The desirable reactions in catalytic reforming include dehydrogenation of naphthenes to aromatics, dehydroisomerization of alkyl-C5-naphthenes, dehydrocyclization of n-paraffins to aromatics, and isomerization of n-alkanes to i-alkanes. Of these chemical reactions, the first three produce the valuable by-product of hydrogen. The primary objective of catalytic reforming is to produce high-octane gasoline. Gasoline, the leading choice of fuel in the transportation sector of the United States, requires higher-octane numbers in order to prevent the undesirable knocking effects in modern, powerful gasoline engines. The feedstock includes the heavy naphtha from the Light Ends Units, and contains many cycloalkanes to be converted into aromatics.

However, there are several limits imposed on these reactions and care must be taken to avoid complications. Firstly, though coke deposition is less favorable with higher pressure, hydrocracking (an undesirable chemical reaction that produces low-octane n-alkanes) also occurs at higher pressures. Therefore, catalytic reformers are typically run at low but sufficient pressure to inhibit hydrocracking while limiting coke deposition.

Dehydrogenation processes that utilize Platinum/Palladium catalysts are also subject to sulfur poisoning. Thus, feedstock typically requires hydrotreatment to remove contaminants before any processing is carried out.

Additionally, in recent years, aromatics such as benzene and toluene have been considered carcinogenic, and restrictions have been enforced on their composition in gasoline. Thus, alkylation – combining smaller molecules into larger ones (the counterpart to cracking) – is alternatively used to produce i-alkanes and higher-octane gasoline without aromatics. Drawbacks with alkylation include the requirement of highly acidic catalysts and the dangers associated with its use.

Another method of creating high-octane gasoline is polymerization. Though similar to alkylation, this process utilizes alkenes exclusively, as opposed to the alkane i-butane in alkylation. One advantage of this method is the use of less acidic catalysts (i.e. phosphoric acid) instead of those used in alkylation (i.e. sulfuric acid and hydrofluoric acid).