High Octane Gasoline from Field Butanes by the UOP Indirect Alkylation (InAlk™) Process

摘要

Processes that convert low value LPG to higher value gasoline are very important to the petroleum refining industry. Historically the most important of these has been paraffin alkylation using either hydrofluoric or sulfu-ric acid. However, use of strong liquid acids is now perceived as threatening to the environment. As a result much recent research has been done to find an alternate processing route. However, another factor has even more recently emerged, that is the increasing amount ofn-butane coming onto the market; it cannot be processed by conventional alkylation or any similar direct alkylation route because these routes require equimolar amounts of isobutane and butenes (iso-or n-). Thus UOP is introducing the InAlk Process which uses environmentally safe solid catalysts to process any mix of butanes and butenes. Even though n-butane is a feed, InAlk-derived gasoline is several octane numbers higher than gasoline from hydrofluoric or sulfuric acid-catalyzed alkylation. The InAlk Process requires three reactions, however, the process does not result from combining three separate processes. In fact an important aspect of InAlk is that the three reactions are complementary and well-set up for integration into one process. The three catalytic reactions occurring during InAlk are: dehydragenation, oligomerization and hydrogenation. Oligomerization is the critical step for determining product branching; since a mild acid is used for this step compared to hydrofluoric or sulfuric acids, less cracking and isomerization occurs resulting in a very high octane number product.