Experience with using coker gasoline as a reforming feedstock
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Coking gasoline can be used as a feedstock for reforming; some domestic companies have already blended it into their products, but the maximum blending ratio has been around 60%, and the period of such blending was short, mainly due to the rapid coking rate of the reforming catalyst. Our factory is a heavy oil processing enterprise, and straight-run naphtha must be purchased from external sources to meet our needs. To address this issue arising from the use of coker gasoline as a reforming feed, we increased the catalyst’s regeneration capacity by one level during the design phase. The plant has been in operation for over a year now; the maximum blending ratio of coker gasoline is 100%, with a hydrogen yield of around 4% and an aromatic yield of approximately 75%.
When coker gasoline is used as a feed for reforming, not only the reforming catalyst but also the pre-hydrogenation catalyst must be taken into consideration. Coker gasoline has a high content of olefins; 100% blending leads to a significant increase in temperature and rapid coking. It is therefore necessary to choose catalysts with good activity at low temperatures, as well as to implement appropriate safety measures to prevent temperature spikes
Catalytic gasoline, after hydrorefining, is not suitable as a feedstock for reforming; it is best suited as an ethylene feedstock, yielding high yields of trienes.
Due to its low aromatic potential and high alkane content, coker gasoline results in lower yields of product oil and hydrogen; it is not an excellent feedstock for reforming. However, coker gasoline after hydrorefining is a good raw material for ethylene production. The key to using coker gasoline as a reforming feedstock is to reduce its sulfur, nitrogen, and olefin content, especially the nitrogen level; it must undergo (medium-pressure) hydrorefining before it can be used as a reforming feedstock. Otherwise, it is not possible to reduce the nitrogen content to below 0.5 ppm in the reforming pre-hydrogenation system.
You are absolutely right; coker gasoline needs to be hydrotreated before it can be used as a feedstock for reforming, and that is exactly what we do as well.
Indeed, coker gasoline is not a good feedstock for reforming, as it has a low aromatic potential and tends to coking rapidly； We simply reprocess about 30%–40% of the coker gasoline; part of it is sent to a heavy catalytic reformer (with some effect), while the remainder is fed into hydrofining as a raw material for ethylene production.
Catalytic gasoline is used as a feedstock for reforming, generally only when there is a shortage of reforming feedstock or when naphtha cannot be sold as a chemical raw material. As the others have said, even after being processed via hydrogenation to serve as a reforming feedstock, issues such as a significant increase in temperature during the pre-hydrogenation reaction and rapid coking of the catalyst still arise； It is said that CNPC’s North China Branch has introduced foreign technology to build a facility for using coker gasoline as a feedstock for reforming. The pre-hydrogenation process and catalysts used are proprietary technologies, and this process differs slightly from conventional pre-hydrogenation.