Britannica Sources used in this answer

How is hydrogen produced as a useful by-product of catalytic reforming?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Aerial view of an oil refinery complex near New Orleans, Louisiana, with storage tanks, industrial structures, and smoke rising from the facility, surrounded by open land. — petroleum refining Aerial view of an oil refinery near New Orleans.

In catalytic reforming, hydrogen is produced as a valuable by-product primarily through the process of dehydrogenation.1

During this chemical process, naphtha feedstock undergoes several structural changes to increase its octane number. A key reaction involves the cyclization of paraffins into naphthenes, which are subsequently dehydrogenated to form aromatic compounds. This dehydrogenation step involves the removal of hydrogen atoms from the hydrocarbon molecules, liberating hydrogen gas in the process.1

While hydrogen is introduced into the reactor system to inhibit the formation of unstable, unsaturated compounds that could otherwise polymerize into heavy deposits, the net production of hydrogen from the reforming reactions exceeds the amount consumed. This surplus hydrogen is separated from the liquid reformate product, compressed, and can then be utilized elsewhere in the refinery for other essential processes, such as hydrocracking or hydrogen treatment.12