Blog 8

Write a blog post discussing the objectives of catalytic reforming and limits on catalytic reforming capacity in the U.S. refineries.

Alkylation, polymerization, catalytic reforming, and isomerization are all catalytic conversion processes performed to produce a high octane number gasoline. This is essential for obtaining high performance and high power. Catalytic reforming developed during the Second World War with a feed stock coming from the Light Ends Unit. The heaviest product of this, the heavy naphtha is used. This is heavy because it has a lot of naphthenes or cycloalkanes in its composition. Catalytic reforming’s objective is to convert these naphthenes or cycloalkanes into aromatics with very high octane numbers. Dehydrogenation of naphthenes using precious metal catalysts is straight forward for a clean heavy naphtha feedstock. However, if sulfur is associated it must have pre hydro treatment to avoid poisoning from occurring with platinum.

After the crude has been distilled and the heavy naphtha has been obtained and treated, if necessary, it is separated in a naphtha fractionator. The light naphtha will be withdrawn and sent to the gasoline pool while the true heavy naphtha will go through a catalytic reformer which will then produce the high octane number reformate and a byproduct of hydrogen gas.  The most important reactions of interest within this process are converting naphthenes to aromatics and the isomerization of n-paraffins to i-paraffins. Reforming a heavy naphtha that contains a higher n-paraffin content requires more severe conditions within the reactor. The desired catalytic reforming reactions within catalytic reforming are dehydrogenation, dehydroisomerization, dehydrocyclization, and isomerization. High temperature, low hydrogen pressure, low space velocity, and a low H2/HC ratio all strongly promote the occurrence of these chemical reactions.

Up until the 1990s catalytic reforming was one of the most popular processes in the refinery for producing high number gasoline. With the introduction of the Clean Air Act amendments the amount of benzene aromatics became limited. This made catalytic reforming undesirable. However, the valuable byproduct of hydrogen gas has become very essential since it is needed in the hydro treating and hydro cracking processes. This being said, catalytic reforming became the cheapest way of obtaining hydrogen.