Hindered diffusion of coal liquids. Quarterly report number 11, March 18--June 17, 1995

The design of industrial catalysts requires that the diffusivity of the reacting species within the catalyst be accurately known. Nowhere is this more important than in the area of coal liquefaction and upgrading of coal liquids. In this area one is faced with the task of processing a number of heavy oils, containing metals and other contaminants, in a variety of process dependent solvents. It is important, therefore, on the basis of predicting catalyst activity, selectivity, and optimizing reactor performance, that the diffusivities of these oil species be accurately known. Contrary to laboratory reactors, where most of the studies of asphaltene`s chemical structure have taken place, most industrial reactors are continuous systems. The state of the asphaltene molecule therefore does not only depend on the temperature, pressure and polarity of the solvent but also on the reactor`s residence time. It is, therefore, very important to have a correct concept of the asphaltene`s structure and through careful experimentation, one can then decide whether such a concept has any practical implications at realistic upgrading conditions. It is the purpose of the project described here to provide such a correct concept of coal asphaltenes by careful and detailed investigations of asphaltenes transport through porous systems under realistic process temperature and pressure conditions. The experimental studies will be coupled with detailed, in-depth statistical and molecular dynamics models intended to provide a fundamental understanding of the overall transport mechanisms. 60 refs