Feedstock Contaminants: A Case Study

An advanced characterization program was designed and implemented to identify the chemical nature of contaminants present in the feed to a flexi-cracker. The solid contaminants removed from the naphtha feed had similar amounts of inorganic and organic materials. Iron and silicone were the most abundant elements present in the inorganic fraction. Iron oxides and hydroxides, iron sulfide, and quartz made up the crystalline portion of the solids. In a unique finding, particles of iron-based compounds were found encapsulated in silicon species. Most significantly, the size of almost half of the particles removed from the naphtha feed was under 1 micron, and about two-third were below 2 micron. Analysis of the organic fraction identified the presence of sulfur-containing chemicals, paraffins, aromatics, olefins, oxygenates, and dienes.