The effect of catalyst dispersion and coal-catalyst contacting on the observed activity of unsupported catalysts for coal liquefaction

Unsupported catalysts have been used in coal liquefaction process schemes. These types of catalysts offer many advantages for coal liquefaction. Among these advantages are the lack of aging and (for inexpensive catalysts such as iron) the ability to simply dispose of the catalysts. Two key variables for predicting the activity of unsupported catalysts are the degree of catalyst dispersion and the extent of coal-catalyst contacting.;The results from this study suggest that a comparison of two catalyst systems should account for differences in catalyst dispersion and coal-catalyst contacting.;This study attempts to quantitatively describe the extent of coal-catalyst contacting and catalyst dispersion. Both of these components affect the observed activity of catalysts. For similar-sized catalysts, increasing the degree of coal-catalyst contacting increases the observed activity. Also, for similar levels of coal-catalyst contacting, increasing the catalyst dispersion by decreasing the catalyst particle size (or increasing the surface area) results in higher observed activity.