As we learned from lesson 8, catalytic reforming is known as a conversion process in the refineries. The main objectives of catalytic reforming is to convert heavy naphtha into high-octane reformate and produce hydrogen as significant by-product. The product of catalytic reforming is also low in sulfur and is a major blending product of gasoline. Platinum (Pt) and palladium (Pd) are contained in most catalyst of reforming. From this process, hydrogen which is one significant byproduct is produced for further hydrotreating and hydrocracking process. Especially the hydrotreating process is necessary for naphtha feedstock before it go through reforming process, because platinum catalyst needs to be protected by poisoning from sulfur and nitrogen.
There are some limits on catalytic reforming capacity in the U.S. Refineries. Firstly, as lesson 8 mentioned, due to regulations and limitations on benzene and total aromatics for gasoline in U.S. and Europe, the amount of reformate can be used is limited. As we mention in reforming’s objectives, hydrogen is still an important byproduct from catalytic reforming to be used in refineries. Secondly, in order to maintain the yield of hydrogen and reformate, hydrocracking is an undesired reaction in reforming process. It would consume hydrogen to produce gaseous hydrocarbon to lower the yield of hydrogen and reformate. Some conditions such as pressure at 50 to 350 psig, hydrogen/feed ratio of 3–8 mol H2/mol feed, and liquid hourly space velocities of 1–3 h^-1 are used to prevent hydrocracking during reforming. Thirdly, coke deposition during reforming process deactivated catalyst even with the usage of hydrogen. Semi-regenerative process was introduced in 1946 and it need to be shut down every 3 to 24 months for catalyst regeneration. Cyclic process expands the on-stream time up to 5 years, but it is not a favorite process by the industries. Continuous process which is introduced in 1971 allows remove and replace catalyst during operation to keep its high activity. However, it is expensive to operate.
Reference
1. F SC class website lesson 8
https://cms.psu.edu/section/content/default.asp?WCI=pgDisplay&WCU=CRSCNT&ENTRY_ID=F20C6357261A4AE2A750C141B721E8C1