Reformer Feeds

The feed to a catalytic reformer is normally a heavy naphtha fraction produced from atmospheric distillation units. Naphtha from other sources such as those produced from cracking and delayed coking may also be used. Before using naphtha as feed for a catalytic reforming unit, it must be hydrotreated to saturate the olefins and to hydrodesulfurize and hydrodenitrogenate sulfur and nitrogen compounds. Olefinic compounds are undesirable because they are precursors for coke, which deactivates the catalyst. Sulfur and nitrogen compounds poison the reforming catalyst. The reducing atmosphere in catalytic reforming promotes forming of hydrogen sulfide and ammonia. Ammonia reduces the acid sites of the catalyst, while platinum becomes sulfided with H₂S.

Types of hydrocarbons in the feed have significant effects on the operation severity. Feeds with a high naphthene content are easier to aromatize than feeds with a high ratio of paraffins (see “Reforming reactions”). The boiling range of the feeds is also an effective parameter. Feeds with higher end points (≈200°C) are favorable because some of the long-chain molecules are hydrocracked to molecules in the gasoline range. These molecules can isomerize and dehydrocyclize to branched paraffins and to aromatics, respectively.