in the initial stage of particle growth. At a concentration of asphaltenes in toluene slightly above the critical micelleconcentration, a crossover between the two types of aggregation kinetics occurs.Besides, the type of the aggregation kinetics was also found to depend on the vanadium content in asphaltenes. We propose a simple theoretical expression for the crossover kinetics and a universal scaled description of the observed phenomena.