Upgrading - Hydrotreating

The fourth major process in upgrading is hydrotreating. This process is used on the gas oils, kerosene, and naptha produced from the original bitumen feedstock. In this process, heated hydrocarbon feedstock is mixed with hydrogen at high pressure and temperature ranging from 300 – 400°C depending on the liquid. The various petroleum liquids pass through separate towers and flow around special catalytic pellets. Hydrotreating stabilizes the crude oil synthesized from the original bitumen by adding hydrogen to some unsaturated molecules. If this were not done, the crude oil produced would continue to react and change its chemical composition on its way to final refining.

Hydrotreating also reduces or removes chemical impurities, such as nitrogen, sulphur and trace metals from hydrocarbon molecules. This is very important because impurities can be environmental concerns and theycause problems at the refineries.

The petroleum liquids are kept in separate storage tanks on site until they are ready to be blended and shipped down the pipeline for refining. Synthetic crude oil is not stored in its blended form anytime on site. The synthetic crude oil that is produced from oil sand is considered easy to refine because it is sweet. Sweet means that the product is very low in sulphur and other impurities.