Ronald H. Fischer

Dependence of resid processing selectivity on catalyst pore size distribution

Abstract In the hydroprocessing of resid, catalyst selectivity and the relationship between metals and sulfur distribution in the resid are key factors in achieving required product specifications. Using gradient elution chromatography as a method of analysis, we have found that catalyst pore size distribution can significantly affect selectivity for different metal and sulfur components in residua. A small pore catalyst was observed to be more selective for non-asphaltene sulfur and metals, while a large pore catalyst was found to be very selective for asphaltene metals and sulfur. This variation of catalyst selectivity is a result of the concentration of metals and sulfur in different portions of the resid. For typical Middle Eastern residua, about 70–75% of the sulfur was found to be present in low molecular weight less aromatic GEC fractions, while 95% of the metals were in highly aromatic high molecular weight fractions. Thus the variation of selectivity with pore size was found to result from concentration of the sulfur and metal species in molecules of different size.