Quarterly progress report on configurational diffusion of asphaltenes in fresh and aged catalyst extrudates, September 20, 1995--December 20, 1995

Abstract

The objective of this research is to determine the relationship between the size and shape of coal and petroleum macromolecules and their diffusion rates i.e., effective diffusivities, in catalyst pore structures. That is, how do the effective intrapore diffusivities depend on molecule configuration and pore geometry. The research is divided into the following tasks: (1) relationship between effective intrapore diffusion coefficients, molecular size and pore geometry; (2) effects of solvent composition, solute concentration, and temperature on the molecular configuration and diffusion rate of coal and petroleum asphaltenes in catalysts pore; and (3) assessment of diffusional limitations in aged catalysts. This quarter, the GPC column efficiency was rechecked by using acetone injection. The calibration curve for the GPC was rechecked through polystyrene standards with narrow molecular weight distributions. Some experiments on adsorption and diffusion of coal asphaltenes through porous catalysts were performed. The asphaltenes were grouped into nine fractions with the concentration being determined via GPC. It was found that the uptake rate for one asphaltene fraction is different from those for other fractions. Comparison of experimental uptake data shows a difference in hindered diffusion behavior between petroleum asphaltenes and coal asphaltenes.