The use of heavy oils as refinery feedstocks is increasing. We offer extensive capabilities and test facilities in the separation and characterization of whole residua and fractions. Heavy oils are distinguished from light oils by API gravity, with heavy oils less than 20 API. Low atomic hydrogen-to-carbon ratios mean that hydrogenation (hydrogen addition) or coking (carbon rejection) is necessary for converting these materials to fuels. In addition, some heavy oil components are highly corrosive to refinery equipment.
WRI’s strategies for upgrading residua emphasize the differences in their compositions and the selection of methods for conversion to products. Our material analyses can be used to develop models that help explain and predict refining characteristics.
Separations are performed at an analytical scale with milligram quantities of material or at a semi-preparative scale with gram quantities. Preparative-scale SAPA (saturate, aromatic, polar, asphaltene) separations are quick, straightforward, relatively inexpensive, and provides characteristic fraction distributions for each residuum. The procedure uses silica gel, which is mildly acidic, or aluminum oxide, which is basic in character.
Size Exclusion Chromatography separates residua or asphaltene components in a solvent such as toluene according to their apparent molecular size. Associated polar species can demonstrate an apparent high molecular weight due to their size, which can affect processing. Analytical scale size exclusion chromotography is also used to determine the polymer content of polymer-modified asphalt formulations.
Non-Aqueous Ion Exchange Resin Separations use ion exchange media to produce fractions with specific chemical functionalities, such as acids, bases, neutrals, and amphoterics.
Automated On-Column Asphaltene Precipitation and Re-Dissolution
WRI developed a separation technique in which asphaltenes are precipitated in a ground PTFE-packed column. An oil or asphaltene solution in methylene chloride or chlorobenzene is injected into the column with a heptane or isooctane mobile phase. Asphaltenes precipitate on the PTFE packing, and the maltenes elute from the column. One or more polar solvent is then used to elute the polar asphaltonic material. Asphaltene content can be determined in minutes, and the polar distribution within asphaltenes can be measured quantitatively. The polar distribution produced by WRI’s technique is diagnostic of the thermal history of the oil or residuum. Another application is the rapid separation of waxes at -20 °C.
WRI’s patented Coking Indexes are a set of simple tests to help refiners gauge when the product stream is getting close to coking during petroleum distillation.
Instruments We Use
Laboratory Methods and Instruments Developed or Adapted by WRI