The catalytic reforming process was somewhat of a “late addition” to the whole petroleum-refining scene. The 1940’s and 1950’s opened up a new world of high compression engines (automobiles & aircraft) and families with multiple automobiles, so naturally the demand for high octane number gasoline skyrocketed. Catalytic reforming solved this issue by taking the heavy straight run naphtha fractions from the atmospheric distillation tower and converting it into a high octane product that proved to be the main fraction of the gasoline blending pool. Beyond the production of high octane number reformates, this process also yields high amounts of hydrogen, which can be separated out and transferred to other processes in the refinery such as hydrocracking and hydrotreating.

This process is fairly complex, in terms of the chemistry, compared to other refining processes. Since this process uses catalysts that contain platinum, the feedstock must first be hydrotreated to eliminate the probability of poisoning. There are desired reactions and undesired reactions that could take place all depending on four variables such as temperature, pressure, H₂/hydrocarbon ratio, and space velocity. The overall reactions that should take place are naphthenes converted to aromatics and n-paraffins converted to i-paraffins, but the four specific reactions are dehydrogenation, dehydroisomerization, dehydrocyclination, and isomerization. Each has their own range of octane number increases but the conditions in which these reactions are favored are all similar. A reactor with high temperature, low pressure, and low H₂/hydrocarbon ratio favors these reactions against undesired hydrocracking. The main problem with controlling conditions is that hydrocracking AND the desired reactions both thrive in a reactor with low space velocity; this aspect of the process is where the refinery has to control the activity of the catalysts and the balance of acidic versus metal sites to have high yield and high quality results. Despite the specifics of these reactions and refinery’s firm grasp of the chemistry of each particular process, regulations on limiting benzene and aromatics in automobile gasoline have limited the catalytic reforming process in the United States.